Downhole motor assembly, system and method

Abstract

The present disclosure relates to improved downhole motor designs. In one illustrative embodiment, primary and secondary thrust bearings held in place by other structural components of the motor are positioned inside the motor housing for protection from cuttings and debris in the drilling fluid without compressive loading of the entire bearing assembly. In some illustrative embodiments, a drive train featuring at least one multi-part segmented flexible joint can allow for a shortened flexible shaft while adequately converting eccentric forces from a power source into rotation of a spindle.

Description

Background Art

[0001] In some applications, the rotary power for the downhole drill bit can be transmitted from a rotary power source at the surface via a drive shaft system, which may include a universal joint, CV joint, or a segmented drive system to allow bending, but requires the entire length of the deployed drill string to rotate. Other methods use a downhole "mud motor" that operates on the deployed drill string to provide rotary power near the operating device (e.g., a downhole drilling rig). Although there are many designs, most include many different bearing assemblies that must be "pre-loaded" in order to seal and operate under the desired conditions.

[0002] Although various forms are adopted, a downhole motor generally comprises an outer housing fixed (usually by threading) to the drilling string, and a rotatable spindle (sometimes called a drive connection) positioned within the housing and extending from the lowermost end of the housing. It is the spindle that is rotated by the circulation of fluid through the drill string and the downhole motor. The drilling bit is connected to the lowermost end of the spindle, usually with a "bit box" connection thereto. Thus, the spindle is free to rotate relative to the housing, but is still longitudinally fixed within the housing.

[0003] The forces between the housing and the spindle are radial (side to side) and axial or thrust loads (acting along the longitudinal axis of the downhole motor). Radial bearings are located within the housing, between the housing and the spindle, to carry the radial loads.

[0004] Thrust loads can be further divided into (1) loads or forces tending to push the mandrel out of the housing; and (2) loads or forces tending to push the mandrel upward into the housing, or in other words, loads or forces transmitted from the housing to the mandrel to force the mandrel downward (such as applying weight on the drill bit during drilling). With respect to the first type of thrust load, a thrust bearing is located within the housing to withstand loads tending to force the mandrel axially away from the lower end of the housing; such loads are generated by the circulation of fluid when the drill bit leaves the bottom (such fluid pressure tends to push the mandrel out of the housing), or by pulling on the drilling drill string when the drill bit and / or mandrel are stuck in the hole. These thrust bearings are called "off-bottom bearings" or secondary thrust bearings.

[0005] Regarding the second type of thrust load, in order to transfer the load to the drilling bit, the weight of the drilling string is first transferred to the housing, then from the housing to the spindle, and then from the spindle to the drilling bit. This downward weight or force transfer between the housing and the spindle is accomplished through one or more thrust bearings, which are called "on-bottom bearings" or main thrust bearings.

[0006] To be practical, most mud motor designs require that one or both thrust bearings, typically in the thrust bearing group, must be compression loaded prior to use. This may require additional components to achieve and maintain the "preload" compression. Typically, this is accomplished by mechanically locking the entire assembly together to apply a torque through the entire assembly to "preload" the entire bearing assembly. The torque applied can be considerable, and such forces can cause excessive wear and can cause problems with temperature changes during use. In addition, most designs use a flexible drive shaft or "flex shaft," which is an elongated member of sufficient length and flexibility to account for eccentric motion during rotation.

[0007] Downhole motors, motor systems and methods that do not require the application of a "preload" would be an improvement over the prior art. Such motors or components that can account for or compensate for eccentricity variations and / or allow for shorter lengths would be an additional improvement over the prior art. Summary of the invention

[0008] The present disclosure relates to improved downhole motor designs. In one illustrative embodiment, primary and secondary thrust bearings held in place by other structural components of the motor are located inside the motor housing for protection from cuttings and debris in the drilling fluid without compressive loading of the entire bearing assembly. In some illustrative embodiments, a drive train featuring at least one multi-part segmented flexible joint can allow for a shortened flexible shaft while adequately converting eccentric forces from a power source into rotation of a spindle. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following drawings, wherein, unless otherwise specified, the same reference numerals refer to the same parts in each view. It will be understood by those of ordinary skill in the art that the various drawings are for illustration purposes only. The nature of the present disclosure and other embodiments according to the present disclosure may be more clearly understood by reference to the following detailed description, the appended claims, and the several drawings.

[0010] Figure 1A 1B and 1B depict a side view and a cross-sectional side view, respectively, of a first illustrative embodiment of a drive unit for a downhole motor according to the present disclosure.

[0011] Figures 2A and 2B depict Figure 1A and 1B , side view and cross-sectional side view of the assembled internal components.

[0012] 3A and 3B depict a side view and a cross-sectional side view, respectively, of another illustrative embodiment of a drive unit for a downhole motor according to the present disclosure.

[0013] 4A and 4B depict a side view and a cross-sectional side view, respectively, of the assembled internal components of FIGS. 3A and 3B .

[0014] 5 is a perspective view of an illustrative embodiment of a top member of a flexible CV joint assembly that may be used alone in the embodiment of FIGS. 3A through 4B .

[0015] 6 is a perspective view of an illustrative embodiment of an intermediate member of a flexible CV joint assembly that may be used alone in the embodiment of FIGS. 3A-4B .

