Patent Application
20170175490
The present disclosure relates generally to downhole tools and, more particularly, to placement of stabilizers, standoffs, and/or rollers on a downhole tool string.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Generally, a downhole tool may be deployed sub-surface, for example, to measure characteristics of a surrounding formation. To facilitate, the downhole tool may be moved within a borehole formed in the formation. For example, the downhole tool may be pushed to move the downhole tool farther into the borehole and/or pulled to remove the downhole tool from the borehole.
To form the borehole, a drill bit may excavate a portion of the formation. A drilling fluid, commonly referred to as “mud” or “drilling mud,” may be pumped through the borehole, for example, to cool and/or lubricate the drill bit. Generally, the drilling mud may include solid particles, such as dirt, suspended in liquid, such as water. When the formation is porous, the liquid component of the drilling mud may be pushed into the formation leaving the solid component on the borehole wall. Overtime, a layer of the solid particles, commonly referred to as “mud cake,” may form along the wall of the borehole.
When in contact, the mud cake may impede movement of the downhole tool within the borehole. For example, when stationary, the mud cake may harden around the downhole tool, thereby holding the downhole tool in place. Moreover, pressure differential (e.g., different between mud pressure and formation pressure) may push the downhole tool firmly against the borehole wall. In some cases, to detach the downhole tool from borehole wall, operations (e.g., fishing) may be performed. However, performing such operations may reduce the productivity time of the downhole tool. Even when in motion, the mud cake may contact the downhole tool, thereby causing friction that resists movement of the downhole tool. The resulting friction may cause movement of tool to be less predictable.
Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.
A first embodiment describes a manufacturing system used to manufacture a downhole tool string to be deployed in a borehole formed in a sub-surface formation, including a model that describes relationship between properties of the downhole tool string, properties of the borehole, properties of the sub-surface formation, and properties of mud cake formed on a surface of the borehole; and a design device that iteratively determines contact parameters that describe one or more contact points expected between the downhole tool string and the mud cake based at least in part on the model, in which the contact parameters comprise contact force expected at each of the contact points, adjusts the properties of the downhole tool string to add a spacer at one of the contact points associated with highest contact force; and indicates location, type, or both of the spacer to enable the manufacturing system to attach the spacer to the downhole tool string before deployment of the downhole tool string in the borehole.
A second embodiment describes a method for manufacturing a downhole tool string to be deployed in a borehole formed in a sub-surface formation including determining, using a design device of a manufacturing system that assembles the downhole tool string, a first set of properties comprising downhole tool string properties, borehole properties, formation properties, and mud cake properties; determining, using the design device, first contact forces expected to occur between the downhole tool string and mud cake formed along a surface of the borehole based at least in part on the first set of the properties; determining, using the design device, a second set of the properties; determining, using the design device, second contact forces expected to occur between the downhole tool string and the mud cake; and indicating, using the design device, location, type, or both of one or more spacers to attach to the downhole tool string to enable the manufacturing system to attach the one or spacer to the downhole tool string before deployment of the downhole tool string in the borehole based at least in part on the first contact forces and the second contact forces.
A third embodiment describes a tangible, non-transitory, computer-readable medium that stores instructions executable by a processor in a manufacturing system used to manufacture a downhole tool string to be deployed in a borehole formed in a sub-surface formation. The instructions include instructions to determine, using the processor, first downhole tool string properties that indicate an initial placement of a plurality of standoffs along the downhole tool string; determine, using the processor, a first contact force expected to occur at each of the plurality of standoffs with mud cake expected to form along a surface of the borehole based at least in part on the first downhole tool string properties, borehole properties, mud cake properties, and formation properties; determine, using the processor, second downhole tool string properties that replace a first standoff of the plurality of standoffs with a first roller, in which the first contact force associated the first standoff is greater than the first contact force associated with rest of the plurality of standoffs; and instruct, using the processor, a design device in the manufacturing system to indicate location, type, or both of the first roller based at least in part on the second downhole tool string properties to facilitate the manufacturing system attaching the first roller to the downhole tool string before deployment in the borehole.
Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:
One or more specific embodiments of the present disclosure will be described below. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions will be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
As mentioned above, a downhole tool may be deployed in a borehole to facilitate determining characteristics of a sub-surface formation. In some instances, multiple downhole tools may be connected together to form a downhole tool string. Additionally, as mentioned above, drilling mud may be pumped into the borehole. In some instances, the drilling mud in the borehole may exert a mud pressure on the formation greater than a formation pressure to facilitate reducing likelihood of fluid from the formation flowing out into the borehole and/or out to the surface. Due to the mud pressure, the liquid component of the drilling mud may flow into porous portions of the formation while the solid component of the drilling mud is blocked by the formation, thereby forming mud cake along the surface of the borehole.
Thus, in some instances, a portion of the downhole tool string may come in contact with the mud cake. For example, when the borehole is deviated (e.g., slanted), gravity and/or the mud pressure may cause the downhole tool string to contact the mud cake. Even when the borehole is vertical, the mud pressure and/or eccentered force exerted on the downhole tool string may cause the downhole tool string to contact the mud cake.
However, contacting the mud cake may impede movement of the downhole tool string within the borehole. For example, the downhole tool string may be stationary when one or more downhole tools are taking measurements. Since liquid content is low, mud cake may quickly harden. Thus, when in contact and stationary, the mud cake may quickly harden around contacting portions of the downhole tool string. After hardening and embedded in the mud cake, force used to resume movement of the downhole tool string may greatly increase.
In fact, in some instances, the force to resume movement may become so large that normal operating techniques may be insufficient to resume movement. In such instances, alternative techniques may be used to dislodge the contacting portions of the downhole tool string from the mud cake. For example, a fishing operation, in which a grasping mechanism is lowered into the borehole and attached to the downhole tool string, may be used. However, to utilize such alternative techniques, normal operation (e.g., drilling and/or logging) may be paused, thereby reducing productivity time.
When already in motion, the mud cake may not have sufficient time to harden around contacting portions of the downhole tool string. Nevertheless, the friction coefficient of the mud cake may be higher than the friction coefficient of the drilling mud. As such, when in contact, the mud cake may exert a greater amount of fiction on the downhole tool string compared to the drilling mud. Since in motion, amount of contact between the downhole tool string and the mud cake may be constantly changing, thereby causing amount of force to overcome friction to also constantly be changing. Thus, force used to move the downhole tool string may be less predictable and may, in fact, cause uneven (e.g., jerky or yo-yo effect) movement that jostles the downhole tools.
Accordingly, to reduce effect drilling mud has on movement of the downhole tool string, spacers may be attached to the downhole tool string to reduce contact area and, thus, contact force between the downhole tool string and the mud cake formed along the borehole wall. For example, when deployed while drilling the borehole, stabilizers (e.g., spacers) may be attached to the downhole tool string. Similarly, when deployed after drilling the borehole (e.g., via conveyance line), standoffs (e.g., spacers) may be attached to the downhole tool string. Generally, attaching a stabilizer and/or standoff may produce raised area along the downhole tool string, thereby increasing clearance between the housing of the downhole tool string and the borehole wall, thus, likelihood of the mud cake directly contacting the housing.
Additionally, rollers may be attached to downhole tool string, for example, when deploying via conveyance line. In some embodiments, a roller may include a mechanical component (e.g., a wheel or a ball) that rotates around a central axis when an external force is exerted. For example, when the mechanical component is in contact the mud cake, friction force between a surface of the mechanical component and the surface of the mud cake may cause the mechanical component to rotate as the downhole tool string is pulled along the borehole. Since the coefficient of friction resisting rotation of the mechanical component may be less than the sliding friction coefficient of the mud cake, force used to move the downhole tool string a travel distance may be reduced when a roller is attached compared to when a standoff is attached.
However, attaching spacers to a downhole tool string may increase the manufacturing cost of the downhole tool string. Additionally, manufacturing cost of a roller may be much larger than manufacturing cost of a standoff. Thus, in some instances, number of rollers available for attachment to a downhole tool string may be more limited compared to number of standoffs available. Moreover, attaching too many stabilizers and/or standoffs may begin to negate their advantage. For example, if standoffs are attached along the entire length of the downhole tool string, contact area between the downhole tool string and the mud cake may actually increase due to the larger radius of the standoffs.
