Device for centering sensor assembly in cartridge

Abstract

An apparatus for centering a sensor assembly in a cartridge includes a first support member and a second support member axially spaced along a central longitudinal axis of the apparatus. The one or both support members are adapted to move axially along the central longitudinal axis. A plurality of arm assemblies are circumferentially spaced about a central longitudinal axis of the device and connected between the first support member and the second support member. Each arm assembly includes a first arm pivotally connected to the first support member by a first pivot joint having a first pivot axis, a second arm pivotally connected to the second support member by a second pivot joint having a second pivot axis, and pivotally connecting the first arm and the second arm together via a third pivot joint having a third pivot axis. To improve mechanical properties, the first pivot axis and the third pivot axis are located on a first side of a plane coincident with the central longitudinal axis of the device, and the second pivot axis is located on a second side of the plane opposite the first side.

Description

[0001] This application is a divisional application of PCT patent application number PCT / NZ2021 / 050123, entitled "Apparatus for Orienting Sensor Assemblies in a Cylinder," filed by the applicant, Patmac IP Ltd., on August 5, 2021. That PCT patent application entered the Chinese national phase on February 6, 2023, with Chinese patent application number 202180057274.2.

[0002] Corresponding application

[0003] This application is based on the provisional specification relating to New Zealand Patent Application No. 766888, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to means for aligning sensor devices in boreholes such as pipes, wells or casing wells, and more particularly to means for aligning sensor devices in wireline logging applications. Background Technology

[0005] Hydrocarbon exploration and development activities rely on information acquired from sensors that capture data related to the geological characteristics of the exploration area. One method for acquiring this data is through wireline logging. Wireline logging is performed in the wellbore immediately after a new section of the wellbore is drilled, and is called open-hole logging. These wellbores are drilled to a target depth that covers the area of ​​interest, typically between 1,000 and 5,000 meters deep. A sensor package, also known as a “logging tool” or “toolstring,” is then lowered into the wellbore and, under gravity, descends to the target depth in the wellbore well. The logging tool is lowered onto a cable, which is a set of communication wires wrapped in a steel cable connected to the logging tool. The steel cable bears the load from the toolstring, the cable itself, friction acting on the downhole equipment, and any over-tension caused by sticking or jamming. Once the logging tool reaches the target depth, it returns through the wellbore at a controlled ascent rate, and the sensors within the logging tool operate to generate and capture geological data.

[0006] Cable logging is also performed in wellbores lined with steel tubing or casing, known as casing logging. After a section of the wellbore is drilled, the casing is lowered into the wellbore and consolidated in place. A consolidating agent is placed in an annulus between the casing and the wellbore wall to ensure isolation between layers of permeable rock that intersect the wellbore at different depths. The consolidating agent also prevents hydrocarbons from flowing through the annulus between the casing and the wellbore, which is important for the integrity and safety of the well. Oil wells are typically drilled in consecutive sections. A large-diameter drill bit is "drilled" into the wellbore to create the first section. This first section of casing is called the conductor pipe. The conductor pipe is consolidated into the new wellbore and secured to the surface wellhead. A smaller drill bit passes through the conductor pipe and drills the surface wellbore to a deeper level. The surface casing string then travels through the wellbore to the bottom. The surface casing, typically 20 inches (nominal outside diameter (OD)), is then secured in place by filling the annulus formed between the surface casing and the new wellbore and conductor tubing. Drilling continues to the next interval with smaller bit sizes. Similarly, intermediate casing (e.g., 13 3 / 8 inches) is secured into the wellbore section. Drilling continues to the next interval with smaller bit sizes. Production casing (e.g., 9 3 / 8 inches outside diameter (OD)) travels to the TD (total depth) and is secured in place. The final casing string (e.g., 7 inches outside diameter (OD)) is secured in place from the stern hanger of the previous casing string. Therefore, the tool string must traverse downwards through the casing wellbore and may need to enter a smaller diameter wellbore.

