Technical Field

[0001 ] The present disclosure relates generally to an assembly for a driveshaft transmission and, more particularly (although not necessarily exclusively), to a driveshaft retention assembly to prevent the loss of driveshaft transmission assembly components.

Background

[0002] Mud motors utilize fluid energy converted to mechanical energy to provide shaft rotation to a drill string or drill bit. Because the mud motor is a highly loaded section of a drilling tool, it is prone to critical damage during motor transmission failure. Failure of the motor transmission may result in critical damage to the transmission assembly, including the separation of components from the transmission assembly. Where such separation occurs, these components may be lost downhole. The lost components dropped downhole can prevent further progression in drilling and can cause significant delays. The loss of components downhole may even result in a drilling project being abandoned.

[0003] A procedure known as "fishing" is sometimes used to retrieve the lost components, but this procedure is costly and time-consuming, and may be ineffective.

Brief Description of the Drawings

[0004] FIG. 1 is a cross-sectional schematic diagram depicting a drilling system that includes a driveshaft transmission assembly with a retention apparatus in a lower end of a driveshaft transmission assembly according to one aspect of the present disclosure. [0005] FIG. 2 is a cross-sectional view of a driveshaft transmission assembly according to one aspect of the present disclosure.

[0006] FIG. 3 is a disassembled perspective view of a retention apparatus according to one aspect of the present disclosure.

[0007] FIG. 4 is a partially assembled perspective view of the retention apparatus of FIG. 3 according to one aspect of the present disclosure.

[0008] FIG. 5 is a partially assembled perspective view of the retention apparatus of FIG. 3 according to one aspect of the present disclosure.

[0009] FIG. 6 is a cross-sectional view of the assembled retention apparatus of FIG. 3 according to one aspect of the present disclosure.

Detailed Description

[0010] Certain aspects and examples of the present disclosure relate to a downhole driveshaft transmission assembly having a retention apparatus. The retention apparatus may include a catch mechanism and a resilient member. The retention apparatus may be coupled to a radial bearing assembly of a driveshaft transmission assembly. The catch mechanism may include ridges on the inner surface corresponding to protrusions on the radial bearing assembly. The ridges may be sized to be received by channels formed by the protrusions on the radial bearing assembly. The ridges may be spaced to form grooves in the catch mechanism that are sized to allow the protrusions on the radial bearing assembly to be received by the grooves. The ridges may also be spaced to correspond to the spacing of the protrusions so the ridges and protrusions may couple the catch mechanism to the radial bearing assembly by the resilient member. The resilient member may apply a compression force onto the catch mechanism in an uphole direction to couple the catch mechanism to the radial bearing assembly by securing the ridges to the protrusions. Should a break occur in the downhole driveshaft transmission assembly, the catch mechanism may prevent the loss of the driveshaft and other driveshaft transmission assembly components downhole.

[001 1 ] The structure of the retention apparatus can allow the catch mechanism to be coupled to the radial bearing assembly without threading. Installing and maintaining the driveshaft transmission assembly may be more cost- effective and efficient as the use of threading may require heightened inspections and testing that may be both costly and time-consuming. Instead of threading, the retention apparatus can allow the catch mechanism to be coupled to the radial bearing assembly through interconnecting components, for example using a J-slot coupling, and a compression force.

[0012] The terms "inner," "outer," "internal," and "between," as used in the present disclosure, may refer to a radial orientation toward or away from the center of the driveshaft transmission assembly. The terms "uphole," "downhole," and "proximate," as used in the present disclosure, may refer to an axial orientation toward or away from the surface.

[0013] Various aspects of the present disclosure may be implemented in various drilling systems. FIG. 1 illustrates an example of such a drilling system 100 that includes a drill string 102. The drill string 102 of a drilling rig (not shown) may include segmented pipes that may extend below the surface 104 in a borehole, such as a wellbore 106. The drill string 102 may transmit drilling fluid (or mud) and the torque necessary to operate a drill bit 108. Also, the weight of the drill string 102 may provide an axial force on the drill bit 108. [0014] The drill string 102 may include a drill pipe 1 10 and a bottom hole assembly 1 12. The bottom hole assembly 1 12 may be include various components, such as a downhole motor assembly 1 14 and the drill bit 108.

[0015] Though placement of the assemblies disclosed herein may vary without departing from the scope of the present subject matter, the assemblies of the present disclosure may be included in the lower end of the downhole motor assembly 1 14 and near the drill bit 108. For example, the driveshaft transmission assembly 1 16 depicted in FIG. 1 represents a placement according to one example. Placement of the assemblies as close to the drill bit 108 as possible may reduce the moment arm load induced from directional drilling. Reducing the moment arm load may result in longevity of the motor assembly and bearings of the drilling installation, and may reduce the likelihood of failure of the motor.

