Patent Publication Number: US-11047207-B2

Title: Controlling the sensitivity of a valve by adjusting a gap

Description:
BACKGROUND 
     Boreholes, which are also commonly referred to as “wellbores” and “drill holes,” are created for a variety of purposes, including exploratory drilling for locating underground deposits of different natural resources, mining operations for extracting such deposits, and construction projects for installing underground utilities. A common misconception is that all boreholes are vertically aligned with the drilling rig; however, many applications require the drilling of boreholes with vertically deviated and horizontal geometries. A well-known technique employed for drilling horizontal, vertically deviated, and other complex boreholes is directional drilling. Directional drilling is generally typified as a process of boring a hole which is characterized in that at least a portion of the course of the bore hole in the earth is in a direction other than strictly vertical—i.e., the axes make an angle with a vertical plane (known as “vertical deviation”), and are directed in an azimuth plane. 
     Conventional directional boring techniques traditionally operate from a boring device that pushes or steers a series of connected drill pipes with a directable drill bit at the distal end thereof to achieve the borehole geometry. In the exploration and recovery of subsurface hydrocarbon deposits, such as petroleum and natural gas, the directional borehole is typically drilled with a rotatable drill bit that is attached to one end of a bottom hole assembly or “BHA.” A steerable BHA can include, for example, a positive displacement motor (PDM) or “mud motor,” drill collars, reamers, shocks, and underreaming tools to enlarge the wellbore. A stabilizer may be attached to the BHA to control the bending of the BHA to direct the bit in the desired direction (inclination and azimuth). The BHA, in turn, is attached to the bottom of a tubing assembly, often comprising jointed pipe or relatively flexible “spoolable” tubing, also known as “coiled tubing.” This directional drilling system—i.e., the operatively interconnected tubing, drill bit, and BHA—can be referred to as a “drill string.” When jointed pipe is utilized in the drill string, the drill bit can be rotated by rotating the jointed pipe from the surface, through the operation of the mud motor contained in the BHA, or both. In contrast, drill strings which employ coiled tubing generally rotate the drill bit via the mud motor in the BHA. 
     Directional drilling typically requires controlling and varying the direction of the wellbore as it is being drilled. Oftentimes the goal of directional drilling is to reach a position within a target subterranean destination or formation with the drill string. For instance, the drilling direction may be controlled to direct the wellbore towards a desired target destination, to control the wellbore horizontally to maintain it within a desired payzone, or to correct for unwanted or undesired deviations from a desired or predetermined path. Frequent adjustments to the direction of the wellbore are often necessary during a drilling operation, either to accommodate a planned change in direction or to compensate for unintended or unwanted deflection of the wellbore. Unwanted deflection may result from a variety of factors, including the characteristics of the formation being drilled, the makeup of the bottomhole drilling assembly, and the manner in which the wellbore is being drilled, as some non-limiting examples. 
     Various options are available for providing steering capabilities to a drilling tool for controlling and varying the direction of the wellbore. In directional drilling applications, for example, one option is to attach a bent-housing or a bent-sub downhole drilling motor to the end of the drilling string as a steering tool. When steering is required, the drill-pipe section of the drilling string can be restrained against rotation and the drilling motor can be pointed in a desired direction and operated for both drilling and steering in a “sliding drilling” mode. When steering is not required, the drilling string and the drilling motor can be rotated together in a “rotary drilling” mode. An advantage to this option is its relative simplicity. One disadvantage to this option, however, is that steering is typically limited to the sliding drilling mode. In addition, the straightness of the borehole in rotary drilling mode may be compromised by the presence of the bent drilling motor. Furthermore, since the drill pipe string is not rotated during sliding drilling, it is more susceptible to sticking in the wellbore, particularly as the angle of deflection of the wellbore from the vertical increases, resulting in reduced rates of penetration. 
     Directional drilling may also be accomplished with a “rotary steerable” drilling system wherein the entire drill pipe string is rotated from the surface, which in turn rotates the bottom hole assembly, including the drilling bit, connected to the end of the drill pipe string. In a rotary steerable drilling system, the drilling string may be rotated while the drilling tool is being steered either by being pointed or pushed in a desired direction (directly or indirectly) by a steering device. Some rotary steerable drilling systems include a component which is non-rotating relative to the drilling string in order to provide a reference point for the desired direction and a mounting location for the steering device(s). Alternatively, a rotary steerable drilling system may be “fully rotating”. Drilling fluids are often used to drive the various parts of the drilling system, including turbines and mud motors used within. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures are included to illustrate certain aspects of the present invention, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to one having ordinary skill in the art and having the benefit of this disclosure. 