[0007] A wide variety of logging tools are designed to measure various physical properties of rocks and the fluids contained within them. Logging tools include transducers and sensors to measure characteristics such as resistance, gamma ray density, and sound velocity. Individual logging tools are combinable and are typically linked together to form a logging tool string. Some sensors are designed to make close contact with the borehole wall during data acquisition, while others are ideally aligned within the wellbore for optimal results. Any device attached to the tool string must meet these requirements. Typical sizes of cable logging tool strings range from 20 feet to 100 feet in length and 2 inches to 5 inches in diameter.

[0008] In cased wells, logging tools are used to assess the strength of the binder bond between the casing and the wellbore wall, as well as the condition of the casing. Several types of sensors exist, and they typically need to be aligned within the casing. One such logging tool utilizes a high-frequency ultrasonic transducer and sensor to record circumferential measurements around the casing. The ultrasonic transducer and sensor are mounted on a rotating head attached to the bottom of the tool. This rotating head rotates, allowing the sensor to record azimuthal ultrasonic reflections from the casing wall, binder sleeve, and wellbore wall as the tool is slowly pulled out of the wellbore. Other tools have transducers and sensors that record the amplitude decreases or attenuates as the acoustic signal propagates along the casing wall. Importantly, these transducers and sensors must be well aligned within the casing to ensure the validity of the recorded data. Other logging tools that measure fluid and gas production in flowing wellbores may also require sensor alignment. Logging tools also travel through production wells to determine the flow characteristics of the produced fluids. Many of these sensors also require alignment to validate the data.

[0009] In open-hole (casingless) wellbore logging, logging tools are used to scan the wellbore wall to determine formation dip, fracture size and orientation, the size and distribution of pore spaces in the rock, and information about the depositional environment. One such tool has multiple sensors on a pad at the periphery of the wellbore to measure microresistivity. Other tools generate acoustic signals that propagate along the wellbore wall and are recorded by multiple receivers spaced apart along the tool and around its azimuth. As with casing-hole logging tools, the measurements from these sensors are optimized through good alignment within the wellbore.

[0010] Drilling and wireline logging operations are expensive tasks. This is primarily due to the capital costs of drilling equipment and the specific nature of wireline logging systems. It is important to initiate and complete these activities as quickly as possible to minimize these costs. Delays in deploying wireline logging tools should be avoided whenever possible.

[0011] One reason for this delay is the difficulty in lowering the wireline logging tool to the target depth in the wellbore. The logging tool descends along the wellbore solely under the influence of gravity via a cable. The cable is flexible and cannot push the tool along the wellbore. Therefore, the operator at the top of the well has virtually no control over the descent of the logging tool.

[0012] For deviated wells, the likelihood of cable logging tool descent failure increases significantly. Deviated wells do not travel vertically downwards, but rather downwards and laterally at an angle to the vertical. Multiple deviated wells are typically drilled from a single surface location to allow exploration and production over large areas. As the cable logging tool travels down the wellbore via the cable under gravity, the tool string will drag along the lower side or bottom of the wellbore wall as it descends to the target depth. Friction or dragging of the tool string against the wellbore wall can prevent the tool from descending to the desired depth. The length of the tool string further exacerbates the problem of guiding the tool string down the wellbore.

[0013] refer to Figure 1 In a deviated shaft, the weight of the tool string exerts a lateral force (PW) perpendicular to the shaft wall. This lateral force generates a drag force that prevents the tool string from descending into the shaft. The axial component (AW) of the tool string weight pulls the tool string along the shaft, and this force is opposite to the drag force acting in the opposite direction. As the shaft deviates, the axial component (AW) of the tool weight decreases, and the lateral force (PW) increases. When the drag force generated by the lateral force (PW) equals the axial component (AW) of the tool string weight, the tool will not descend into the shaft.