[0016] 7 is a side view of an illustrative embodiment of a retaining pin assembly of a flexible CV joint assembly that may be used alone in the embodiment of FIGS. 3A through 4B .

[0017] 8A is a perspective view of an illustrative embodiment of a lower secondary thrust bearing that may be used alone in the embodiment of FIGS. 3A through 4B .

[0018] 8B is a perspective view of an illustrative embodiment of a lower main thrust bearing that may be used alone in the embodiment of FIGS. 3A through 4B .

[0019] 9A is a perspective view of an illustrative embodiment of an upper main bearing that may be used alone in the embodiment of FIGS. 3A-4B .

[0020] 9B is a perspective view of an illustrative embodiment of an upper secondary thrust bearing that may be used alone in the embodiment of FIGS. 3A through 4B . DETAILED DESCRIPTION

[0021] A detailed description of systems and methods consistent with embodiments of the present disclosure is provided below. Although several embodiments are described, it should be understood that the present disclosure is not limited to any one embodiment, but rather encompasses many replacements, modifications, and equivalents. In addition, although many specific details are set forth in the following description in order to provide a comprehensive understanding of the embodiments disclosed herein, some embodiments may be practiced without some or all of these details. In addition, for the sake of clarity, certain technical materials known in the relevant art are not described in detail to avoid unnecessarily obscuring the present disclosure.

[0022] Go to Figure 1A, 1B, 2A and 2B, depict a first illustrative embodiment of a drive unit 10 for a downhole motor according to the present disclosure. It should be understood that the drive unit can be connected to a stator housing (not shown) that includes a top connection for attachment to a drilling drill string and an internal rotor actuated by a drilling fluid. At the top end of the drive unit 10, a drive shaft or flexible shaft 102 can have a threaded upper end 103 for attachment to the rotor, an elongated shaft 101 and a lower end 105, which can include an internal threaded hole 107 for attachment to a flexible joint assembly 200.

[0023] The flexible joint assembly 200 can be formed as a multi-part CV joint. In the illustrated embodiment, the flexible joint assembly 200 can include three interlocking members: an upper member 300, an intermediate member 400, and a lower member 500. Each member has a hole that is generally aligned when assembled. A retaining pin 600 extends from a lower base having a flat bottom to an upwardly extending shaft, the retaining pin passing through the generally aligned holes. A retaining nut 602 can be threadedly fixed around an upper portion of the shaft. The lower surface of the retaining nut and the transition from the lower base to the shaft can be curved to allow movement of the three interlocking members.

[0024] As shown, the three interlocking members include corresponding interlocking portions that can be formed as a series of recessed splines separated by grooves. It should be understood that the splines and grooves of each interlocking portion can correspond to the grooves and splines of the paired interlocking portions of the adjacent interlocking members. In the assembled form, the corresponding adjacent interlocking portions of the interlocking members are inserted into each other as shown.

[0025] The lower member 500 may have a connection portion for connecting to the flexible joint bottom adapter 800. In the embodiment shown, it may be a threaded connection. At the lower end, the hole may have a tapered opening corresponding to the retaining pin 600.

[0026] It should be understood that the grooves and splines of the interlocking portions of the components of the flexible joint can extend in a generally top-to-bottom direction aligned with the long axis of the motor assembly, and can extend in a generally lateral direction to allow the components to move in two directions so that the flexible joint can provide rotational power drive to the bottom adapter 800 while allowing the components 300, 400 and 500 to move angularly relative to each other on the pin 600, thereby providing flexibility and addressing rotational eccentricity when power is applied.

[0027] It should be understood that in other embodiments, the internal and external positioning of the various interlocking parts and the specific number and shape of the splines and grooves can be varied, as long as the ability to transmit rotational power is provided while providing the necessary flexibility. It should be understood that in other embodiments, there may be one or more additional intermediate section members to provide increased flexibility. For example, two or three intermediate members can be used with a suitable pin 600.

[0028] The bottom adapter 800 has an upper connection portion 802 adapted to be connected to the lower interlocking member 500 by means of a threaded socket. At the lower end, the spindle connection portion 804 allows connection to the spindle 1000 by means of a threaded socket accessible from the lower surface. In addition, the lower surface may have a connection for the upper secondary thrust bearing 902. In the embodiment shown, this may be an external thread to which the upper secondary thrust bearing 902 is fixed.

[0029] It should be understood that the spindle 1000 extends from a lower connecting portion 1004 at the bottom, which lower connecting portion may be a threaded socket allowing connection to a drilling bit or other tool provided with rotational power, to an upper end, and the upper end may include a connecting structure for connecting to the bottom adapter 800, such as an external threaded portion.

[0030] The secondary thrust bearing assembly 900 includes an upper secondary thrust bearing 902 and a lower secondary thrust bearing 904, which are separated by a gap 905 in the assembled condition. Each of the upper secondary thrust bearing 902 and the lower secondary thrust bearing 904 can be a ring with opposing lateral faces, wherein hardened material (e.g., PCD or PCBN buttons) is disposed facing the opposing thrust bearing. The gap 905 can limit the movement of the spindle when the spindle is from an "off-bottom" position to an "on-bottom" position, and vice versa. In the case of using a PCD or PCBN "button" to form the thrust bearing, the size of the gap 905 can be less than the thickness of the "button" to further reduce the possibility that the bearing element may shift during operation. It should be understood that the "on-bottom / off-bottom" longitudinal movement of the spindle / drive connection is dependent on the connection of the bottom adapter 800 to the spindle 1000. The upper end of the internal bore of the adapter 800 serves as a "stop-point", defining the size of the gap 905 for the longitudinal movement of the spindle 1000. If this hole is too long, the bottom adapter will be able to unscrew and unload the thrust bearing, which will completely jam the assembly. If this hole is too short, the bottom adapter will obviously stop suddenly and the longitudinal movement will be too large.

