Patent Grant
7389830
The present invention relates to underground drilling. More specifically, the invention relates to a system for rotating and guiding a drill bit as the drill bit forms an underground bore.
Underground drilling, such as gas, oil, or geothermal drilling, generally involves drilling a bore through a formation deep in the earth. Such bores are formed by connecting a drill bit to long sections of pipe, referred to as a “drill pipe,” so as to form an assembly commonly referred to as a “drill string.” The drill string extends from the surface, to the bottom of the bore.
The drill bit is rotated so that the drill bit advances into the earth, thereby forming the bore. In a drilling technique commonly referred to as rotary drilling, the drill bit is rotated by rotating the drill string at the surface. In other words, the torque required to rotate the drill bit is generated above-ground, and is transferred to the drill bit by way of the drill string.
Alternatively, the drill bit can be rotated by a drilling motor. The drilling motor is usually mounted in the drill string, proximate the drill bit. The drill bit can be rotated by the drilling motor alone, or by rotating the drill string while operating the drilling motor.
One type of drilling motor known as a “mud motor” is powered by drilling mud. Drilling mud is a high pressure fluid that is pumped from the surface, through an internal passage in the drill string, and out through the drill bit. The drilling mud lubricates the drill bit, and flushes cuttings from the path of the drill bit. The drilling mud then flows to the surface through an annular passage formed between the drill string and the surface of the bore.
In a drill string equipped with a mud motor, the drilling mud is routed through the drilling motor. The mud motor is equipped with a rotor that generates a torque in response to the passage of the drilling mud therethrough. The rotor is coupled to the drill bit so that the torque is transferred to the drill bit, causing the drill bit to rotate.
So called “smart” drilling systems include sensors located down hole, in the drill string. The information provided by these sensors permits the drill-string operator to monitor relevant properties of the geological formations through which the drill string penetrates. Based on an analysis of these properties, the drill string operator can decide to guide the drill string in a particular direction. In other words, rather than following a predetermined trajectory, the trajectory of the drill string can be adjusted in response to the properties of the underground formations encountered during the drilling operation. The technique is referred to as “geosteering.”
Various techniques have been developed for performing both straight hole and directional (steered) drilling, without a need to reconfigure the bottom hole assembly of the drill string, i.e., the equipment located at or near the down-hole end of the drill string. For example, so called steerable systems use a drilling motor with a bent housing in the drilling motor. A steerable system can be operated in a sliding mode in which the drill string is not rotated, and the drill bit is rotated exclusively by the drilling motor. The bent housing or subassembly steers the drill bit in the desired direction as the drill string slides through the bore, thereby effectuating directional drilling. Alternatively, the steerable system can be operated in a rotating mode in which the drill string is rotated while the drilling motor is running. This technique results in a substantially straight bore.
Although steerable systems have been used for many years, these types of systems possess disadvantages. For example, when a steerable system is operated in the sliding mode, the rate of penetration of the drill bit can be relatively low, and stick slip, differential sticking, and difficulties with cuttings removal can be prevalent. Operating a steerable system in the rotating mode can result in an oversize and tortuous bore.
So-called rotary steerable tools have been used over the past several years to perform straight-hole and directional drilling. One particular type of rotary steerable system can include pads located on the drill string, proximate the drill bit. The pads can extend and retract with each revolution of the drill string. Contact the between the pads and the surface of the drill hole exerts a lateral force on the string. This force pushes or points the drill bit in the desired direction of drilling. Straight-hole drilling is achieved when the pads remain in their retracted positions.
Rotary steerable tools can form an in-gauge bore while drilling directionally, and do not posses the disadvantages associated with sliding the drill string. The drill bit in a rotary steerable tool, however, is rotated exclusively by torque generated at the surface and transferred to the drill bit by way of the drill string. Thus, the torque available to rotate the drill string can be limited by drag on the drill string, especially in a highly-deviated bore. Moreover, the drill-bit torque can be further limited by the torque requirements of the hydraulic system that extends and retracts the pads during directional drilling.
A preferred embodiment of a system for rotating and guiding a drill bit in an underground bore comprises a drilling motor comprising a housing, and a rotor mounted in the housing so that the rotor rotates in relation of the housing. The system also comprises a drive shaft coupled to the rotor and the drill bit so that drill bit rotates in response to rotation of the rotor.
The system further comprises a guidance module comprising a housing coupled to the housing of the drilling motor so that the housing of the guidance module rotates with the housing of the drilling motor and the drive shaft extends through the housing of the guidance module. The guidance module also comprises an actuating arm mounted on the housing of the guidance module. The actuating arm is movable in relation to the housing of the guidance module between an extended position wherein the actuating arm can contact a surface of the bore and thereby exert a force on the housing of the guidance module, and a retracted position.
A preferred embodiment of a rotary steerable motor system for use in drilling an underground bore comprises a drilling motor capable of generating a torque, a drive shaft coupled to the drilling motor for transmitting the torque to a drill bit, and a guidance module. The guidance module comprises a housing having a portion of the drive shaft concentrically disposed therein, an actuating arm movably mounted on the housing; and a hydraulic system.
The hydraulic system comprises a pump having an outlet for discharging a pressurized hydraulic fluid, a piston disposed in a cylinder formed in the housing so that the piston can extend from the cylinder and urge the actuating arm away from the housing in response to the pressurized hydraulic fluid, and a valve for selectively placing the cylinder in fluid communication with the outlet of the pump.
Another preferred embodiment of a system for rotating and guiding a drill bit in an underground bore comprises a drilling motor capable of generating a torque, a drive shaft coupled to the drilling motor for transmitting the torque to a drill bit, and means coupled to the drive shaft for generating contact with a surface of the bore so that the contact urges the drive shaft in a direction other than a direction coinciding with an axis of rotation of the drive shaft.