[0014] As wellbore deviation increases, sliding friction, or drag force, prevents the logging tool from descending. The practical limit is a 60° deviation from the vertical, and in these large-angle wells, any device that can reduce friction is highly valuable. Drag force is the product of the lateral component of the tool weight acting perpendicularly to the wellbore wall and the coefficient of friction. Reducing the coefficient of friction is desirable to reduce drag force. The coefficient of friction can be reduced by using low-friction materials, such as Teflon. Drag force can also be reduced by using wheels.

[0015] A common device for centering logging tools is the bow-spring centerer. The bow-spring centerer consists of numerous bent leaf springs. The leaf springs are attached at their ends to an attachment structure that secures the logging tool. The midpoints of the bent leaf springs (or bows) are arranged to project radially outward from the attachment structure and the tool string. When the bow-spring centerer is not constrained by the wellbore, its outer diameter is larger than the diameter of the wellbore or casing to which it is to be deployed. Once deployed in the wellbore, the bow springs flatten, and the flattened bow springs provide a centering force on the tool string. In deviated wells, this centering force must be greater than the lateral weight component of the tool string acting perpendicular to the wellbore or casing wall. Therefore, a larger centering force is required at greater well deviations. If the centering force is too small, the centerer will collapse, and the tool sensor will fail to center. If the centering force is too large, the excessive force will create unnecessary resistance, which may prevent the tool from descending or cause stick-slip movement of the logging tool. Stick-slip refers to a point where the tool moves upwards along the wellbore at a series of sudden increases rather than a constant speed. Stick-slip action can impair or invalidate acquired measurement data. The practical limitation of using a bow-spring centerer for gravity descent is approximately 60 degrees to the vertical. The wellbore is vertical in shallow depths and deviates with increasing depth. Therefore, the required centering force will vary within the same wellbore. Because bow-spring centerers must be constructed for maximum deviance, the drag force is always greater than the required drag force for most survey sections.

[0016] A bow-spring centerer provides a greater centering force in smaller wellbores because the leaf spring has greater deflection (more compression) than in larger wellbores. Therefore, stronger or multiple bow-springs are required in larger wellbore sizes. These centerers often have "reinforcement" kits to apply even greater centering forces in larger wellbores or those with higher skewness.

[0017] When the deviation is greater than 60 degrees, other methods must be used to overcome friction and allow the tool string to descend into the wellbore. One method is to use a drive unit (traction machine) attached to the tool string. The traction machine contains a drive wheel that forces contact with the wellbore wall to drive the tool string downhole. Another method is to push the tool string downhole using drill pipe or coiled tubing. These methods involve additional risks, more equipment, and more time, and are therefore much more expensive.

[0018] To reduce the resistance of the centering device, a wheel can be attached to the center of the bow spring to contact the wellbore wall. However, fundamental problems related to leaf spring collapse or excessive force remain.

[0019] Another known type of centering device consists of a set of levers or arms with wheels at or near where the levers are pivotally connected. Multiple sets of lever-wheel assemblies are oriented around the central axis of the device. Typically, there are three to six sets. The end of each lever set is connected to a block that can slide freely axially on the central axis of the centering device. Springs force these blocks to slide toward each other, thereby forcing the arms to deflect at an angle to the axis of the centering device (and tool string), allowing the wheels to extend radially outward to apply force against the wellbore wall. For this type of device, the centering force depends on the type and arrangement of the energizing device or spring. Centering devices are typically energized by axial or radial springs or a combination of both. The advantage of this type of centering device is the reduced drag caused by wheels that roll rather than slide along the wellbore wall.

[0020] The centering device can also be powered by a spring mechanism that directly applies a radially outward force. Such a spring mechanism can be a coil spring, torsion spring, or leaf spring acting between the centering arm and the center spindle. For leaf springs acting on the articulated arm or coil springs arranged radially from the centering / tool ​​string axis, the limitations mentioned above for bow-spring centering devices still apply. That is, the centering force is greater in a smaller wellbore than in a larger wellbore, where the spring experiences greater deflection. A greater centering force is required as wellbore inclination increases. If the centering force is too small, the centering device will collapse, and the tool sensors will misalign. If the centering force is too large, the excessive force will cause unnecessary resistance, which may prevent the tool from descending or cause stick-slip movement of the logging tool.

