Patent Application
20230011364
Directional drilling involves drilling a borehole that deviates from a vertical path, such as drilling horizontally through a subterranean formation. Rotary steerable systems are employed to control the direction of a drill bit while drilling. In a point-the-bit rotary steerable system, an internal shaft within the system is deflected to direct the drill bit. In a push-the-bit rotary steerable system, a pad pushes against the subterranean formation to direct the bit.
A push-the-bit rotary steerable system includes a motor with a bearing section. The bearing section may be sealed and lubricated by internal oil, or unsealed and lubricated by drilling fluid flowing through the mud motor to the drill bit. For an unsealed bearing section, loss of drilling fluid to the annulus is inevitable due to bearing tolerances, manufacturing constraints, and erosive wear from the flowing mud. The fluid flow to annulus can be used to lubricate the bearing section, but the flow must be controlled to provide pad force to steer the drill bit while avoiding excess erosion. A need exists, therefore, for a means of controlling the bypass flow of drilling fluid to the annulus
Embodiments of the systems for plugging a well are described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components. The features depicted in the figures are not necessarily shown to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form, and some details of elements may not be shown in the interest of clarity and conciseness.
The present disclosure provides a mud motor bearing assembly for use with a drilling system. The bearing assembly includes radial bearings, thrust bearings, and/or ball bearings or roller bearings that support a driveshaft that extends between the mud motor and a drillbit. The bearing assembly also includes a fluid flowpath through the bearings and into an annulus surrounding the bearing assembly that allows drilling fluid to pass through the bearings, lubricating and cooling the bearings. The bearing assembly also includes a choke assembly that restricts the flow of drilling fluid through the bearings.
Although the bearing assembly may be used with many types of drilling systems having a mud motor, the bearing assembly is particularly applicable to a motor-assisted rotary steerable system (“MARSS”). An MARRS utilizes drilling fluid that has passed through the mud motor and the bearing assembly, to extend pads to push the drill bit in a desired direction. By restricting the flow of drilling fluid through the bearings of the bearing assembly, the choke assembly maintains the drilling fluid passing through the bearing assembly to the pads at a sufficient pressure to extend the pads.
A subterranean formation containing oil or gas hydrocarbons may be referred to as a reservoir, in which a reservoir may be located on-shore or off-shore. Reservoirs are typically located in the range of a few hundred feet (shallow reservoirs) to tens of thousands of feet (ultra-deep reservoirs). To produce oil, gas, or other fluids from the reservoir, a well is drilled into a reservoir or adjacent to a reservoir.
A well can include, without limitation, an oil, gas, or water production well, or an injection well. As used herein, a “well” includes at least one borehole having a borehole wall. A borehole can include vertical, inclined, and horizontal portions, and it can be straight, curved, or branched. As used herein, the term “borehole” includes any cased, and any uncased, open-hole portion of the borehole. Further, the term “uphole” refers a direction that is towards the surface of the well, while the term “downhole” refers a direction that is away from the surface of the well.
The drill string 102 may include one or more logging while drilling (LWD) or measurement-while-drilling (MWD) tools 132 that collect measurements relating to various borehole and formation properties as well as the position of the bit 108 and various other drilling conditions as the bit 108 extends the borehole 104 through the formations 122. The LWD/MWD tool 132 may include a device for measuring formation resistivity, a gamma ray device for measuring formation gamma ray intensity, devices for measuring the inclination and azimuth of the drill string 102, pressure sensors for measuring drilling fluid pressure, temperature sensors for measuring borehole temperature, etc.
The drill string 102 may also include a telemetry module 134. The telemetry module 134 receives data provided by the various sensors of the drill string 102 (e.g., sensors of the LWD/MWD tool 132), and transmits the data to a surface unit 136. Data may also be provided by the surface unit 136, received by the telemetry module 134, and transmitted to the tools (e.g., LWD/MWD tool 132, rotary steering tool 106, etc.) of the drill string 102. Mud pulse telemetry, wired drill pipe, acoustic telemetry, or other telemetry technologies known in the art may be used to provide communication between the surface control unit 136 and the telemetry module 134. The surface unit 136 may also communicate directly with the LWD/MWD tool 132 and/or the rotary steering tool 106. The surface unit 136 may be a computer stationed at the well site, a portable electronic device, a remote computer, or distributed between multiple locations and devices. The unit 136 may also be a control unit that controls functions of the equipment of the drill string 102.