[0031] The lower secondary thrust bearing 904 may be disposed at the upper end of the drive bearing housing 1200. The drive bearing housing 1200 may be generally formed as a tube having an inner hole, which is mounted on the middle portion of the spindle 1000. Near the upper end, the drive bearing housing may include a connection structure for fixing the lower secondary thrust bearing 904.

[0032] Moving downward from the upper end, the upper radial bearing assembly 1300 , the main thrust bearing assembly 1100 , and the lower radial bearing assembly 1400 may all be disposed between the drive bearing housing 1200 and the spindle 1000 .

[0033] The upper radial bearing assembly 1300 may include an inner upper radial bearing sleeve 1302 that may be attached to the outer surface of the spindle 1000 at a position lower than the lower secondary thrust bearing 904. In the described embodiment, the attachment may be achieved by a slip fit to a key connection and secured with a snap ring placed at an appropriate position on the spindle. It should be understood that this may also be achieved by placing threads in an appropriate position. The outer upper radial bearing sleeve 1304 may be attached to the drive housing 1200 and secured in a groove in the internal bore of the drive housing 1200 above the inner upper radial bearing sleeve 1302. The face of the bearing sleeve may be a suitable hardened material, such as carbide, PCD or PCBN.

[0034] The main thrust bearing assembly 1100 may be disposed inside the drive bearing housing assembly 1200. In the depicted embodiment, the main thrust bearing assembly may be disposed between the upper radial bearing assembly 1300 and the lower radial bearing assembly 1400. The main thrust bearing assembly 1100 includes an upper main thrust bearing 1102 and a lower main thrust bearing 1104, each of which is formed as a ring having lateral faces in which hardened material, such as PCD or PCBN buttons, may be disposed. The opposing lateral faces are arranged to face each other.

[0035] The lower main thrust bearing 1104 can be attached to the outer surface of the spindle 1000 at a location higher than the lower radial bearing assembly 1400. In the depicted embodiment, the attachment is located above a ridge or shelf formed on the spindle so that the lateral surface faces upward. The bearing can be secured by placing on threads. The upper main thrust bearing 1102 can be attached to the drive housing 1200, secured in a groove in the internal bore of the drive housing 1200, such as by placing on threads or using a suitable adhesive.

[0036] The lower radial bearing assembly 1400 may include an inner lower radial bearing sleeve 1402 that may be attached to the outer surface of the spindle 1000 at a location lower than the main thrust bearing assembly 1100. In the depicted embodiment, the lower radial bearing assembly 1400 is disposed at the lower end of the housing 1200, above the lower connection portion 1004 of the spindle 1000. The inner lower radial bearing sleeve 1402 may be attached by placing threads at appropriate locations. The outer lower radial bearing sleeve 1404 may be attached to the drive housing 1200, secured in a groove in the internal bore of the drive housing 1200 above the inner lower radial bearing sleeve 1402. The face of the bearing sleeve may be a suitable hardened material, such as carbide, PCD, or PCBN.

[0037] It is understood that, in addition to PCD, other suitable materials, such as CBN, carbide or other hardened surfaces may also be used for the bearing surface, and it is further understood that the bearing assembly is assembled in the correct position by the assembly of the drive unit, and does not require compression loading before use, especially for thrust bearings. Instead, such bearings do not carry any load until the motor is running, and the movement of the motor used with the tool applies force to the bearing.

[0038] The housing may be used to cover and protect the drive unit bearings and transmission. In the depicted embodiment, a two-part housing is shown. The lower housing H1 may be formed as a tube that is placed above the drive housing 1200 and extends upward over at least a portion of the transmission adapter 800. In the lower portion of the lower housing, the lower housing H1 may include internal threads to allow it to be secured to matching external threads on the drive housing 1200. The upper housing H2 may be similarly threadedly secured to the upper portion of the lower housing H2 and extend upward, with an internal bore covering the flexible joint and at least a portion of the drive shaft. Figure 1A 1B, the lower end of the mandrel 1000, the lower end of the drive bearing housing 1200, and the housings H1 and H2 can all have substantially similar diameters to provide a relatively smooth, rounded exterior to reduce friction and facilitate use in a wellbore by eliminating external features that can get stuck. It should also be understood that the inner sidewall of the housing can conform to the internal components by having thinner and thicker areas to strengthen and hold the components in place.

[0039] In one illustrative embodiment, the placement of the bearings inside the motor provides additional protection from debris, such as cuttings, that may be present in the wellbore. Thus, a motor including a drive unit according to the present disclosure may be particularly advantageous for use in coal bed methane wells, where the abrasive nature of the cuttings and the configuration required for a suitable wellbore may be difficult to achieve with a standard motor.

