Patent Grant
11613929
The present disclosure relates to dynamic drilling systems and methods, including hypocycloidal bearings for use with progressive cavity positive displacement motors and pumps; dynamic lateral impulse drilling systems; and dynamic torsional detent drilling systems; as well as to methods of making and using the same.
Hydrocarbon retorts, for the most part, reside beneath layers of dirt and rock (and sometimes water as well). To access and retrieve the hydrocarbons, companies drill wells that extend from the surface to the hydrocarbon retorts. Wells may be vertical or non-vertical. Vertical wells provide a reasonably straight drill path that is generally intended to be perpendicular to the Earth's surface, with the drill bit operational along the axis of the drill string to which it is attached. Non-vertical wells, also known as directional wells, usually involve directional drilling. Directionally drilling a well requires movement of the drill bit off the axis of the drill string. Generally, a directionally drilled wellbore includes a vertical section up to a kickoff point where the wellbore deviates from vertical to or towards horizontal.
Drill strings used in directional drilling typically include a number of segments, including drill piping or tubulars extending from the surface, a mud motor (e.g., a positive displacement progressive cavity mud powered motor) and a drill bit. The mud motor may include a rotor catch assembly, a power section, a transmission, a bearing package, and a bit drive shaft with a bit box. The power section generally includes a stator housing connected to and part of the drill string, and a rotor. The mud motor is powered by energy harvested from drilling mud as the mud passes through the power section. The drilling mud is pumped at high pressures and volumes from the surface down the internal cavities of a drill string and through the power section. Mud passing through the power section rotates the rotor with respect to the stator housing. The rotor, in-turn, drives rotation, through a transmission driveline and bit drive shaft, to a drill bit.
Mud motors typically take advantage of a hypocycloid motion of the rotor within the stator. A “hypocycloid motion” of an object (e.g., a rotor), is a pattern of movement of the object for which a fixed point on the object (e.g., a blade of the rotor) traces a hypocycloid as the object rolls within another object (e.g., as the rotor rolls within a stator), where the hypocycloid is a plane curve. In a typical mud motor, the rotor is made out of metal. The stator is configured to receive the rotor and includes a rubber interior. As the rotor rotates, it rolls against the rubber interior of the stator. This rolling of the metal rotor on the rubber interior of the stator results in the degradation of the rubber interior, potentially exposing a metal interior surface of the stator. For example, the rubber may “chunk,” such that pieces of the rubber separate and fall off the stator, and/or the rubber may crack. Upon degradation of the rubber interior, the metal rotor rolls on the metal interior surface of the stator. This results in a change in the hypocycloidal motion path of the rotor within the stator, such that the output rotation axis of the rotor within the stator is no longer centered within the stator, but is off-center. Off-center hypocycloid motion of the rotor can result in stalling of the motor and a loss of angular momentum. Thus, the mud motor may exhibit a loss of efficiencies and an accompanying fluid leakage.
Some embodiments of the present disclosure include a downhole drilling assembly. The downhole drilling assembly includes a mud motor, including a motor housing having a stator disposed on an inner surface thereof. The motor housing and stator define a cavity, and a progressive cavity rotor is positioned within the cavity and engaged with the stator. Rotation of the rotor within the cavity follows a hypocycloidal motion. A drill bit or cutting assembly may be coupled to the rotor. At least one hypocycloid radial bearing is engaged with the rotor and configured to support the rotor as the rotor rotates within the stator.
Other embodiments of the present disclosure include a progressive cavity pump or motor. The pump or motor includes a progressive cavity rotor positioned within at least one progressive cavity stator. At least one hypocycloid radial bearing is coupled with the rotor and configured to support the rotor as the rotor rotates within the stator.
Other embodiments of the present disclosure include a method of limiting hypocycloidal motion of a progressive cavity rotor within a progressive cavity stator. The method includes coupling the rotor with at least one hypocycloidal radial bearing that is configured to support the rotor as the rotor rotates within the stator. In some aspects, the method includes limiting excessive hypocycloidal motion of the progressive cavity rotor within the progressive cavity stator. As used herein “excessive” hypocycloidal motion of a rotor refers to hypocycloidal motion of the rotor beyond a predetermined limit where orbit of the rotor imparts sufficient load on the stator to cause degradation of the stator or to cause an undesirable degree of degradation to the rubber interior of the stator.
Some embodiments of the present disclosure include a dynamic lateral impulse drilling assembly of a drill string. The assembly includes a mandrel shaft and a bearing housing. The bearing housing is coupled with the mandrel shaft via sliding engagement between at least one primary bearing pad and at least one primary bearing surface, and via sliding engagement between at least one wear element and at least one secondary bearing surface. The at least one secondary bearing surface is an undulating surface. In some such embodiments, the mandrel shaft includes the at least one primary bearing pad and the at least one wear-resistant element thereon, and the bearing housing includes the at least one primary bearing surface and the at least one secondary bearing surface thereon. In other such embodiments, the bearing housing includes the at least one primary bearing pad and the at least one wear-resistant element thereon, and the mandrel shaft includes the at least one primary bearing surface and the at least one secondary bearing surface thereon.
Other embodiments of the present disclosure include a method of drilling using a drill string that includes a mandrel shaft slidingly coupled with a bearing housing. The method includes rotating the mandrel shaft relative to the bearing housing. While rotating the mandrel shaft, the method includes laterally moving the mandrel shaft relative to a longitudinal axis of the bearing housing. In some embodiments, the lateral movement of the mandrel shaft is induced by sliding a wear-resistant element along an undulating bearing surface between the mandrel shaft and the bearing housing.
Other embodiments of the present disclosure include a dynamic torsional detent drilling assembly of a drill string. The assembly includes a mandrel shaft and a lower bearing housing. The lower bearing housing is rotatably coupled with the mandrel shaft via sliding contact between a contoured race and at least one wear-resistant element. The contoured race includes at least one concave pocket and at least one ridge. In some such embodiments, the mandrel shaft includes the contoured race on an outer surface thereof, and the lower bearing housing includes the at least one wear-resistant element on an inner surface thereof. In other such embodiments, the lower bearing housing includes the contoured race on an inner surface thereof, and the mandrel shaft includes the at least one wear-resistant element on an outer surface thereof.
Other embodiments of the present disclosure include a method of drilling using a drill string that includes a mandrel shaft slidingly coupled with a bearing housing. The method includes rotating the mandrel shaft relative to the bearing housing. While rotating the mandrel shaft, the method includes imparting a torsional impulse to the mandrel shaft. The torsional impulse is induced by sliding a wear-resistant element along a contoured race, capturing the wear-resistant element within a concave pocket on the contoured race, and applying torque to the wear-resistant element captured within the concave pocket until the applied torque is sufficient to release the wear-resistant element from the concave pocket.
Other embodiments of the present disclosure include a method of drilling. The method includes providing a helical positive displacement motor that includes a rotor and a stator. The rotor is an elongated body positioned to roll inside of an inner diameter of the stator. A mandrel shaft and drill bit are coupled with the rotor. The method includes rotating the rotor within the stator. While rotating the rotor within the stator, cusps of the rotor maintain contact with cusps of the stator. Rotation of the rotor within the stator follows a hypocycloidal motion. Rotation of the rotor within the stator imparts a hypocycloidal orbiting motion to the drill bit.
So that the manner in which the features and advantages of the systems, products, and/or methods of the present disclosure may be understood in more detail, a more particular description briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only various exemplary embodiments and are therefore not to be considered limiting of the disclosed concepts as it may include other effective embodiments as well.
Products, apparatus, systems, and methods according to present disclosure will now be described more fully with reference to the accompanying drawings, which illustrate various exemplary embodiments. Concepts according to the present disclosure may, however, be embodied in many different forms and should not be construed as being limited by the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough as well as complete and will fully convey the scope of the various concepts to those skilled in the art and the best and preferred modes of practice.
Certain aspects of the present disclosure include a hypocycloid bearing assembly and a drill string incorporating the same. While depicted and described herein as incorporated into a drill string, one skilled in the art would understand that the hypocycloid bearing assemblies disclosed herein are not limited to use with drill strings, and may be incorporated into positive displacement progressive cavity pumps or motors used in a variety of other applications, such as sewer system pumps and mine dewatering pump systems. In some embodiments, the hypocycloid bearing assemblies disclosed herein may be incorporated into preexisting industrial hypocycloid progressive cavity pumps, such as those manufactured by MOYNO™. U.S. Pat. Nos. 1,892,217; 2,028,407; and 3,260,318 provide background helpful in the understanding of certain subject matter discussed herein, and are, therefore, hereby incorporated by reference for all purposes and made a part of the present disclosure.