         FIG. 1  is a diagram of a drilling system according to embodiments of the disclosure. 
         FIGS. 2A-C  are diagrams illustrating an example steering assembly according to embodiments of the disclosure. 
         FIG. 3  illustrates a valve assembly according to embodiments of the invention. 
         FIG. 4  illustrates a poppet valve assembly according to embodiments of the invention. 
         FIG. 5  illustrates a shear valve assembly according to embodiments of the invention. 
         FIG. 6  represents a profile view of a shear valve and valve gap according to embodiments of the invention. 
         FIGS. 7A-C  represent gap adjusting mechanisms according to embodiments of the disclosure. 
         FIG. 8  is a graph depicting flow splits in the shear valve at various shear valve angles and valve gaps. 
     
    
    
     DETAILED DESCRIPTION 
     Flow Splitting 
     The present disclosure relates to controlling the flow rates through a valve in a downhole tool that requires a certain flow rate of drilling mud to operate. Different portions of the tool may require more flow than others. In an embodiment, a shear valve may be used to distribute the mud flow to the various portions of the downhole tool. For example, if the tool as a whole requires between 400 GPM and 800 GPM, a turbine within the tool may only require between 50 GPM and 200 GPM. Thus, when pumping 800 GPM through the tool, the maximum flow the shear valve can be supplying to the turbine is 25% of the total flow, and when pumping 400 GPM, the shear valve needs to supply a maximum of 50% of the total flow to the turbine. To use the full rotation of the shear valve when pumping 800 GPM, a smaller gap, for example about 32 mm is needed, and a gap greater than about 80 mm is needed when pumping at 400 GPM. 
     Generally, an “orifice” as used in this disclosure is a change in flow area whose pressure drop may be approximated by standard orifice calculations as described in Section 8-10 of  Introduction to Fluid Mechanics , by Fox &amp; McDonald, Fifth Edition. 
     Embodiments of the present invention disclose that if the valve gap is small, a change in the valve angle may result in a larger change in the flow fraction than if the valve gap is larger with the same change in the valve angle. Thus, adjusting the valve gap may allow a larger tool flow range and may increase the effectiveness of the shear valve. 
     In an embodiment, a downhole tool comprises a tool body, multiple orifices in the tool body defining at least a first and a second flow path; and a valve that adjusts to change a ratio of fluid flow between the first and second flow paths, the valve being offset from the multiple orifices by a gap that is adjustable to customize a sensitivity of the change to each adjustment. The tool may further comprise a turbine, wherein the first path of the valve is in fluid communication with the turbine. The valve type may be one selected from the group consisting of gate, shear, globe, and poppet. In a preferred embodiment, the valve is a poppet valve. In exemplary embodiments, the gap is adjustable using at least one of a manual adjustment, an active adjustment, an automatic adjustment, and combinations thereof. The manual adjustments may be made using shims. In the actively adjusting embodiments, springs may be used to passively adjust the gap. If automatic adjusting of the gap is desired, an actuator may be used. In some embodiments, a smaller valve gap results in greater shear valve sensitivity than a relatively larger valve gap. 
     In another embodiments, a method for regulating flow along a first fluid path in a downhole tool comprises adjusting a valve relative to multiple orifices that define the first fluid path and a second fluid path, said adjusting including changing a ratio of fluid flow between the first and second flow paths; and adjusting a gap between the valve and the multiple orifices to modify a sensitivity of the change. 
     Yet another embodiment is directed to a system for regulating flow along a first fluid path, the system comprising: a downhole tool including: a valve coupled to multiple orifices that define the first fluid path and a second fluid path and a gap between the valve and the multiple orifices; said tool configured to adjust the valve relative to the multiple orifices, said adjustment including changing a ratio of fluid flow between the first and second flow paths; and adjust the gap between the valve and the multiple orifices to modify a sensitivity of the change. The system may further include a turbine, wherein the first path of the valve is in fluid communication with the turbine. 
     Drilling Systems 
       FIG. 1  is a general diagram illustrating an example drilling system  100 , according to embodiments of the present disclosure. The drilling system  100  includes rig  102  mounted at the surface  101  and positioned above borehole  104  within a subterranean formation  103 . In the embodiment shown, a drilling assembly  105  may be positioned within the borehole  104  and may be coupled to the rig  102 . The drilling assembly  105  may comprise drill string  106  and bottom hole assembly (BHA)  107 . The drill string  106  may comprise a plurality of segments threadedly connected. The BHA  107  may comprise a drill bit  109 , a measurement-while-drilling (MWD) apparatus  108  and a steering assembly  114 . The steering assembly  114  may control the direction in which the borehole  104  is being drilled. As will be appreciated by one of ordinary skill in the art in view of this disclosure, the borehole  104  will be drilled in the direction perpendicular to the tool face  110  of the drill bit  109 , which corresponds to the longitudinal axis  116  of the drill bit  109 . Accordingly, controlling the direction of the borehole  104  may include controlling the angle between the longitudinal axis  116  of the drill bit  109  and longitudinal axis  115  of the steering assembly  114 , and controlling the angular orientation of the drill bit  109  relative to the formation  103 . 
