The present disclosure describes apparatus, systems, and methods for orienting a downhole tool in a wellbore.
Downhole wellbore tools that are fixed to a downhole conveyance from the surface (for example, by a coiled tubing, wireline, or other conveyance) are conventionally run into and out of the wellbore to perform operations. Each downhole tool has some freedom to move in three-dimensional space within the wellbore even attached to the downhole conveyance. In some examples, however, wireline downhole tools have a high aspect ratio that limits their ability to yaw and pitch within the three-dimensional space. Such tools may remain within the wellbore during their travel which also limits their positional freedom in one or more planes. Conventionally, centralizers or decentralizers can be used to further constrain these freedoms of wireline tools. Even though the friction and adhesive forces can be high under these conditions, the weight of a wireline tool pulling it downhole and amount of tension that can be applied through a steel wire to pull it up help wireline tools to move.
In an example implementation, a downhole tool includes a body configured to move in a wellbore formed from a terranean surface to a subterranean formation in a direction downhole of the terranean surface independent of a downhole conveyance attached to the body; one or more sensors positioned in the body, the one or more sensors configured to measure a value associated with at least one of the wellbore or the terranean surface; and at least one mass positioned in the body and configured to adjust an orientation of the body in response to one or more forces acting on the body as the downhole tool moves in the wellbore in the direction downhole of the terranean surface.
In an aspect combinable with the general implementation, the at least one mass includes a buoyant portion positioned within, or attached to, a first location of the body; and a ballast portion positioned within, or attached to, a second location of the body.
In another aspect combinable with any of the previous aspects, the first location is at or near an uphole end of the body, and the second location is at or near a downhole end of the body.
In another aspect combinable with any of the previous aspects, the buoyant portion includes a first buoyant portion attached to an exterior surface of the body at a first exterior location and a second buoyant portion attached to the exterior surface of the body at a second exterior location radially opposite the first exterior location.
In another aspect combinable with any of the previous aspects, the at least one mass further includes at least one magnet positioned within, or attached to, a third location of the body.
In another aspect combinable with any of the previous aspects, the at least one mass includes at least one magnet positioned within, or attached to, a location of the body.
In another aspect combinable with any of the previous aspects, the at least one magnet is positioned within the body to align, with a magnetization force, the body with a casing, the at least one magnet including a casing collar locator.
In another aspect combinable with any of the previous aspects, the at least one magnet includes an electro-permanent magnet.
In another aspect combinable with any of the previous aspects, the electro-permanent magnet includes a casing collar detector.
In another aspect combinable with any of the previous aspects, the body includes a cap portion located at an uphole end of the body and a nose portion located at a downhole end of the body.
In another aspect combinable with any of the previous aspects, the cap portion includes a sharp cap, a rounded cap, a flat cap, or a conic cap.
In another aspect combinable with any of the previous aspects, the nose portion includes a sharp nose, a rounded nose, or a conic cap.
In another aspect combinable with any of the previous aspects, the nose portion further includes at least one wheel or roller mounted to a downhole end of the nose portion.
Another aspect combinable with any of the previous aspects further includes one or more wheels coupled to an exterior surface of the body.
In another aspect combinable with any of the previous aspects, the one or more forces includes a buoyant force and a gravitational force.
In another aspect combinable with any of the previous aspects, the one or more sensors includes at least one of a casing collar detector or a corrosion detector.
In another example implementation, a method for running an untethered downhole tool in a wellbore includes inserting the untethered downhole tool into the wellbore at a terranean surface, the untethered downhole tool including a body, one or more sensors positioned in the body, and at least one mass positioned in the body; running the untethered downhole tool within the wellbore in a direction downhole of the terranean surface and toward a subterranean formation independent of a downhole conveyance attached to the body; and adjusting, with the at least one mass positioned in the body, an orientation of the body in response to one or more forces acting on the body as the downhole tool runs in the wellbore in the direction downhole of the terranean surface.
In an aspect combinable with the general implementation, adjusting, with the at least one mass positioned in the body, the orientation of the body relative to the one or more forces acting on the body includes: adjusting the orientation of the body relative to the one or more forces acting on the body with a buoyant portion of the at least one mass that is positioned within, or attached to, a first location of the body; and adjusting the orientation of the body relative to the one or more forces acting on the body with a ballast portion of the at least one mass that is positioned within, or attached to, a second location of the body.
In another aspect combinable with any of the previous aspects, the first location is at or near an uphole end of the body, and the second location is at or near a downhole end of the body.