A preferred embodiment of a rotary steerable drilling apparatus for drilling a bore hole through an earthen formation comprises a drill pipe comprised of a plurality of drill pipe sections, a first motor for rotating the drill pipe at a first RPM relative to the earthen formation, and a second motor mounted within the drill pipe so that rotation of the drill pipe by the first motor rotates the second motor at the first RPM.
The apparatus also includes a drive shaft coupled to the second motor and extending thru the drill pipe so that rotation of the drive shaft by the second motor rotates the drive shaft relative to the drill pipe at a second RPM, and a drill bit coupled to the drive shaft, whereby rotation of drill pipe by the first motor at the first RPM and rotation of the drive shaft by the second motor at the second RPM causes the drill bit to rotate relative to the earthen formation at rotational speed that is essentially the sum of the first RPM and the second RPM.
The apparatus further comprises a guidance module for controlling the direction in which the drill bit drills, the guidance module incorporated into the drill pipe so that the guidance module rotates with the drill pipe at the first RPM relative to the earthen formation.
A preferred method for forming an underground bore comprises rotating a drill collar at a first rotational speed using a first motor, and rotating a drill bit coupled to the drill collar so that the drill bit can rotate in relation to the drill collar, using a second motor, so that the drill bit rotates at a second rotational speed greater than the first rotational speed. The preferred method also comprises guiding a path of the drill bit by periodically extending and retracting actuating arms coupled to the drill collar and rotating at a rotational speed approximately equal to the rotational speed of the drill collar so that the actuating arms contact a surface of the underground bore.
The foregoing summary, as well as the following detailed description of a preferred embodiment, are better understood when read in conjunction with the appended diagrammatic drawings. For the purpose of illustrating the invention, the drawings show an embodiment that is presently preferred. The invention is not limited, however, to the specific instrumentalities disclosed in the drawings. In the drawings:
The drill collar 14 is rotated by a motor 21 of a drilling rig 15 located on the surface. Drilling torque can be transmitted from the motor 21 to the drill bit 13 through a turntable 22, a kelly (not shown), and the drill collar 14. The rotating drill bit 13 advances into the earth formation 16, thereby forming a bore 17.
Drilling mud is pumped from the surface, through the drill collar 14, and out of the drill bit 13. The drilling mud is circulated by a pump 18 located on the surface. The drilling mud, upon exiting the drill bit 13, returns to the surface by way of an annular passage 19 formed between the drill collar 14 and the surface of the bore 17.
Operation of drilling rig 15 and the drill string 12 can be controlled in response to operator inputs by a surface control system 20.
The bottom hole assembly 11 can also include a measurement while drilling (MWD) tool 300 (see
The MWD tool 30 can also include three magnetometers 330 for measuring azimuth about three orthogonal axes, three accelerometers 332 for measuring inclination about the three orthogonal axes, and a signal processor 334 (see
The MWD tool 30 also includes a short-hop telemetry device 336 that facilitates communication with the system 10 by way of short-range radio telemetry.
The system 10 comprises a drilling motor 25 and a drive shaft assembly 31. The drilling motor can be a helicoidal positive-displacement pump, sometimes referred to as a Moineau-type pump. The drilling motor 25 includes a housing 26, and a stator 27 mounted on an interior surface of the housing 26 (see
Drilling mud at bore pressure is forced between the rotor 28 and the stator 27. The stator 27 and the rotor 28 are shaped so that the movement of the drilling mud therethrough imparts rotation to the rotor 28 in relation to the stator 27. In other words, the rotor 28 extracts hydraulic energy from the flow of drilling mud, and converts the hydraulic energy into mechanical energy. As the housing 26 forms part of the drill collar 14, the rotational speed of the drill collar 14 is superimposed on the rotational speed of the rotor 28 induced by the flow of drilling mud. The drive shaft assembly 31 and the drill bit 13 are coupled to the rotor 28 so that the rotation of the rotor 28 is imparted to the drive shaft 31 and the drill bit 13.
A suitable drilling motor 25 can be obtained, for example, from Bico Drilling Tools, Inc., of Houston, Tex. It should be noted that the use of a Moineau-type pump as the drilling motor 25 is disclosed for exemplary purposes only. Other types of pumps and motors, including pumps driven by an electric motor, can be used as the drilling motor 25 in alternative embodiments.
As shown in
The flexible coupling 30 comprises a first universal joint 32, a rigid shaft 34, and a second universal joint 36 (see
The first universal joint 32 is secured to the rotor 28 of the drilling motor 25 by a suitable means such as a threaded connection, so that the first universal joint rotates with the rotor 28. The first universal joint 32 is coupled to the shaft 34 so that the rotor 28 can pivot in relation to the shaft 34.
The drive shaft assembly 31 includes a diverter 40 (see
The flexible coupling 30 transfers rotational motion between the rotor 28 of the drilling motor 25 and the diverter 40. The flexible coupling 30 acts as a constant-velocity joint that can facilitate rotation of the rotor 28 and the diverter 40 when the rotational axes of the rotor 28 and the diverter 40 are misaligned.
The housing 38 and the flexible coupling 30 define a passage 39 (see
The diverter 40 has four passages 42 defined therein (see
The system 10 also comprises a stabilizer 50 (see
The blades 52 preferably are arranged in a helical pattern. The height of the blades 52, i.e., the distance by which the blades 52 project from the body 51, is selected so that the maximum diameter of the stabilizer 50 is slightly smaller than the diameter of the bore 17. Contact between the blades 52 and the surface of the bore 17 helps to center the system 10 within the bore 17. Alternative embodiments of the stabilizer 50 can include more, or less than three of the blades 52.