Accordingly, the present disclosure provides techniques for determining placement of spacers (e.g., standoffs, stabilizers, and/or rollers) along a downhole tool string, for example, to reduce effect the mud cake may have on movement of the downhole tool string. In some embodiments, a design device may be used to determine design parameters, such as placement of spacers, of a downhole tool string. For example, to determine placement of spacers, the design device may use a model that describes expected interaction between the downhole tool string, the mud cake, the surrounding formation, and/or the borehole. In some embodiments, properties of the downhole tool string, properties of the mud cake, properties of the surrounding formation, and/or properties of the borehole may provide an indication of how each is expected to interact with its surroundings. As such, based on the properties, the design device may use the model to determine contact parameters, such as location of contact points between the downhole tool string and the mud cake, number of contact points, whether a contact point is between the housing or a spacer, and/or contact force at a contact point.
Based at least in part on the contact parameters, the design device may determine place of spacers along the downhole tool string. For example, the design device may determine a contact metric based on the contact parameters and compare the contact metric to a threshold to determine placement of standoffs and/or stabilizers along the downhole tool string. In some embodiments, the contact metric may be number of contact points between the downhole tool string housing and the mud cake, average contact force between the downhole tool string housing and the mud cake, and/or total contact force along the downhole tool string. When the contact metric is greater than the threshold, the design device may place a standoff and/or stabilizer at a contact point associated with the highest contact force.
Since adding a spacer (e.g., a standoff or stabilizer) increase clearance between the downhole tool string housing and the mud cake, the deformation (e.g., properties) of the downhole tool string may change, thereby also changing interaction with the mud cake. As such, the design device may iteratively use the model to determine the contact parameters after a spacer is added until the contact metric is no longer greater than the threshold and/or no more spacers are available. In this manner, the design device may determine number and/or location of standoffs and/or stabilizers to attach to the downhole tool string.
As described above, attaching rollers may reduce effect mud cake has on movement of the downhole tool string, but may be more limited in number compared to standoffs. Thus, in some embodiments, the design device may replace standoffs with rollers based at least in part on the contact parameters. For example, the design device may use the model to determine contact force at each standoff attached to the downhole tool string. When rollers are available, the design device may replace the standoff associated with the highest contact force with a roller. The design device may then iteratively use the model to determine the contact parameters after a roller is added until no more rollers are available and/or all standoffs have been replaced.
Furthermore, in some instances, properties of the mud cake, the formation, and/or the borehole surrounding the downhole tool string may change as the downhole tool string is moved along the borehole. Additionally, in some instances, the properties of the mud cake, the mud cake, the formation, and/or the borehole may include some uncertainty (e.g., ranges). To help account for variations in the properties, the design device may determine multiple sets of properties and determine contact parameters for each. In some embodiments, the design device may determine placement of spacers based on average contact forces along the downhole tool string. In other embodiments, the design device may determine placement of spacers based on peak contact forces along the downhole tool string.
To help illustrate,
Additionally, as depicted, the lower end of the drill string 18 includes a downhole tool string 34 that includes various downhole tools, such a measuring-while-drilling (MWD) tool 36 and a logging-while-drilling (LWD) tool 38. Generally, the downhole tools (e.g., MWD tool 36 and LWD tool 38) may facilitate determining characteristics of the surrounding formation 12. For example, the LWD tool 38 may include an electrically operated radiation generator, which outputs radiation into the surrounding formation 12, and one or more sensors, which may measure radiation returned from the surrounding formation 12, surrounding pressure, and/or surrounding temperature.
After drilling, downhole tools may be also be deployed in the borehole 26, for example, via a conveyance line. To help illustrate, a conveyance line system 40, which may be used to deploy downhole tools in the borehole 26, is described in
Additionally, the conveyance line system 40 includes a cable 44 to facilitate controlling movement of the downhole tool string 34. In some embodiments, the conveyance line system 40 may be a wireline system when the cable 44 is an armed electrical cable that enables bi-directional communication between the downhole tool string 34 and the surface. In other embodiments, the conveyance line system 40 may be a slickline system when the cable 44 is used to support the downhole tool string 46, but does not provide direct communication between the downhole tool string 46 and the surface. Thus, in a wireline system or a slickline system, movement of the downhole tool string 34 may be controlled by exerting force on the cable 44 to pull the downhole tool string 34 up the borehole 24 and/or by reducing force exerted on the cable 44 to enable gravity to pull the downhole tool string 34 down the borehole 24.