Hypocycloid Bearing Assembly—Upper Mount
Stator 22 defines an inner cavity within which rotor 12 is positioned. Rotor 12 may be made of steel, for example. As would be understood by one skilled in the art, with rotor 12 engaged within stator 22, the hydraulic horsepower of drilling mud flowing through the cavity of stator 22 causes rotor 12 to rotate within the cavity of stator 22. Rotor 12 is coupled with transmission (here shown as a flex joint 26), the transmission is coupled with bit shaft 24, and the bit shaft 24 is coupled with bit 34. The rotational force of rotor 12 is transmitted to bit shaft 24 through the transmission, which, in this embodiment, is includes flex joint 26 positioned within transmission housing 28. Transmission housing 28 may be a part of the drill string of drill string assembly 100a. Thus, the transmission couples rotor 12 with bit shaft 24 via a transmission driveline, which, here, includes the flex joint 26. However, one skilled in the art would understand that the transmission is not limited to the particular transmissions shown in the Figures provided herein.
Bit shaft 24 is positioned within a bearing package which, in this embodiment, includes bearing housing 30, which is a part of the drill string of drill string assembly 100a. Bearing housing 30 contains bearings 32. As shown, bearing housing 30 contains thrust and radial bearings 32. However, one skilled in the art would understand that other types of bearings and bearing arrangements may be used.
Bit shaft 24 transmits the rotational force to bit 34. Bit 34 may be any of a number of different styles or types of drill bits. Bit 34 may be a polycrystalline diamond cutter (PDC) design, a roller cone (RC) design, an impregnated diamond design, a natural diamond cutter (NDC) design, a thermally stable polycrystalline (TSP) design, a carbide blade/pick design, a hammer bit (a.k.a. percussion bits) design, or another bit design. Each different rock destruction mechanisms (i.e., drill bit) has qualities that make it a desirable choice depending on the formation to be drilled and the available energy in association with the drilling apparatus.
Rotor 12 is coupled with drill string 18 via rotor extension 14 (e.g., a rotor catch assembly of rotor 12). With mud flow, drilling mud (not shown) travels down internal cavities of drill string assembly 100a, including through the cavity of stator 22, causing rotor 12 to rotate with respect to stator 22 and motor housing 20 and therefore drill string 18. Rotor 12 drives rotation through the transmission flex joint 26 and bit shaft 24, to bit 34. Depending on the direction of rotation (clockwise or counter clockwise) of rotor 12 relative to drill string 18, the power section can increase, decrease or reverse the relative rotation rate of bit 34 with respect to the rotating drill string 18.
In the embodiment shown in
The loads on the stator wall increase with the speed of the rotor and pressure across the motor. When the loads get high enough, the stator material begins to compress and deform. When this happens, the rotor orbit increases beyond the predicted orbit r. Still higher loads on the stator degrade and eventually destroy the stator.
In the configuration shown in
In some embodiments, the hypocycloid bearing diameters and hypocycloid bearing span (generally the bearing length) are equal, or the hypocycloid bearing span is greater than the hypocycloid bearing diameters, preventing cocking of the hypocycloid bearings. In some embodiments, the hypocycloid bearing may be made shorter by having the hypocycloid bearing contact area ground to a desired profile, such as a “watermelon” profile with the hypocycloid bearing having a larger diameter in a middle portion and a slight (e.g., 0.002-0.003″) taper at the ends of the hypocycloidal bearing. For example, in some applications, the “watermelon” profile of a hypocycloid bearings accommodates for a bend or flex shaft.
While not shown, in some embodiments, an additional bend may be incorporated into drill string assembly 100c, such as by incorporating a bent connection between transmission housing 28 and bearing housing 30. The incorporation of such a bent connection may include timing of the threads such that the multiple bends are in the same plane.
In some embodiments, the timing of the two stators 22a and 22b may be optimized. The length of hypocycloid bearings coupler 10e and the mating rotor extensions 14c and 14d will allow for timing, including identifying and/or creating a thrust path for upper rotor 12a.
Between rotor 12 and motor housing 20, drill string assembly 100g includes hypocycloid bearing 10n, outer radial bearing pad 29a, and inner radial bearing pad 29b. In the embodiment shown in
Depicted in
The radial bearing pads 29a and 29b define a radial bearing surface on the inner diameter (ID) of motor housing 20, which is larger than the stator major diameter. This radial bearing surface may include one or multiple materials including, but not limited to, polycrystalline diamond composite (PDC), tungsten carbide (WC), flame sprayed hard facing, and hardened steel. In some embodiments, the drive shaft (i.e., a bit shaft) is an extension of, or directly connected to the rotor 12, and also has a radial bearing surface thereon. In such embodiments, the radial bearing surface of the drive shaft may be formed of one or multiple materials including, but not limited to, PDC, WC, flame sprayed hard facing, and hardened steel.
Having described the components of the assembly 100g, the hypocycloid bearing 10n structure and function will now be described. In the embodiment shown, hypocycloid bearing 10n is a hollow cylinder body having a relatively large, off-center through-hole or cavity within the body. The rotor 12 is engaged within and through the cavity of the hypocycloid bearing 10n. As used herein, “off-center,” refers to the state of not being in coaxial alignment. For example, the central axis of the “off-center through-hole or cavity” of hypocycloid bearing 10n body is not coaxially aligned with the cavity formed by stator 22 and/or the cavity formed in the motor housing 20. On the outer diameter (OD) and the offset inner diameter (ID) of hypocycloid bearing 10n are radial bearing pads 29a and 29b. The radial bearing pads 29a and 29b may be formed of one or multiple materials including, but not limited to, PDC, WC, flame sprayed hardfacing, and hardened steel. In some embodiments, with no compliance in the mounting of hypocycloid bearing 10n, there is a few thousands of an inch difference in the mating bearing (e.g., radial bearing pads 29a and 29b).
As indicated in
The off-center through-hole in the hypocycloid bearing 10n body is off-set by the radius of the rotor orbit 48 in the stator 22 (i.e., “r” as shown in
In some embodiments, the inner radial bearing pad 29b is tipped to compensate for the centripetal force of the spinning rotor 12, counterbalance pressure loading, and at least partially compensate for bending from the transmission. In some embodiments, the inner and/or outer radial bearing pads 29a and 29b clearance is increased to provide a measure of compliance between the rotor 12 and stator 22, potentially resulting in increased lateral shock in the respective radial bearing pads 29a and 29b.
Without being bound by theory, it is believed that a hypocycloid bearing that is positioned above the rotor, such as hypocycloid bearings 10a, 10b, 10d, 10g, 10i, and 101 as shown in
Without being bound by theory, it is believed that a hypocycloid bearing that is positioned below the rotor, such as hypocycloid bearings 10c, 10f, 10h, 10j, and 10m as shown in
In some embodiments, thrust bearing pads 27 are used when the hypocycloid bearing carries axial load. Thrust bearing pads 27 may maintain and control the axial position of the hypocycloid bearing and prevent axial loads from affecting rotor 12 and the interaction between rotor 12 and stator 22.
In embodiments with a hollow rotor drive shaft, as shown in
In some embodiments, the body of hypocycloid bearing 10n is a solid body with an off-set cavity formed therethrough. The weight of the hypocycloid bearing 10n body may be reduced by machining the hypocycloid bearing 10n body to eliminate unneeded surface area for placement of radial bearing pads 29a and 29b, as well as to eliminate unneeded mass. In some aspects, bore holes, channels, or flow paths may be formed through hypocycloid bearing 10n body, such as by machining; thereby, reducing surface area and mass of hypocycloid bearing 10n, as well as providing mud flow paths through hypocycloid bearing 10n.
In some embodiments in which rotor 12 is used as the drill bit drive shaft, characteristics of the extended portion of rotor 12 that is used as the drill bit drive shaft are the same as those of the remainder of rotor 12. For example, this extended portion of rotor 12 has the same pitch and/or radii as the remainder of rotor 12. In other embodiments, the extended portion of rotor 12 has one or more different characteristics than the remainder of rotor 12, for example a different pitch and/or radii. In a preferred embodiment, for optimal performance, the rotor orbit 48 is maintained along the extended portion of rotor 12 (i.e., rotor 12 and the rotor extension 14 have the same, axially aligned, concentric orbits).
As described above in reference to
While the hypocycloid bearings are described as being used in a drilling motor with reference to
Certain embodiments include a hypocycloidal bearing that provides a single axis of rotation. In some such embodiments, the rotor outer diameter directly rides on hypocycloidal bearings that are in the form of circular ring bearings that are concentric with the stator housing (motor housing). In some such embodiments, such circular ring-type hypocycloidal bearings are integral to the stator housing, with the elastomer of the stator being formed (e.g., molded/injected molded) between and/or around the circular ring-type hypocycloidal bearings. Such circular ring-type hypocycloidal bearings may be in contact with the stator housing, and be molded into the elastomer that forms the stator.