[0040] Turning to Figures 3A, 3B, 4A and 4B, a second illustrative embodiment of a drive unit 20 for a downhole motor according to the present disclosure is depicted. It should be understood that the drive unit can be connected to a stator housing (not shown) that includes a top connection for attachment to a drilling drill string and an internal rotor actuated by a drilling fluid. At the top end of the drive unit 20, a drive coupling member 2102 has a threaded upper end 2103 for attachment to the rotor and a lower end 2105 that can include an internal threaded hole 2107 for attachment to a first flexible joint assembly 2200A.

[0041] The flexible joint assembly 2200A can be formed as a multi-part CV joint. In the depicted embodiment, the flexible joint assembly 2200A can include three interlocking members: an upper member 2300A, an intermediate member 2400A, and a lower member 2500A. Each member has an internal hole that is generally aligned when assembled. A suitable embodiment of the upper member 2300A is depicted separately in FIG. 5 to show additional details thereof. It should be understood that for ease of assembly, the depicted upper member 2300A can be the same as the lower member 2500A, but simply inverted for use. Similarly, a suitable embodiment of the intermediate member 2400A is depicted separately in FIG. 6 to show additional details thereof.

[0042] The retaining pin 2600A extends from a lower base having a circular bottom 2601A to an upwardly extending shaft 2602A that passes through generally aligned holes of the interlocking members. A retaining cap 2603A may be threadedly secured around an upper portion of the shaft 2602A. The retaining cap 2603A may have a circular upper surface similar to the circular surface of the lower base 2601A. A suitable embodiment of the retaining pin 2600A and retaining cap 2603A is depicted separately in FIG. 7 to show additional details thereof.

[0043] The upper hinge plate 2613A may be disposed at its upper end in the internal bore 2107 of the drive connection member 2102. The lower face of the hinge plate 2613A includes a groove corresponding to the rounded end of the retaining cap 2603A. Similarly, the lower hinge plate 2615A may be disposed at its upper end in the upper internal bore 2117 of the connecting shaft 2110. The upper face of the lower hinge plate 2615A includes a groove corresponding to the rounded end of the rounded bottom base of the retaining pin 2600A.

[0044] In use, the rounded end of the retaining pin assembly can be hinged in the hinge plate, thereby providing additional flexibility for the flexible joint assembly. In addition, the axis of the pin 2600A provides a limit to the compression of the assembly, thereby maintaining at least the minimum space available for longitudinal movement between the interlocking members.

[0045] As shown in the figure, three interlocking members include corresponding interlocking parts, and the interlocking parts can be formed into a series of recessed splines separated by grooves.It should be understood that the splines and grooves of each interlocking part can correspond to the grooves and splines of the matching interlocking parts of adjacent interlocking members.In the assembled form, the corresponding adjacent interlocking parts of the interlocking members are inserted into each other, as shown in the figure.As depicted, the intermediate member 2400A can be positive to positive, or have a generally protruding interlocking part on either end, and the upper member 2300A and the lower member 2500A have a female or recessed interlocking part.It should be understood that in different embodiments, the arrangement of specific interlocking parts can be different.

[0046] The lower member 2500A can have a lower connection portion for connecting to the connection shaft 2110. In the depicted embodiment, the lower connection portion can include external threads 2502A, which can attach to corresponding threads in the upper internal bore 2117 of the connection shaft 2110.

[0047] It should be understood that the grooves and splines of the interlocking portions of the components of the flexible joint can extend in a generally top-to-bottom direction and in a generally lateral direction aligned with the long axis of the motor assembly to allow the components to move in two directions so that the flexible joint can provide rotational power drive to the connecting shaft 2110 while allowing components 2300A, 2400A and 2500A to move angularly relative to each other on pin 2600A, thereby providing flexibility and addressing rotational eccentricity when power is applied.

[0048] It should be understood that in other embodiments, the internal and external positioning of the various interlocking parts and the specific number and shape of the splines and grooves can be varied, as long as the rotational power can be transmitted while providing the necessary flexibility. It should be understood that in other embodiments, there can be one or more additional intermediate section members to provide increased flexibility. For example, two or three intermediate members can be used with a suitable pin 2600A.

[0049] The connecting shaft 2110 extends downwardly to a lower portion 2120 which may include an internally threaded hole 2127 accessible at a lower end thereof for attachment to the second flexible joint assembly 2200B.

[0050] Similar to the first flexible joint assembly 2200A discussed earlier herein, the second flexible joint assembly 2200B can be formed as a multi-part CV joint. In the depicted embodiment, the flexible joint assembly 2200B can include three interlocking members: an upper member 2300B, an intermediate member 2400B, and a lower member 2500B. Each member has an internal hole that is generally aligned when assembled. For ease of assembly, the components of the second flexible joint assembly 2200B can be the same as the components of the first flexible joint assembly 2200A.

[0051] The retaining pin 2600B can extend from a lower base having a circular bottom 2601B to an upwardly extending shaft 2602B that passes through generally aligned holes of the interlocking members. A retaining cap 2603B can be threaded around an upper portion of the shaft 2602B. The retaining cap 2603B can have a circular upper surface similar to the circular surface of the lower base 2601B.