[0021] Any reference to prior art in the specification is not, and should not be construed as, an admission or any form of implication that the prior art constitutes part of common general knowledge in any country. Summary of the Invention

[0022] The object of the present invention is to solve any one or more of the above-mentioned problems, or at least to provide the industry with a useful device for aligning sensor devices in a cylinder or pipe.

[0023] According to a first aspect of the invention, an apparatus is provided for aligning a sensor assembly in a cylinder, the apparatus comprising: spindle; A first support member and a second support member are axially spaced apart along the central longitudinal axis of the device, and one or both of the first support member and the second support member are adapted to move axially along the spindle. Multiple arm assemblies, circumferentially spaced around the longitudinal axis of the device and connected between a first support member and a second support member, each arm assembly including: The first arm is pivotally connected to the first support member via a first pivot joint having a first pivot axis. The second arm, which is pivotally connected to the second support member via a second pivot joint having a second pivot axis, and the first and second arms are pivotally connected together via a third pivot joint having a third pivot axis, and The third pivot axis is located on the first side of a plane coinciding with the longitudinal axis of the device, and the first and second pivot axes are located on the opposite second side of this plane, radially outward from the outer diameter of the spindle. The first and second pivot joints are aligned in azimuth angle, and the first and second pivot joints are misaligned with the third pivot joint by 180 degrees in azimuth angle.

[0024] In some embodiments, the first pivot axis and the second pivot axis do not intersect the mandrel.

[0025] In some embodiments, the third pivot joint is located radially outside the outer diameter of the mandrel.

[0026] In some embodiments, the plane is a first plane, and the first pivot and the second pivot are aligned on a second plane that coincides with the longitudinal axis of the centering device, the second plane being orthogonal to the first plane.

[0027] In some embodiments, the plane is a first plane, and the first pivot, the second pivot, and the third pivot are aligned on a second plane that coincides with the longitudinal axis of the centering device, the second plane being orthogonal to the first plane.

[0028] In some embodiments, the plane is a first plane, and the first pivot joint, the second pivot joint, and the third pivot joint and / or the wheel carried by the arm assembly to contact the wellbore wall are aligned on a second plane that coincides with the longitudinal axis, the second plane being orthogonal to the first plane.

[0029] In some embodiments, each arm assembly extends or bends circumferentially around and along the longitudinal axis of the centerer.

[0030] In some embodiments, each arm assembly extends spirally around and along the longitudinal axis.

[0031] In some embodiments, the arm components are circumferentially nested or entangled together around the mandrel.

[0032] In some embodiments, the arm assembly is arranged such that the first pivot joint and the first pivot axis of the arm assembly are aligned in a first plane orthogonal to the longitudinal axis, and the second pivot joint and the second pivot axis of the arm assembly are aligned in a second plane orthogonal to the longitudinal axis.

[0033] In some embodiments, the arm assembly is arranged such that the third pivot joint and the third pivot axis are aligned in a third plane orthogonal to the longitudinal axis.

[0034] In some embodiments, the device includes one or more spring elements to radially outward bias the arm assembly. In some embodiments, the device includes one or more spring (axial) elements that act on a first support member and / or a second support member to axially bias the first and second support members together and radially outward bias the arm assembly.

[0035] In some embodiments, the device includes one or more (radial) spring elements that act on one or more arm assemblies to radially outward bias the arm assemblies.

[0036] In some embodiments, one or more spring elements are configured together at an angle (A), which: i) Within a certain range between the line extending through the first and third pivot axes and the longitudinal axis, and / or ii) Within a certain range between the line extending through the second and third pivot axes and the longitudinal axis, This allows each arm assembly to provide a substantially constant radial force for a range of wellbore diameters.