The drive shaft assembly 31 also includes an upper drive shaft 53. The upper drive shaft 53 is secured to the diverter 40 by a suitable means such as a threaded connection, so that the upper drive shaft 53 rotates with the diverter 40. The upper drive shaft 53 extends through the stabilizer 50. An outer surface of the upper drive shaft 53, and an inner surface of the stabilizer 50 further define the internal volume 49.
The upper drive shaft 53 has a centrally-located passage 54 formed therein. The passage 54 adjoins the passage 44 of the diverter 40. The passage 54 receives the drilling mud from the passage 44, and permits the drilling mud to pass down-hole through the upper drive shaft 53.
The system 10 also comprises a compensation and upper seal bearing pack assembly 70 (see
The assembly 70 also comprises a bearing support 72 positioned within the housing 71 (see
The bearing support 72 has a plurality of circumferentially-spaced, axially-extending passages 78 formed therein. The passages 78 facilitate the flow of drilling mud through the bearing support 72. The drilling mud reaches the passages 78 by way of an annulus formed between the up-hole end of the bearing support 72, and an inner circumference of the housing 71.
The assembly 70 also comprises a piston 80, and a piston shaft 82. An up-hole end of the piston shaft 82 is positioned within the bearing support 72. A down-hole end of the piston shaft 82 is supported by a mounting ring 84 secured to an inner circumference of the housing 71 (see
The piston 80 is disposed around the piston shaft 82, so that the piston 80 can translate in the axial direction in relation to the piston shaft 82. The assembly 70 also comprises a spring 86 positioned around the piston shaft 82. The spring 86 contacts an up-hole end of the piston 80, and a spring retainer 87 disposed around the piston shaft 82 (see
The housing 71, the bearing support 72, the piston shaft 82, and the up-hole end of the piston 80 define an internal volume 88. The volume 88 receives drilling mud, at bore pressure, from the volume 49 by way of the passages 78 formed in the bearing support 72. The piston 80 defines the down-hole end of the internal volume 88. The up-hole face of the piston 80 therefore is exposed to drilling mud at annulus pressure.
The housing 71, the piston shaft 83, the upper drive shaft 53, and the down-hole end of the piston 80 define an internal volume 89 down hole of the piston 80 (see
The oil can be a suitable high-temperature, low compressability oil such as MOBIL 624 synthetic oil. The oil, as discussed below, functions as a lubricant, a hydraulic fluid, and a oil.
The piston 80 can move axially in relation to the piston shaft 82. The piston 80 therefore can raise or lower the pressure of the oil in the volume 89, in response a pressure differential between the drilling mud and the oil. In particular, the combined force of the drilling mud and the spring 86 on the piston 80 urges the piston 80 in the down-hole direction, thereby increasing the pressure of the oil, until the force of the oil on the piston 80 is approximately equal to the combined, opposing force of the drilling mud and the spring 86 on the piston 80. The additional force provided by the spring 86 helps to ensure that the pressure of the oil in the first hydraulic circuit is higher than the pressure of the drilling mud, thereby reducing the potential for infiltration of the drilling mud into the oil.
The pressure of the drilling mud can vary with the depth of the system 10 within the bore 17. The piston 80 causes the pressure of the oil in the first hydraulic circuit to vary proportionately with changes in the pressure of the drilling mud, so that the pressure of the oil remains higher than the pressure of the drilling mud. In other words, the piston 80 compensates for variations in the pressure of the drilling mud during drilling operations.
The bearings 76 are wetted by oil from the volume 88. The oil reaches the bearings 76 by way of an annulus formed between the inner circumference of the piston shaft 82, and the upper drive shaft 53. The annulus and the wetted volume around the bearings 76 form part of the first hydraulic circuit.
The assembly 70 also comprises a first and a second seal 92, 94. The first and second seals 92, 94 can be, for example, rotary shaft lip seals or rotary shaft face seals.
The first and second seals 92, 94 are positioned around the upper drive shaft 53 (see
The oil in the second hydraulic circuit, while isolated from the oil in the first hydraulic circuit, can be the same type of oil used in the first hydraulic circuit.
The second seal 94 is located within an annulus formed in a seal housing 95. The seal housing 95 is positioned within the bearing support 72. A down-hole end of the second seal 94 is exposed to the oil in the second hydraulic circuit. An up-hole end of the second seal 94 is exposed to drilling mud. The second seal 94 substantially isolates the oil from the drilling mud.
A second piston 96 is positioned around the seal housing 95, so that the piston 96 can translate axially in relation to the seal housing 95. A down-hole face of the piston 96 is exposed to the oil in the second hydraulic circuit. An up-hole face of the piston 96 is exposed to drilling mud, at bore pressure, in the volume 49. O-ring seals 98 are positioned around the inner and outer circumference of the of piston 96. The O-ring seals 98 substantially isolate the oil from the drilling mud, and thereby reduce the potential for contamination of the oil by the drilling mud.
The pressurization of the oil in the second hydraulic circuit by the piston 96 substantially equalizes the pressure across the second seal 94. Equalizing the pressure across the second seal 94 can discourage infiltration of the drilling mud into the second hydraulic circuit, and can reduce the rate of wear of the second seal 94 resulting from by contact with the upper drive shaft 53.
The pressurization of the oil in the second hydraulic circuit by the piston 96 also substantially equalizes the pressure across the first seal 92, potentially reducing the rate of wear of the first seal 92 resulting from by contact with the upper drive shaft 53.
The drive shaft assembly 31 further comprises a lower drive shaft 99. The up-hole end of the lower drive shaft 99 is secured to the down-hole end of the upper drive shaft 53 by a suitable means such as a threaded connection, so that the lower drive shaft 99 rotates with the upper drive shaft 53. The drill bit 13 is mounted on a bit box 105 that forms the down-hole end of the lower drive shaft 99. Drilling torque therefore is transferred from the drilling motor 25 to the drill bit 13 by way of the diverter 40, the upper drive shaft 53, and the lower drive shaft 99.
