SHOCK ABSORBING TOOL AND METHODS OF USE

Abstract

According to embodiments, an apparatus and methods of use are provided for simultaneously and continuously absorbing both axial and torsional shock imparted on drilling equipment conventionally used during the drilling of a subterranean wellbore in the oil and gas industry.

Description

FIELD

Embodiments herein relate to an improved shock absorbing tools and methods of use in the oil and gas industry, the tools operative to absorb and control (dampen) both axial and radial shock and vibration imparted on commonly used components of drilling assemblies.

BACKGROUND

In the oil and gas industry, there is a need to protect downhole equipment from the high-shock downhole environment, particularly during directional drilling where measurement while drilling (MWD), logging while drilling (LWD), and logging while tripping (LWT) procedures are performed. For instance, some directional drilling procedures use a rotary steerable system (RSS) where the drill string is rotated from surface and downhole devices cause the drill bit to drill in the desired direction. Such downhole systems contain sensitive equipment (e.g., electronics, sensors, etc.) the reliability of which can be impacted by the severe torsional, axial, and lateral vibration and shock caused when the drilling system moves up/down and is rotated in the wellbore.

Controlling shock and vibration in the downhole environment becomes increasingly difficult where interactions between the drill bit and the rock formation are impacted by diverse geological complexities, varying angles of the intersection between the drill bit and the specific strata of the rock formation, and even the type of drill bit being used. In some horizontal drilling cases, severe torsional stresses can be imposed on the drill string due to the friction of a long section of stationary drill pipe lying against a lower surface of the wellbore. In such deviated sections, a drill string may “wound up” as rotation of the string commences and the frictional forces of the string against the well must be overcome before the rotation of the drill string occurs, often leading to a violent release of torsional energy.

More specifically, torsional vibration is most noticeable to the driller and is commonly referred to as ‘stick-slip’. Symptoms of stick-slip can cause power fluctuations in the power required to maintain a constant rate of surface rotation. These fluctuations are caused when the drill bit momentarily stops rotating (stick), which builds torque in the drill string. The torque builds to a point where it suddenly releases (slip), and the bit and drill string unwind rapidly to catch up. Stick-slip causes fatigue to drill-collar and pipe connections, invokes bit damage, and slows down the drilling operation. Axial vibration, commonly called ‘bit bounce’, is produced when the drill bit cannot maintain constant contact with the formation. Axial shock and vibration can be detected at the surface by variations in hook load as the drill string bounces up and down. Bit bounce can destroy bits, resulting in slower drilling and more bit trips.

Various anti-vibration tools have been developed and are known in the industry. Many tools, such as described in U.S. Pat. No. 9,109,410, require the use of at least one and often multiple elastomeric elements (springs), which serve to transmit torque and weight (bounce). However, such tools are subject to mechanical failures due to cyclical fatigue, and often require that elastomeric components be lubricated. Unfortunately, even where sensitive equipment is engineered to withstand stress and loading, including High Frequency Torsional Oscillations (“HTFO”) characterized by oscillations over 50 Hz, such systems are prone to premature damage and failure, reducing the system's overall life expectancy.

There remains a need in the oil and industry for improved shock and vibration absorbing tools operative to simultaneously reduce both severe reactive torques and axial vibrations imparted on the drill string, particularly during deviated/directional drilling into hard formations. It would be beneficial for such improved tools to be capable of withstanding excessive Ibs-force in excess of acceptable drilling parameters.

SUMMARY

According to embodiments, an apparatus is provided for simultaneously dampening at least axial and torsional forces imparted on drilling equipment during drilling of a subterranean wellbore. In some embodiments, the apparatus may comprise at least one housing forming a housing central bore extending longitudinally therethrough, and having an inner surface, a portion of which may form a plurality of longitudinally extending splines, at least one spline assembly, slidably received within the housing bore, and forming a spline assembly bore extending longitudinally therethrough, the spline assembly having an outer surface, at least a portion of which may form a plurality of longitudinally extending grooves for corresponding with the plurality of longitudinally extending splines, an inner surface, at least a portion of which may form a plurality of helical keys radially disposed about the inner surface, and at least one piston, operably connected to the at least one spline assembly, at least one mandrel, telescopically received in a first tool-neutral position within the spline assembly bore, and forming a mandrel bore extending longitudinally therethrough, the at least one mandrel having an outer surface, at least a portion of which may form a plurality of helical grooves for corresponding with the plurality of helical keys of the at least one spline assembly, at least two hydraulic fluid chambers, the at least two hydraulic fluid chambers being axially spaced and fluidically distinct from one another, a first one of the at least two hydraulic fluid chambers configured to house the at least one piston and controllably dampen movement thereof, wherein, at least the axial forces cause the at least one mandrel to travel relative to the at least one spline assembly, imparting forces on the at least one spline assembly, causing the longitudinally extending grooves of the spline assembly to move along the corresponding splines of the housing, and wherein, at least the torsional forces cause the at least one mandrel to telescopically rotate within the least one spline assembly, imparting forces on the at least one spline assembly, causing the helical groves of the mandrel to move along the corresponding helical keys of the spline assembly, and wherein movement of the at least one mandrel relative to the at least one spline assembly into a second shock-absorbing position is hydraulically absorbed and opposed by movement of the piston within the first one of the at least two hydraulic fluid chambers returning the at least one mandrel to the first tool-neutral position.