[0037] In some embodiments, angle (A): i) Between the line extending through the first pivot axis and the third pivot axis and the longitudinal axis, and / or ii) Between the line extending through the second and third pivot axes and the longitudinal axis, Keep it within a range that is substantially greater than 10 degrees and substantially less than 75 degrees.

[0038] In some embodiments, the angle (A) is maintained in the range of 25 degrees to 65 degrees.

[0039] In some embodiments, the centerer is a passive device, wherein the radially outward empowerment of the arm assembly is provided solely by one or more spring elements of the device.

[0040] In some embodiments, the mandrel includes a plurality of cross-sections spaced apart around an outer surface of the mandrel, and the first support member and / or the second support member have corresponding plurality of cross-sections spaced apart around an inner surface of the support member, for rotatingly keying the first support member and / or the second support member to the mandrel.

[0041] In some embodiments, the cross-sections are arranged such that the mandrel has a polygonal outer surface and the first support member and / or the second support member has a corresponding polygonal inner surface.

[0042] According to a second aspect of the invention, a cable logging tool string is provided, the cable logging tool string including one or more elongated sensor assemblies and means for aligning the cable logging tool string in the wellbore during cable logging operations, the means being as described in any one or more of the foregoing.

[0043] According to a third aspect of the invention, an apparatus is provided for aligning a sensor assembly in a cylinder, the apparatus comprising: The first support member and the second support member are axially spaced apart along the longitudinal axis of the device. Multiple arm assemblies, circumferentially spaced around the longitudinal axis of the device and connected between a first support member and a second support member, each arm assembly including: The first arm is pivotally connected to the first support member via a first pivot joint having a first pivot axis. The second arm is pivotally connected to the second support member via a second pivot joint having a second pivot axis, and the first and second arms are pivotally connected together via a third pivot joint having a third pivot axis. The first and third pivot axes are located on the first side of a plane that coincides with the central longitudinal axis of the device, while the second pivot axis is located on the opposite second side of the plane. The first and second pivot joints are offset by 180 degrees in azimuth around the central longitudinal axis of the device.

[0044] In some embodiments, one or both of the first support member and the second support member are adapted to move axially along the longitudinal axis to allow the arm assembly to extend and retract radially relative to the longitudinal axis.

[0045] In some embodiments, the first arm and the second arm are of different lengths, such that the distance between the second pivot axis and the third pivot axis is different from the distance between the first pivot axis and the third pivot axis.

[0046] In some embodiments, the angle between the line extending between the first pivot axis and the third pivot axis and the longitudinal axis is smaller than the angle between the line extending between the second pivot axis and the third pivot axis and the longitudinal axis.

[0047] In some embodiments, each arm assembly includes a wheel for contacting the wellbore wall.

[0048] In some embodiments, the wheel is rotatably connected to the first or second arm on a rotation axis perpendicular to the longitudinal axis and offset from the third pivot axis.

[0049] In some embodiments, the device includes one or more spring elements to radially outward bias the arm assembly.

[0050] In some embodiments, the device includes one or more spring (axial) elements that act on a first support member and / or a second support member to axially bias the first and second support members together and radially outward bias the arm assembly.

[0051] In some embodiments, the device includes one or more (radial) spring elements that act on one or more arm assemblies to radially outward bias the arm assemblies.

[0052] In some embodiments, one or more spring elements are constructed together such that the angle (A) between the line extending through the second and third pivot axes and the longitudinal axis is within a certain range, such that each arm assembly provides a substantially constant radial force for a range of wellbore diameters.

[0053] In some embodiments, the angle (A) between the line extending through the second pivot axis and the third pivot axis and the longitudinal axis is maintained in the range of substantially greater than 10 degrees and substantially less than 75 degrees.

[0054] In some embodiments, the angle (A) between the line extending through the second pivot axis and the third pivot axis and the longitudinal axis is maintained in the range of 25 degrees to 65 degrees.

[0055] In some embodiments, the plane is a first plane, and the first pivot and the second pivot are aligned on a second plane that coincides with the longitudinal axis of the centering device, the second plane being orthogonal to the first plane.