The lower drive shaft 99 has a centrally-located passage 106 formed therein. The passage 106 adjoins the passage 54 of the upper drive shaft 53. The passage 106 receives the drilling mud from the passage 54, and directs the drilling mud to pass down-hole to the drill bit 13.
The system 10 further comprises a crossover subassembly 100 (see
The crossover subassembly 100 also comprises a thrust bearing 102, and a spacer 103 located immediately down-hole of the bearing 102 (see
The bearing 102 supports the lower drive shaft 99 and the drill bit 13 by way of the spacer 103 and the housing 101, as the drill string 12 is raised and lowered within the bore 17. The bearing 102 and the spacer 103 are sized so that an axial clearance exists between the bearing 102 and the spacer 103 during drilling operations. The bearing 102 therefore is unloaded as the drill string 12 is urged in the down-hole direction during drilling operations. The manner in which axial loads are transmitted during through the system 10 drilling operations is discussed below.
The crossover subassembly 100 includes two needle roller bearings 104 positioned around the lower drive shaft 99, between the spacer 103 and the housing 101. The bearings 104 substantially center the lower drive shaft 99 within the housing 101, while facilitating rotation of the lower drive shaft 99 in relation to the housing 101. The bearings 104 are lubricated by the oil in the first hydraulic circuit. The oil reaches the bearing 104 by way of various passages and clearances within the crossover subassembly 100 and other components of the system 10.
The system 10 further includes a guidance module 110 (see FIGS. 2 and 5-15). and 4). The guidance module 110 can guide the drill bit 13 in a direction coinciding with a desired direction of the bore 17 at a particular location in the earth formation 16.
The guidance module 110 comprises three actuating arms 112 that extend and retract on a selective basis to push the drill bit 13 in a desired direction (see
The extension and retraction of the actuating arms 112 is controlled by a microprocessor-based controller 118, and three electro-hydraulic valves 120 that direct the oil toward a respective one of the actuating arms 112 in response to commands from the controller 118 (see
The guidance module 110 also includes a housing 122. The housing 122 is secured to the housing 101 of the crossover assembly 100 by a suitable means such as a threaded connection, so that the housing 122 rotates with the housing 101. The housing 122 thus forms part of the drill collar 14.
The guidance module 110 includes two needle roller bearings 124 positioned around the lower drive shaft 99 (see
The pump 114 is positioned immediately down hole of the bearing housing 126. The pump 114 preferably is a hydraulic vane pump. The pump 114 comprises a stator 127, and a rotor 128 disposed concentrically within the stator 127 (see
The manifold 130 has three inlet ports 131a, and three outlet ports 131b formed therein. Oil from within the third hydraulic circuit enters the hydraulic pump 114 by way of the inlet ports 131a. The oil in the third hydraulic circuit, while isolated from the oil in the first and second hydraulic circuits, can be the same type of oil used in the first and second hydraulic circuits. (Other types of fluids can be used in the third hydraulic circuit, in the alternative.)
The lower drive shaft 99 extends through the pump 114 so that the housing 122, the pump 114, and the lower drive shaft 99 are substantially concentric. The stator 127, bearing seal housing 129, and manifold 130 of the pump 114 are restrained from rotating in relation to the housing 122, as discussed below.
The rotor 128 is rotated in relation to the stator 127 by the drive shaft 99, as discussed below. Spring-loaded vanes 132 are disposed in radial grooves 133 formed in the rotor 128. Three cam lobes 134 are positioned around the inner circumference of the stator 127. The cam lobes 134 contact the vanes 132 as the rotor 128 rotates within the stator 127. The shape of the cam lobes 134, in conjunction with the spring force on the vanes 132, causes the vanes 132 to retract and extend into and out of the grooves 133.
Each vane 132 moves radially outward as the vane 132 rotates past the inlet ports 131a, due to the shape of the cam lobes 134 and the spring force on the vane 132. This movement generates a suction force that draws oil through the inlet ports 131a, and into an area between the rotor 128 and the stator 127.
Further movement of the vane 132 sweeps the oil in the clockwise direction, toward the next cam lobe 134 and outlet port 131b (from the perspective of
The use of a hydraulic vane pump such as the pump 114 is described for exemplary purposes only. Other types of hydraulic pumps that can tolerate the temperatures, pressures, and vibrations typically encountered in a down-hole drilling environment can be used in the alternative. For example, the pump 114 can be an axial piston pump in alternative embodiments.
The pump 114 is driven by the lower drive shaft 99. In particular, the portion of the lower drive shaft 99 located within the rotor 128 preferably has splines 135 formed around an outer circumference thereof. The spines 135 extend substantially in the axial direction. The splines 135 engage complementary splines 136 formed on the rotor 128, so that rotation of the lower drive shaft 99 in relation to the housing 122 imparts a corresponding rotation to the rotor 128 (see
A ball bearing 148 is concentrically within on the manifold 130. The bearing 148 helps to center the lower drive shaft 99 within the pump 114, and thereby reduces the potential for the pump 114 to be damaged by excessive radial loads imposed thereon by the lower drive shaft 99. The bearing 148 is lubricated by the oil in the third hydraulic circuit.
The guidance module 110 further includes a hydraulic manifold assembly 140 located down hole of the pump 114 (see FIGS. 5 and 9-10F). The hydraulic manifold assembly 140 comprises the valves 120, a body 141, a casing 162 positioned around a portion of the body 141, and a bypass valve 144. The valves 120 and the bypass valve 144 are mounted on the body 141.