In some embodiments, return movement of the at least one mandrel to the first tool-neutral position is hydraulically absorbed and opposed by a second of the at least two hydraulic fluid chambers.

In some embodiments, the at least one housing may comprise at least two housing tubulars.

In some embodiments, one of the at least two fluid chambers is formed between the inner surface of the at least one housing and the outer surface of the at least one mandrel.

In some embodiments, the at least one housing comprises at least one upper seal assembly tubular, and the second one of the at least two fluid chambers are formed between an inner surface of the at least one upper seal assembly tubular and the outer surface of the at least one mandrel.

In some embodiments, the at least two fluid chambers contain different volumes of hydraulic fluid. In some embodiments, the hydraulic fluids are pre-loaded into the at least two fluid chambers prior to operation of the apparatus.

In some embodiments, the apparatus is threadably engaged within and rotatable with a drilling string for drilling the subterranean wellbore.

According to embodiments, methods are provided for simultaneously dampening at least axial and torsional forces imparted on drilling equipment during drilling of a subterranean wellbore, the method comprising providing an apparatus having at least one housing, the at least one housing having an inner surface, at least a portion of which forming a plurality of longitudinally extending splines, at least one spline assembly, slidably received within the housing. The spline assembly may have an outer surface, at least a portion of which may form a plurality of longitudinally extending grooves for corresponding with the plurality of longitudinally extending splines of the at least one housing, and an inner surface, at least a portion of which my form a plurality of helical keys, the at least one spline assembly operably connected to at least one piston. The apparatus may further comprise at least one mandrel, telescopically received within the spline assembly, the mandrel having an outer surface, a least a portion of which may form a plurality of helical grooves for corresponding with the helical keys of the spline assembly, and at least two fluid chambers, the at least two fluid chambers being axially spaced and fluidically distinct from one another, and the at least one piston being positioned within a first one of the at least two fluid chambers, wherein the methods may comprise allowing the apparatus to receive and dampen at least the at least the axial and torsional forces, or both, wherein the axial and torsional forces cause the at least one mandrel to telescope about the plurality of helical keys relative to the plurality of helical grooves of the at least one spline assembly, and further cause the at least one spline assembly to move along the plurality of longitudinal grooves relative to the longitudinal splines of the at least one housing.

In some embodiments, movement of the at least one spline assembly is hydraulically opposed by the at least one piston, recoiling the at least one spline assembly to a tool-neutral position.

In some embodiments, recoil movement of the spline assembly to the tool neutral position is hydraulically opposed by a second of the at least two fluid chambers.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.

FIG. 1 is a side view of the presently improved apparatus, according to embodiments;

FIG. 2A and FIG. 2B are cross-sectional side views of the presently improved apparatus, with an uphole end of the apparatus shown in FIG. 2A and a downhole end of the apparatus shown in FIG. 2B;

FIG. 3 is an isolated cross-section side view of a top sub housing tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 4 is an isolated cross-section side view of an upper seal housing tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 5 is an isolated cross-section side view of a main housing tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 6 is an isolated cross-section side view of a piston assembly housing tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 7 is an isolated cross-section isolated side view of a bottom sub housing tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 8A and FIG. 8B show isolated views of a main housing tubular of the apparatus shown in FIGS. 2A and 2B, the main housing being shown in an isolated cross-section side view (FIG. 8A, taken along lines A-A of FIG. 8B) and a cross-section top view (FIG. 8B), according to embodiments;

FIG. 9 shows an isolated view of an upper mandrel tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 10 shows an isolated view of a lower mandrel extension tubular of the apparatus shown in FIGS. 2A and 2B, according to embodiments;

FIG. 11A and FIG. 11B show isolated views of a spline assembly tubular of the apparatus shown in FIGS. 2A and 2B, the spline assembly tubular being shown in an isolated cross-section side view (FIG. 11A, taken along lines A-A of FIG. 11B) and a cross-section top view (FIG. 11B), according to embodiments;