In other embodiments, the conveyance line system 40 may be a coil tubing system when the cable 44 is a coiled tube. In such embodiments, movement of the downhole tool string 34 may be controlled again by exerting force on the cable 44 to pull the downhole tool string 34 up the borehole 24. However, to supplement force exerted by gravity, force may be exerted on the coiled cable 44 to push the downhole tool string 34 down the borehole 24. Thus, using a coiled cable 44 may facilitate controlling movement of the downhole tool string 34 particularly when the borehole 24 is deviated (e.g., slanted away from vertical).
Even after drilling, the drilling mud 28 may remain in the borehole 26 to exert a mud pressure on the formation 12. In some embodiments, the mud pressure may be greater than the formation pressure to reduce likelihood of fluid from the formation 12 leaking into the borehole 26 and/or out to the surface. Thus, when porous, the mud pressure may cause the formation 12 to filter the drilling mud 28. More specifically, since greater than the formation pressure, the mud pressure may cause a liquid component (e.g., water) of the drilling mud 28 to follow into pores of the formation 12. When the pores are smaller than size of a particle component (e.g., dirt) of the drilling mud 28, the formation 12 may block the particle component. In such instances, a mud cake (e.g., particle component with decreased liquid component) may form along the surface of the borehole 26 and, thus, may contact the downhole tool string 34.
To help illustrate, a downhole tool string 34 deployed in two examples of boreholes 26 is described in
As described above, the downhole tool string 34 may include multiple downhole tools 50. In some embodiments, the downhole tools 50 may be connected using field joints 52. For example, as depicted in
Additionally, as described above, drilling mud 28 may be disposed in the borehole 26 to exert a mud pressure on the formation 12 greater than the formation pressure. Furthermore, as described above, the mud pressure may cause the formation 12 to filter the liquid component of the drilling mud 28 from the solid component. As depicted in
Furthermore, as described above, the downhole tool string 34 may come in contact with the mud cake 54. For example, as depicted in
Additionally, as depicted in
As depicted in
To facilitate reducing force used to move the downhole tool string 34, spacers may be attached to the downhole tool string 34 to increase clearance between the housing 55 and the mud cake. Examples of spacers that may be attached to the downhole tool string 34 are described in
As depicted in
Additionally, in some embodiments, the standoffs 58 may be connected at field joint 52 locations. For example, in the depicted embodiment, the first standoff 58A is connected at the first field join 52A. However, in other embodiments, the standoffs 58 may be connected at any suitable location along the downhole tool string 34. For example, in the depicted embodiment, the second standoff 58B is connected at the third downhole tool 50C and not at a field joint 52.
In a drilling system 10, stabilizers may be used instead of standoffs 58. In some embodiments, a stabilizer may be a balloon attached around the housing 55 of the downhole tool string 34. As such, a stabilizer may function similarly to a standoff 58 by increasing clearance between the mud cake 54 and the housing 55. Thus, one of ordinary skill in the art should recognize the techniques describe with reference to standoffs 58 used in a conveyance line system 40 may be interchanged with stabilizers when used in a drilling system 10.
As depicted in
Similar to standoffs 58, in some embodiments, roller 60 may be connected at field joint locations 52. For example, in the depicted embodiment, the roller 60 is connected at the first field join 52A. However, in other embodiments, the roller 50 may be connected at any suitable location along the downhole tool string 34. For example, in such embodiments, the second standoff 58B may additionally or alternatively be replaced with a roller 60.
In some embodiments, a manufacturing system (e.g., plant) may include machines and/or equipment that assemble the downhole tool string 34 before deployment in the borehole 26. For example, the manufacturing system may attach spacers to the downhole tool string 34. However, determining location and/or type of spacers to attach to the downhole tool string 34 may include consideration of various factors. For example, since spacers are generally additional components attached to the downhole tool string 34, increasing number of spacers may increase manufacturing cost of the downhole tool string 34. Additionally, number of different types (e.g., standoffs 58 and rollers 60) of spacers available for use with the downhole tool string 34 may vary. Moreover, attaching too many stabilizers and/or standoffs may begin to negate their advantage. Thus, the manufacturing system may include a design device that determine location and type of the spacers to attach to the downhole tool string 34 based at least in part on the various factors.