     The steering assembly  114  may include an offset mandrel (not shown) that causes the longitudinal axis  116  of the drill hit  109  to deviate from the longitudinal axis  115  of the steering assembly  114 . The offset mandrel may be counter-rotated relative to the rotation of the drill string  106  to maintain an angular orientation of the drill bit  109  relative to the formation  103 . The steering assembly  114  may receive control signals from a control unit  113 . The control unit  113  may comprise an information handling system with a processor and a memory device, and may communicate with the steering assembly  114  via a telemetry system. The control unit  113  may transmit control signals to the steering assembly  114  to alter the longitudinal axis  115  of the drill bit  109  as well as to control counter-rotation of portions of the offset mandrel to maintain the angular orientation of the drill bit  109  relative to formation  103 . As used herein, maintaining the angular orientation of a drill bit relative to formation  103  may be referred to as maintaining the drill bit in a “geo-stationary” position. In certain embodiments, a processor and memory device may be located within the steering assembly  114  to perform some or all of the control functions. Moreover, other BHA  107  components, including the MWD apparatus  108 , may communicate with and receive instructions from control unit  113 . 
       FIGS. 2A-C  are diagrams illustrating an example steering assembly  200 , according to embodiments of the present disclosure, that may be used, in part, to maintain a drill bit in a geostationary position during drilling operations.  FIGS. 2B-C  depict illustrative portions of the steering assembly  200 . The steering assembly  200  may include a housing  201  that may be coupled directly to a drill string or indirectly to a drill string, such as through a MWD apparatus. The housing  201  may comprise separate segments  201   a - c , or may comprise a single unitary housing. Section  201   a  may house the control mechanisms, and may communicate with a control unit at the surface and/or receive control signals from the surface and control mechanisms within the steering assembly. Section  201   b  may comprise drive elements, including a variable flow pathway and a flow-controlled drive mechanism. Section  201   c  may comprise steering elements that control the drilling angle and axial orientation of a drill bit coupled to bit shaft  202  of the steering assembly  200 . 
     In certain embodiments, the steering assembly  200  may be coupled, directly or indirectly, to a drill string, through which drilling fluid may be pumped during drilling operations. The drilling fluid may flow through ports  204  into an annulus  205  around a flow control module  206 . Once in the annulus  205 , the drilling fluid may either flow to an inner annulus  208 , in fluid communication with a fluid-controlled drive mechanism  209 , or may be diverted to a bypass annulus  207 . A flow control valve  210  may be included within the flow control module  206  and may control the amount/flow of drilling fluid that enters the inner annulus  208  to drive the fluid-controlled drive mechanism  209 . 
     In certain embodiments, the fluid pathway from port  204  to inner annulus  208  may comprise a variable flow fluid pathway  203 , with the fluid-controlled drive mechanism  209  being in fluid communication with the variable flow fluid pathway  203  via inner annulus  208 . The flow control valve  210  may be disposed within the variable flow fluid pathway  203 , and configured to vary or change the fluid flow through the variable flow fluid pathway  203 . The rotational speed of the fluid-controlled drive mechanism  209  may be controlled by the amount and rate of drilling fluid that flows into the inner annulus  208 . In certain embodiments, the flow control valve  210 , therefore, may be used to control the rotational speed of the fluid-controlled drive mechanism  209  by varying the amount or rate of drilling fluid that flows into the inner annulus  208 . As would be appreciated by one of ordinary skill in the art in view of this disclosure, other variable flow fluid pathways are possible, using a variety of valve configurations that may meter the flow of drilling fluid across a fluid-controlled drive mechanism. 
     As described above, the steering assembly  200  may comprise a fluid-controlled drive mechanism  209  in fluid communication with the variable flow fluid pathway  203  via the inner annulus  208 . In the embodiment shown, the fluid-controlled drive mechanism  209  comprises a turbine, but other fluid-controlled drive mechanisms are possible, including but not limited to a mud motor. The turbine  209  may comprise a plurality of rotors and stators that generate rotational movement in response to fluid flow within the inner annulus  208 . The turbine  209  may generate rotation at an output shaft  211 . In the embodiment shown, a speed reducer  213  may be placed between the turbine  209  and the output shaft  211  to reduce the rate of rotation generated by the turbine  209 . 