FIG. 12 shows an isolated view of a piston tubular of the apparatus shown in FIGS. 2A and 2B, the piston tubular being shown in an isolated cross-section view, according to embodiments;

FIG. 13A, FIG. 13B, FIG. 13C, and FIG. 13D show isolated views of at least one split ring of the apparatus shown in FIGS. 2A and 2B, the split ring being shown in a perspective side view (FIG. 13A), a top view (FIG. 13B), a cross-sectional side view (FIG. 13C, taken along lines A-A of FIG. 13B), and a bottom view (FIG. 13D), according to embodiments; and

FIG. 14A, FIG. 14B, and FIG. 14C show isolated views of at least one threaded plug of the apparatus shown in FIGS. 2A and 2B, the plug shown in a perspective side view (FIG. 14A), a top view (FIG. 14B), and a cross sectional view (FIG. 14C) according to embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to embodiments, an apparatus and methods of use are provided for simultaneously and continuously absorbing both axial and torsional shock imparted on drilling equipment conventionally used during the drilling of a subterranean wellbore in the oil and gas industry.

As will be described, apparatus 100 may be configured for use with a drilling system for drilling a wellbore within a subterranean formation, apparatus 100 operative to provide independent axial (load) and radial vibration (torque) absorption, equalizing the weight on bit (WOB) applied to the drilling system while establishing and accelerating beneficial harmonics in the system. In this manner, it is an object of the presently improved apparatus 100 to isolate and reduce vibration and string agitation forces acting against directional drilling systems, e.g., measuring while drilling (MWD) systems, helping to mitigate telemetry interference and system damage. It is a further object of the presently improved apparatus 100 to equalize and improve the rate of penetration (ROP), preventing premature motor stalls, and mitigating the effects of stick-slip (i.e., characterized by fluctuations in the rotational speed of the bottom hole assembly, BHA).

The presently improved apparatus 100 and its methods of use will now be described in more detail having regard to FIGS. 1-14.

In the present description of embodiments, the terms “above/below” and “upper/lower” are used for ease of understanding and are generally intended to mean the relative uphole and downhole direction from the apparatus towards surface vs. deeper into the subterranean wellbore being drilled.

In the present description of embodiments, the term “axial load” may be used to refer to a tension or compression force, usually imparted along the length of the apparatus. The term “torque” or “reactive torque” may refer to the rotational forces, usually imparted on the apparatus by a drive shaft.

According to embodiments, having regard to FIG. 1, the presently improved apparatus 100 generally comprises an outer housing 10 configured to receive at least one mandrel 20 therein, the housing 10 and mandrel 20 operatively connected, and coaxially aligned, with the drilling string (not shown) along longitudinal axis a. In some embodiments, apparatus 100 may be operably (e.g., rotatably) engaged with conventional drilling string for operating a drill bit used to drill a subterranean formation (not shown).

Advantageously, the present apparatus 100 may be configured to be positioned at or near at least one downhole motor (not shown) for providing power to the drill bit. In some embodiments, such as with conventional directional drilling systems, e.g., measurement while drilling (MWD) systems and the like, apparatus 100 may be positioned at or above the motor. In other embodiments, such as with rotary steerable systems (RSS) commonly used to drill subterranean wellbores having longer lateral/horizontal sections, apparatus 100 may be positioned at or below (downhole) the motor, enabling optimized tool face control, weight-on-bit (WOB), and absorbing both axial and torsional forces from the motor, allowing the motor to continue rotating without stalling.

According to embodiments, having regard to FIGS. 2A and 2B, the presently improved apparatus 100 may further comprise at least one spline assembly 30. In some embodiment, housing 10, mandrel 20, and spline assembly 30 may align to form a longitudinal bore extending therethrough and having a sufficient internal diameter to allow the uninhibited passage of drilling fluids through apparatus 100 to downhole elements of the drilling assembly and the drill bit. In this regard, the drilling fluid flow passes from the bore of the drill string into the upper portion of mandrel 20 and through apparatus 100 out of the downhole end of housing 10 without interruption.

In some embodiments, housing 10 may comprise at least one housing tubular having an uphole end 11 and a downhole end 13, and forming central bore 12 extending therebetween. In some embodiments, having regard to FIG. 2A, at its uphole end 11, housing 10 may comprise at least one top sub tubular 14 (FIG. 3), such top sub 14 being operably engaged with housing 10 such as via threaded engagement or any other suitable connection means known in the industry. In some embodiments, having regard to FIG. 2B, at its downhole end 13, housing 10 may comprise at least one bottom sub tubular 18 (FIG. 7), such bottom sub 18 being operably engaged with housing 10 such as via threaded engagement or any other suitable connection known in the industry.