To help illustrate, one embodiment of a design device 57 that may be used in a manufacturing system is described in
In the depicted embodiment, the processor 59 may execute instruction stored in memory 59 to perform operations, such determining location and/or type of spacers to attach to the downhole tool string 34. As such, the processor 59 may include one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. Additionally, the memory 61 may be a tangible, non-transitory, computer-readable medium that store instructions executable by and data to be processed by the processor 59. For example, in the depicted embodiment, the memory 61 may store a model 69 that describes interaction between the downhole tool string 34, the formation 12, the borehole 26, and/or the mud cake 54. Thus, the memory 61 may include random access memory (RAM), read only memory (ROM), rewritable non-volatile memory, flash memory, hard drives, optical discs, and the like.
Furthermore, I/O ports 67 may enable the design device 67 to interface with various other electronic devices. For example, the I/O ports 67 may enable the design device 67 to communicatively couple to a network, such as a personal area network (PAN), a local area network (LAN), and/or a wide area network (WAN). Accordingly, in some embodiments, the design device 57 may receive the model 69 from another electronic device and/or communicate determined location and/or type of spacers to another electronic device via the I/O ports 67, for example, to enable the manufacturing system to implement when assembling the downhole tool string 34.
Additionally, the input devices 65 may enable a user to interact with the design device 57, for example, to input properties and/or input instructions (e.g., control commands). Thus, in some embodiments, the input device 65 may include buttons, keyboards, mice, trackpads, and the like. Additionally or alternatively, the display 63 may include touch components that enable user inputs to the design device 57 by detecting occurrence and/or position of an object touching its screen (e.g., surface of the display 63). In addition to enabling user inputs, the display 64 may present visual representations of information, such as indication of the location and/or type of spacers to attach to a downhole tool string 34 to facilitate implementation (e.g., assembly) by the manufacturing system.
As described above, the design device 57 may use the model 69 to facilitate determine location and/or type of spacers to attach to the downhole tool string 34. In some embodiments, the model 69 may be finite element analysis (FEA) model. Additionally, in some embodiments, the model 69 may describes expected interaction between the downhole tool string 34, the mud cake 54, the formation 12, and/or the borehole 26. In some embodiments, properties of the downhole tool string 34, properties of the mud cake 54, properties of the formation 12, and/or properties of the borehole 26 may provide an indication of how each is expected to interact with its surroundings and, thus, be inputs to the model 69.
For example, the properties of the downhole tool string 34 may include length of the downhole tool string 34, weight of the downhole tool string 34, size of the housing 55, weight distribution along the downhole tool string 34, material composition of the housing 55, rigidity of the material composition, type of downhole tools 55 included in the downhole tool string 34, location of spacers attached to the downhole tool string, size (circumference and/or geometry) of each spacer attached to the downhole tool string 34, type (e.g., stabilizer, standoff 58, or roller 60) of each spacer attached to the downhole tool string 34, and/or the like. Additionally, the properties of the mud cake 54 may include material composition of the mud cake 54, thickness of the mud cake 54, and the like. Furthermore, the properties of the formation 12 may include permeability of the formation 12, porosity of the formation 12, and/or the like. The properties of the borehole 26 may include the deviation (e.g., degrees from vertical) of the borehole 26, size (e.g., circumference) of borehole 26, and/or the like.
Using the model 69, the design device 57 may determine contact parameters that describe expected contact points between the downhole tool string 34 and the mud cake 54. In some embodiments, the contact parameters may include location of contact points, number of contact points, what part (e.g., standoff 58, roller 60, and/or housing 55) of the downhole tool string 34 is at the contact point, contact force at each contact point, and/or the like. Based at least in part on the contact parameters, the design device 57 may then determine location and/or type of spacers to attach to the downhole tool string 34.
To help illustrate, one embodiment of a process 62 for determining placement of spacers along a downhole tool string 34 is described in
Accordingly, in some embodiments, the design device 57 may determine the model 69 (process block 64). When stored in memory 61, the design device 57 may retrieve the model 69 from memory 61. Additionally or alternatively the design device 57 may receive the model 69 from another electronic device, for example, via the I/O ports 67.