The rotor 302 is operatively positioned in the cavity 306 such that the rotor lobes cooperate with the stator lobes 304 in that applying fluid pressure to the cavity 306 by flowing fluid within the cavity 306 causes the rotor 302 to rotate within the stator 300. For example, referring to
As shown in
Turning now to
A fluid flowpath 406 extends from the bore of the driveshaft 404, through the bearings 400, 402. As discussed above, a portion of drilling fluid passing through the driveshaft 404 is diverted through the fluid flowpath 406 to cool and lubricate the bearings 400, 402. A choke assembly 408, discussed in more detail below, is disposed within the fluid flowpath 406. The choke assembly 408 controls the amount of fluid that passes through the fluid flowpath 406 and into an annulus 428 surrounding the bearing assembly 412, for example, by restricting flow out of the flowpath 406 and into the annulus. By controlling the amount of drilling fluid passing into the annulus via the fluid flowpath 406, sufficient hydraulic pressure is maintained in the drilling fluid flowing through the driveshaft 404 to extend the pads of the RSS (not shown).
In at least one embodiment, one or both of the radial bearing assemblies 400 may also act to restrict the flow of fluid through the fluid flowpath 406. Specifically, a gap 410 formed between an inner cylinder 414 and an outer cylinder 416 may be sized to restrict the flow of fluid through the gap 410 and, thus, the fluid flowpath 406.
Turning now to
The choke 500 and the seat 502 control the amount of drilling fluid that is diverted from the driveshaft to cool and lubricate the bearings. The baising force shifts the choke 500 into contact with the seat such that the exemplary choke assembly 408 maintains hydraulic pressure available for pads. For example, the choke assembly may only allow a range between approximately 1% and approximately 7% of the drilling fluid passing through the driveshaft 404 to be diverted into the fluid flowpath 406. Additionally, the choke 500 and/or the seat may include channels (not shown) extending axially through the choke 500 and/or the seat 502 to ensure that between approximately 1% and approximately 7% of the drilling fluid can pass through the choke assembly 408 when the choke 500 contacts the seat. However, other choke assemblies 408 may allow less than 1% or more than 7% of the drilling fluid to pass through the fluid flowpath 406 as appropriate.
The choke assembly 408 also includes one or more keys 506 coupled to or integral with the choke 500 that engage with one or more respective slots 508 formed in an inner housing 510 surrounding the driveshaft 404 or the driveshaft 404 itself. Once the choke 500 is installed around the inner housing 510, the key 506 and slot 508 allow relative axial movement between the choke 500 and the inner housing 510 such that the choke 500 can contact the seat 502, but prevent relative rotational movement between the choke 500 and the inner housing 510, since relative rotation between the choke 500 and the seat 502 can cause increased wear on the choke 500 and/or seat 502.
Turning now to
The choke assembly 608 includes a tortuous flowpath 600 created between an outer labyrinth choke portion 602 coupled to or integral with an outer housing 612 surrounding a driveshaft 604 and an inner labyrinth choke portion 614 coupled to or integral with an inner housing 610 surrounding the driveshaft 604. The tortuous flowpath 600 controls the amount of drilling fluid that is diverted from the driveshaft to cool and lubricate the bearings. As there is no key assembly within the choke assembly 608, the inner labyrinth choke may rotate relative to the outer labyrinth choke. Similar to the choke assembly 408 described above with reference to
Further examples include:
Example 1 is a drilling system for drilling a borehole. The drilling system includes a drill string, a drill bit coupled to the drill string, a mud motor coupled to the drill string uphole of the drill bit and operable to rotate the drill bit via a driveshaft, a bearing assembly coupled to a downhole end of the mud motor and operable to support the driveshaft, and a rotary steerable system (“RSS”) operable to push the drill bit in a desired direction via pads extended using drilling fluid flowing through the driveshaft and to the RSS. The bearing assembly includes bearings positioned circumferentially around a bore of the bearing assembly, a fluid flowpath through the bearings to allow drilling fluid to pass through the bearings, and a choke assembly positioned in the fluid flowpath and operable to restrict a flow of the drilling fluid through the fluid flowpath.
In Example 2, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly includes a choke axially movable within the fluid flowpath to contact a seat and restrict fluid flow through the fluid flowpath and a biasing mechanism positioned within the fluid flowpath to bias the choke into contact with the seat.
In Example 3, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly further includes a key coupled to the choke and positioned in a slot formed in an inner housing surrounding the driveshaft to prevent relative rotational movement between the inner housing and the choke and allow relative axial movement between the inner housing and the choke.
In Example 4, the embodiments of any preceding paragraph or combination thereof further include wherein the bearings comprise a radial bearing assembly shaped to restrict the flow of the drilling fluid through the fluid flowpath.