As will be described, housing 10 may further comprise at least upper seal housing 15 (FIG. 4), at least one spline assembly housing 16 (FIG. 2A), and at least one piston assembly housing 17 (FIG. 6), each of the upper seal housing 15, spline assembly housing 16, and piston assembly housing 17, being operably engaged within main housing 10 such as via threaded engagement or any other suitable connection known in the industry. Moreover, top sub 14, upper seal housing 15, spline assembly 16, piston assembly 17, and bottom sub 18, may be coaxially aligned to form the central bore 12, central bore 12 having a sufficient internal diameter so as to slidably receive mandrel 20 therein (as will be described).

According to embodiments, the presently improved apparatus 100 may comprise both a ‘motion’ portion for dampening severe loads imparted on the downhole equipment, and a ‘hydraulic fluid’ portion for enhancing such dampening.

For instance, in some embodiments, the motion portion may comprise movement of mandrel 20 relative to the stationary housing 10, such movement serving to transmit (and absorb) forces therebetween. Movement between mandrel 20 and housing 10 may be transferred via the at least one spline assembly 30.

More specifically, in some embodiments, having regard to FIGS. 8A and 8B, spline assembly housing 16 may form a plurality of longitudinally extending splines 42 (e.g., extending substantially along axis a, positioned radially about the inner surface of spline housing 16. Splines 42 may be configured to correspondingly engage with longitudinally extending grooves 44 positioned radially about outer surface of spline assembly 30 (FIG. 11B), as will be described in more detail. In this manner, forces imparted on apparatus 100 may cause mandrel 20 to telescopically travel within apparatus 100, causing spline assembly 30 to travel relative to spline assembly housing 16, via the corresponding splines and grooves 42, 44. More specifically, as will be described, forces imparted on apparatus 100 (initially upon mandrel 20) may be transferred to and absorbed by the longitudinal translation or movement of spline assembly 30 within spline assembly housing 16. For example, without limitation, axial (compression) forces imparted on apparatus 100 may cause mandrel 20 to travel downwardly (towards the drill bit) relative to housing 16 (via spline assembly 30). Herein, the foregoing is contemplated as a first ‘motion’ portion of apparatus 100 operative to absorb axial loads (and/or torsional loads).

According to embodiments, returning to FIGS. 2A and 2B, apparatus 100 may further comprise at least one mandrel 20, mandrel 20 being substantially circular in cross-section, so as to be slidably received and coaxially aligned within housing bore 12. In some embodiments, mandrel 20 may comprise a singular tubular having an uphole end 21 and a downhole end 23, and forming a central mandrel bore 22 extending therethrough. In other embodiments, as depicted in FIGS. 9 and 10, mandrel 20 may comprise at least one upper tubular 24 (FIG. 9) operably connected to at least one downhole tubular mandrel extension 28 (FIG. 10).

In some embodiments, upper mandrel 24 may comprise a tubular having an uphole end 21 and a downhole end 23, and forming a central mandrel bore 22 extending therethrough. At its uphole end 21, upper mandrel 24 may be operably connected to and rotatable with conventional drilling string, such as via threaded engagement, or any other suitable connection known in the industry. At its downhole end 23, mandrel 24 may be operably connected with the at least one downhole mandrel extension tubular 28, such as via threaded engagement, or any other suitable connection known in the industry.

In some embodiments, having regard to FIG. 10, mandrel extension tubular 28 may comprise a tubular having a corresponding uphole end 21e and a downhole end 23e, and forming a central mandrel bore 22e extending therethrough. As above, at its uphole end 21e, mandrel extension 28 may be operably connected to upper mandrel 24, such as via threaded engagement, or any other suitable connection known in the industry. At its downhole end 23e, mandrel extension 28 may be operably connected to and rotatable with conventional drilling string, such as via threaded engagement, or any other suitable connection known in the industry.