Additionally, the design device 57 may determine properties of the downhole tool string 34 (process block 66). As described above, the properties of the downhole tool string 34 may include length of the downhole tool string 34, weight of the downhole tool string 34, size of the housing 55, weight distribution along the downhole tool string 34, material composition of the housing 55, rigidity of the housing 55, type of downhole tools 55 included in the downhole tool string 34, location of spacers attached to the downhole tool string, size (circumference and/or geometry) of each spacer attached to the downhole tool string 34, type (e.g., stabilizer, standoff 58, or roller 60) of each spacer attached to the downhole tool string 34, and/or the like. In some embodiments, the properties of the downhole tool string 34 may be directly measured while on the surface 16, for example, in the manufacturing system. Thus, the properties of the downhole tool string 34 may be determined with relative certainty. In some embodiments, the properties of the downhole tool string 34 may be manually entered into the design device 57 via the user inputs 65. Additionally or alternatively, the design device 57 may receive the properties of the downhole 34 from another electronic device (e.g., a sensor), for example, via the I/O ports 67.
The design device 57 may also determine properties of the formation 12 (process block 68). As described, the properties of the formation 12 may include permeability of the formation 12, porosity of the formation 12, and/or the like. When deep under the surface 16, properties of the formation 12 may be difficult to directly determine, particularly since the downhole tools 50 used to determine the properties of the formation 12 are part of the downhole tool string 34 and, thus, not yet deployed. As such, the properties of the formation 12 may include some uncertainty. In some embodiments, the properties of the formation 12 may be manually entered into the design device 57 via the user inputs 65. Additionally or alternatively, the design device 57 may receive the properties of the formation 12 from another electronic device (e.g., a sensor), for example, via the I/O ports 67.
Additionally, the design device 57 may determine properties of the mud cake 54 (process block 70). As described above, the properties of the mud cake 54 may include material composition of the mud cake 54, thickness of the mud cake 54, and/or the like. Thus, in some embodiments, the properties mud cake 54 may be dependent on at least properties of drilling mud 58 in the borehole 26, mud pressure, pumping pressure with which the drilling mud 58 is pumped into the borehole, and/or properties of the formation 12 (e.g., porosity). Properties of the drilling mud 28 may be determined on the surface 16 with relative certainty, but may change as the drilling mud 28 follows in the borehole 26. Additionally, since based on properties of the formation 12, the properties of the mud cake 54 may also include some uncertainty. In some embodiments, the properties of the mud cake 54 may be manually entered into the design device 57 via the user inputs 65. Additionally or alternatively, the design device 57 may receive the properties of the mud cake 54 from another electronic device (e.g., a sensor), for example, via the I/O ports 67.
Furthermore, the design device 57 may determine properties of the borehole 26 (process block 71). As described above, the properties of the borehole 26 may include angle (e.g., degrees from vertical) of the borehole 26, size of borehole 26, and/or the like. In some instances, properties of shallow portions of the borehole 26 may be determined with relative certainty. However, properties of the borehole 26 may change over its length. As such, properties of deeper portions of the borehole 26 may be determined with less certainty. In other words, certainty of the properties of the borehole 26 may vary based on depth. In some embodiments, the properties of the borehole 26 may be manually entered into the design device 57 via the user inputs 65. Additionally or alternatively, the design device 57 may receive the properties of the borehole 26 from another electronic device (e.g., a sensor), for example, via the I/O ports 67.
Using the model 69, the design device 57 may then determine the location and/or type of spacers to attach along the downhole tool string 72 based at least in part on the properties of the downhole tool string 34, the formation 12, the mud cake 54, and the borehole 26 (process block 72). For example, in some embodiments, the design device 57 may determine where to place standoffs 58 along the downhole tool string 34. In other embodiments, the design device 57 may determine what standoffs 58 to replace with roller 60. In further embodiments, the design device 57 may determine where to place a combination of roller 60 and standoffs 58.
To help illustrate, one embodiment of a process 74 for determining placement of standoffs 58 along a downhole tool string 34 is described in
Accordingly, in some embodiments, the design device 57 may use the model 69 to determine locations (e.g., contact points) where the downhole tool string 34 is expected to contact the mud cake 54 (process block 76) and the contact force at each location (process block 78). In some embodiments, the design device 57 may determine what portion of the downhole tool string 34 is expected to contact the mud cake 54 based at least in part on profile of the contact force. Additionally, in some embodiments, the design device 47 may determine number contact points between the downhole tool string 34 and the mud cake based at least in part on number of peaks in the profile of the contact force.