In another aspect combinable with any of the previous aspects, adjusting the orientation of the body relative to the one or more forces acting on the body with a buoyant portion of the at least one mass that is positioned within, or attached to, a first location of the body includes adjusting the orientation of the body relative to the one or more forces acting on the body with a first buoyant portion attached to an exterior surface of the body at a first exterior location; and adjusting the orientation of the body relative to the one or more forces acting on the body with a second buoyant portion attached to the exterior surface of the body at a second exterior location radially opposite the first exterior location.
In another aspect combinable with any of the previous aspects, adjusting, with the at least one mass positioned in the body, the orientation of the body relative to the one or more forces acting on the body includes adjusting, with at least one magnet positioned within, or attached to, a third location of the body, the orientation of the body relative to the one or more forces acting on the body by generating a magnetic force with the at least one magnet relative to a casing positioned in the wellbore.
In another aspect combinable with any of the previous aspects, adjusting, with the at least one mass positioned in the body, the orientation of the body relative to the one or more forces acting on the body includes adjusting, with at least one magnet positioned within, or attached to, a location of the body, the orientation of the body relative to the one or more forces acting on the body by generating a magnetic force with the at least one magnet relative to a casing positioned in the wellbore.
In another aspect combinable with any of the previous aspects, the at least one magnet includes at least one electro-permanent magnet.
Another aspect combinable with any of the previous aspects further includes adjusting the generated magnetic force by changing a magnetization of the at least one electro-permanent magnet; and based on the adjusted magnetic force, changing a position of the body relative to the casing.
Another aspect combinable with any of the previous aspects further includes detecting one or more casing collars with the at least one electro-permanent magnet during the running the untethered downhole tool within the wellbore.
Another aspect combinable with any of the previous aspects further includes adjusting one or more hydrodynamic forces that acts on the body as the untethered downhole tool runs in the wellbore in the direction downhole of the terranean surface with at least one of a cap portion located at an uphole end of the body or a nose portion located at a downhole end of the body.
In another aspect combinable with any of the previous aspects, the cap portion includes a sharp cap, a rounded cap, a flat cap, or a conic cap.
In another aspect combinable with any of the previous aspects, the nose portion includes a sharp nose, a rounded nose, or a conic cap.
Another aspect combinable with any of the previous aspects further includes contacting, with at least one wheel or roller mounted to a downhole end of the nose portion, the wellbore or a casing installed in the wellbore as the untethered downhole tool runs in the wellbore in the direction downhole of the terranean surface.
Another aspect combinable with any of the previous aspects further includes contacting, with one of more wheels coupled to an exterior surface of the body, the wellbore or a casing installed in the wellbore as the downhole tool runs in the wellbore in the direction downhole of the terranean surface.
In another aspect combinable with any of the previous aspects, the one or more forces includes a buoyant force and a gravitational force.
Another aspect combinable with any of the previous aspects further includes measuring a value associated with at least one of the wellbore or the terranean surface with the one or more sensors as the untethered downhole tool runs in the wellbore in the direction downhole of the terranean surface.
In another example implementation, a downhole tool system includes an untethered downhole tool that includes a housing and a sensor package mounted in the housing, the housing including a downhole end and an uphole end; and means for orienting the untethered downhole tool with respect to a radial alignment angle and one or more vertical alignment angles in response to one or more forces acting on the untethered downhole tool as the untethered downhole tool runs in a wellbore in a direction downhole of a terranean surface, the means for orienting the untethered downhole tool mounted within or attached to the housing.
In an aspect combinable with the general implementation, the means for orienting the untethered downhole tool includes a first mass having a first density positioned at or near the downhole end and a second mass having a second density less than the first density positioned at or near the uphole end.
In another aspect combinable with any of the previous aspects, the means for orienting the untethered downhole tool includes one or more magnets positioned in or attached to the housing.
In another aspect combinable with any of the previous aspects, the second mass includes an uphole cap mounted on the uphole end.
In another aspect combinable with any of the previous aspects, the first mass includes a downhole cap mounted on the downhole end.
In another aspect combinable with any of the previous aspects, the means for orienting the untethered downhole tool includes one or more magnets positioned in or attached to the housing.
In another aspect combinable with any of the previous aspects, the means for orienting the untethered downhole tool includes one or more wheels mounted to the housing.
In another aspect combinable with any of the previous aspects, the sensor package includes an inertial sensor that includes a casing collar locator.