In some embodiments, having regard to FIG. 9, mandrel 20 may form a radial helical groove 46, or plurality of radial helical grooves (e.g., at least a 9-start thread having a substantially deep pitch), extending about its outer surface. Helical groove 46 may be configured to correspondingly engage with a radial helical key 48 (FIG. 11B), or plurality of helical keys, radially disposed and extending about the inner surface of spline assembly 30, as will be described in more detail. In this manner, forces imparted on apparatus 100 may cause mandrel 20 to telescopically travel within apparatus 100, and specifically to rotate along helical groove 46 about longitudinal axis a, causing spline assembly 30 to correspondingly rotate along helical key 48. Such movement of spline assembly 30 causes the assembly 30 to further travel longitudinally relative to spline assembly housing 16, via the corresponding splines and grooves 42, 44 (as described above). More specifically, both axial and torsional loads imparted on apparatus 100 (initially upon mandrel 20) may be simultaneously transferred to and absorbed by the rotational and longitudinal movement of mandrel 20 relative to housing 16, via spline assembly 30. Herein, the foregoing is contemplated as a second ‘motion’ portion of apparatus 10, such first and second motion portions operative to occur alone and/or in combination, depending upon the severity of the loads being dampened. Without limitation, apparatus 100 may react to and controllably absorb axial and torsional forces by providing for mandrel 20 to travel rotationally along helical grooves 46 (e.g., about longitudinal axis a) relative to spline assembly 30 keys 48, while simultaneously traveling longitudinally along splines 42 (e.g., along longitudinal axis a) relative to spline housing grooves 44.

According to embodiments, having regard to FIGS. 11A and 11B, apparatus 100 may comprise at least one spline assembly 30, the spline assembly 30 positioned within an annular space formed between housing 10 (e.g., spline assembly housing 16) and mandrel 20, wherein the at least one spline assembly 30 may be configured to correspondingly engage with both spline assembly housing 16 and mandrel 20, simultaneously transferring both axial (longitudinal) and torsional (rotational) forces therebetween.

In some embodiments, the at least one spline assembly 30 may comprise a substantially cylindrical tubular 34 having an uphole end 31 and a downhole end 33, and forming a central sleeve bore 32 extending therethrough. At its downhole end 33, spline assembly 30 may be operably engaged with at least one piston 36 (FIG. 12, described in more detail below) such as via threaded engagement or any other suitable connection known in the industry. Spline tubular 34 may comprise two circumferential surfaces, outer surface 35, at least a portion of which forming a plurality of longitudinally extending grooves 44 (FIG. 11B) for correspondingly engaging the plurality of longitudinally extending splines 42 about the inner surface of spline assembly housing 16, and inner surface 37, at least a portion of which forming a radial key(s) 48 (FIG. 11A) for correspondingly engaging helical groove(s) 46 extending about the outer surface of mandrel 20.

In this manner, as described, axial load (e.g., bit bounce forces) imparted on mandrel 20 may be transferred to housing 10, via spline assembly 30, when mandrel 20 travels rotationally along radial keys 48 of spline assembly 30, which may then cause spline assembly 30 to travel longitudinally along splines 42 of assembly housing 16. At the same time, rotational torque (e.g., stick-slip) imparted on mandrel 20 may simultaneously be transferred to housing 10, via spline assembly 30, when mandrel 20 travels rotationally along radial keys 48 of spline assembly 30, which may then cause spline assembly 30 to then travel longitudinally along splines 42 of assembly housing 16.

According to embodiments, as above, the presently improved apparatus 100 may comprise both a ‘motion’ portion for dampening severe loads imparted on the downhole equipment, and a ‘hydraulic fluid’ portion for enhancing such dampening.

For instance, in some embodiments, the hydraulic fluid portion may serve to absorb and balance the motion portion, providing a rapid and efficient response to loads being dampened by apparatus 100. In this manner, the presently improved apparatus 100 is not subject to the failure of spring components, which are known to fatigue and fail as the springs weaken over time/use.

According to embodiments, apparatus 100 may further comprise at least one sealed hydraulic fluid chamber positioned therein. In some embodiments, advantageously, apparatus 100 may form at least two distinct sealed hydraulic fluid chambers, such chambers being axially spaced along apparatus 100 and operative to provide opposed hydraulic balancing forces, enhancing overall absorption capabilities of apparatus 100. It should be appreciated that the present apparatus 100 may be specifically engineered so as to eliminate the need for mechanical, elastomeric elements (e.g., springs) conventionally used in the industry.

In some embodiments, each of the at least two fluid chambers may be the same and/or different in size (e.g., compressible hydraulic fluid volume capacities). In some embodiments, each of the at least two fluid chambers may sealably contain the same and/or different high-pressure fluids (e.g., hydraulic oils, silicone based hydraulic fluids, etc.).

It is contemplated that the quantity and fluid characteristics of the fluids contained within each of the at least two chambers may be predetermined and selected based upon the desired hydraulic delay achieved by apparatus 100, and upon the operating conditions within the subterranean formation (e.g., wellbores having different operating temperatures). The present apparatus 100 may be specifically engineered such that the at least two fluid chambers are fully sealed and fluidically isolated from abrasive drilling fluids, preventing such drilling fluids from contacting the internal components of the apparatus 100.