[0016] During operation of the drilling system, dynamic loads may be placed on a drill motor by the action of the drill bit 108 and by vibrations of the drill string 102. In certain instances, the dynamic loads may cause the drill motor to fail and components of the driveshaft transmission assembly 1 16 to separate. The driveshaft transmission assembly 1 16 can include a retention apparatus to prevent the loss of components downhole in the event of a separation.

[0017] FIG. 2 shows an example of the driveshaft transmission assembly 1 16 that includes a retention apparatus according to one aspect of the present disclosure. The driveshaft transmission assembly 1 16 also includes a bearing housing 200 and certain bearings of a driveshaft 202. The catch mechanism can be separate and independent of the bearing housing 200 and the driveshaft 202. One or more radial bearing assemblies may be included internal to the bearing housing 200. For example, FIG. 2 includes a stationary radial bearing 204 and a rotating radial bearing 206. A thrust bearing assembly 208 may also be included internal to the bearing housing 200. In some aspects, the rotating radial bearing 206 may be radially positioned between the driveshaft 202 and the stationary radial bearing 204 and may be coupled to the driveshaft 202. The stationary radial bearing 204 may be radially positioned between the rotating radial bearing 206 and the bearing housing 200. The stationary radial bearing 204 may be coupled to the bearing housing 200 and may be configured to support the driveshaft in the radial direction. The thrust bearing assembly 208 may be radially positioned between the rotating radial bearing 206 and the bearing housing 200. Although only these radial and thrust bearing assemblies are shown in FIG. 2, alternative or additional bearing assemblies may be included in various configurations in the driveshaft transmission assembly 1 16 without departing from the scope of the present disclosure.

[0018] The retention apparatus in FIG. 2 includes a catch mechanism 210 and a resilient member 212. The catch mechanism 210 and resilient member 212 may be received by the rotating radial bearing 206 such that the catch mechanism 210 and resilient member 212 surround a portion of the rotating radial bearing 206. The catch mechanism 210 and resilient member 212 are radially positioned between the rotating radial bearing 206 and the bearing housing 200 and are independent of the bearing housing 200. The catch mechanism 210 and resilient member 212 are axially positioned between the thrust bearing assembly 208 (on the uphole side) and the stationary radial bearing 204 (on the downhole side). The catch mechanism 210 is axially positioned directly uphole of the resilient member 212.

[0019] The catch mechanism 210 may have an outer diameter greater than the outer diameter of the rotating radial bearing 206. As such, at least a portion of the catch mechanism 210 may extend beyond the outer diameter of the rotating radial bearing 206 when the catch mechanism 210 is coupled to the rotating radial bearing 206. The resilient member 212 may be axially positioned between the catch mechanism 210 on a portion of the rotating radial bearing 206. The rotating radial bearing 206 may have an enlarged portion having a greater outer diameter than the outer diameter of the portion of the rotating radial bearing 206 where the resilient member 212 is positioned. In some aspects, the catch mechanism 210 and resilient member 212 may surround an indented portion of the rotating radial bearing 206.

[0020] Following a failure of the drill motor, the retention apparatus of the driveshaft transmission assembly 1 16 may prevent certain components of the driveshaft transmission assembly 1 16, including the driveshaft 202 and drill bit 108, from falling, or being lost, downhole in the event of separation. For example, when a separation occurs, the outer surface of the catch mechanism 210 may create an interference with the contact shoulder 214 of the stationary radial bearing 204 to prevent the retention apparatus from moving in a downhole direction beyond the contact shoulder 214. Because the catch mechanism 210 may be coupled to the rotating radial bearing 206, the interference of the catch mechanism 210 with the contact shoulder 214 of the stationary radial bearing 204 may prevent the rotating radial bearing 206 and any components directly or indirectly coupled thereto (e.g., driveshaft 202, drill bit 108) from falling downhole.

[0021 ] FIGs. 3 through 6 illustrate an example of a retention apparatus 300 that may be used to prevent the loss of driveshaft transmission assembly components downhole. FIG. 3 shows a disassembled view of a retention apparatus 300 that may be received for positioning on a radial bearing assembly (e.g., rotating radial bearing 206). The retention apparatus 300 may be received separately from or together with the radial bearing assembly (or other components of the driveshaft transmission assembly. The retention apparatus 300 may include the catch mechanism 210 and the resilient member 212. The catch mechanism 210 may be a cylindrical component with an inner diameter sized to slide onto the rotating radial bearing 206. The catch mechanism 210 may be rigid and capable of withstanding a load when interfering with the contact shoulder 214 of the stationary radial bearing 204. In some aspects, the catch mechanism 210 may be made of the same material as other components of the driveshaft transmission assembly 1 16 (e.g., steel). The resilient member 212 may be a flexible, ring-shaped component that is sized to slide onto the rotating radial bearing 206. An example of the resilient member 212 is a spring, such as a Belleville spring, a compression spring, or a wave spring. When the retention apparatus 300 is fully assembled, the resilient member 212 may provide a compression force on the catch mechanism 210 in the uphole direction.