Implementations of an untethered downhole tool according to the present disclosure may include one or more of the following features. For example, an untethered downhole tool according to the present disclosure can be adjusted into a favorable orientation with respect to, for example, a casing installed in a wellbore to enable measurements related to the casing (for example, casing collar location). As another example, an untethered downhole tool according to the present disclosure can be adjusted in orientation absent of a conventional centralizer or decentralizer, which can possibly jam the tool especially when there is a transition between different size casings. As another example, an untethered downhole tool according to the present disclosure can be adjusted in orientation to offset a center of gravity for low side self-positioning. As further examples, an untethered downhole tool according to the present disclosure can, as compared to conventional wireline tools, lower drag forces, maximize effective fluid contact area, and increase sensor signal amplitude by strategically orienting the tool along a low-side of the tool. As a further example, an untethered downhole tool according to the present disclosure can resist rotational force due to fluid heterogeneity as well as provide a corrective moment in a vertical axis. As a further example, an untethered downhole tool according to the present disclosure can be optimally oriented without creating higher fluid friction forces. As another example, an untethered downhole tool according to the present disclosure can pass through restrictions and complex profiles (for example, a nipple, a seal assembly, a cross-over) that conventional wirelines tools cannot.
The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.
In some aspects, the untethered downhole tool 100 comprises a relatively lightweight miniaturized tool (for example, a tool with a length several times smaller than the wellbore diameter). For such tools, there are not many limiting factors for the alignment within a wellbore; thus all the degrees of freedoms are available. Conventional centralizers and decentralizers that are used for wireline tools may not be suitable for such miniaturized untethered tools since they increase the chance of jamming in the wellbore.
In some aspects, the untethered downhole tool 100 can serve various purposes, such as collecting physical or chemical information regarding the downhole fluids or the formation rocks of the wellbore system 10. Such collection of information may be enhanced by adjusting an orientation of the untethered downhole tool 100 in three-dimensional space within the wellbore 20. As an example, for any measurement that involves one or more casings installed in the wellbore system (for example, of casing collars or otherwise), an orientation of a sensor package within the untethered downhole tool 100 with respect to the casing can affect the collection of information. Conventionally, a wireline downhole tool (in other words, a downhole tool attached to a downhole conveyance) with a casing collar locator is either centralized or decentralized to fix a sensor position relative to the casing. However, the untethered downhole tool that, for instance, includes no active steering, can have varying orientations in the wellbore 20 depending on, for example, its hydrodynamics and composition, geometry of the wellbore 20, and fluids inside the wellbore 20 (or wellbore tubular 17). This varying of orientation can complicate any measurements, for example, that involves the casing such as casing collar location.
As described in more detail herein, in some aspects, the untethered downhole tool 100 includes one or more mass components, such as one or more components that adjust a density, center of gravity, center of mass, or hydrodynamics (or a combination thereof) that adjust an orientation of the untethered downhole tool 100 in the wellbore 20. In some aspects, the one or more mass components may adjust the orientation of the untethered downhole tool 100 during the running in process, during the running out process, while the tool 100 is stationary (or substantially stationary) within the wellbore 20, or a combination thereof.
As shown, the wellbore system 10 accesses a subterranean formation 40 and provides access to hydrocarbons located in such subterranean formation 40. In an example implementation of system 10, the system 10 may be used for a production operation in which the hydrocarbons may be produced from the subterranean formation 40 within the wellbore tubular 17 (for example, as a production tubing or casing). However, tubular 17 may represent any tubular member positioned in the wellbore 20 such as, for example, coiled tubing, any type of casing, a liner or lining, another downhole tool connected to a work string (in other words, multiple tubulars threaded together), or other form of tubular member.
A drilling assembly (not shown) may be used to form the wellbore 20 extending from the terranean surface 12 and through one or more geological formations in the Earth. One or more subterranean formations, such as subterranean zone 40, are located under the terranean surface 12. As will be explained in more detail below, one or more wellbore casings, such as a surface casing 30 and intermediate casing 35, may be installed in at least a portion of the wellbore 20. In some embodiments, a drilling assembly used to form the wellbore 20 may be deployed on a body of water rather than the terranean surface 12. For instance, in some embodiments, the terranean surface 12 may be an ocean, gulf, sea, or any other body of water under which hydrocarbon-bearing formations may be found. In short, reference to the terranean surface 12 includes both land and water surfaces and contemplates forming and developing one or more wellbore systems 10 from either or both locations.
In some embodiments of the wellbore system 10, the wellbore 20 may be cased with one of more casings. As illustrated, the wellbore 20 includes a conductor casing 25, which extends from the terranean surface 12 shortly into the Earth. A portion of the wellbore 20 enclosed by the conductor casing 25 may be a large diameter borehole. Additionally, in some embodiments, the wellbore 20 may be offset from vertical (for example, a slant wellbore). Even further, in some embodiments, the wellbore 20 may be a stepped wellbore, such that a portion is drilled vertically downward and then curved to a substantially horizontal wellbore portion. Additional substantially vertical and horizontal wellbore portions may be added according to, for example, the type of terranean surface 12, the depth of one or more target subterranean formations, the depth of one or more productive subterranean formations, or other criteria.