[0056] In some embodiments, the plane is a first plane, and the first pivot, the second pivot, and the third pivot are aligned on a second plane that coincides with the longitudinal axis of the centering device, the second plane being orthogonal to the first plane.

[0057] In some embodiments, the plane is a first plane, and the first and third pivot joints and / or the wheels carried by the arm assembly to contact the wellbore wall are aligned on a second plane that coincides with the longitudinal axis, the second plane being orthogonal to the first plane.

[0058] In some embodiments, the second arm extends circumferentially about a longitudinal axis to position the second pivot joint on opposite sides of a plane.

[0059] In some embodiments, the second arm extends spirally around and along the longitudinal axis.

[0060] In some embodiments, the centerer is a passive device, wherein the radially outward empowerment of the arm assembly is provided solely by one or more spring elements of the device.

[0061] In some embodiments, the device has a spindle and a first support member and / or a second support member adapted to move axially along the spindle, and the spindle includes a plurality of cross-sections spaced apart around an outer surface of the spindle, and the first support member and / or the second support member has a corresponding plurality of cross-sections spaced apart around an inner surface of the support member, to rotatably key the first support member and / or the second support member to the spindle.

[0062] In some embodiments, the cross-sections are arranged such that the mandrel has a polygonal outer surface and the first support member and / or the second support member has a corresponding polygonal inner surface.

[0063] According to a fourth aspect of the invention, a cable logging tool string is provided, the cable logging tool string including one or more elongated sensor assemblies and means for centering the cable logging tool string in the wellbore during cable logging operations, the means being as described with respect to the third aspect.

[0064] According to a fifth aspect of the invention, an apparatus is provided for aligning a sensor assembly in a cylinder, the apparatus comprising: spindle; The first support member and the second support member are axially spaced apart along the central longitudinal axis of the device, and the first support member and the second support member are adapted to move axially along the spindle. Multiple arm assemblies, circumferentially spaced around the central longitudinal axis of the device and connected between a first support member and a second support member, each arm assembly including: The first arm is pivotally connected to the first support member via a first pivot joint having a first pivot axis. The second arm, which is pivotally connected to the second support member via a second pivot joint having a second pivot axis, and the first and second arms are pivotally connected together via a third pivot joint having a third pivot axis, and The third pivot axis is located on a first side of a plane coinciding with the central longitudinal axis of the device, and at least one of the first and second pivot axes is located on a second opposite side of the plane, wherein the first and second pivot axes are located radially outward of the outer diameter of the spindle. in: (i) When both the first and second pivot axes are located on the second side of the plane, the first and second pivot joints are aligned in azimuth, and the first and second pivot joints are offset from the third pivot joint by 180 degrees in azimuth around the central longitudinal axis of the mandrel, or (ii) In the case that one of the first pivot axis and the second pivot axis is located on the second side of the plane, one of the first pivot joint and the second pivot joint is aligned with the third pivot joint in the azimuth angle, and the first pivot joint and the second pivot joint are offset by 180 degrees in the azimuth angle around the central longitudinal axis of the device.

[0065] According to a sixth aspect of the invention, an apparatus is provided for aligning a sensor assembly in a cylinder, the apparatus comprising: spindle; A first support member and a second support member are axially spaced apart along the central longitudinal axis of the device, and the first support member and the second support member are adapted to move axially along the spindle. Multiple arm assemblies, circumferentially spaced around the central longitudinal axis of the device and connected between a first support member and a second support member, each arm assembly including: The first arm is pivotally connected to the first support member via a first pivot joint having a first pivot axis. The second arm, which is pivotally connected to the second support member via a second pivot joint having a second pivot axis, and the first and second arms are pivotally connected together via a third pivot joint having a third pivot axis, and The third pivot axis is located on a first side of a first plane coinciding with the central longitudinal axis of the device, and at least one of the first and second pivot axes is located on a second side opposite to the first plane. Among them, the first pivot axis and the second pivot axis are located radially outside the outer diameter of the spindle, and The first pivot joint, the second pivot joint, and the third pivot joint, and / or the wheel carried by the arm assembly to contact the cylinder wall, are aligned on a second plane that coincides with the central longitudinal axis, wherein the second plane is orthogonal to the first plane.