[0022] The catch mechanism 210 may include ridges 302 positioned on the inner surface of the catch mechanism. The catch mechanism 210 in FIG. 3 includes four ridges 302 that are evenly spaced. However, the number of ridges 302 is not limited to four, and may include two, three, or five or more ridges 302. The spacing of the ridges 302 may also vary. The spacing of the ridges 302 may form grooves on the catch mechanism 210. The rotating radial bearing 206 includes protrusions 306 on the outer surface of the rotating radial bearing 206. The number of protrusions 306 may be equal to the number of ridges 302 on the catch mechanism 210 such that each ridge 302 may have a corresponding protrusion 306. The protrusions 306 are evenly spaced in FIG. 3, but the spacing of the protrusions 306 on the rotating radial bearing 206 may vary. The grooves 304 on the catch mechanism 210 may be sized to allow the protrusions 306 to be received by the grooves 304 when the catch mechanism 210 is installed onto the rotating radial bearing 206. Similar to the grooves 304 on the catch mechanism 210, the spacing of the protrusions 306 may create channels 308. The channels 308 may be sized to allow the ridges 302 on the rotating radial bearing 206 to be received by the channels 308 when the catch mechanism 210 is installed onto the rotating radial bearing 206. The number of channels 308 may be equal to the number of ridges 302 such each ridge 302 may have a corresponding channel 308.

[0023] FIGs. 4 and 5 show the retention apparatus 300 at different stages of assembly. The resilient member 212 is shown in FIG. 4 as having been slidably received by the rotating radial bearing 206. In this position, the resilient member 212 may contact the uphole edge of an enlarged portion of the rotating radial bearing 206. In FIG. 5, the catch mechanism 210 is shown as being slidably received by the rotating radial bearing 206. The ridges 302 of the catch mechanism 210 are positioned in the channels 308 created by the protrusions 306 on the rotating radial bearing 206 and the protrusions 306 are positioned in the grooves 304 created by the ridges on the catch mechanism 210. When the ridges 302 be received by channels 308, the catch mechanism 210 may contact the resilient member 212 as shown in FIG. 6.

[0024] FIG. 6 shows a cross-sectional view of the retention apparatus 300 assembled on a rotating radial bearing 206. The catch mechanism 210 of the retention apparatus 300 may be coupled to the rotating radial bearing 206 using J- slot coupling. Specifically, the catch mechanism 210 may be slidably received by the rotating radial bearing 206 and may make contact with the resilient member 212. When the ridges 302 of the catch mechanism 210 have been received by the channels 308 of the rotating radial bearing 206, the catch mechanism 210 may apply a compression force onto the resilient member 212 in a downhole direction such that the compression force compresses the resilient member 212.

[0025] The catch mechanism 210 or the rotating radial bearing 206 may be rotated until the ridges 302 are positioned proximate to the protrusions 306. For, example, the catch mechanism 210 or the rotating radial bearing 206 may be rotated by a number of degrees in a clockwise or counterclockwise direction until the ridges are axially aligned with the protrusions 306. The axis of rotation to axially align the ridges 302 and the protrusions 306 may be equal to a longitudinal axis 602 of the rotating radial bearing 206. When the ridges 302 of the catch mechanism 210 are positioned proximate to the protrusions 306 of the rotating radial bearing 206, the resilient member 212 may apply an uphole compression force such that each of the ridges 302 of the catch mechanism 210 contacts a downhole edge of a corresponding protrusion 306 on the rotating radial bearing 206. In some aspects, the downhole edge of the protrusions 306 may be shaped to receive the ridges 302. The shape of the downhole edge may further prevent decoupling of the catch mechanism 210 from the rotating radial bearing 206, as shown in FIGs. 3 through 5.

[0026] The foregoing description of the examples, including illustrated examples, has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the subject matter to the precise forms disclosed. Numerous modifications, combinations, adaptations, uses, and installations thereof can be apparent to those skilled in the art without departing from the scope of this disclosure. The illustrative examples described above are given to introduce the reader to the general subject matter discussed here and are not intended to limit the scope of the disclosed concepts.