[0052] The upper hinge plate 2613B may be disposed at its upper end in the internal hole 2127 of the lower portion of the connecting shaft 2110. The lower side of the hinge plate 2613B may include a groove corresponding to the rounded end of the retaining cap 2603B. Similarly, the lower hinge plate 2615B may be disposed in the upper internal hole 2803 of the bottom adapter 2800. The upper side of the lower hinge plate 2615B may include a groove corresponding to the rounded end of the rounded bottom base of the retaining pin 2600B. It should be understood that in some embodiments, rather than using separate hinge plates, the hinge grooves may be provided directly attached to the upper and / or lower interconnecting members. The use of hinge plates allows replacement due to wear when it is advantageous.

[0053] In use, the rounded end of the retaining pin assembly can be hinged in the hinge plate, thereby providing additional flexibility for the flexible joint assembly. In addition, the axis of the pin 2600B provides a limit to the compression of the assembly, thereby maintaining at least the minimum space available for longitudinal movement between the interlocking members.

[0054] As shown in the figure, three interlocking members include corresponding interlocking parts, and these interlocking parts can be formed into a series of recessed splines separated by grooves.It should be understood that the spline and groove of each interlocking part can correspond to the groove and spline of the interlocking part of the pairing of adjacent interlocking members.In the assembled form, the corresponding adjacent interlocking parts of interlocking members are inserted into each other, as shown in the figure.As depicted, intermediate member 2400B can be positive to positive, or have a generally protruding interlocking part on either end, and upper member 2300B and lower member 2500B have a female or recessed interlocking part.It should be understood that in different embodiments, the arrangement of specific interlocking parts can be different.

[0055] The lower member 2500B can have a lower connection portion for connecting to the bottom adapter 2800. In the depicted embodiment, the lower connection portion can include external threads 2502B. The bottom adapter 2800 has an upper connection portion 2802, which is adapted to connect to the lower interlocking member 2500B through a threaded socket. At the lower end, the spindle connection portion 2804 allows connection to the spindle 3000, such as by having a threaded socket accessible from the lower surface. In addition, the lower surface can have a connection for the upper secondary thrust bearing 2902. In the embodiment shown, this can be an external thread to which the upper secondary thrust bearing 2902 is fixed.

[0056] It will be appreciated that the spindle 3000 extends from a lower connection portion 3004 at the bottom, which may be a threaded socket that allows connection to a drilling bit or other tool to be provided with rotational power, to an upper end that may include a connection structure, such as an external threaded portion, for connecting to the bottom adapter 2800. In addition, it will be appreciated that the "on / off bottom" longitudinal movement of the spindle / drive connection is largely dependent on the connection of the bottom adapter 2800 to the spindle 3000. The upper end of the internal bore of the adapter 2800 serves as a "stop point" to define the "clearance" for the longitudinal movement of the spindle 3000. If this hole is too long, the bottom adapter will be able to unscrew and unload the thrust bearing, which will completely jam the assembly. If this hole is too short, the bottom adapter will obviously stop suddenly and the longitudinal movement will be too large. In the depicted embodiment, the ideal "clearance" for the movement of the spindle in the longitudinal direction may be about 0.100 inches.

[0057] The secondary thrust bearing assembly 2900 includes an upper secondary thrust bearing 2902 and a lower secondary thrust bearing 2904. Each of the upper secondary thrust bearing 2902 and the lower secondary thrust bearing 2904 can be a ring with opposing lateral faces, wherein hardened material (e.g., PCD or PCBN buttons) is disposed facing the opposing thrust bearing. A set of suitable embodiments of the upper secondary thrust bearing 2902 and the lower secondary thrust bearing 2904 are depicted separately in FIG. 9B and FIG. 8A to show additional details thereof.

[0058] and Figure 1A 2B, instead of having a gap between the upper secondary thrust bearing 2902 and the lower secondary thrust bearing 2904, a chamber 2907 may be provided below the upper portion of the lower secondary thrust bearing 2904, and a spring 2908 may be provided in the chamber, the spring pressing upward on the bearing to maintain contact between the upper and lower bearings. Thus, the spring 2908 may respond to the movement of the spindle when moving from the "off-bottom" position to the "on-bottom" position, and vice versa.

[0059] The lower secondary thrust bearing 2904 may be disposed on the upper end of the drive bearing housing 3200, such as by using a slip fit to key connection or other suitable connection, with a chamber 2907 defined between the lower side wall of the secondary thrust bearing and the inner wall of the drive housing 3200. The drive bearing housing 3200 may be generally formed as a tube having an internal bore that is mounted on the middle portion of the spindle 3000.

[0060] Moving downward from the upper end, the upper radial bearing assembly 3300 , the main thrust bearing assembly 3100 , and the lower radial bearing assembly 3400 may all be disposed between the drive bearing housing 3200 and the spindle 3000 .

[0061] The upper radial bearing assembly 3300 may include an inner upper radial bearing sleeve 3302 that may be attached to the outer surface of the spindle 3000 at a position lower than the lower secondary thrust bearing 2904. In the described embodiment, the attachment may be achieved by a slip fit to a key connection and secured with a snap ring placed at an appropriate location on the spindle. It should be understood that this may also be achieved by a thread placed at an appropriate location. The outer upper radial bearing sleeve 3304 may be attached to the drive housing 3200 and secured in a groove in the internal bore of the drive housing 3200 above the inner upper radial bearing sleeve 3302. The face of the bearing sleeve may be a suitable hardened material, such as carbide, PCD or PCBN.