The pump 114 and hydraulic manifold assembly 140 are positioned between the housing 101 of the crossover subassembly 100, and a lip 122a of the housing 122. A crush ring 149 is positioned between the housing 101, and the up-hole end of the pump 114.
The crush ring 149 is sized so that the stacked length (axial dimension) of the crush ring 149, pump 114, and hydraulic manifold assembly 140 is greater than the distance between the down-hole end of the housing 101, and the lip 122a. The crush ring 149 deforms as the crossover subassembly 100 and the guidance module 110 are mated. The interference generated by the crush ring 149 results in axial and frictional forces between the housing 101, crush ring 149, pump 114, hydraulic manifold assembly 140, and housing 122. These forces help to secure the pump 114 and the hydraulic manifold assembly 140 to the housing 122. The pump 114 and the hydraulic manifold assembly 140 are restrained from rotating in relation to the housing 112 by pins.
The body 141 of the hydraulic manifold assembly 140 has circumferentially-extending, outwardly-facing first and second grooves 163a, 163b formed therein (see
The first annulus 143a is in fluid communication with the inlet ports 131a of the pump 114 by way of passages 165a formed in the body 141 (see
The second annulus 143b is in fluid communication with the outlet ports 131b of the pump 114 by way of passages 165b formed in the body 141. The second annulus 143b therefore holds oil at a pressure approximately equal to the outlet (discharge) pressure of pump 114 during operation of the system 10.
Each valve 120 has a first inlet 121a and a second inlet 121b (see
The body 141 has three passages 166 formed therein (see
The hydraulic manifold assembly 140 also includes four pistons 145 (see
The hydraulic manifold assembly 140 also includes two spring-loaded pistons 139 (see
A down-hole end of each piston 139 is exposed to drilling mud at bore pressure, by way of various passages formed in the body 141 and the housing 122. The combined force of the drilling mud and the associated spring against the down-hole end of the piston 139 helps to maintain the pressure in the up-hole of the piston 139 above bore pressure. Each bore 167 and its associated piston 139 thus function as an accumulator 142 that stores a reservoir of high-pressure oil in fluid communication with the second inlet 121b of the valves 120.
The optimal number of accumulators 142 is application-dependent, and can vary, for example, with the amount of force required to actuate the arms 112. More, or less than two accumulators 142 can be used in alternative embodiments. Other alternative embodiments can be configured without any accumulators 142.
The housing 122 has three deep-drilled holes 150 (see
The housing 122 has three banks 151 of cylinders 152 formed therein (see
The cylinders 152 each receive a respective piston 154. The diameter of the each piston is sized so that the piston 154 can translate in a direction substantially coincident with the central (longitudinal) axis of its associated cylinder 152. An end of each piston 154 is exposed to the oil in its associated cylinder 152. The opposite end of the piston 154 contacts the underside of an associated actuating arm 112. Seals 157 are mounted on the housing 122 (or on the pistons 154) to seal interface between the cylinder 152 and the associated piston 154, and thereby contain the high-pressure oil in the cylinder 152.
Each actuating arm 112 is pivotally coupled to the housing 122 by a pin 158, so that the arm 112 can pivot between an extended position (
Ends of the pin 158 are received in bores formed in the housing 122, and are retained by a suitable means such as clamps. Recesses 160 are formed in the housing 122 (see
The valves 120 preferably are double-acting spool valves. The first inlet 121a of each valve 120 has is in fluid communication with the inlet of the pump 114 by way of the first annulus 143a, and the second inlet 121b in fluid communication with the outlet of the pump 114 by way of the second annulus 143b, as noted above. The outlet of each valve 120 is in fluid communication with a respective one of the holes 150, by way of the passages 166.
The valve 120 permits relatively low-pressure oil from the inlet of the pump 114 to enter the associated hole 150, when the valve 120 is not energized. In other words, the valve 120 places the associated hole 150 and cylinder bank 151 in fluid communication with the inlet of the pump 114 when the valve 120 is not energized. As the relatively low-pressure oil from the inlet of the pump 114 is insufficient to force the associated actuating arm 112 against the borehole wall, the actuating arm 112 remains in (or near) its retracted position under this condition.
Energizing the valve 120 activates a solenoid within the valve 120. The solenoid reconfigures the flow path within the valve 120 so that the outlet of the valve 120 is placed in fluid communication with the outlet of the pump 114 by way of the second inlet 120b of the valve 120.
Energizing the valve 120 therefore causes the oil from the discharge of the pump 114 to be directed to the associated hole 150 and cylinder bank 151. The relatively high-pressure oil acts again the underside of the associated pistons 154, and causes the pistons 154 to move outwardly, against the actuating arm 112. The outward movement of the pistons 154 urges the actuating arm 112 outward. The restraint of the arm 112 exerted by the associated pin 158 causes the actuating arm 112 to pivot about the pin 158, toward its extended position.
An outwardly-facing surface portion 175 of the actuating arm 112 contacts the surface of the bore 17, i.e., the borehole wall, and exerts a force thereon in a first direction (see
The surface portion 175 of the actuating arm 112 preferably is curved, to substantially match the curvature of the surface of the bore 17 (see
De-energizing the valve 120 causes the solenoid to reconfigure the flow path within the valve 120, so that the outlet of the valve 120 is placed in fluid communication with the inlet of the pump 114 by way of the first inlet 121a of the valve 120. As the relatively low-pressure oil from the inlet of the pump 114 is insufficient to force the associated actuating arm 112 against the borehole wall, the actuating arm 112 returns to its retracted position.
Details concerning the manner in which the extension and retraction of the actuating arms 112 is controlled during directional drilling are presented below.