Downhole of the conductor casing 25 may be the surface casing 30. The surface casing 30 may enclose a slightly smaller borehole and protect the wellbore 20 from intrusion of, for example, freshwater aquifers located near the terranean surface 12. The wellbore 20 may than extend vertically downward. This portion of the wellbore 20 may be enclosed by the intermediate casing 35. Any of the illustrated casings, as well as other casings that may be present in the wellbore system 10, may include one or more casing collars 55 (as shown in
As shown, the untethered downhole tool 100 may be run into the wellbore 20 and through the tubular 17. In some aspects, as shown, the untethered downhole tool 100 may be inserted into the wellbore 20, which may be filled with a fluid, such as a drilling fluid or otherwise. In such aspects, the untethered downhole tool 100 may be oriented and weighted (as discussed in more detail later) to move downhole from the terranean surface 12 and toward the subterranean formation 40 through the wellbore fluid.
In some aspects, the wellbore fluid is not static in the wellbore 20 but is a circulated (for example, pumped) wellbore fluid 50 that dynamically moves the untethered downhole tool 100 through the wellbore 20. Thus, in some aspects, the untethered downhole tool 100 is moved through the wellbore 20 in a fluid (either static or dynamic) without being connected to any other form of downhole conveyance, such as a working string of downhole conductor (for example, wireline or slickline or other conductor).
Rotation or other movement of the untethered downhole tool 100 in three-dimensions within the wellbore 20 may adjust or change an orientation of the untethered downhole tool 100. For example,
Conventional wireline tools can have a high aspect ratio that largely limits their ability to yaw and pitch. Such conventional tools remain within a wellbore during travel, which also limits their positional freedom in an x-y-plane (where z is along the axis of the wellbore). Moreover, centralizers or decentralizers can be used to further constrain these freedoms. In addition, a weight of a wireline tool pulling it downhole and amount of tension that can be applied through a steel wire to pull it uphole help wireline tools to move under these conditions. However, even wireline tools can be stuck in some cases.
An untethered downhole tool, in contrast, may include no such active steering and may mainly displace in the z direction thanks to forces such as gravity, buoyancy, or flow pressure. However, there can be little to no control over an untethered downhole tool its remaining five degrees of freedom if an axial dimension of such a tool is shorter than the well diameter. Thus, the methods used by wireline tools to maintain orientation within the wellbore can be difficult to apply for untethered tools, which can be shorter than a diameter of the wellbore itself.
Indeed, due to cylindrical geometry of a wellbore, displacements in the x-y plane can be replaced by a radial measurement in a global frame 300 (with x-axis 202, y-axis 204, and z-axis 206). For example,
The untethered downhole tool 100 may have a circular symmetry (in cross-section as shown in
In this example, the one or more mass components include a ballast 406 positioned on or in the housing 402 at or near the downhole end 416 and a buoyant member 404 positioned on or in the housing 402 at or near the uphole end 418. In some aspects, the ballast 406 may be a weight or member that is of a higher density or overall mass as compared to the buoyant member 404. In some aspects, the buoyant member 404 can be an empty or fluid-filled portion of the housing 402. In some aspects, the buoyant member 404 can have a lower density or weight relative to the ballast 406. In some aspects, the untethered downhole tool 400 may include only the ballast 406 or only the buoyant member 404, for example, depending on a desired orientation of the untethered downhole tool 400 within the wellbore 20.
In some aspects, one or both of the ballast 406 or buoyant member 404 can adjust an orientation of the untethered downhole tool 400 in the wellbore, either alone or in combination. For example, the ballast 406 and/or buoyant member 404 may create a separation of a center of gravity (Cg) 408 (from which a gravitational force 414 originates) of the untethered downhole tool 400 and a center of buoyancy (Cb) 410 (from which a buoyant force 412 originates) of the untethered downhole tool 400. This separation can create a corrective (for example, righting) moment that rotates the housing 402 of the untethered downhole tool 400 to a stable position and minimizes its potential energy. For example, to create a separation between the two centers 408 and 410, a variation in density along an axis of the untethered downhole tool 400 is created by, for example, placement of the ballast 406 and/or the buoyant member 404. For instance, by grouping higher density components such as the sensor package 999 and the ballast 406 at the downhole end 416 and placing low density components such as the buoyant member 404 (for example, made of syntactic foam) at the uphole end 418, the righting moment can align yaw and pitch of the untethered downhole tool 400. In some aspects, this alignment occurs with respect to the direction of gravity 318 (in other words, angle β is 0° or approximately 0°) and a degree of the alignment with the casing 35 may depend on the well deviation angle 320 (α).