In some such embodiments, rotor extensions extend at either or both ends of the rotor, and roll on the circular ring-type hypocycloidal bearings or roll directly on the stator housing. In certain embodiments, each rotor extension is in the form of an axle with an axle diameter that is less than the minimum rotor diameter, and includes an integral or attached spoked wheel that rolls on the circular ring-type hypocycloidal bearings or rolls directly on the stator housing.
In some embodiments, the rotor has a hypocycloid outer profile that rides on hypocycloidal bearing materials formed with a full, partial, or approximated hypocycloid stator profile that is complementary with the hypocycloid profile of the rotor and is concentric with the stator housing. In some such embodiments, the profiled hypocycloidal bearing(s) are integral to the stator housing and the elastomer that forms the stator is positioned between the profiled hypocycloidal bearing rings, with each of the profiled hypocycloidal bearings mutually timed to the rotor and to the stator elastomer. The profiled hypocycloidal bearing(s) may be in contact with the stator housing, with the stator elastomer positioned between the profiled hypocycloidal bearing rings that are mutually timed to the rotor and the stator elastomer.
Certain embodiments include to hypocycloidal bearings that provide dual axes of rotation. In some such embodiments, the hypocycloidal bearings are formed as a circular plate or thin cylinder that is rotationally fitted to an inner diameter of the stator housing, with an off-center circular hole that is consistent with the rotor outer diameter or with a concentric extension from the rotor. In such embodiments, the distance off-center of the circular hole is defined by the hypocycloid orbit. The circular plate or thin cylinder hypocycloidal bearings include spokes, flow passages (e.g., mud flow passages), and/or chokes. In some such embodiments, the outer perimeters of the hypocycloidal bearings rotate true to the stator housing, and the off-center circular hole of the circular plate or thin cylinder hypocycloidal bearings rotates true to the rotor and/or the rotor extension.
In some embodiments, a drill string assembly is provided that is configured for direct drive of the drill bit via the mud motor. In some such embodiments, the drill bit is gear driven or rotor driven.
In some embodiments, a drill string assembly is provided with a drill bit that is configured to rotate with a hypocycloidal motion. In some such embodiments, the hypocycloidal rotation of the drill bit is natural, reduced, or exaggerated.
Some embodiments include a steerable drill string assembly having one or more hypocycloid bearings, as provided herein. Some embodiments include a steerable drill string assembly with a drill bit configured for hypocycloid bit motion. In some such embodiments, the steerable drill string assembly includes a single axis hypocycloid bearing fixedly coupled to the motor output shaft (e.g., bit shaft or rotor extension) and rotationally coupled to a bearing race located in a housing or sub positioned below the mud motor, and preferably near the drill bit. The bearing race may be round and located off-center relative to the housing or sub positioned below the mud motor. In such embodiments, the off-center bearing race acts upon the hypocycloid bearing drive shaft to create an eccentric orbit for the spinning drill bit; thereby, enhancing side-cutting action of the drill bit. Alternatively, a hypocycloid bearing that does not have a round profile (i.e., non-round profile) may be coupled with a cam follower, providing for more aggressive side-cutting with the drill bit (i.e., providing an increased rate of side extension of the drill bit). In some such embodiments, the drill string assembly including such a hypocycloid bearing includes a flex shaft or flex joint, providing for side-cutting movement of the drill bit.
In some such embodiments, the steerable drill string assembly includes dual axis hypocycloid bearing rotationally coupled to the mud motor output shaft (i.e., bit shaft or rotor extension) and rotationally coupled to a bearing race. The bearing race may be located in a housing or sub positioned below the motor, and preferably positioned near the drill bit. In some such embodiments, the bearing race is round, and is positioned off-center relative to the housing or sub below the motor. The off-center bearing race acts through the circular plate or thin cylinder hypocycloid bearing on the drive shaft of the hypocycloid bearing to create an eccentric orbit for the spinning drill bit; thereby, enhancing side-cutting action of the drill bit. In some embodiments of the steerable drill string assembly including the dual axis hypocycloid bearing, a non-round profiled hypocycloid bearing is coupled with a cam follower, providing for more aggressive side-cutting with the drill bit (i.e., providing an increased rate of side extension of the drill bit). In some such embodiments, the drill string assembly including such a hypocycloid bearing includes a flex shaft or flex joint, providing for side-cutting movement of the drill bit.
In some embodiments, the coefficient of thermal expansion (CTE) of the material of the stator is modified by modifying the material composition of the stator. In general, the CTE for metals are typically lower (e.g., ˜15×10−6 m/(m K)) as compared to the CTE of rubbers (e.g., ˜58×10−6 m/(m K)). For a rubber stator, the CTE of the rubber stator may be modified by inclusion of a filler in the rubber; thereby, forming a rubber/filler composite. The filler may include, but is not limited to, glass, which typically has a CTE of about 0.56×10−6; diamond, which typically has a CTE of about 1.2×10−6; carbon black; silicone, which typically has a CTE of about 2.7×10−6; boron nitride, which typically has a CTE of about 3.7×10−6; or combinations thereof. For example, a mixture of about 75 weight percent of diamond dust and about 25 weight percent of a rubber may have a combined CTE of about 15.4. Modification of the CTE of the stator may reduce or eliminate any differential expansion between the stator metal parts coupled thereto (e.g., the motor housing and the rotor).
In some embodiments, the rubber/filler composite has a reduced wear rate relative to the rubber without the filler. As used herein, “wear rate” refers to the rate of degradation of the rubber as a result of frictional interaction with the rotor (e.g., thickness of stator degraded per amount of time). In some embodiments, the rubber/filler composite has an increased strength relative to the rubber without the filler.
Some embodiments include closely spaced profiled, small outer diameter stator tube sections, including a relatively thin layer of elastomer disposed between the motor housing and between the bearings that bond the stator tubes to the motor housing, hydraulically seals the mud motor, and provides for articulation (for a bending mud motor) and compliance (for minor dimensional variations) for the mud motor (e.g., as shown in
In some such embodiments, such a mud motor may be formed by a method that includes injecting rubber to into the motor housing to form the relatively thin layer of elastomer as the stator. In such embodiments, the stator tubes carry a substantial portion of the hoop stress (circumferential stress). The use of a multiplicity of relatively small outer diameter stator tube sections provides articulation to the mud motor. In some such embodiments, the method of forming such a mud motor includes adding a filler, such as lead, to the injected rubber that forms the stator. The filler may be added in sufficient quantity to provide added articulation and compliance to the mud motor.
In some such embodiments, the method of forming such a mud motor includes injecting a homogeneously dispersed gas, preferably an inert gas such as nitrogen, into the elastomer that forms the stator. The injection of the inert gas into the elastomer reduces the effective CTE of the elastomer. For example, injection of about 70% by volume of nitrogen into the elastomer may reduce the effective CTE to about 5. In some such embodiments, a smaller volume of inert gas is injected into the elastomer that forms the stator, such as about 5-10% by volume. Injection of this smaller volume of inert gas into the elastomer forms multiple discrete pockets or voids within the elastomer. The pockets or voids within the elastomer provide space for the relatively incompressible elastomer rubber to expand and move, due, at least in part, to the compressibility of any of the gas within the pockets or voids. In some such embodiments, the pockets or voids provide for an expansion volume for the elastomer that forms the O-ring glands and/or adjacent strips of rubber used to attach the reduced O.D. stator tube sections to the stator tube. The O-rings, alone, provide the required axial seal, but additional provisions may be required to carry the axial load. The rubber strips may be in the form of a spiral, provided there are provisions to carry the axial load and, preferentially, provided there is also an axial seal (such as an O-ring). In some embodiments, the rubber strips are circumferential and bonded to the reduced O.D. stator tube sections and the stator tube, providing both a seal and carrying the axial load.
Some embodiments include relatively closely spaced profiled, reduced outer diameter stator tube sections with an elastomer in the form of an O-ring or similar seal and/or rubber rings positioned between each profiled bearing section and the stator housing to hydraulically seal the mud motor between each of the profiled bearing elements to allow transfer of torque to the stator housing, prevent axial movement, and provide articulation and compliance to the mud motor. Some such embodiments include torsional locks (such as splines), an axial lock (such as a shoulder), and an articulated joint (such as matching spherical contacts).