[0062] The main thrust bearing assembly 3100 can be disposed inside the drive bearing housing assembly 3200. In the depicted embodiment, the main thrust bearing assembly can be disposed between the upper radial bearing assembly 3300 and the lower radial bearing assembly 3400. The main thrust bearing assembly 3100 includes an upper main thrust bearing 3102 and a lower main thrust bearing 3104, each formed as a ring having a lateral face in which a hardened material, such as a PCD or PCBN button, can be disposed. The opposing lateral faces are arranged to face each other. A set of suitable embodiments of the upper main thrust bearing 3102 and the lower main thrust bearing 3104 are depicted separately in Figures 9A and 8B to show additional details thereof.

[0063] The lower main thrust bearing 3104 can be attached to the outer surface of the spindle 3000 at a location above the lower radial bearing assembly 3400. In the depicted embodiment, the attachment is located above a ridge or shelf formed on the spindle so that the lateral surface faces upward. In the depicted embodiment, the attachment can be a simple slip fit over a keyed connection on a retaining ring that is threaded onto the spindle 3000 just above the lower radial bearing 3402. In addition to providing a slip-fit ​​key surface for the lower main thrust bearing 3104 to slide over, such a ring can be used as a "safety" retaining ring to prevent the lower radial bearing 3402 from backing out because it can be threaded onto the shaft at a different pitch than the radial bearing pitch. In other embodiments, the lower main thrust bearing 3104 can be secured by being placed on threads directly on the spindle.

[0064] The upper main thrust bearing 3102 may be attached to the drive housing 3200. Figure 1A 2B, instead of having a gap between the upper main thrust bearing 3102 and the lower main thrust bearing 3104, a chamber 3107 may be provided above the lower portion of the upper main thrust bearing 3102, and a spring 3108 may be provided in the chamber, the spring pressing down on the bearing to maintain contact between the upper and lower bearings. Thus, the spring 3108 may respond to the movement of the spindle when moving from the "off-bottom" position to the "on-bottom" position, and vice versa. The movement allowed by the springs 3108 and 2908 may be equivalent, and the spring recesses 3107 and 2907 may be similar in size to allow the same springs to be used for ease of assembly.

[0065] The lower radial bearing assembly 3400 may include an inner lower radial bearing sleeve 3402 that may be attached to the outer surface of the spindle 3000 at a location lower than the main thrust bearing assembly 3100. In the depicted embodiment, the lower radial bearing assembly 3400 is disposed at the lower end of the housing 3200, above the lower connection portion 3004 of the spindle 3000. The inner lower radial bearing sleeve 3402 may be attached by placing threads at appropriate locations. The outer lower radial bearing sleeve 3404 may be attached to the drive housing 3200, being fixed in a groove in the internal bore of the drive housing 3200 above the inner lower radial bearing sleeve 3402. The face of the bearing sleeve may be a suitable hardened material, such as carbide, PCD, or PCBN.

[0066] It is understood that, in addition to PCD, other suitable materials, such as CBN, carbide or other hardened surfaces can be used for the bearing surface, and it is further understood that the bearing assembly is assembled in the correct position by the assembly of the drive unit, and no significant compression loading is required before use, especially for the thrust bearing. The springs 3108 and 2908 only keep the corresponding thrust bearing assemblies in contact to prevent them from colliding during the movement from the bottom position to the bottom position, and vice versa, to prevent potential impact damage. In the depicted embodiment, the springs 3108 and 2908 can apply a vertical force in the range of about 42 pounds or less, such as in the range of 40 to 42 pounds. This is in contrast to the design of the prior art, in which a ratchet or compression assembly is used to keep the thrust bearing under a significant load. In contrast, the thrust bearing assembly does not carry any significant load until the motor is operated, and the movement of the motor used with the tool applies force to the bearing. In addition, it should be understood that the spring can provide the bearing with a range of motion exceeding the expected longitudinal motion (or "clearance") to ensure that the bearing surfaces remain in contact. Note that unlike many current motor designs that use carbide or roller bearings, the current design uses this unique approach to protect the PCD bearing surface from impact damage. The use of PCD bearing surfaces is intended to create longer service intervals for the drive section, and the lower coefficient of friction should improve the performance and life of other motor components.

[0067] The housing can be used to cover and protect the drive unit bearing and adapter. In the depicted embodiment, a two-part housing is shown. The lower housing 2H1 can be formed as a tube that is connected to the drive housing 3200 and extends upward on at least a portion of the bottom adapter 2800. In the lower portion of the lower housing, the lower housing 2H1 can include internal threads to allow it to be fixed to the matching external threads on the drive housing 3200. The upper housing 2H2 can be similarly threaded to the upper portion of the lower housing 2H1 and extend upward, with its internal hole covering at least a portion of the second or lower flexible joint and the connecting shaft. As depicted in Figures 3A and 3B, the lower end of the mandrel 3000, the lower end of the drive bearing housing 3200, and the housings 2H1 and 2H2 can all have substantially similar diameters to provide a relatively smooth rounded exterior, thereby reducing friction and facilitating use in the wellbore by removing external features that may get stuck. It should also be understood that the inner sidewall of the housing can conform to the internal components by having thinner and thicker areas to strengthen and keep the components in place.