In this example, the one or more mass components include a magnet 510 positioned on or in the housing 502. In this example, the magnet 510 is positioned with its axial centerline aligned with an axial centerline of the untethered downhole tool 500. In some aspects, the magnet 510 can be permanent, electro-permanent, or an electromagnet. According to the present disclosure, an electro-permanent magnet is a permanent magnet with a coil wrapped around it. A magnetization state can be changed by applying a current through the coil. Depending on the magnet type and dimensions, number of turns on the coil, and the amplitude of the current, the change in the magnetization can be temporary or permanent. Electro-permanent magnets can also have benefits over the other two such that it can be turned off unlike a permanent magnet. An electro-permanent magnet can create a magnetic pull force with a smaller foot-print compared to an electromagnet and requires power only to change the magnetic polarization, whereas an electromagnet requires continuous power to create a magnetic field. In some aspects, using an electro-permanent magnet can be useful if the untethered downhole tool 500 is immobilized due to the magnetic pull force, and needs to free itself autonomously while downhole in the wellbore 20.
In example aspects, the untethered downhole tool 500 (as well as other untethered downhole tools according to the present disclosure) includes a microcontroller (that is or is part of or separate from the sensor package 999) with a time reference, electro-permanent magnet(s), and one or more sensors such as a pressure sensor, a temperature sensor, an accelerometer, or a magnetometer (or a combination thereof). The microcontroller in the tool 500 detects a motion of the tool 500 by recording and evaluating sensor outputs. In some aspects, the microcontroller includes one or more microprocessors and one or more memory modules connected to the one or more microprocessors.
For example, the microcontroller can calculate changes in pressure, temperature, acceleration, and/or magnetic field over time. As the untethered downhole tool 500 travels in the wellbore 20, pressure changes with the fluid column height and/or the interaction with the casing 35 produces an acceleration that is different than the gravitational acceleration, and the magnetic field varies due to the permanent magnetic field of the casing imparted during manufacturing process. If the change in one or more of these sensors over a time window stays below a threshold value (for example, less than 3 psi change in 1 minute, and/or less than 0.2° C. change in 1 minute, and/or less than 0.1 g change in acceleration in 1 minute, and/or less than 0.01 Gauss in 1 minute), the microcontroller can determine that the tool 500 is immobilized. The microcontroller reduces one or several electro-permanent magnet(s)'s magnetization to reduce the pull force towards the casing 35 until the immobilization conditions are not detected. As the microcontroller detects that the tool 500 is in motion, the microcontroller can decide to increase the magnetization of electro-permanent magnet(s) again to realign the tool 500 with the casing 35.
In some aspects, the magnet 510 (and other magnets as described herein) can serve dual purposes. First, the magnet 510 can orient or help orient the untethered downhole tool 500 as described herein, such as aligning the untethered downhole tool 500 with the casing 35. Second, the magnet 510 can create a magnetic field distribution. The magnetic field distribution is subject to change due to casing thickness or spacing between two casing joints. These changes can be detectable using magnetic sensors such coils, hall effect sensors, or giant magneto-resistive magnetometers within the sensor package 999. When an electro-permanent magnet is used, the added sensing element for the untethered downhole tool 500 as a casing collar locator (for example, a magnetometer) can also provide a feedback to a microprocessor about the polarization state of the magnet 510. This feedback can be used to time the magnetic field as necessary.
Further, in some aspects, the sensor package 999 can include an inertial sensor (for example, an accelerometer) that can be used to detect relatively rapid changes in diameter of the casing 35 (or other casing), which usually happens around a casing collar (such as casing collar 55). In example implementations as shown in
In the example implementation of
In this example, the one or more mass components include a magnet 610 positioned on or in the housing 502. In this example, the magnet 610 is positioned such that it is adjacent or near an interior surface of housing 602. In some aspects, the magnet 610 can be permanent, electro-permanent, or an electromagnet. Electro-permanent magnets can have benefits over the other two such that it can be turned off unlike a permanent magnet. An electro-permanent magnet can create a magnetic pull force with a smaller foot-print compared to an electromagnet and requires power only to change the magnetic polarization, whereas an electromagnet requires continuous power to create a magnetic field. In some aspects, using an electro-permanent magnet can be useful if the untethered downhole tool 600 is immobilized due to the magnetic pull force, and needs to free itself autonomously while downhole in the wellbore 20.
In some aspects, the magnet 610 (and other magnets as described herein) can serve dual purposes. First, the magnet 610 can orient or help orient the untethered downhole tool 600 as described herein, such as aligning the untethered downhole tool 600 with the casing 35. Second, the magnet 610 can create a magnetic field distribution. The magnetic field distribution is subject to change due to casing thickness or spacing between two casing joints. These changes can be detectable using magnetic sensors such coils, hall effect sensors, or giant magneto-resistive magnetometers within the sensor package 999. When an electro-permanent magnet is used, the added sensing element for the untethered downhole tool 600 as a casing collar locator (for example, a magnetometer) can also provide a feedback to a microprocessor about the polarization state of the magnet 610. This feedback can be used to time the magnetic field as necessary.