Some embodiments of the present disclosure include methods, systems, and apparatus for dynamically imparting a lateral movement to a mandrel shaft and/or drill bit of a drill string. Some embodiments include dynamic lateral impulse drilling mechanisms, apparatus, systems, and methods. Imparting lateral movement to the mandrel shaft and drill bit of a drill string provides an additional force component to the cutting action during drilling operations. Such additional lateral force may increase cutting efficiency and speed, reduce frictional engagement between the drill string and wellbore, and provide other additional enhancements to the drilling operations.
Each of U.S. patent application Ser. Nos. 16/049,588; 16/049,608; 16/049,617; and Ser. No. 16/049,631; as well as U.S. Provisional Patent Application No. 62/713,681, describe the use of diamond-on-steel for bearing applications, and are incorporated herein by reference in their entireties as if set out in full herein. In some embodiments, the bearing surfaces disclosed herein are, or include, the same materials as disclosed in U.S. patent application Ser. Nos. 16/049,588; 16/049,608; 16/049,617; or 16/049,631; or in U.S. Provisional Patent Application No. 62/713,681, such as diamond-on-steel bearing surfaces.
Wear resistant element 1107 is coupled with mandrel shaft 1100. Wear resistant element 1107 is in sliding contact with bearing race 1106 on an internal surface of bearing housing 1101.
In operation, drilling fluid, which may be used to lubricate and cool the lateral impulse drilling mechanism 1600a, flows through fluid port 1102 and subsequently passes through the inner diameter of a drill bit exiting out into an annulus of a borehole within which lateral impulse drilling mechanism 1600a is positioned. Without being bound by a specific ratio, in some embodiments approximately 90 percent of fluid volume flows though the center of mandrel shaft 1100 and approximately 10 percent of the fluid volume flows around the outside of mandrel shaft 1100 making contact with the various sliding bearing contact surfaces thereon.
In some embodiments, the bearing race 1106 has an undulating surface profile, such that, as the mandrel 1100 rotates within the bearing housing 1101, the wear resistant element 1107 slides along the undulating surface of the bearing race 1106. Thus, as the wear resistant element 1107 slides along the undulating surface of the bearing race 1106, the axial alignment of the mandrel 1100 relative to the bearing housing 1101 varies. Thus, movement of the wear resistant element 1107 along the undulating surface of the bearing race 1106 induces a lateral movement of the mandrel 1100 relative to the bearing housing 1101. For example, at some positions of the wear resistant element 1107 along the undulating surface of the bearing race 1106, the mandrel 1100 and the bearing housing 1101 are coaxially aligned along shared longitudinal axis 1111, as shown in
Turning now to
Lateral impulse drilling mechanism 1600b includes two primary bearing pads 1105. Primary bearing pads 1105 are moveably captured within respective keyway style, recessed pockets 1108 within mandrel shaft 1100. Each primary bearing pad 1105 is positioned to be in sliding contact with two corresponding bearing race surfaces 1104 within bearing housing 1101. While lateral impulse drilling mechanism 1600b is shown as including two primary bearing races 1104 and two primary bearing pads 1105, the lateral impulse drilling mechanisms disclosed herein are not limited to having two primary bearing races and pads, and may include more or less than two primary bearing races and pads. The lateral impulse drilling mechanisms disclosed herein include at least one primary bearing race and at least one corresponding primary bearing pad.
Three wear resistant elements 1107 are coupled with mandrel shaft 1100. Wear resistant elements 1107 are in sliding contact with a corresponding bearing race 1106 within bearing housing 1101. While lateral impulse drilling mechanism 1600b is shown as including three wear resistant elements 1107 and one secondary bearing race 1106, the lateral impulse drilling mechanisms disclosed herein are not limited to having three wear resistant elements and one secondary bearing race, and may include more or less than three wear resistant elements and more than one secondary bearing race. The lateral impulse drilling mechanisms disclosed herein include at least one wear resistant element and at least one secondary bearing race. In some aspects, wear resistant elements 1107 have contoured, curved outer surfaces.
In operation, the drilling fluid used to lubricate and cool the lateral impulse drilling mechanism 1600b, primarily flows through the center of mandrel fluid port 1102 and subsequently passes through the inner diameter of a drill bit exiting out into an annulus of a borehole within which lateral impulse drilling mechanism 1600b is positioned. Without being bound by a specific ratio, in some embodiments approximately 90 percent of fluid volume flows though the center of mandrel shaft 1100 and approximately 10 percent of the fluid volume flows around the outside of mandrel shaft 1100 making contact with the various sliding bearing contact surfaces thereon.
Lateral impulse drilling mechanism 1600b includes at least one axial thrust bearing 1103. Axial thrust bearing 1103 is coupled between mandrel shaft 1100 and bearing housing 1101. Axial thrust bearing 1103 may be or include a sliding, dual carrier ring that holds a plurality of polycrystalline diamond elements or other bearing material elements. Such thrust bearing rings may be designed with extra width to accommodate prescribed lateral movement. Furthermore, such axial thrust bearings may be positioned at any location on mandrel shaft 1100, including at the distal end near mandrel bit box 1109, at the proximal end of mandrel shaft 1100, or any position there-between.
Primary bearing pads 1105 are coupled to springs 1117 within pockets 1108 of mandrel shaft 1100. Thus, primary bearing pads 1105 are compressible towards mandrel 1100 and expandable towards bearing housing 1101. In embodiments where the bearing surface 1106 is an undulating surface, as wear resistant elements 1107 moves along the undulating surface and forces mandrel 1100 out of coaxial alignment with bearing housing 1101, the springs 1117 are compressible to facilitate this movement of the mandrel 1100. Also, the springs are expandable to facilitate that movement of the mandrel 1100 back into alignment with the bearing housing 1101.
Turning now to
The primary bearing pads disclosed herein, including bearing pads 1205, may be or include a relatively high-strength steel. For example, the primary bearing pads may be or include a high-performance steel including, but not limited to, 4130, 4330, 8630, S7, and 17-4 PH 1150 stainless, or other grades of steel that are typically used in oil tool drilling applications. In some embodiments, the sliding contact surfaces of primary bearing pads (i.e., the surfaces of primary bearing pads that are in contact with the surfaces of primary bearing races) are metallurgically coated or treated to increase the hardness or wear resistance thereof. One non-limiting example of a coating is hard-facing with macro-crystalline tungsten carbide matrix containing cobalt, nickel or a copper-based binder. In some embodiments, the sliding contact surfaces of primary bearing pads may be treated by carburizing, boronizing, nitriding or similar treatments. In some embodiments, shaped wear resistant elements with contoured surfaces are fitted into primary bearing pads to optimally match the inner diameter of primary bearing races. Such elements may be made of cemented tungsten carbide, polycrystalline diamond, natural diamond, compacted diamond composite segments, or thermally stable diamond segments, for example.
Primary bearing races 1204 are in sliding contact with primary bearing pads 1205. Primary bearing races 1204 may be either integrated into bearing housing 1201 or made as a separate sleeve coupled therewith. The primary bearing races, such as races 1204, may be made or include a relatively high-performance steel including, but not limited to, 4130, 4330, 8630, S7, and 17-4 PH 1150 stainless, or other grades of steel typically used in oil tool drilling applications. Bearing housing races may also be coated or metallurgically treated to further increase the hardness or wear resistance of the sliding contact surface thereof. One non-limiting example of a coating that may be applied onto primary bearing races is hard-facing with macro-crystalline tungsten carbide-based matrix containing a cobalt, nickel or copper-based binder. In some embodiments, the sliding contact surfaces of primary bearing races are treated by carburizing, boronizing, nitriding or similar surface treatments. In some embodiments, primary bearing races are constructed and metallurgically treated for increased wear-resistance as a separate and individually manufactured sleeve that is then coupled within bearing housing, which could be replaced as a consumable component.
The secondary bearing races disclosed herein, such as race 1206, may be made of a relatively high-performance steel such as 4330, 8630, S7, or 17-4 PH 1150 stainless steel, or other steel grades typically used in oil tool drilling applications. Secondary bearing races may also be coated or metallurgically treated to further increase the hardness or wear resistance of the surface thereof. One non-limiting example of a coating on secondary bearing race is a hard face metal containing macro-crystalline tungsten carbide-based matrix with a cobalt, nickel or copper-based binder. In some embodiments, the contact surface of secondary bearing race may also be treated by carburizing, boronizing, nitriding or similar metallurgical treatments. In some embodiments of secondary bearing races, hard material elements or segments are integrated or mounted into the sliding contact surfaces thereof, improving wear-resistance of the surface forming undulating slopes or ridges on the surface thereof. Such mounted segments may be or include polycrystalline diamond, cemented tungsten carbide or other similar wear resistant materials.