In Example 5, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly includes a tortuous flowpath to restrict the flow of drilling fluid through the fluid flowpath.
In Example 6, the embodiments of any preceding paragraph or combination thereof further include wherein an outer labyrinth choke portion and an inner labyrinth choke portion are positioned within the fluid flowpath to form the tortuous flowpath.
In Example 7, the embodiments of any preceding paragraph or combination thereof further include wherein the fluid flowpath exits the bearing assembly to an annulus surrounding the bearing assembly.
In Example 8, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly allows a range between approximately 1% and approximately 7% of the drilling fluid flowing through the drill string to be diverted into the fluid flowpath.
In Example 9, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly is operable to restrict the flow of drilling fluid such that a pressure of the drilling fluid flowing through the driveshaft is sufficient to extend the pads of the RSS.
Example 10 is a method of drilling a borehole. The method includes pumping drilling fluid down a drill string within the borehole to a mud motor, a bearing assembly, a RSS, and a drill bit. The method also includes rotating a drill bit with the mud motor via a driveshaft. The method further includes extending pads of the RSS via the drilling fluid passing through the driveshaft to push a drill bit in a desired direction using the drilling fluid. The method also includes diverting a portion of the drilling fluid through bearings of the bearing assembly. The method further includes restricting a flow of the drilling fluid through the bearings via a choke assembly.
In Example 11, the embodiments of any preceding paragraph or combination thereof further include wherein restricting the flow of the drilling fluid through the bearings via the choke assembly includes biasing a choke of the choke assembly positioned within a fluid flowpath through the bearings against a seat of the choke assembly positioned within the fluid flowpath.
In Example 12, the embodiments of any preceding paragraph or combination thereof further include preventing relative rotational movement between the choke and an inner housing of the choke assembly.
In Example 13, the embodiments of any preceding paragraph or combination thereof further include restricting the flow of the drilling fluid through the bearings via the choke assembly includes restricting the flow of the drilling fluid through the bearings via a tortuous flowpath formed by the choke assembly.
In example 14, the embodiments of any preceding paragraph or combination thereof further include flowing the portion of the fluid from the bearings to an annulus surrounding the bearing assembly.
In Example 15, the embodiments of any preceding paragraph or combination thereof further include wherein restricting the flow of the drilling fluid through the bearings via the choke assembly includes restricting the flow of the drilling fluid through the bearings via the choke assembly such that a pressure of the drilling fluid flowing through the driveshaft is sufficient to extend the pads of the RSS.
Example 16 is bearing assembly for use with a downhole motor rotated via drilling fluid. The bearing assembly includes bearings positioned circumferentially around a bore of the bearing assembly to support a driveshaft extending from the downhole motor, a fluid flowpath through the bearings to allow drilling fluid to pass through the bearings, and a choke assembly positioned in the fluid flowpath and operable to restrict a flow of the drilling fluid through the fluid flowpath.
In Example 17, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly includes a choke axially movable within the fluid flowpath to contact a seat and restrict fluid flow through the fluid flowpath and biasing mechanism positioned within the fluid flowpath to bias the choke into contact with the seat.
In Example 18, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly further includes a key coupled to the choke and positioned in a slot formed in an inner housing surrounding the driveshaft to prevent relative rotational movement between the inner housing and the choke and allow relative axial movement between the inner housing and the choke.
In Example 19, the embodiments of any preceding paragraph or combination thereof further include wherein the choke assembly includes a tortuous flowpath to restrict the flow of drilling fluid through the fluid flowpath.
In Example 20, the embodiments of any preceding paragraph or combination thereof further include wherein the fluid flowpath exits the bearing assembly to an annulus surrounding the bearing assembly.
Certain terms are used throughout the description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function.
As used herein, a range that includes the term between is intended to include the upper and lower limits of the range; e.g., between 50 and 150 includes both 50 and 150. Additionally, the term “approximately” includes all values within 5% of the target value; e.g., approximately 100 includes all values from 95 to 105, including 95 and 105. Further, approximately between includes all values within 5% of the target value for both the upper and lower limits; e.g., approximately between 50 and 150 includes all values from 47.5 to 157.5, including 47.5 and 157.5.
Reference throughout this specification to “one embodiment,” “an embodiment,” “embodiments,” “some embodiments,” “certain embodiments,” or similar language means that a particular feature, structure, or characteristic described in connector with the embodiment may be included in at least one embodiment of the present disclosure. Thus, these phrases or similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.