Further, in some aspects, the sensor package 999 can include an inertial sensor (for example, an accelerometer) that can be used to detect relatively rapid changes in diameter of the casing 35 (or other casing), which usually happens around a casing collar (such as casing collar 55). In example implementations as shown in
In the example implementation of
In this example, the one or more mass components include a ballast 712 positioned on or in the housing 702 at or near the downhole end 704 and a buoyant member 714 positioned on or in the housing 702 at or near the uphole end 706. In some aspects, the ballast 712 may be a weight or member that is of a higher density or overall mass as compared to the buoyant member 714. In some aspects, the buoyant member 714 can be an empty or fluid-filled portion of the housing 702. In some aspects, the buoyant member 714 can have a lower density or weight relative to the ballast 712. In some aspects, the untethered downhole tool 700 may include only the ballast 712 or only the buoyant member 714, for example, depending on a desired orientation of the untethered downhole tool 700 within the wellbore 20.
In some aspects, one or both of the ballast 712 or buoyant member 714 can adjust (or help adjust) an orientation of the untethered downhole tool 700 in the wellbore, either alone or in combination. For example, the ballast 712 and/or buoyant member 714 may create a separation of a center of gravity (Cg) 716 (from which a gravitational force 718 originates) of the untethered downhole tool 700 and a center of buoyancy (Cb) 720 (from which a buoyant force 722 originates) of the untethered downhole tool 700. This separation can create a corrective (for example, righting) moment that rotates the housing 702 of the untethered downhole tool 700 to a stable position and minimizes its potential energy. For example, to create a separation between the two centers 716 and 720, a variation in density along an axis of the untethered downhole tool 700 is created by, for example, placement of the ballast 712 and/or the buoyant member 714. For instance, by grouping higher density components such as the sensor package 999 and the ballast 712 at the downhole end 704 and placing low density components such as the buoyant member 714 (for example, made of syntactic foam) at the uphole end 706, the righting moment can align yaw and pitch of the untethered downhole tool 700. In some aspects, this alignment occurs with respect to the direction of gravity 318 (in other words, angle β is non-zero) and a degree of the alignment with the casing 35 may depend on the well deviation angle 320 (α).
In this example, the one or more mass components also include a magnet 710 positioned on or in the housing 702. In this example, the magnet 710 is positioned such that it is adjacent or near an interior surface of housing 702. In some aspects, the magnet 710 can be permanent, electro-permanent, or an electromagnet. Electro-permanent magnets can have benefits over the other two such that it can be turned off unlike a permanent magnet. An electro-permanent magnet can create a magnetic pull force with a smaller foot-print compared to an electromagnet and requires power only to change the magnetic polarization, whereas an electromagnet requires continuous power to create a magnetic field. In some aspects, using an electro-permanent magnet can be useful if the untethered downhole tool 700 is immobilized due to the magnetic pull force, and needs to free itself autonomously while downhole in the wellbore 20.
In some aspects, the magnet 710 (and other magnets as described herein) can serve dual purposes. First, the magnet 710 can orient or help orient the untethered downhole tool 700 as described herein, such as aligning the untethered downhole tool 700 with the casing 35. Second, the magnet 710 can create a magnetic field distribution. The magnetic field distribution is subject to change due to casing thickness or spacing between two casing joints. These changes can be detectable using magnetic sensors such coils, hall effect sensors, or giant magneto-resistive magnetometers within the sensor package 999. When an electro-permanent magnet is used, the added sensing element for the untethered downhole tool 700 as a casing collar locator (for example, a magnetometer) can also provide a feedback to a microprocessor about the polarization state of the magnet 710. This feedback can be used to time the magnetic field as necessary.
In the example implementation of
In this example, the one or more mass components include a ballast 808 positioned on or in the housing 802 at or near the downhole end 804 and a buoyant member 810 positioned on or in the housing 802 at or near the uphole end 806. In some aspects, the ballast 808 may be a weight or member that is of a higher density or overall mass as compared to the buoyant member 810. In some aspects, the buoyant member 810 can be an empty or fluid-filled portion of the housing 802. In some aspects, the buoyant member 810 can have a lower density or weight relative to the ballast 808. In some aspects, the untethered downhole tool 800 may include only the ballast 808 or only the buoyant member 810, for example, depending on a desired orientation of the untethered downhole tool 800 within the wellbore 20.