The primary bearing pads disclosed herein (e.g., primary bearing pads 1205) may be of a shape having a rectangular aspect ratio, with the radial length longer than the axial width. However, other non-limiting geometries of primary bearing pads include square, ovoid and round. In some embodiments, the length of primary bearing pads is equivalent to, at minimum, a 45-degree arc section of the bearing housing race inner diameter surface and, at a maximum, a 355-degree arc section of the bearing housing race inner diameter surface. In some embodiments, the length of primary bearing pads is equivalent to from a 45-degree arc section of the bearing housing race inner diameter surface to a 355-degree arc section of the bearing housing race inner diameter surface, or from a 60-degree arc section of the bearing housing race inner diameter surface to a 340-degree arc section of the bearing housing race inner diameter surface, or from a 90-degree arc section of the bearing housing race inner diameter surface to a 325-degree arc section of the bearing housing race inner diameter surface, or from a 120-degree arc section of the bearing housing race inner diameter surface to a 300-degree arc section of the bearing housing race inner diameter surface, or from a 180-degree arc section of the bearing housing race inner diameter surface to a 280-degree arc section of the bearing housing race inner diameter surface, or from a 220-degree arc section of the bearing housing race inner diameter surface to a 250-degree arc section of the bearing housing race inner diameter surface. In some aspects, the radial positioning of the primary bearing pads is 180-degrees from the position of the wear resistant elements 1207 with a tolerance of plus or minus 45-degrees, as measured from the center point of the primary bearing pads to the center of the wear resistant elements.
In some embodiments, primary bearing pads 1205, recessed pockets 1208, and primary bearing races 1204 include sliding contact surfaces that are curved (e.g., concave or convex), as opposed to flat, to accommodate minor angular alignment variations encountered by mandrel shaft 1200.
The lateral impulse drilling mechanism may include more than one primary bearing pad, each positioned within a shared axial plane. That is, in one axial (from distal end to proximal end) location of the bearing housing, there may be a plurality of relatively small primary bearing pads (also referred to as sliding pads) to distribute and balance the elastic restoring force imposed on the wear resistant element.
The apex 1299 of each contoured wear resistant element 1207 shown in
In some embodiments, each wear resistant element 1207 has a wear resistant, sliding contact surface that is highly polished or at least partially polished. As used herein, “polished” is defined as a surface finish of less than about 10 μin, or of from about 2 to about 10 μm. As used herein, “highly polished” is defined as a surface finish of less than about 2 μin, or from about 0.5 μin to less than about 2 μin. As would be understood by one skilled in the art, surface finish may be measured with a profilometer or with Atomic Force Microscopy.
While three contoured wear resistant elements 1207 are shown in
The undulations of secondary bearing race 1306 can be seen in
The undulation amplitude displacement distance may be, in one example, 0.025 inches or greater, such as from 0.025 to 0.1 inches, or from 0.03 to 0.09 inches or from 0.04 to 0.08 inches, or from 0.05 to 0.06 inches. As used herein, the “undulation amplitude displacement distance” refers to the distance that the mandrel shaft is laterally moved in the z- or y-direction as a result of movement of wear resistant element 1307 along the undulating surface of secondary bearing race 1306. That is, movement of wear resistant element 1307 along the undulating surface of secondary bearing race 1306 cyclically imparts lateral forces to mandrel shaft 1300, causing mandrel shaft 1300 to move laterally along the z- and/or y-directions. In some aspects, movement of wear resistant element 1307 along the undulating surface of secondary bearing race 1306 cyclically forces mandrel shaft 1300 into and out of coaxial alignment with bearing housing 1301. The impulse frequency of the lateral impulse drilling mechanisms disclosed herein may be 1 impulse per 360-degree rotation or greater. As used herein, the “impulse frequency” refers to the number of lateral impulses (lateral movements) imparted to the mandrel shaft per 360-degree rotation of the wear resistant element(s) along the secondary bearing race. For example, in the embodiment shown in
Secondary bearing race 1306 can be contoured to have a prescribed pattern of undulation that is synchronized and/or timed to coincide with a bottom hole assembly scribe line associated with the direction of steer on a steerable motor. Such synchronization can be used to amplify, attenuate or otherwise influence various factors or tendencies related to the steering of a bottom hole assembly while slide drilling. As used herein, “slide drilling” is defined as the drill bit rotating while the drill string is not rotating, allowing the drill string to steer or build in a desired direction by means of a bent housing section contained in the bottom hole assembly.
Thrust bearing 1403 may be the same or substantially similar to those described with reference to
Lateral impulse drilling mechanism 1600e also includes primary bearing pad 1405 coupled with mandrel 1400 via spring 1417 and engaged with bearing race 1404. Lateral impulse drilling mechanism 1600e also includes wear resistant elements 1407 engaged with bearing race 1406. Also shown in
In
Primary bearing race 1504 is located within the inner diameter of bearing housing 1501. Primary bearing pad 1505 is positioned to make sliding contact with primary bearing race 1504, within the inner diameter of bearing housing 1501. Secondary bearing race 1506 is located near the proximal end of mandrel shaft 1500. Wear resistant element 1507 is mounted in mandrel shaft 1500 to make sliding contact with secondary bearing race 1506 within bearing housing 1501. Wear resistant element 1507 may include one single element or a plurality of elements. Wear resistant element 1507 may be shaped with a contoured surface to make optimal sliding contact while mandrel shaft 1500 rotates, and to function as a cam follower. Secondary bearing race 1506 is contoured with an undulating pattern to induce prescribed lateral movement of mandrel shaft 1500, while mandrel shaft 1500 is rotating. The combination radial and thrust bearing 1503 acts as a rotating pivot point to support both axial and radial forces between mandrel shaft 1500 and bearing housing 1501. This arrangement allows for mandrel shaft 1500 and a connected drill bit (not shown) to be angularly manipulated or pointed in various directions per 360-degree rotation, according to the drilling application. Also shown in
Having now described the components of some embodiments of the lateral impulse drilling mechanisms disclosed herein, the operation thereof will now be described in more detail. During standard drilling with a steerable motor, fluid is pumped from the drill rig floor through the drill string and bottom hole assembly to ultimately be expelled through the drill bit nozzles into the wellbore annulus. Upon first entering the bottom hole assembly, drilling fluid drives a positive displacement motor and associated transmission assembly, converting hypocycloid rotation to concentric rotation. A fixed blade bit attached to the mandrel shaft rotates to shear and remove rock in discrete radial paths. Similarly, three cone bits rotate concentrically, but instead crush rock as the primary cutting mechanism.
Referring to
With a continuous, sinewave undulating surface pattern of the secondary bearing race (as shown in
A sawtooth undulating surface pattern of the secondary bearing race can create a gradual lateral shift followed by an abrupt retraction of the mandrel shaft back to its original position, thus creating a momentary, higher energy lateral movement event or impulse. Such a lateral, high energy impulse occurring multiple times, per one 360-degree bit rotation, will induce advantageous rock fracturing. A sawtooth undulating surface pattern 2206 is shown in
A lateral move or impulse can be imposed on a drill bit when the movement of the drill bit is aligned or synchronized with the direction of steer or scribe line of a bottom hole assembly. With the lateral impulse of the drill bit aligned or synchronized with the direction of steer of the bottom hole assembly, the steering tendency can be augmented or made more effective.
High frequency undulating patterns may be used to provide small amplitude, higher frequency lateral vibrations or oscillations in the mandrel shaft, and thus in the attached drill bit. Lateral vibrations or oscillations of the mandrel shaft and drill bit connected therewith may result in reduced drill string friction while sliding in an extended horizontal section of a wellbore. That is, by repeatedly, laterally moving out of contact with the wellbore, the drill string experiences reduced friction when sliding within the wellbore.
Referring again to
During both slide and rotate drilling, various types of resonance or resonant oscillations can occur along the drill string, which can be potentially harmful or even lead to eventual failure of the bottom hole assembly. These resonant oscillations can originate from an inherent natural frequency for a particular drill string design, can be induced by an excitation factor, such as drill string friction against a formation, or can be induced by the aggressiveness of a particular bit design. Dynamic lateral impulse mechanisms, such as those shown and described with reference to
Some embodiments of the present disclosure include methods, systems, mechanisms, and apparatus for dynamically imparting a torsional movement to a mandrel shaft and/or drill bit of a drill string. Some such embodiments include dynamic torsional detent drilling mechanisms, and methods of use thereof. Imparting torsional movement to the mandrel shaft and drill bit of a drill string provides an additional force component to the cutting action during drilling operations. Such additional torsional force may increase cutting efficiency and speed, reduce frictional engagement between the drill string and wellbore, and provide other additional enhancements to the drilling operations.