To help illustrate, a plot 86 of a contact force curve 88 relative to length of the downhole tool string 34 is described in
Returning to the process 74 of
When standoffs 58 are available, the design device 57 may determine whether a contact metric is greater than a threshold (decision block 82). In some embodiments, the contact metric may be number of contact points between the housing 55 and the mud cake 54. For example, assuming sufficient (e.g., infinite) number of standoffs 58, the design device 57 may iteratively perform the process 74 until number of contact points between the housing 55 and the mud cake 54 is less than or equal to a threshold number (e.g., zero). In other embodiments, the contact metric may be total contact force between the downhole tool string 34 and the mud cake 54. For example, assuming sufficient (e.g., infinite) number of standoffs 58, the design device 57 may iteratively perform the process 74 until total contact force between the downhole tool string 34 and the mud cake 54 is below a threshold force.
When the contact metric is greater than the threshold, the design device 57 may place a standoff 58 corresponding with a location (e.g., contact point) expected to have largest contact force between the housing 55 and the mud cake 54. For example, with regard to
Returning to the process 74 described in
To help illustrate, the plot 86 of the contact force curve 88 after the standoff 58 is added to the downhole tool string 34 is described in
Returning to the process 74 described in
As described above, the design device 57 may determine what standoffs 58 to replace with rollers 60. In some embodiments, the placement of standoffs 58 may already be determined, for example, using the process 74 described in
To help illustrate, a process 92 describing for determining placement of roller 60 along a downhole tool string 34 is described in
Accordingly, in some embodiments, the design device 57 may use the model 69 to determine contact force at each standoff 58 (process block 94). To help illustrate, a plot 102 of a contact force curve 104 relative to length of the downhole tool string 34 is described in
Returning to the process 92 described in
When roller 60 are available, the design device 57 may replace the standoff 58 associated with the highest expected contact force with a roller 60 (process block 99). For example, with regard to
Returning to the process 92 described in
To help illustrate, the plot 102 of the contact force curve 104 after the standoff 58 is replace with the roller 60 is described in
Returning to the process 92 described in
As described above, properties of the formation 12, properties of the borehole 12, and/or properties of the mud cake 54 may contain uncertainty. Additionally, as described above, properties of the formation 12, properties of the borehole 12, and/or properties of the mud cake 54 may change, for example, as the downhole tool string 34 moves along the borehole 12. To facilitate taking the uncertainty and/or changes in the properties into account, the design device 57 may determine placement of the standoffs 58 and/or roller 60 based on multiple different sets of properties.
One embodiment of a process 110 for determining placement of standoffs 58 and/or rollers 60 based on multiple sets of properties is described in
Accordingly, in some embodiments, the design device 57 may determine multiple sets of mud cake 54, formation 12, and/or borehole 26 properties (process block 112). In some embodiments, the design device 57 may select the sets such that one or more of the properties varies within an uncertainty range between the sets. For example, the design device 57 may select a first set with a mud cake property at a first value within an uncertainty range, a second set with the mud cake property at a second value within the uncertainty range, and so on. In this manner, the design device 57 may determine placement of the standoffs 58 and/or rollers 60 while taking into account uncertainty of properties input to the model 69 and/or uncertainties of the model 69 itself.
In other embodiments, the design device 57 may select the sets such that each set represents properties at different locations in the borehole 26. For example, the design device 57 may select a first set of properties determined for a first location, a second set of properties determined for a second location, and so on. By taking into account properties of the mud cake 54, formation 12, and/or borehole 26 at different locations, the design device 57 may determine placement of the standoffs 58 and/or rollers 60 to reduce effect of the mud cake 54 while moving through the borehole 26.
As such, the technical effects of the present disclosure include improving manufacture (e.g., assembly) of a downhole tool string, for example, by improving determination of spacer placement along the downhole tool string. In some embodiments, a design device may use a model, which describes relationship between properties of the downhole tool string, a borehole, a surrounding formation, and a mud, to determine contact parameters that provide an indication of contact between the downhole tool string and the mud cake. For example, based on the contact parameters may indicate location of contact points, number of contact points, contact force at each contact point, and/or what portion (e.g., spacer or housing) of the downhole tool string contacts the mud cake. Thus, based at least in part on the contact parameters, the design device may determine location and/or type of spacers to attach to the downhole tool string. For example, the design device may iteratively place a standoff at a contact point between the housing and the mud bake associated with the highest contact force. Additionally, the design device may iteratively replace a standoff at a contact point associated with the highest contact force with a roller.
The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.