The valves 120, when energized, subject the associated holes 50 and the cylinders 152 to a hydraulic pressure approximately equal to the discharge pressure of pump 112. The valves 120 do not otherwise regulate the hydraulic pressure. Alternative embodiments can be equipped with proportional valves that can change the pressure and flow to the holes 150 and cylinders 152 in response to a control input to the valve. This feature can be used, for example, to maintain a desired pressure and flow rate to the holes 150 and cylinders 152 as the pump 114 wears or otherwise deteriorates.
The cylinders 152 preferably are oriented at an angle of approximately ninety degrees in relation to the radial direction of the housing 122 (see
The actuating arms 112 preferably are formed from a relatively hard, wear-resistant material capable of withstanding the contact forces generated when the actuating arm 112 contacts the borehole wall. For example, the actuating 112 arms can be formed from 17-4PH stainless steel, or other suitable materials. A wear coating, such as a tungsten carbide coating (or other suitable coatings) can be applied to the surfaces of the actuating arms 112 that contact the borehole wall and the pistons 154, to provide additional durability.
The bypass valve 144 is configured to route the discharge of the pump 114 to the inlet of the pump 114 when the pressure of the oil in the manifold 143 exceeds a predetermined value. The bypass valve 144 can accomplish this bypass function by placing the first and second annuli 143a, 143b in fluid communication so that oil can flow from the second annulus 143b to the first annulus 143a. The predetermined value should be chosen so that the bypass valve 144 performs its bypass function when none of the three valves 120 is activated, i.e., when outlet of pump 114 is not in fluid communication with any of the cylinder banks 151. This feature can reduce the potential for deadheaded oil to cause an overpressure condition in the third hydraulic circuit.
Alternative embodiments of guidance module 110 can include more, or less than three actuating arms 112 and cylinder banks 151. Moreover, each cylinder bank 151 can include more, or less than three cylinders 152 in alternative embodiments. The actuating arms 112 and cylinder banks 151 can be circumferentially spaced in unequal angular increments in alternative embodiments.
A thrust bearing 176 and a spacer 178 are mounted between a lip formed on the housing 122 of the guidance module 110, and a neck 99a of the lower drive shaft 99 (see
The guidance module 110 also includes an alternator 180. The alternator 180 is mounted on the housing 122, within a cavity 182 formed in the housing 122. The cavity 182 is covered and sealed by a hatch cover 184 (see
The alternator 180 is driven by the lower drive shaft 99, by way of a gear train 186. The gear train 186 is mounted on the housing 122, within the cavity 182. A portion of the lower drive shaft 99 has teeth 188 formed thereon (see
The cavity 182 is filled with oil from the first hydraulic circuit. The oil lubricates the alternator 180 and the gear train 186. The oil reaches the cavity 182 by way of various passages and clearances within the guidance module 110 and other components of the system 10.
The controller 118 is mounted in a cavity 201 formed in the housing 122 (see
The guidance module 110 also includes a voltage regulator board 204 (see
The voltage regulator board 204 comprises a rectifier and a voltage regulator. The rectifier receives the alternating-current (AC) output of the alternator 180, and converts the AC output to a direct-current (DC) voltage. The voltage regulator regulates the DC voltage to a level appropriate for the controller 118 and the other electrical components powered by the alternator 180.
Wiring (not shown) that interconnects the alternator 180 with the voltage regulator board 204 is routed through a header 215, and through a passage 216 formed in the housing 122 between the cavities 182, 206 (see
The guidance module 110 also includes a short-hop circuit board and transducer 220 (see
The guidance module 110 also includes a valve control and magnetometer board 226 (see
The valve control and magnetometer board 226 can also include a biaxial magnetometer that facilitates calculation of tool face angle, as discussed below.
The controller 118, voltage regulator board 204, short-hop circuit board and transducer 220, and valve control and magnetometer board 226 can be isolated from shock and vibration as required, by a suitable means such as a suspension.
The system 10 also comprises a lower seal bearing pack assembly 280 (see
The assembly 280 comprises three radial bearings 284 for substantially centering the lower drive shaft 99 within the housing 282. The bearings 284 are lubricated by the oil from the first hydraulic circuit. The oil reaches the bearing 284 by way of various passages and clearances formed in the guidance module 100 and other components of the system 10.
The assembly 280 also comprises a first and a second seal 286, 288. The first and second seals 286, 288 can be, for example, rotary shaft lip seals or rotary shaft face seals.
The first and second seals 286, 288 are positioned around the lower drive shaft 99. The first seal 286 is located within an annulus formed in the housing 282. An up-hole end of the first seal 286 is exposed to the oil used to lubricate the bearings 284, i.e., the oil in the first hydraulic circuit. An up-hole end of the first seal 286 is exposed to oil contained within a fourth hydraulic circuit. The second seal 288 substantially isolates the oil in the first hydraulic circuit from the oil in the fourth hydraulic circuit.
The oil in the fourth hydraulic circuit, while isolated from the oil in the first hydraulic circuit, can be the same type of oil used in the first hydraulic circuit.
The second seal 288 is located within an annulus formed in a piston shaft 289 (see
A piston 290 is positioned around the piston shaft 289, so that the piston 290 can translate axially in relation to the piston shaft 289. An up-hole face of the piston 290 is exposed to the oil in the fourth hydraulic circuit. A down-hole face of the piston 290 is exposed to the drilling mud in the annular passage 19 formed between the drill collar 14 and the surface of the bore 17. O-ring seals 292 are positioned around the inner and outer circumference of the of piston 290. The O-ring seals 292 substantially isolate the oil from the drilling mud, and thereby reduce the potential for contamination of the oil by the drilling mud.
The pressurization of the oil in the fourth hydraulic circuit by the piston 290 substantially equalizes the pressure across the second seal 288. Equalizing of the pressure across the second seal 288 can discourage infiltration of the drilling mud into the fourth hydraulic circuit, and can reduce the rate of wear of the second seal 288 resulting from by contact with the lower drive shaft 99.