Some embodiments include a torsional detent mechanism configured to create discrete and prescribed torque impulse events at the drill bit. The detent mechanisms disclosed herein are configured to cause an amount of potential torsional energy to buildup and then to quickly release to provide for increased drilling energy, reduced friction due to vibration, and to breakup inherent drill string harmonics. In addition, the detent mechanisms disclosed herein may induce a lateral hammering or jarring effect to augment steering tendency of the drill string.
In some embodiments, a bottom hole assembly with a bearing housing is provided. The torsional detent mechanism disclosed herein may be generally located in the bottom hole assembly of the drill string. The bottom hole assembly may or may not have a bent housing.
The torsional detent mechanism shown in
Wear resistant elements 3102 coupled with bearing housing 3100 via springs 3107 such that elements 3102 are extendable and retractable generally perpendicular as the contoured mandrel race 3103 rotates, thus creating a cam following action. The variable distance of the extending and retracting of wear resistant elements 3102 is determined by a prescribed geometry of concave pockets 3104 on contoured mandrel race 3103. Concave pockets 3104 may be equally spaced on the surface of the contoured mandrel race 3103. When the wear resistant elements 3102 slidingly engage the concave pockets 3104, the rotation of mandrel shaft 3101 is momentarily resisted allowing a torsional energy to build up in the drill string after which is then released once the detent resisting force is exceeded. As used herein, “detent” is defined as a mechanism or structure that temporarily maintains a component or part in a certain position relative to another component or part, which can be released from that certain position by applying force to one of the components or parts. Such detent action provides for the momentary buildup of torsional potential energy, and then quickly releases the built-up energy to create a dynamic torsional impulse to the rotating mandrel shaft 3101 and connected drill bit (not shown). Without being bound by theory, such torsional impulse action may augment rock destruction and increase drilling efficiency. The torsional impulse provides a temporary increase in the angular velocity of the rotating component (e.g., mandrel shaft). That is, the rotating component is rotating at a higher angular velocity immediately after the rotating component passes the detent than the angular velocity of the rotating component immediately before passing the detent.
Belville spring 3107 is positioned within the element retention pocket 3106 to provide an elastic restoring force between lower bearing housing 3100 and wear resistant element 3102. While
Thrust ring 3105 is positioned to provide a flat, first axial load support surface against a plurality of inner bearing support races 3108. Thrust ring 3105 also has a radiused second axial load support surface to minimize corner stress against mandrel race 3103.
Bearing retainer shaft 3109 is threaded onto mandrel shaft 3101, providing a restoring clamping force to retain the inner bearing races 3108. A plurality of ball bearings (not shown) are distributed in bearing channel 3118 between the inner bearing support races 3108 and outer bearing support races 3112 to provide axial load rotational support for the bottom hole assembly. The proximal end of the bearing retainer shaft 3109 is connected to a transmission shaft assembly (not shown). This assembly can include a flex shaft, dog bone, knuckle or constant velocity type transmission to convert hypocycloid rotation from the rotor shaft of a positive displacement motor to concentric rotation utilized by the drill bit. Upper bearing housing 3111 is connected via threads to lower bearing housing 3100 to provide a compressive force on the outer bearing support races 3112 (also referred to as stack races).
Coating 3115 is disposed on the inner diameter of lower bearing housing 3100 and is in rotating sliding contact with second coating 3116, which is disposed on the outer diameter of mandrel shaft 3101, forming a lower (distal) radial bearing assembly. Coating 3113 is disposed on the inner diameter of the upper bearing housing 3111 and is in rotating, sliding contact with coating 3114, which is disposed on the outer diameter of bearing retainer shaft 3109, forming an upper (proximal) radial bearing assembly. Coatings 3115, 3116, 3113 and 3114 may each be a hard material coating. The hard material coatings of the upper radial bearing set and lower radial bearing set may be or include macro-crystalline tungsten carbide hard facing with a cobalt, nickel or brass binder, or contoured, cemented tungsten carbide tiles or polycrystalline diamond elements.
In some embodiments, the contoured mandrel race 3103 of mandrel shaft 3101, with prescribed, discrete detent concave pockets 3104, is or includes a high-performance steel, such as 4140, 4340, 8630, S7, or 17-4 PH 1150 stainless steel, or another steel grade that is typically used in oil tool drilling applications. Contoured mandrel race 3103 may additionally be treated to improve wear resistance, including carburizing, nitriding and boronizing. Other materials of which the convex pockets 3104 or portions thereof (e.g., the ridges thereof), contoured mandrel race 3103, or other adjacent surfaces may be at least partially composed of include polycrystalline diamond, cemented tungsten carbide or other wear resistant materials.
Mandrel shaft 3101 includes fluid passage 3117 through the center thereof. Drilling fluid flow is split or diverted at the proximal, entrance of the bearing retainer shaft 3109 with a volume flow of approximately 10% passing between the mandrel shaft 3101 and lower bearing housing 3100, and approximately 90% of the remaining fluid passing through the central fluid passage 3117 within mandrel shaft 3101. These volume percentages are not limiting, and are merely exemplary percentages.
Wear resistant elements 3102 may be generally cylindrical, having domed sliding contact surfaces. The domed surfaces may be coated with high pressure/high temperature sintered polycrystalline diamond containing a secondary phase of cobalt alloy, for example. The wear resistant element 3102 may also be made of or include cemented tungsten carbide or macro-crystalline tungsten infiltrated with nickel, cobalt or brass.
While
With reference to
One exemplary detent torque resistance force threshold range is between 1% and 80% of the maximum torque delivered by the positive displacement motor. The detent resistance can be adjusted in at least several ways. For example, the number of Belville springs 3307 can be varied within an element retention pocket 3306 to increase or decrease the imposed restoring force. The penetration depth of the wear resistant elements 3302 into the concave pockets 3304 can be increased or decreased. The radius of the wear resistant elements 3302 can be increased or decreased, as well as corresponding adjustments to the concave pockets 3304. The quantity of wear resistant elements 3302 and corresponding concave pockets 3304 can be increased or decreased. Dynamic torsional detent mechanism 2300b includes at least one wear resistant element 3302 and at least one corresponding concave pocket 3304. The number of additional sets of contoured mandrel races 3303 and corresponding wear resistant elements 3302 can be increased or decreased on the mandrel shaft 3301, allowing the option for an increased frequency of detent engagements or simultaneous, redundant detent engagements. Dynamic torsional detent mechanism 2300b includes at least one contoured mandrel race 3303 on the mandrel shaft 3301.
The radial detent pattern on the contoured mandrel race 3303 is equally spaced and symmetric, as depicted in
Depicted between the sliding contact surfaces of wear resistant elements 3302 and concave pockets 3304 is a radius ratio of 1/1.5. However, the radius ratio between the wear resistant elements 3302 and convex surface of concave pockets 3304 can range between 1/1 to 1/4, or from 1/1.5 to 1/3.5, or from 1/2 to 1/3. In some embodiments, the sliding contact surface of wear resistant elements 3302 may be polished or highly polished. The polished contact surface of the wear resistant elements 3302 may have a hard material coating, which may be or include polycrystalline diamond; polycrystalline cubic boron nitride; macro-crystalline tungsten carbide matrix with a cobalt, nickel or brass infiltrate; cemented tungsten carbide; or infiltrated thermally stable diamond.
A plurality of convex wear resistant elements 3402 are moveably fitted on springs 3407 and captured into element retention pockets 3406 on the secondary mandrel surface 3409. Each wear resistant element 3402 is in sliding contact with the bearing housing race 3403. The convex contact surface of each sliding wear resistant element 3402 can be coated with a wear resistant hard material, such as polycrystalline diamond; cemented tungsten carbide; microcrystalline tungsten carbide infiltrated with cobalt; nickel or brass; and polycrystalline cubic boron nitride. The Belville spring 3407 is positioned between the bottom of the element retention pocket 3406 and the base of the wear resistant element 3402 provides an elastic restoring force between the two constrained surfaces.
Similar to dynamic torsional detent mechanism 2300a of
Bearing retainer shaft 3410 is threaded onto mandrel shaft 3401, providing a restoring clamping force to retain the inner bearing races 3408. The upper bearing housing 3411 is connected via threads to the bearing housing 3400 to provide a restoring clamping force on the outer bearing support races 3412.
A plurality of ball bearings (not shown) are distributed between the inner bearing support race 3408 and outer bearing support race 3412 to provide axial load rotational support of mandrel shaft 3401. The proximal end of the bearing retainer shaft 3410 is connected to a motor drive assembly (not shown) which converts rotor shaft hypocycloid rotation of a positive displacement motor to concentric rotation to be utilized by the drill bit. Examples of typical motor drive transmission assemblies include flex shaft, knuckle, dog bone, or constant velocity type systems.