According to embodiments, returning to FIGS. 2A and 2B, apparatus 100 may form an annular space between the inner surface of housing 10 and the outer surface of mandrel 20, such annular space comprising a first uphole sealed hydraulic fluid chamber 50. In some embodiments, first fluid chamber 50 may be formed between upper seal housing 15 and upper mandrel 24, such that increasing fluid pressures within chamber 50 impart movement on at least one annular shoulder 2 of mandrel 20 (FIG. 9) and correspondingly opposed surface 4 of upper seal housing 15 (FIG. 4). In this manner, upper fluid chamber 50 may serve to controllably reduce and oppose recoil forces (uphole travel), imposed upon and causing downhole movement of mandrel 20, as will be described.

In some embodiments, upper seal housing 15 may form at least one fluid port 3 for introducing pre-loaded fluids into chamber 50, such port 3 being sealed using at least one threaded plug 62 (FIGS. 14A, 14B, and 14C). In some embodiments, upper seal housing 15 may further provide at least one bleed valve for circulating excess fluids (allowing fluids to U-tube within chamber 50), preventing apparatus 100 from fluid locking.

According to embodiments, apparatus 100 may also form an annular space between the inner surface of housing 10 and the outer surface of mandrel 20, such annular space comprising a second downhole sealed hydraulic fluid chamber 52. In some embodiments, second fluid chamber 52 may be formed between main housing 10 and downhole mandrel extension 28 and may house the at least one piston 36 therein. In this manner, axial and torsional forces, or a combination thereof, imparted upon and causing downhole movement of mandrel 20 are absorbed by mandrel 20 actuating longitudinally and/or rotating about spline assembly 30, causing movement of spline assembly 30 and, correspondingly, movement of piston 36 within chamber 52. Where assembly 30 causes piston 36 to travel downhole within chamber 52, piston 36 may serve as a plunger within chamber 52, compressing hydraulic fluids and serving as a second motion portion to rapidly and efficiently absorb the first motion portion of apparatus 100. Such absorption of movement by the hydraulic fluids enables direct and abrupt reduction in severe reactive torques and vibrations (e.g., caused during hard formation drilling), effectively mitigating drilling deficiencies such as reactive torque and stick-slip.

In some embodiments, main housing 10 may form at least one second fluid port 5 for introducing pre-loaded fluids into chamber 52, such port 5 being sealed using at least one threaded plug 62 (FIGS. 14A, 14B, and 14C). In some embodiments, main housing tubular 10 may provide for at least one bleed valve for circulating excess fluid within chamber 52, preventing apparatus 100 from fluid locking.

According to embodiments, in operation, high-impact forces imparted on mandrel 20, causing mandrel 20 to travel relative to housing 10 (i.e., downwardly and along spline sleeve 30), are efficiently absorbed and dampened hydraulically by fluid pressures within downhole chamber 52. More specifically, axial loads and/or reactive torque imparting movement of mandrel 20, and corresponding movement of spline assembly 30, causes movement of piston 36 positioned within downhole chamber 52 (increasing fluid pressures within chamber 52). Once forces are dampened, increased fluid pressures within chamber 52 serve to return piston 36 back uphole (e.g., to a tool-neutral position), causing spline assembly 30 and ultimately mandrel 20 to return therewith. In this manner, downhole chamber 52 may serve to provide a continuous, more rapid dampening of harmful reactive torque and vibration, having substantially faster reaction times than spring-biased systems conventionally used in the industry. Downhole chamber 52 may also serve to maintain consistent load/deflection characteristics, regardless of the depth of the wellbore, the bit weight, pump pressures, mud weight, and/or torque.

As the mandrel 20 returns back up-hole (to a tool-neutral state), any recoil forces imposed upon apparatus 100 may be absorbed and dampened by increasing fluid pressures within upper chamber 50, serving to react to and oppose fluid pressures within downhole chamber 52. In this manner, upper chamber 50 may serve to continuous balance fluid pressure changes within downhole chamber 52, enabling the presently improved apparatus 100 to provide an entirely hydraulic fluid system for absorbing and dampening harmful axial and torsional forces.

According to embodiments, having regard to FIG. 12, apparatus 100 may further comprise at least one piston 36 operably connected to spline assembly 30, such as via threaded engagement or any other suitable connection known in the industry. As described, piston 36 may be operably connected to the at least one spline assembly 30 so as to be positioned within the at least one downhole fluid chamber 52, serving to absorb forces imparted on the mandrel 20 (and correspondingly on spline assembly 30), and operative to return mandrel 20 to a relatively tool-neutral state.