[0068] It should be appreciated that the motor design according to the present disclosure utilizes components that are simply stacked and easily attached to each other (e.g., by slip fit, threads, and snap rings). In contrast, most known downhole motor bearing assemblies may require careful handling and be difficult to align as the components are stacked and preloaded. This simplifies the assembly process, saving time. In addition, the internal nature of the bearing assembly and the elimination of springs and "preload" components provide longer service intervals, reducing costs and downtime in use.

[0069] The "example" mentioned throughout the specification means that a particular feature, structure, or characteristic described in conjunction with the example is included in at least one embodiment of the present disclosure. Therefore, the phrase "in an example" appearing in different places throughout the specification does not necessarily refer to the same embodiment.

[0070] As used herein, for convenience, multiple items, structural elements, constituent elements and / or materials may appear in a common list. However, these lists should be interpreted as if each member in the list is individually identified as an independent and unique member. Therefore, in the absence of contrary instructions, any single member in the list should not be interpreted as a de facto equivalent of any other member in the same list based solely on its appearance in a common group. In addition, various embodiments and examples of the present disclosure are cited in this article together with substitutes for its various parts. It should be understood that such embodiments, examples and substitutes should not be interpreted as de facto equivalents to each other, but should be considered as independent and autonomous representations of the present disclosure.

[0071] Although the foregoing has been described in detail for the sake of clarity, it is apparent that certain changes and modifications may be made without departing from the principles thereof. It should be noted that there are many alternative ways to implement the processes and devices described herein. Therefore, the present embodiment is considered to be illustrative rather than restrictive.

[0072] Those skilled in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the basic principles of the present disclosure. Therefore, the scope of the present disclosure should be determined solely by the claims, if any.

Claims

1. A drive unit for a downhole motor, comprising: Connecting shaft; At least a first multi-part segmented constant velocity joint having increased flexibility attached to the first end of the connecting shaft, wherein the multi-part segmented constant velocity joint comprises: at least a first top member having a longitudinal bore, an upper attachment section for attachment to a first end of said connecting shaft, and a lower interconnecting portion with a series of splines and grooves; at least a first intermediate member having a longitudinal bore, an upper interconnecting portion with a series of splines and grooves corresponding to a lower interconnecting portion of said at least first top member, and a lower interconnecting portion with a series of splines and grooves; at least a first lower member having a longitudinal bore and an upper interconnecting portion with a series of splines and grooves corresponding to the lower interconnecting portion of said at least first intermediate member; and at least a first connecting pin extending through the longitudinal aperture of the top member, the longitudinal aperture of the at least first intermediate member, and the longitudinal aperture of the lower member to align and secure the members for use; and A spindle is operatively connected to the at least first multi-piece segmented constant velocity joint such that when a rotational force is applied to the connecting shaft, the rotational force is transmitted to the spindle.

2. The drive unit of claim 1, further comprising a second multi-part segmented constant velocity joint having increased flexibility, the second multi-part segmented constant velocity joint being attached to the second end of the connecting shaft.

3. The drive unit according to claim 2, wherein: The second multi-part segmented constant velocity joint comprises: a second top member having a longitudinal bore, an upper attachment section for attachment to the drive connection member, and a lower interconnecting portion with a series of splines and grooves; at least a second intermediate member having a longitudinal bore, an upper interconnecting portion with a series of splines and grooves corresponding to the lower interconnecting portion of said at least first top member, and a lower interconnecting portion with a series of splines and grooves; a second lower member having a longitudinal bore, an upper interconnecting portion with a series of splines and grooves corresponding to the lower interconnecting portion of said at least first intermediate member, and a lower attachment section for attachment to a second end of said connecting shaft; and A second connecting pin extends through the longitudinal hole of the second top member, the longitudinal hole of at least the second middle member, and the longitudinal hole of the second lower member to align and secure the members for use.

4. The drive unit according to claim 1, wherein: The at least first connecting pin has a base with a rounded bottom hinged in a curved groove.

5. The drive unit according to claim 1, wherein: The upper and lower interconnecting portions of the at least first top member are each formed as a protrusion extending from the middle portion of the at least first middle member.

6. The drive unit according to claim 1, wherein: The at least first lower member comprises a lower attachment section for attachment to an upper end of the mandrel.

7. The drive unit according to claim 6, further comprising: case; a main thrust bearing assembly disposed between the housing and the spindle at a first location; and A secondary thrust bearing assembly is disposed between the housing and the spindle at a second location, wherein the primary and secondary thrust bearing assemblies are held in place by other structural components of the motor in the absence of compressive loading that prevents longitudinal movement of the spindle.

8. The drive unit according to claim 7, wherein: The main thrust bearing includes a lower main thrust bearing element, an upper main thrust bearing element and a main thrust bearing spring, wherein the main thrust bearing spring is located in a main thrust bearing spring groove to push the upper main thrust bearing element downward to contact the lower main thrust bearing element, wherein the main thrust bearing spring expands or contracts during use in response to movement of the spindle between a bottom position and an off-bottom position.

9. The drive unit according to claim 7, wherein: The secondary thrust bearing includes an upper secondary thrust bearing element, a lower secondary thrust bearing element and a secondary thrust bearing spring, wherein the secondary thrust bearing spring is located in a secondary thrust bearing spring groove to push the lower secondary thrust bearing element upward to contact the upper secondary thrust bearing element, wherein the secondary thrust bearing spring expands or contracts in response to the movement of the spindle between a bottom position and an off-bottom position during use.