While
While
While
While
Mandrel shaft 3401 is rotated by a positive displacement motor (not shown), the wear resistant elements 3402 make sliding contact with the bearing housing race 3403. Upon engagement with concave pocket(s) 3404, the wear resistant elements 3402 dynamically extend as a result of the imposed elastic restoring force of the Belville springs 3407, thus causing the mandrel shaft 3401 to momentarily resist rotation. After a short interval of time, torque buildup from the positive displacement motor will soon overcome the torque threshold limit of the engaged wear resistant elements 3402 and concave pockets 3404. At that point, the wear resistant elements 3404 retract back into their respective element retention pockets 3406, allowing the mandrel shaft to once again turn freely. At the same time, the stored torsional potential energy from the elasticity of the drill string is quickly released providing a momentary, supplemental torque in the form of a discrete and sequenced impulse.
Bearing housing 3400 and bearing housing race 3403 can be made of any high strength steel, such as 4140, 4340, 8630, S7, and 17-4 PH 1150 stainless steel or other steel grades typically used in oil tool drilling applications. However, other materials may also be used to form all or a portion of the detent concave pocket ridges or other race contact surfaces subject to higher wear potential, such as polycrystalline diamond, cemented tungsten carbide or other wear resistant materials.
Bearing housing race 3403 may be an integral, unitary part of bearing housing 3400, or the bearing housing race 3403 may be a separate, replaceable sleeve or liner coupled to bearing housing 3400 to facilitate easy customization of detent patterns.
Dynamic torsional detent mechanism 2300c also includes coated surfaces 3413, 3414, 3415, and 3415, which are the same or substantially similar to coatings 3113, 3112, 3115, and 3116 of
Wear resistant elements 3502 are spherical or generally spherical, but with flat contact areas 3510 in the region that makes sliding contact with the bearing housing race. Flat contact areas 3510 will facilitate increased elastic restoring forces imposed by the Belville springs, reduce the amount of load per unit area to further reduce sliding friction when not in a detent event, and reduce the amount of sliding wear imposed on the secondary mandrel surface, thus extending the service life of the detent mechanism.
Having now described the components of the dynamic torsional detent mechanism disclosed herein, certain considerations, parameters, and variables will now be described with reference to the designing of such dynamic torsional detent mechanisms. To design a dynamic torsional detent mechanism, one or more of the following determinations, and designations may be made: (1) determine the maximum torque output of the positive displacement motor (PDM) for application; (2) designate a detent torque limit threshold which falls between 1-80% or from 1-10% of the max torque output of the PDM; (3) determine the number of detent impulse events desired per one 360-degree rotation; (4) determine if the detent impulse events will be a symmetric or asymmetric pattern spacing; (5) determine if the wear resistant elements are to be a full spherical contact surface or include a planar top portion; (6) designate the number of wear resistant elements to number of concave pockets ratio per 360-degrees of race surface; (7) designate the curvature ratio between the concave pocket(s) and wear resistant element(s); (8) designate the depth of concave pocket to wear resistant element; (9) designate the number of races to be stacked axially; (10); designate the timing scheme between multiple races (if used) to achieve either a detent redundancy or to create an aggregate higher frequency detent timing pattern; and (11) designate Belville spring type and quantity, stack quantity, spring redundancy distributed over required surface to achieve the desired detent torque as per the drilling application and designer's discretion. Not all of these steps are necessarily required in order to design a dynamic torsional detent mechanism. Some steps may be omitted, and some steps not listed may be added. Also, these design steps, when performed, do not necessarily have to be performed in the above listed order.
Having now described the components of the dynamic torsional detent mechanism and well as design considerations, the operation of such dynamic torsional detent mechanisms will now be described.
During drilling, a steerable motor has two general modes of operation, including rotate and slide drilling. “Rotate drilling” is generally characterized as both the drill string and drill bit rotating at the same time. In other words, the drill string is rotated by the rotary table drive on the drill rig floor, while at the same time the drill bit is also rotated by a positive displacement motor of the bottom hole assembly. “Slide drilling” is generally characterized as the drill bit rotating while the drill string is not rotating, allowing the drill string to steer or build in a desired direction by means of a bent housing section contained in the bottom hole assembly. While not being bound by theory or drilling methodology, various configurations of the dynamic torsional detent mechanism will now be discussed.
During rotate mode drilling, both a drill bit and drill string will rotate at the same time. Included in a bottom hole assembly is a dynamic torsional detent mechanism in accordance with the present disclosure and configured for a lower frequency, higher torque limit threshold resistance. As the bit rotates, the bit will turn freely until detent engagement occurs between the wear resistant elements (e.g., 3102) and concave pockets (e.g., 3104). Upon engagement, bit rotation will be momentarily resisted causing torsional potential energy to be stored in the drill string while the drill string continues to rotate. Once the torsional detent resistance threshold is exceeded, the stored torsional potential energy in the drill string is released, allowing the bit to resume free rotation while also imparting a momentary reactive torque impulse to the bit. Without being bound by theory, prescribed torque impulse releases have the propensity to mitigate or breakup excessive torque buildups from occurring instead of an uncontrolled release of high torque and RPM, causing bit and cutting structure damage. The dynamic torsional detent mechanism will increase ROP by means of momentary, short duration energy torque impulses transmitted to the cutting structures to provide a chiseling effect.
During slide mode drilling, a drill bit rotates while the drill string and bearing housing generally does not rotate. Included in the bottom hole assembly, a dynamic torsional detent mechanism in accordance with the present disclosure is configured for a higher frequency and lower torque limit threshold resistance. As the bit rotates, it will turn freely until detent engagement occurs between the wear resistant elements and concave pockets. Upon engagement, bit rotation will be momentarily resisted. A higher frequency, lower torque resistance threshold will create a high frequency pulsing effect to reduce the propensity of or disrupt the buildup of macro torque events. A reduction of macro torque buildup events will result in better tool face control. That is, the dynamic torsional detent mechanism provides for reduced directional steer variation during slide mode drilling. The dynamic torsional detent mechanism will create an advantageous high frequency torsional vibration of the drill string to reduce sliding friction of the drill pipe in the borehole, particularly during drilling of the extended lateral section of a well.
During both side and rotate drilling, the drill bit of a bottom hole assembly is in constant rotation while powered by a positive displacement motor. Included in the bottom hole assembly, a dynamic torsional detent mechanism in accordance with the present disclosure is configured to first have a series of high frequency, low torsional resistance impulses, followed by one high torsional resistance impulse event to create a detent pattern that varies both as a function of impulse frequency and amplitude per 360-degree rotation. Such a patterned sequence may provide advantageous effects during drilling. The low frequency, large torsional impulse has the propensity to mitigate an excessive torque buildup and resultant deleterious uncontrolled torque release. The high frequency, low energy torsional impulse portion of the rotation will induce a torsional vibration or oscillation to advantageously reduce drill string friction, allowing the drill string to slide more easily while drilling particularly in the lateral section of a well.
During both slide and rotate drilling, various modes of resonant oscillations or harmonics that can occur along the drill string, which can be potentially harmful or even lead to eventual failure of the bottom hole assembly. These resonant oscillations can be an inherent natural frequency for a particular drill string design, or an oscillation that is induced by an excitation factor, such as drill string friction against the borehole wall, stabilizer blade contact or the design aggressiveness of a particular drill bit. A dynamic torsional detent mechanism incorporated into the drill string may be synchronized to cancel, breakup or significantly reduce the magnitude of these various deleterious resonant vibrations or oscillations. This can be accomplished by configuring the dynamic torsional detent mechanism to include asymmetric detent patterns, variations in detent resistance per 360 degrees of rotation, and by utilizing specific frequency cancelling detent patterns derived from empirical data taken from an MWD or similar measuring system. Such detent configurations can be effective at reducing the damaging effects of undesirable torsional vibrations or oscillations. The detent configurations may also reduce spiraling during both slide and rotate mode drilling.