The pressurization of the oil in the fourth hydraulic circuit by the piston 290 also substantially equalizes the pressure across the first seal 286, and can reduce the rate of wear of the first seal 286 resulting from by contact with the lower drive shaft 99.
Further operational details of the system 10 are as follows. The casing 122 of the guidance module 110 forms part of the drill collar 14, a discussed above. The casing 122, and the attached actuating arms 112, therefore rotate in response to the torque exerted on the drill string 12 by the drilling rig 15, in the direction denoted by the arrow 300 in
The actuating arms 112 are in their retracted positions during straight-hole drilling. Directional drilling can be achieved by selectively extending and retracting each actuating arm 112 on a periodic basis, so that the drill bit 13 is pushed in the desired direction of drilling. Each arm 112 can be extended and retracted once per revolution of the housing 122. Alternatively, each arm 112 can be extended and retracted once per a predetermined number of revolutions. The optimal frequency of the extension and retraction of the actuating arms 112 can vary with factors such as the pressure and flow rate of the oil or other hydraulic fluid used to actuate the actuating arms 112, the amount of angle built each time he actuating arms 112 are extended, etc.
The extension and retraction of the actuating arms 112 is effectuated by energizing and de-energizing the associated valves 120, as discussed above. This process is controlled by the controller 118. In particular, the controller 118 can determine the instantaneous angular orientation of each actuating arm 112 based on the tool face angle of the housing 122. The controller 118 includes algorithms that cause the controller 118 to energize and de-energize each valve 120 as a function of its angular position. The controller 118 determines the angular positions at which the valves 120 are energized and de-energized based on the desired direction of drilling, and the lag between energization of the valve and the point at which the valve is fully extended.
For example, the drill bit 13 can be guided in the 270° direction denoted in
Since the drill string 12 can rotate at a relatively high speed (250 rpm or greater), the actuating arms 112 should be extended and retracted in a precise, rapid sequence, so that the actuating arms 112 push the drill bit 13 in the desired direction. In the example depicted in
The third actuating arm 112′″ should begin extending at a predetermined distance from the 90° position, so that the third actuating arm 112′″ is fully extended upon reaching the 90° position. The predetermined distance is a function of the lag time between the activation of the associated valve 120, and the point at which the actuating arm 112 reaches its fully extended position. The lag time is application dependent, and can vary with factors such as the discharge pressure of the pump 114, the size and weight of the actuating arms 112, the size of the holes 150 and cylinders 152, etc. A specific value for the predetermined distance therefore is not specified herein.
The accumulators 142 provide a reservoir of the relatively high-pressure oil used to actuate the actuating arms 112. Moreover, the pistons 145 help to ensure that the pressure in the accumulators 142 remains above bore pressure as the valve 120 is energized and the oil within the accumulators is drawn into the associated hole 150. The accumulators 142 can thereby help to minimize the lag time between activation of the valve 120 and the point at which the associated actuating arm 112 is fully extended, by ensuring that a sufficient amount of high-pressure oil is available to actuate the actuator arms 112.
The second actuating arm 112″ should remain retracted as the first and third actuating arms 112′, 112′″ are retracting and extending, respectively, so that the second actuating arm 112″ does not exert any substantial force on the drill bit 13 during this period.
Each actuating arm 112 preferably has features that help urge the actuating arm 112 toward the retracted position as the bottom hole assembly 11 is removed from the bore 17, to help minimize the potential for the actuating arms 112 to be damaged by, or become stuck against the borehole wall. For example, the up-hole end of each actuating arm 112 can be chamfered, and/or can have a helical curvature that causes the actuating arm 112 to move toward the retracted position as the housing 122 of the guidance module 110 is pulled up-hole or rotated during removal from the bore 17.
The signal processor 334 of the MWD tool 300 can be configured to calculate tool face angle based on the azimuth and inclination measurements obtained from the magnetometers 330 and accelerometers 332, using conventional techniques known to those skilled in the art of underground drilling. Alternatively, tool face angle can be calculated based on the techniques described in U.S. provisional application entitled “Method and Apparatus for Measuring Instantaneous Tool Orientation While Rotating,” Ser. No. 60/676,072, filed Apr. 29, 2005, the contents of which is incorporated by reference herein in its entirety.
The calculated tool face angle can be transmitted from the signal processor to the controller 118 by way of the short-hop telemetry device 336, and the short-hop circuit board and transducer 220.
Information and commands relating to the direction of drilling can be transmitted between the surface and the system 10 using the mud-pulse telemetry system 321, short-hop telemetry device 336, and the short-hop circuit board and transducer 220 (see
The pulser 323 of the mud-pulse telemetry system 321 can generate pressure pulses in the drilling mud being pumped through the drill collar 14, using techniques known to those skilled in the art of underground drilling. The controller 322 can encode the directional information it receives from the controller 118 as a sequence of pressure pulses, and can command the pulser 323 to generate the sequence of pulses in the drilling mud, using known techniques.
A strain-gage pressure transducer (not shown) located at the surface can sense the pressure pulses in the column of drilling mud, and can generate an electrical output representative of the pulses. The electrical output can be transmitted to surface control system 17, which can decode and analyze the data originally encoded in the mud pulses. The drilling operator can use this information, in conjunction with predetermined information about the earth formation 16, and the length of the drill string 12 that has been extended into the bore 17, to determine whether, and in what manner the direction of drilling should be altered.