10. A drive assembly for a downhole motor, comprising: Drive shaft; at least a first multi-part segmented constant velocity joint having increased flexibility attached to a first end of the drive shaft; a mandrel attached to the at least first multi-part segmented constant velocity joint; case; a main thrust bearing assembly disposed between the housing and the spindle at a first location; and A secondary thrust bearing assembly is disposed between the housing and the spindle at a second location, wherein the primary and secondary thrust bearing assemblies are held in place by other structural components of the motor in the absence of compressive loading that prevents longitudinal movement of the spindle.

11. The drive assembly according to claim 10, wherein: The main thrust bearing assembly includes a lower main thrust bearing element, an upper main thrust bearing element and a main thrust bearing spring, wherein the main thrust bearing spring is located in a main thrust bearing spring groove to push the upper main thrust bearing element downward to contact the lower main thrust bearing element, wherein the main thrust bearing spring expands or contracts during use in response to movement of the spindle between a bottom position and an off-bottom position.

12. The drive assembly according to claim 10, wherein: The secondary thrust bearing assembly includes an upper secondary thrust bearing element, a lower secondary thrust bearing element and a secondary thrust bearing spring, wherein the secondary thrust bearing spring is located in a secondary thrust bearing spring groove to push the lower secondary thrust bearing element upward to contact the upper secondary thrust bearing element, wherein the secondary thrust bearing spring expands or contracts during use in response to movement of the spindle between a bottom position and an off-bottom position.

13. The drive assembly according to claim 10, wherein: The at least first multi-part segmented constant velocity joint comprises: a top member having a longitudinal bore, an upper attachment section for attachment to a first end of said drive shaft, and a lower interconnecting portion with a series of splines and grooves; at least a first intermediate member having a longitudinal bore, an upper interconnecting portion with a series of splines and grooves corresponding to a lower interconnecting portion of said at least first top member, and a lower interconnecting portion with a series of splines and grooves; a lower member having a longitudinal bore and an upper interconnecting portion with a series of splines and grooves corresponding to the lower interconnecting portion of said at least first intermediate member; and At least a first connecting pin extends through the longitudinal hole of the top member, the longitudinal hole of at least the first intermediate member and the longitudinal hole of the lower member to align and secure the members for use.

14. The drive assembly according to claim 13, wherein: The at least first connecting pin has a base with a rounded bottom hinged in a curved groove.

15. The drive assembly of claim 10, further comprising a second multi-piece segmented constant velocity joint having increased flexibility, the second multi-piece segmented constant velocity joint attached to the second end of the drive shaft.

16. The drive assembly of claim 12, further comprising a first radial bearing assembly including a first inner radial bearing sleeve attached to the outer surface of the spindle and a first outer radial bearing sleeve attached to the housing and aligned with the first inner radial bearing sleeve.

17. The drive assembly of claim 16, wherein: The first radial bearing assembly is disposed at a position lower than the lower secondary thrust bearing element, and the drive assembly further includes a second radial bearing assembly disposed at a position below the primary thrust bearing assembly.

18. A downhole motor comprising: case; Mandrel; a main thrust bearing assembly disposed between the housing and the spindle at a first location, the main thrust bearing assembly comprising a lower main thrust bearing element, an upper main thrust bearing element, and a main thrust bearing spring, the main thrust bearing spring being located in a main thrust bearing spring recess to urge the upper main thrust bearing element downwardly into contact with the lower main thrust bearing element, such that the main thrust bearing assembly is held in place by the main thrust bearing spring expanding or contracting in response to longitudinal spindle movement; A secondary thrust bearing assembly is arranged between the housing and the spindle at a second position, and the secondary thrust bearing assembly includes an upper secondary thrust bearing element, a lower secondary thrust bearing element and a secondary thrust bearing spring, wherein the secondary thrust bearing spring is located in a secondary thrust bearing spring groove to push the lower secondary thrust bearing element upward to contact the upper secondary thrust bearing element, so that the secondary thrust bearing is maintained in a suitable position by the expansion or contraction of the secondary thrust bearing spring in response to the longitudinal movement of the spindle.

19. The downhole motor of claim 18, further comprising a first radial bearing assembly comprising a first inner radial bearing sleeve attached to the outer surface of the spindle and a first outer radial bearing sleeve attached to the housing and aligned with the first inner radial bearing sleeve.

20. The downhole motor of claim 18, further comprising: Drive shaft; as well as at least one multi-piece segmented constant velocity joint operatively connected to the spindle such that when a rotational force is applied to the drive shaft, the rotational force is transmitted to the spindle, the at least one multi-piece segmented constant velocity joint comprising: a top member having a longitudinal bore, an upper attachment section for attachment to a first end of said drive shaft, and a lower interconnecting portion with a series of splines and grooves; at least a first intermediate member having a longitudinal bore, an upper interconnecting portion with a series of splines and grooves corresponding to a lower interconnecting portion of said at least first top member, and a lower interconnecting portion with a series of splines and grooves; a lower member having a longitudinal bore and an upper interconnecting portion with a series of splines and grooves corresponding to the lower interconnecting portion of said at least first intermediate member; and At least a first connecting pin extends through the longitudinal hole of the top member, the longitudinal hole of at least the first intermediate member and the longitudinal hole of the lower member to align and secure the members for use.

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