In some embodiments, the at least one piston 36 may form at least one tubular having an uphole end, a downhole end, and a longitudinal central bore extending therethrough, piston central bore being coaxially with central spline tubular bore 32, along longitudinal axis a. In some embodiments, about its inner surface piston 36 may form a plurality of inner seal grooves 6 for receiving at least one seal (e.g., O-rings, etc.). In some embodiments, about its outer surface, piston 36 may form a plurality of outer seal grooves 7 for receiving at least one seal (e.g., O-rings, etc). In this manner, and in combination with at least one annular seal positioned about the outer surface of spline assembly 30, downhole fluid chamber 52 is fluidically sealed from uphole fluid chamber 50.

According to embodiments, apparatus 100 may provide at least one split ring 60 (FIGS. 13A-13D), and at least one threaded plug 62 (FIGS. 14A-14C). As may be appreciated, split ring 60 may serve as a fail-safe, ensuring movement of mandrel 20 is maintained within operational limits (e.g., within a finite distance of travel), and that apparatus 100 does not become unscrewed from the drill string.

According to embodiments, methods of simultaneously absorbing axial and torsional shock imparted on drilling equipment during drilling of a subterranean wellbore in an oil and gas formation are provided. In some embodiments, method may comprise providing at least one of the presently improved apparatus described herein within a drilling string for drilling the wellbore. Once the drill bit is placed on the bottom of the hole, fluid flow to the bit may be started and drilling may commence, with apparatus 100 remaining in an essentially tool-neutral state.

During drilling, axial (load/compression) forces imparted on the drill string may be received and absorbed by apparatus 100. For example, axial loads caused by the drill bit (e.g., bit bounce) may be absorbed by the at least one mandrel 20 telescopically moving longitudinally within apparatus 100, causing spline assembly 30 to travel along its grooves 44 relative to assembly housing 16 splines 42. Longitudinal movement of spline assembly 30 correspondingly actuates piston 36 within downhole hydraulic fluid chamber 52 into a shock-absorbing state, allowing the loads to be absorbed by the hydraulic fluids therein. Increased fluid pressures within chamber 52 then serve to actuate the at least one piston 36 back uphole, returning or recoiling the spline assembly 30 and correspondingly mandrel 20 to the tool-neutral state. Advantageously, recoiling travel of the mandrel 20 may be absorbed and opposed by hydraulic fluid within the uphold hydraulic fluid chamber 50, the fluid pressures within uphole chamber 50 acting upon annular shoulder 2 of mandrel 20 and the correspondingly opposed annular surface 4 of the upper seal housing 15.

Simultaneously, torsional (rotational) forces imparted on the drill string may be received and absorbed by apparatus 100. For example, torsional forces caused by the drill bit (stick slip) may also be absorbed by the at least one mandrel 20 telescopically rotating within apparatus 100, causing mandrel 20 to rotate along its helical grooves 46 relative helical keys 48 of spline assembly 30. Depending upon the strength of the forces, such rotation may also cause longitudinal travel of the spline assembly 30 relative to assembly housing 16 as described above in response to axial forces. Herein, the foregoing is intended to describe the first ‘motion’ portion of the presently improved apparatus 100.

In addition, any forces large enough to cause movement of spline assembly 30 correspondingly cause piston 36 to move, compressing hydraulic fluids contained within the at least one downhole fluid chamber 52. As such, the shock-absorbing state of apparatus 100 is rapidly absorbed by hydraulic fluids within chamber 52. Once absorbed, fluid pressures within chamber 52 serve to actuate piston 36, and correspondingly spline assembly 30, back towards the initial tool-neutral state. As above, advantageously, recoiling travel of the spline assembly 30, and mandrel 20, may be absorbed and opposed by hydraulic fluid within the uphold hydraulic fluid chamber 50, the fluid pressures within uphole chamber 50 acting upon annular shoulder 2 of mandrel 20 and the correspondingly opposed annular surface 4 of the upper seal housing 15. Herein, the foregoing is intended to describe the first ‘hydraulic fluid’ portion of the presently improved apparatus 100. In operation, the motion and hydraulic fluid absorption capabilities of apparatus 100 combine to provide faster, enhanced capacity (greater load), and continuous dampening reaction to axial forces, torsional forces, or both.

Although a few embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications can be made to these embodiments without changing or departing from their scope, intent or functionality. The terms and expressions used in the preceding specification have been used herein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and the described portions thereof.