Pulsers suitable for use as the pulser 323 are described in U.S. Pat. No. 6,714,138 (Turner et al.), and U.S. application Ser. No. 10/888,312, filed Jul. 9, 2004 and titled “Improved Rotary Pulser for Transmitting Information to the Surface From a Drill String Down Hole in a Well.” A technique for generating, encoding, and de-coding pressure pulses that can be used in connection with the mud-pulse telemetry system 321 is described in U.S. application Ser. No. 11/085,306, filed Mar. 21, 2005 and titled “System and Method for Transmitting Information Through a Fluid Medium.” Each of these patents and applications is incorporated by reference herein in its entirety.
Pressure pulses also can be generated in the column of drilling mud within the drill string 12, by a pulser (not shown) located on the surface. Directional commands for the system 10 can be encoded in these pulses, based on inputs from the drilling operator.
The pressure pulsation sensor 324 can sense the pressure pulses, and can send an output to the controller 322 representative of the sensed pressure pulses. The controller 322 be programmed to decode the information encoded in the pressure pulses. This information can be relayed to the controller 118 by the short-hop telemetry device 336 of the MWD tool 300, and the short-hop circuit board and transducer 220, so that the controller 118 can direct the drill bit 13 in a direction commanded by the drilling operator.
A pressure pulsation sensor suitable for use a the pressure pulsation sensor 324 is disclosed in U.S. Pat. No. 6,105,690 (Biglin, Jr. et al.), which is incorporated by reference herein in its entirety.
The switching device 326 senses whether drilling mud is being pumped through the drill string 12. The switching device 326 is communicatively coupled to the controller 322. The controller 322 can be configured to store data received from the controller 118 and the other components of the MWD tool 300 when drilling mud is not being pumped, as indicated by the output of the switching device 326. The controller 322 can initiate data transmission when the flow of drilling mud resumes. A suitable switching device 326 can be obtained from APS Technology, Inc. as the FlowStat™ Electronically Activated Flow Switch.
Additional information concerning the manner in which the actuating arms 112 can be extended and retracted to guide the drill bit 13 in a desired direction can be found in U.S. Pat. No. 6,257,356 (Wassell).
Alternative embodiments of the system 10 can be configured so that the guidance module 110 can be located more remotely from the drill bit 13 than in the system 10. Extending the actuating arms 112 in a system configured in this manner adds curvature to the bottom-most portion of the drill string 12, and thereby tilts the drill bit 13. Systems that operate by tilting the drill bit 13 are sometimes referred to as “three point systems” or “point the bit” systems. The drill bit 13 of a three-point system does not require side-cutting capability.
An example of a three point system 10a is depicted in
The system 10 (and the system 10a) can facilitate directional drilling using a drilling motor, without a need for a bent drilling-motor housing or a bent subassembly. Hence, the drill string 12 can drill an in-gauge bore 18 during straight-hole drilling, in contradistinction to a conventional steerable system.
Moreover, as the drill string 12 rotates during directional drilling, the drill string 12 does not need to slide during directional drilling. Hence, it is believed that the drill string 12 can achieve a relatively high rate of penetration during directional drilling, in comparison to a conventional steerable system. Moreover, it is believed that the drill string 12 is not subject to the bit whirl, stick slip, and cuttings-removal difficulties that can be prevalent in conventional steerable systems during directional drilling.
The use of a drilling motor such as the drilling motor 25 in the system 10 can substantially increase the power available to rotate the drill bit 13, in comparison to a conventional rotary steerable tool that does not include a drilling motor. Hence, it is believed that the rate of penetration of a drill string equipped with the system 10 is substantially higher than the rate of penetration of a comparable drill string equipped with a conventional rotary steerable tool.
Moreover, the system 10 allows the drill bit 13 to rotate at velocity different than the rotational velocity of the drill collar 14. Hence, the drill bit 13 can be rotated at a relatively high velocity that results in relatively high rate of penetration, while the housing 122 of the guidance module 110 can rotate at a relatively low velocity suitable for contact between the arms 112 and the surface of the bore 17.
The foregoing description is provided for the purpose of explanation and is not to be construed as limiting the invention. While the invention has been described with reference to preferred embodiments or preferred methods, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Furthermore, although the invention has been described herein with reference to particular structure, methods, and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all structures, methods and uses that are within the scope of the appended claims. Those skilled in the relevant art, having the benefit of the teachings of this specification, may effect numerous modifications to the invention as described herein, and changes may be made without departing from the scope and spirit of the invention as defined by the appended claims.
Pursuant to 35 U.S.C. §202(c), it is acknowledged that the U.S. government may have certain rights to the invention described herein, which was made in part with funds from the U.S. Department of Energy National Energy, Grant No. DE-FG02-02ER83368.
| Number | Name | Date | Kind |
|---|---|---|---|
| 6050346 | Hipp | Apr 2000 | A |
| 6089332 | Barr et al. | Jul 2000 | A |
| 6102681 | Turner | Aug 2000 | A |
| 6105690 | Biglin, Jr. et al. | Aug 2000 | A |
| 6230823 | Sieniawski | May 2001 | B1 |
| 6257356 | Wassell | Jul 2001 | B1 |
| 6328119 | Gillis et al. | Dec 2001 | B1 |
| 6392561 | Davies et al. | May 2002 | B1 |
| 6595303 | Noe et al. | Jul 2003 | B2 |
| 6626254 | Krueger et al. | Sep 2003 | B1 |
| 6659200 | Eppink | Dec 2003 | B1 |
| 6714138 | Turner et al. | Mar 2004 | B1 |
| 20040016571 | Kruger | Jan 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 530 045 | Mar 1993 | EP |
| 0 540 045 | May 1993 | EP |
| 0 770 760 | May 1997 | EP |
| 0 874 128 | Oct 1998 | EP |
| 2 259 316 | Mar 1993 | GB |
| 2 408 526 | Jun 2005 | GB |
| 2 410 042 | Jul 2005 | GB |
| 0125586 | Apr 2001 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20060243487 A1 | Nov 2006 | US |