In some aspects, one or both of the ballast 808 or buoyant member 810 can adjust (or help adjust) an orientation of the untethered downhole tool 800 in the wellbore, either alone or in combination. For example, the ballast 808 and/or buoyant member 810 may create a separation of a center of gravity (Cg) 814 (from which a gravitational force 816 originates) of the untethered downhole tool 800 and a center of buoyancy (Cb) 822 (from which a buoyant force 820 originates) of the untethered downhole tool 800. This separation can create a corrective (for example, righting) moment that rotates the housing 802 of the untethered downhole tool 800 to a stable position and minimizes its potential energy. For example, to create a separation between the two centers 814 and 822, a variation in density along an axis of the untethered downhole tool 800 is created by, for example, placement of the ballast 808 and/or the buoyant member 810. For instance, by grouping higher density components such as the sensor package 999 and the ballast 808 at the downhole end 804 and placing low density components such as the buoyant member 810 (for example, made of syntactic foam) at the uphole end 806, the righting moment can align yaw and pitch of the untethered downhole tool 800. In some aspects, this alignment occurs with respect to the direction of gravity (in other words, angle β is non-zero) and a degree of the alignment with the casing 35 may depend on the well deviation angle.
In this example, the one or more mass components also include one or more fins 812a and 812b mounted to an exterior surface of the housing 802. For example, as described herein, righting moments and magnetic forces are (generally) static forces that may not depend on a travel speed 337 of the untethered downhole tool 800. However, hydrodynamic shape of the untethered downhole tool 800 (or any untethered downhole tool according to the present disclosure) becomes more influential as the tool's relative velocity with respect to a fluid in the wellbore 20 increases. For instance, a hydrodynamic design can urge an untethered downhole tool towards a side of the casing 35 and keep the tool against the casing 35 during motion. In some aspects, fins 812a and 814a mounted on opposed radial sides (for example, 180° apart on the exterior surface of the housing 802) may act to generate one or both of a vertical hydrodynamic force 818 or a radial hydrodynamic force 824 (for example, in combination with a fluid in the wellbore 20) to urge the untethered downhole tool 800 towards a side of the casing 35 and keep the tool 800 against the casing 35 during motion. As shown, each fin 812a and 812b is angled relative to an axial axis of the untethered downhole tool 800.
For example, hydrodynamic forces can be used to constrain ρ, β, and γ which are necessary to align the untethered downhole tool 900 with respect to a casing in a wellbore. Since hydrodynamics forces may act on the untethered downhole tool 900 during motion of the untethered downhole tool 900, such forces can be combined with, for example, a righting moment and/or a magnetic force (as previously described) to have a more stable orientation that is not disturbed by the magnitude of the velocity of the untethered downhole tool 900 in a downhole direction. Thus, in some aspects, the untethered downhole tool 900 may include, for example, one or more of a ballast, a buoyant member, one or more magnets, or one or more fins as previously described.
In some aspects, as shown in
In this example, the one or more mass components include a ballast 1005 positioned on or in the housing 1002 at or near the downhole end 1004 and a buoyant member 1010 positioned on or in the housing 1002 at or near the uphole end 1006. In some aspects, the ballast 1005 may be a weight or member that is of a higher density or overall mass as compared to the buoyant member 1010. In some aspects, the buoyant member 1010 can be an empty or fluid-filled portion of the housing 1002. In some aspects, the buoyant member 1010 can have a lower density or weight relative to the ballast 1005. In some aspects, the untethered downhole tool 1000 may include only the ballast 1005 or only the buoyant member 1010, for example, depending on a desired orientation of the untethered downhole tool 1000 within a wellbore.
In some aspects, one or both of the ballast 1005 or buoyant member 1010 can adjust (or help adjust) an orientation of the untethered downhole tool 1000 in the wellbore, either alone or in combination as described herein. Further, in this example, the one or more mass components also include a magnet 1012 positioned on or in the housing 1002. In this example, the magnet 1012 is positioned such that it is aligned with an axial centerline of the untethered downhole tool 1000. In some aspects, the magnet 1012 can be similar to, for example, the magnet 710 as shown and described in
As shown in this example, the one or more mass components also include one or more wheels or rollers 1014 attached or coupled to the housing 1002. In some aspects, the wheels 1014 (four shown here, radially spaced 90° apart around the housing 1002) can reduce a surface area of the untethered downhole tool 1000 in contact with the casing 35 and keep a certain distance between the housing 1002 and the casing 35. In some aspects, a smaller contact area can reduce the magnitude of adhesion force between the untethered downhole tool 1000 and the casing 35. In some aspects, the wheels 1014 can also reduce an energy loss due to friction (for example, if there is no slip). In the presence of the magnet 1012, parameter such as wheel size, magnet position inside the tool 1000, and magnet strength can be optimized to tune a side pulling force (Fm). In some aspects, the wheels 1014 include suspensions that can smooth the motion if there are irregularities on the casing surface such as scale build-ups or joint gaps.