     In certain embodiments, a generator  214  may be coupled to the fluid-controlled drive mechanism  209 . In the embodiment shown, the generator  214  may be magnetically coupled to a rotor  209   a  of the turbine  209 . The generator  214  may comprise a wired stator  214   a . The wired stator  214   a  may be magnetically coupled to a rotor  209   a  of the rotor  209  via magnets  215  coupled to the rotor  209   a . As the turbine  209  rotates, so does the rotor  209   a , which may cause the magnets  215  to rotate around the wired stator  214   a . This may generate an electrical current within the generator  214 , which may be used to power a variety of control mechanisms and sensors located within the steering assembly  200 , including control mechanisms within segment  201   a.    
     Valves 
     The valves of the present disclosure may be any valve including gate, shear, globe, and poppet valves. The tool assembly  300  in  FIG. 3 , includes a valve  302 , first flow path  304 , and second flow path  306 . As valve driver  308  adjusts valve  302 , orifice  310  is exposed more or is closed off, depending upon the amount of flow needed. One of skill in the art will realize that as the orifice&#39;s exposure to the flow channel increases in size, for a given pressure, more flow may be admitted. Additionally, there is a nozzle  312  in fluid communication with the second flow path  306 . As the valve  302  adjusts, the orifice&#39;s  310  exposure may grow in size, thereby increasing the flow in the first flow path  304 , and decreasing the flow in the second flow path  306 . The sensitivity of the valve  302  may be changed by adjusting the gap  314 , which is how far the valve body travels into orifice  310 . 
     The tool assembly  400  in  FIG. 4 , includes a poppet valve  402 , first flow path  404 , and second flow path  406 . As valve driver  408  adjusts poppet valve  402 , orifice  410  is exposed more or is closed off, depending upon the amount of flow needed. One of skill in the art will realize that as the orifice&#39;s exposure to the flow channel increases in size, for a given pressure, more flow may be admitted. Additionally, there is a nozzle  412  in fluid communication with the second flow path  406 . As the valve  402  adjusts, the orifice&#39;s  410  exposure may grow in size, thereby increasing the flow in the first flow path  404 , and decreasing the flow in the second flow path  406 . The sensitivity of the valve  402  may be changed by adjusting the gap  414  which is how far the valve body travels into orifice  410 . 
     Shear Valves 
     The tool assembly  500  in  FIG. 5 , includes a shear valve  501  and orifices  502 . As shear valve  501  rotates or swivels, the orifices  502  are exposed more or are closed off, depending upon the amount of flow needed. One of skill in the art will realize that as the orifice&#39;s exposure to the flow channel increases in size, for a given pressure, more flow may be admitted. As the shear valve  501  swivels, one orifice&#39;s exposure may grow in size, and one may reduce in size. It is also possible that both may be fully exposed, or fully covered. In an embodiment, the shear valve may be swiveled throughout the range of about 0 degrees to about 180 degrees in another embodiment, the shear valve may be swiveled throughout the range of about 0 degrees to about 85 degrees. In a preferred embodiment, the shear valve may swivel from about 10 degrees to about 75 degrees. 
     Gap Adjustments 
     Gap adjustments will be described utilizing a shear valve; however, one of skill in the art will realize that the same techniques may apply to other types of valves, including gate, globe, and poppet valves. Drilling tool  600  in  FIG. 6  is illustrated with a profile view of the shear valve  601  and the orifice plate  603 , including an orifice  604 . Other orifices  604  may also be present. A gap  602  is shown between the shear valve  601  and the orifice plate  603 . The gap  602  may be adjusted in order to vary the sensitivity of the shear valve  601  and the flow splits between the orifices  604 . The valve gap  602  may be adjusted either manually, actively, or automatically to gain the desired sensitivity and flow splits. In some embodiments, a smaller valve gap results in greater shear valve sensitivity than a relatively larger valve gap. For example, a small gap of less than about 50 mm may result in a greater shear valve sensitivity than a gap of larger than about 100 mm. 
     Manual gap adjustment is illustrated in  FIG. 7A . Drilling tool  700 A includes shear valve  701  and orifice plate  703 , which includes an orifice  704 . Other orifices  704  may also be present. Valve gap  702  may be adjusted by utilizing shims  702 A or other types of spacers. If a larger gap is desired, more shims  702 A or larger shims may be used. If a smaller gap is desired, fewer shims  702 A, or smaller shims  702 A may be used. 