The dynamic torsional detent mechanisms disclosed herein can be configured to create a lateral hammering or jarring effect, which can be used to augment a steering tendency; introduce additional cutting mechanisms, such as rock fracturing with shear cutting; and to reduce contact friction of the drill string with formation, particularly while slide drilling in the lateral section of a well. This may be accomplished by modifying the contour of the concave pockets (e.g., 3104) on the secondary mandrel surface (e.g., 3103), as well as the contour of the wear resistant elements (e.g., 3102). One non-limiting example would be to utilize a saw tooth pattern on the secondary mandrel race in lieu of concave pockets on the secondary mandrel surface. A wear resistant element would be aligned with a scribe line, or in the direction of steer for a steerable motor. As the secondary mandrel surface and mandrel shaft (e.g. 3101) rotate, a wear resistant element is gradually retracted into its respective element retention pocket (e.g., 3106) while riding up the sawtooth form. This causes the Belville spring (e.g., 3107) to become compacted. After passing the crest of a saw tooth, the wear resistant element abruptly extends back out of the retention pocket, causing a high energy lateral impulse or hammering event. This effect can be augmented by increasing the number of wear resistant elements that are axially stacked along the mandrel shaft in the same radial position being synchronized to create one high energy lateral impulse with increased aggregate mass. This effect is further augmented by using high-density materials, such as tungsten carbide, for the wear resistant elements. Furthermore, thicker Belville springs or a greater quantity of Belville springs will increase the elastic restoring force to correspondingly increase the hammering energy of the lateral impulse event. There may be a minimum of one impulse event per one 360-degree rotation, or as many impulse events as can configured on the secondary mandrel surface in one 360-degree rotation. The lateral jarring or hammering effect may be achieved by mounting the wear resistant elements on the mandrel shaft (as shown in
Certain embodiments of the present disclosure include methods of drilling utilizing hypocycloidal motion. In some such embodiments, the apparatus, systems, components, and mechanisms described herein with reference to
Hypocycloidal motion of a drill string and/or drill bit may provide for increased modes of rock destruction. Hypocycloidal motion drilling creates multi-directional movement of cutting structures for rock excavation while drilling. More specifically, hypocycloidal motion provides for cutting structures to remove rock by shearing, lateral scoring, pivot grinding and crushing, as well as any combination of these modes.
In geometry, a hypocycloid is a special plane curve generated by the trace of a fixed point on a small circle that rolls within a larger circle. The pattern is created when referencing a single point on the small circle that rotates within the larger circle to create a trace with a series of cusps or points over 360 degrees.
Hypocycloidal movement can be created in a variety of ways, including helical positive displacement motors (PDM) and planetary gear systems. A positive displacement motor contains a rotor and stator. The rotor represents an elongated and helixed hypocycloid shaped body “rolling” inside a larger hypocycloid inner diameter representing the stator. Both the rotor and stator are elongated and helixed to create a motor drive mechanism. While rolling, the cusps of the rotor maintain continuous contact with the cusps of the larger hypocycloid or stator. This motion of the rotor is the same as that of the planet gears of a planetary gearing system. When a mandrel shaft and corresponding bit are directly connected to the rotor of a positive displacement motor, the bit will move in a hypocycloidal orbiting motion. Additionally, all cutting structures on the bit will trace or track with a discrete hypocycloidal pattern. This hypocycloidal pattern is changeable based on the number of cusps designed into the rotor and stator.
The hypocycloidal pattern related to drilling with a steerable motor is governed generally by three primary factors. These factors are orbit diameter, desired bit RPM/torque, and the PDM rotor/stator ratio required for a given drilling application. When designing a system, one of these factors is given priority as the determining factor upon which the others will become dependent factors.
When the PDM motor rotor/stator ratio is prioritized, the positive displacement motor and associated rotor/stator ratio are selected for a bottom hole assembly. The PDM motor will then dictate the bit orbit diameter. A low ratio leads to a larger orbit diameter (e.g., 1/2 ratio motor creates larger orbit diameter). A high ratio leads to a small orbit diameter (e.g., 5/6 ratio motor creates smaller orbit diameter). The PDM motor then dictates the bit revolutions per minute rotation. A low ratio PDM leads to higher rpm and lower torque (e.g., 1/2 ratio=higher rpm, low torque). A high ratio PDM leads to lower rpm, higher torque (e.g., 5/6 ratio=lower rpm, high torque).
When orbit diameter is prioritized, the desired orbit diameter of the bit is selected. The orbit diameter then dictates the ratio of motor that must be used. A larger orbit diameter leads to a low ratio motor (e.g., 1/2 ratio motor or similar may be required). A smaller orbit diameter leads to a high ratio motor (e.g., 5/6 ratio motor or similar may be required). The orbit diameter then dictates the bit RPM. A large orbit diameter leads to high RPM (e.g., a higher rpm output from a 1/2 ratio motor). A smaller orbit diameter leads to a low RPM (e.g., a lower rpm output from a 5/6 ratio motor).
When rotor RPM is prioritized, the desired rotor RPM is selected. The RPM dictates the motor ratio. A high RPM leads to a low motor ratio (e.g., a low ratio 1/2 motor to generate a high rpm). A low RPM leads to a high motor ratio (e.g., a high ratio 5/6 motor to generate a low rpm). The RPM dictates the orbit diameter. A high RPM leads to a large orbit diameter (e.g., higher rpm from a 1/2 ratio motor to create a large orbit). A low RPM leads to a small orbit diameter (e.g., lower rpm from a 5/6 ratio motor to create a small orbit).
Bit design for concentric drilling includes the following types: rolling cones or tri-cone, polycrystalline diamond fixed cutter bits, natural diamond bits, and thermally stable diamond bits. Hybrid varieties also exist that combine attributes between these various bit types. Each of these bit types drill with a particular rock cutting methodology. For example, rolling cone bits predominantly crush rock via point loading stress. Fixed cutter bits predominantly shear rock. Natural diamond and thermally stable diamond (TSP) bits predominantly grind rock.
Hypocycloidal motion provides the ability to drill with a combination of rock cutting mechanisms. Both bits and associated cutting structures, such as polycrystalline diamond cutters (PDC), can take advantage of the multi-directional movement of hypocycloidal motion. With hypocycloid motion, a polycrystalline diamond cutter may shear when moving forward, crush and grind when pivoting, and/or score or fracture rock when moving laterally, as well as take advantage of any combinations of such movements.
As hypocycloidal motion introduces variable surface speed cutting and different cutting modes to remove rock formation, the cutting structure elements can more effectively dissipate deleterious heat. This is particularly important with polycrystalline diamond cutting elements and the localized edge point contact made with the rock. Slower surface speed intervals, the pivoting motion of cutting elements, and rock scoring to fracture rock all provide the ability to better dissipate thermal buildup at the cutting edge with improved thermal diffusion into the cutter body during slow surface speeds and pivot events while also reducing friction when the rock is laterally fractured instead of only sheared.
As hypocycloidal motion introduces multidirectional cutting action, there is a higher propensity for an increased amount of cutting element edge to be utilized during rock drilling. With traditional concentric drilling, the first signs of abrasive wear on polycrystalline diamond cutters generally initiate at the apex or static contact tip with the rock, as created by the bit shape profile. Hypocycloidal motion combines both forward, lateral and pivot motion, thus allowing a greater radial arc of polycrystalline diamond edge to engage the rock formation. This increased utilization of edge will further increase the life of the cutting elements.
As hypocycloidal motion introduces multiple directions of movement, there is a propensity for improved cutting efficiency in the cone or center most area of a bit, particularly for a fixed cutter PDC style bit. Due to the inherently low cutting surface speeds in the cone area of a fixed cutter bit, the cutting elements are more prone to higher forces and breakage. Hypocycloid motion provides both forward shearing and lateral fracturing to better remove the centermost formation of the borehole.
Traditional fixed cutter drill bits mount polycrystalline diamond cutters generally tangential to the bit profile. This traditional cutter mounting is best suited for concentric bit rotation, creating discrete radial cutting paths. More specifically, the cutting element cylindrical side (shank) and end portion made of tungsten carbide are metallurgically brazed at an angle to a mating bit pocket, allowing the cutting element to have a negative rake angle to cut the rock formation. The cutting element face subsequently shears the rock formation as the bit is rotated.
Hypocycloid motion of a bit can utilize traditional cutter mounting techniques, or take advantage of alternative cutter mounting techniques. One non-limiting example is to position cutting elements perpendicular to the bit profile, or in other words, mounting a cutting element to stand with the diamond table face making sliding contact with the rock formation and being generally tangent to the bit profile. Alternatively, the cutting element would be brazed on the bit to stand, but also be positioned with a degree of angle in any direction within 360 degrees as per the designer's discretion.
Hypocycloid motion of a bit can utilize traditional geometry cylindrical cutters or take advantage of alternative cutting element geometries. As hypocycloid motion allows a cutting structure to move in multiple directions, including forward, lateral, pivoting, backward and any combination of the movement thereof. Thus, a cutter may be mounted perpendicularly to the bit face, with the cutter and diamond table standing. In this position, the diamond table may be shaped to be non-round, including non-limiting shapes of square, rectangular, hexagonal, or ovoid. Alternatively, the diamond table top can have non-limiting surface contours including a concave top, convex top or other non-planar surfaces.
Although the present embodiments and advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
The present application claims the benefit of U.S. Provisional Patent Application No. 62/932,990, filed on Nov. 8, 2019, and entitled “Dynamic Drilling Systems and Methods,” the entirety of which is incorporated herein by reference.
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