Turning to
In this example, the one or more mass components include a ballast 1025 positioned on or in the housing 1022 at or near the downhole end 1024 and a buoyant member 1030 positioned on or in the housing 1022 at or near the uphole end 1026. In some aspects, the ballast 1025 may be a weight or member that is of a higher density or overall mass as compared to the buoyant member 1030. In some aspects, the buoyant member 1030 can be an empty or fluid-filled portion of the housing 1022. In some aspects, the buoyant member 1030 can have a lower density or weight relative to the ballast 1025. In some aspects, the untethered downhole tool 1020 may include only the ballast 1025 or only the buoyant member 1030, for example, depending on a desired orientation of the untethered downhole tool 1020 within a wellbore.
In some aspects, one or both of the ballast 1025 or buoyant member 1030 can adjust (or help adjust) an orientation of the untethered downhole tool 1020 in the wellbore, either alone or in combination as described herein. Further, in this example, the one or more mass components also include a magnet 1032 positioned on or in the housing 1022. In this example, the magnet 1032 is positioned such that it is adjacent an interior surface of the housing 1022 of the untethered downhole tool 1020. In some aspects, the magnet 1032 can be similar to, for example, the magnet 710 as shown and described in
As shown in this example, the one or more mass components also include one or more wheels or rollers 1034 attached or coupled to the housing 1022. In some aspects, the wheels 1034 (two shown here, radially spaced 90° apart from each other around the housing 1022) can reduce a surface area of the untethered downhole tool 1020 in contact with the casing 35 and keep a certain distance between the housing 1022 and the casing 35. As compared to untethered downhole tool 1000, the magnet 1032 that is misaligned with a centerline axis of the tool 1020 can create a preferred rotational alignment direction with respect to the casing 35. Therefore, the wheels 1034 are placed on a same radial side of the housing 1022 with the magnet 1032 where attachment to the casing 35 will most likely occur to maximize contact between the wheels 1034 and the casing 35 (and minimize a surface area contact between the untethered downhole tool 1020 and the casing 35).
Turning to
In this example, the one or more mass components include a ballast 1045 positioned on or in the housing 1042 at or near the downhole end 1044 and a buoyant member 1050 positioned on or in the housing 1042 at or near the uphole end 1046. In some aspects, the ballast 1045 may be a weight or member that is of a higher density or overall mass as compared to the buoyant member 1050. In some aspects, the buoyant member 1050 can be an empty or fluid-filled portion of the housing 1042. In some aspects, the buoyant member 1050 can have a lower density or weight relative to the ballast 1045. In some aspects, the untethered downhole tool 1040 may include only the ballast 1045 or only the buoyant member 1050, for example, depending on a desired orientation of the untethered downhole tool 1040 within a wellbore.
In some aspects, one or both of the ballast 1045 or buoyant member 1050 can adjust (or help adjust) an orientation of the untethered downhole tool 1040 in the wellbore, either alone or in combination as described herein. Further, in this example, the one or more mass components also include a magnet 1052 positioned on or in the housing 1042. In this example, the magnet 1052 is positioned such that it is adjacent an interior surface of the housing 1042 of the untethered downhole tool 1040. In some aspects, the magnet 1052 can be similar to, for example, the magnet 710 as shown and described in
As shown in this example, the one or more mass components also include one or more wheels or rollers 1054 attached or coupled to the housing 1042. In some aspects, the wheels 1054 (four shown here, with pairs radially spaced 180° apart around the housing 1042 and one of each pair positioned near the uphole end 1046 and one positioned near the downhole end 1044) can reduce a surface area of the untethered downhole tool 1040 in contact with the casing 35 and keep a certain distance between the housing 1042 and the casing 35. In this example, the wheels 1054 may be large enough to contact the casing 35 at two locations each and can generate larger torque (relative to wheels 1014 and 1034), which can provide for easier rotation in a presence of adhesive forces or relatively large surface irregularities of the casing 35.
A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, example operations, methods, or processes described herein may include more steps or fewer steps than those described. As another example, in some aspects, sleds may be substituted for wheels in an untethered downhole tool that includes wheels, as sleds can provide similar benefits with wheels, such as reducing the contact area and spacing the tool body from the casing but can also provide a smaller footprint as compared to wheels and have no moving parts as compared to wheels. As another example, an untethered downhole tool according to the present disclosure may include a low friction material added to or as part of a housing, such as Teflon™ or other material. Further, the steps in such example operations, methods, or processes may be performed in different successions than that described or illustrated in the figures. Accordingly, other implementations are within the scope of the following claims.
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20220243583 A1 | Aug 2022 | US |