     Active gap adjustment is illustrated in  FIG. 7B . Active refers to a mechanical system that may adjust based on conditions, and does not necessarily rely on “smart” control electronics. Active adjustment may also be referred to as passive adjustment. Drilling tool  700 B includes shear valve  701  and orifice plate  703 , which includes an orifice  704 . Other orifices  704  may also be present. Valve gap  702  may be passively adjusted by utilizing springs  702 B or devices acting like springs, such as a folded piece of metal. Any type of spring known in the art may be used. If a larger gap is desired, stronger springs  702 B or several springs  702 B may be used. If a smaller gap is desired, weaker springs  702 B, or fewer springs  702 B may be used. 
     Automatic gap adjustment is illustrated in  FIG. 7C . Drilling tool  700 C includes shear valve  701  and orifice plate  703 , which includes an orifice  704 . Other orifices  704  may also be present. Valve gap  702  may be adjusted by utilizing actuators  702 C. If a larger gap is desired, the actuators are triggered to open  702 C. The actuators  702 C may be adjustable between different widths, or may be “energized or de-energized” without incremental adjustments. If a smaller gap is desired, either the actuator  702 C is de-energized, or the width may be adjusted. Any type of actuator known in the art may be used. 
     The invention having been generally described, the following example is given as an embodiment of the invention and to demonstrate the practice and advantages hereof. It is understood that the example is given by way of illustration and is not intended to limit the specification or the claims to follow in any manner. 
     EXAMPLE 
     In a directional drilling tool, a shear valve may regulate the amount of mud flow to a turbine within the tool. The tool may operate with mud flow rates between 350 GPM and 650 GPM; however, the turbine may only require between 50 GPM and 200 GPM at all tool flow rates. Therefore, when pumping 650 GPM through the tool, the maximum flow the shear valve can be supplying to the turbine is 30% of the total flow, and when pumping 350 GPM, the shear valve needs to supply a maximum of 60% of the total flow to the turbine. Thus, to use the full rotation of the shear valve when pumping 650 GPM, a valve gap of roughly about 40 min is needed and greater than about 128 mm when pumping at 350 GPM. The relation between flow splits and valve gap is shown in  FIG. 8 . When using a small valve gap, such as about 32 mm, a change in valve angle, from 10 degrees and 15 degrees has an 11% change in flow fraction. However, when using a large valve gap, such as about 128 mm, a change in valve angle from 10 degrees and 15 degrees has an 4% change in flow fraction. Thus, a smaller valve gap increases the shear valve&#39;s sensitivity. 
     While preferred embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Use of the term “optionally” with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. 
     Embodiments disclosed herein include: 
     A: A downhole tool comprises a tool body, multiple orifices in the tool body defining at least a first and a second flow path, and a valve that adjusts to change a ratio of fluid flow between the first and second flow paths, the valve being offset from the multiple orifices by a gap that is adjustable to customize a sensitivity of the change to each adjustment. 
     B: A method for regulating flow along a first fluid path in a downhole tool, the method comprising adjusting a valve relative to multiple orifices that define the first fluid path and a second fluid path, said adjusting including changing a ratio of fluid flow between the first and second flow paths, and adjusting a gap between the valve and the multiple orifices to modify a sensitivity of the change. 
     C: A system for regulating flow along a first fluid path, the system comprising a downhole tool including: a valve coupled to multiple orifices that define the first fluid path and a second fluid path and a gap between the valve and the multiple orifices; said tool configured to adjust the valve relative to the multiple orifices, said adjustment including changing a ratio of fluid flow between the first and second flow paths; and adjust the gap between the valve and the multiple orifices to modify a sensitivity of the change. 
     Each of embodiments A, B and C may have one or more of the following additional elements in any combination: Element 1: further comprising a turbine, wherein the first path of the valve is in fluid communication with the turbine. Element 2: wherein the valve type is one selected from the group consisting of gate, shear, globe, and poppet. Element 3: wherein the valve type is a poppet valve. Element 4: wherein the gap is adjustable using at least one of a manual adjustment, an active adjustment, an automatic adjustment, and combinations thereof. Element 5: further comprising shims, wherein the shims are used to manually adjust the gap. Element 6: further comprising a spring, wherein the spring is used to passively adjust the gap. Element 7: further comprising an actuator, wherein the actuator is used to automatically adjust the gap. Element 8: wherein a smaller valve gap results in greater valve sensitivity than a relatively larger valve gap. 
     Numerous other modifications, equivalents, and alternatives, will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such modifications, equivalents, and alternatives where applicable.