Claims

1. An apparatus for simultaneously dampening at least axial and torsional forces imparted on drilling equipment during drilling of a subterranean wellbore, the apparatus comprising: at least one housing having an uphole end, a downhole end, and forming a housing central bore extending longitudinally therethrough, the at least one housing having an inner surface a portion of which forming a plurality of longitudinally extending splines,at least one spline assembly, slidably received within the housing bore, the at least one spline assembly having an uphole end, a downhole end, and forming a spline assembly bore extending longitudinally therethrough, the spline assembly havingan outer surface, at least a portion of which forming a plurality of longitudinally extending grooves for corresponding with the plurality of longitudinally extending splines of the at least one housing,an inner surface, at least a portion of which forming a plurality of helical keys radially disposed about the inner surface, andat least one piston, operably connected to the at least one spline assembly,at least one mandrel, telescopically received in a first tool-neutral position within the spline assembly bore, having an uphole end, a downhole end, and forming a mandrel bore extending longitudinally therethrough, the at least one mandrel having an outer surface, at least a portion of which forming a plurality of helical grooves for corresponding with the plurality of helical keys of the at least one spline assembly,at least two hydraulic fluid chambers, the at least two hydraulic fluid chambers being axially spaced and fluidically distinct from one another, a first one of the at least two hydraulic fluid chambers configured to house the at least one piston and controllably dampen movement thereof,wherein, at least the axial forces cause the at least one mandrel to travel relative to the at least one spline assembly, imparting forces on the at least one spline assembly, causing the longitudinally extending grooves of the spline assembly to move along the corresponding splines of the housing, andwherein, at least the torsional forces cause the at least one mandrel to telescopically rotate within the least one spline assembly, imparting forces on the at least one spline assembly, causing the helical groves of the mandrel to move along the corresponding helical keys of the spline assembly, andwherein movement of the at least one mandrel relative to the at least one spline assembly into a second shock-absorbing position is hydraulically dampened and opposed by movement of the piston within the first one of the at least two hydraulic fluid chambers returning the at least one mandrel to the first tool-neutral position.

2. The apparatus of claim 1, the return movement of the at least one mandrel to the first tool-neutral position is hydraulically dampened and opposed by a second of the at least two hydraulic fluid chambers.

3. The apparatus of claim 1, wherein the at least one housing may comprise at least two housing tubulars.

4. The apparatus of claim 3, wherein the first of the at least two fluid chambers is formed between the inner surface of the at least one housing and the outer surface of the at least one mandrel.

5. The apparatus of claim 3, wherein the at least one housing comprises at least one upper seal assembly tubular, and the second of the at least two fluid chambers is formed between an inner surface of the at least one upper seal assembly tubular and the outer surface of the at least one mandrel.

6. The apparatus of claim 1, wherein the at least two fluid chambers contain different volumes of hydraulic fluid.

7. The apparatus of claim 6, wherein the hydraulic fluids are pre-loaded into the at least two fluid chambers prior to operation of the apparatus.

8. The apparatus of claim 1, wherein the apparatus is threadably engaged within and rotatable with a drilling string for drilling the subterranean wellbore.

9. A method for simultaneously dampening at least axial and torsional forces imparted on drilling equipment during drilling of a subterranean wellbore, the method comprising: providing an apparatus having at least one housing, the at least one housing having an inner surface, at least a portion of which forming a plurality of longitudinally extending splines,at least one spline assembly, slidably received within the housing, the spline assembly havingan outer surface, at least a portion of which forming a plurality of longitudinally extending grooves for corresponding with the plurality of longitudinally extending splines of the at least one housing, andan inner surface, at least a portion of which forming a plurality of helical keys, the at least one spline assembly operably connected to at least one piston,at least one mandrel, telescopically received within the spline assembly, the mandrel having an outer surface forming a plurality of helical grooves for corresponding with the helical keys of the spline assembly, andat least two fluid chambers, the at least two fluid chambers being axially spaced and fluidically distinct from one another, and the at least one piston being positioned within a first one of the at least two fluid chambers,and allowing the apparatus to dampen at least the axial and torsional forces, or both, wherein the axial and torsional forces cause the at least one mandrel to telescope about the plurality of helical keys relative to the plurality of helical grooves of the at least one spline assembly, and further cause the at least one spline assembly to move along the plurality of longitudinal grooves relative to the longitudinal splines of the at least one housing.

10. The method of claim 9, wherein movement of the at least one spline assembly is hydraulically opposed by the at least one piston, recoiling the at least one spline assembly to a tool-neutral position.

11. The method of claim 10, wherein recoil movement of the spline assembly to the tool neutral position is hydraulically opposed by a second of the at least two fluid chambers.

12. The method of claim 9, wherein the apparatus may be operably connected within the drilling equipment for drilling the subterranean formation.

13. The method of claim 12, wherein drilling fluids for operating the drilling equipment may pass through the housing central bore.