[0066] According to a seventh aspect of the invention, an apparatus is provided for aligning a sensor assembly in a cylinder, the apparatus comprising: spindle; A first support member and a second support member are axially spaced apart along the central longitudinal axis of the device, and one or both of the first support member and the second support member are adapted to move axially along the spindle. Multiple arm assemblies, circumferentially spaced around the central longitudinal axis of the device and connected between a first support member and a second support member, each arm assembly including: The first arm is pivotally connected to the first support member via a first pivot joint having a first pivot axis. The second arm is pivotally connected to the second support member via a second pivot joint having a second pivot axis, and the first and second arms are pivotally connected together via a third pivot joint having a third pivot axis. The mandrel includes a plurality of cross-sections spaced apart around the outer surface of the mandrel, and the first support member and / or the second support member have corresponding plurality of cross-sections spaced apart around the inner surface of the support member, so as to rotatably key the first support member and / or the second support member to the mandrel.

[0067] In some embodiments, the facets are arranged such that the mandrel has a polygonal outer surface and the first support member and / or the second support member has a corresponding polygonal inner surface. Preferably, the polygon is a regular polygon; for example, the mandrel may have a hexagonal or octagonal outer surface. In some embodiments, the outer surface of the mandrel has facets aligned azimuthally with adjacent first or second pivot joints at the first or second support member. The number of facets may be equal to the number of arm assemblies. The mandrel may have facets extending between adjacent first or second pivot joints such that the number of facets is equal to the number of arm assemblies or twice the number of arm assemblies. For example, the centering device includes four arm assemblies and the mandrel includes eight facets or octagonal outer surfaces, wherein the first support member and / or the second support member has a corresponding octagonal inner surface; or in an alternative embodiment, the centering device includes three arm assemblies and the mandrel includes six facets or hexagonal outer surfaces, wherein the first support member and / or the second support member has a corresponding hexagonal inner surface.

[0068] The fifth, sixth and / or seventh aspects of the present invention may include any one or more features described above with respect to the first to fourth aspects of the present invention.

[0069] Of the seven aspects of the invention described above, the apparatus is suitable for aligning cable logging tools in the wellbore during cable logging operations.

[0070] Unless the context otherwise requires, the term "wellbore" can refer to a wellbore with or without casing. Therefore, the term "wellbore wall" can refer to the wellbore wall or the wall of the casing within the wellbore.

[0071] Unless the context otherwise requires, the term "tool string" refers to an elongated package or assembly of sensors, also known in the industry as a "logging tool," and may include components other than sensors, such as guidance and orientation devices and bracket assemblies attached to the sensor components or tool string assembly. A tool string may include a single elongated sensor assembly, or two or more sensor assemblies connected together.

[0072] Unless the context clearly requires otherwise, throughout the specification and claims, the words “comprising”, “including”, etc., shall be interpreted as encompassing, rather than as exclusive or exhaustive, that is, “including but not limited to”.

[0073] In the foregoing description, reference has been made to specific parts or the whole of the invention having known equivalents, and these equivalents are incorporated herein as if described separately.

[0074] This invention may also be broadly interpreted to include any combination or combination of two or more components, elements or features individually or collectively as described or illustrated in the specification of this application, and wherein specific wholes having known equivalents in the field of this invention are referred to herein, and such known equivalents are considered to be incorporated herein as they are described separately.

[0075] Other aspects of the invention that should be considered in all its novel aspects will become apparent from the following description, given by way of examples of possible embodiments of the invention. Attached Figure Description

[0076] Exemplary embodiments of the invention will now be discussed with reference to the accompanying drawings.

[0077] Figure 1 This is a schematic diagram of the well site and the tool string descending along the wellbore during cable logging operations.

[0078] Figures 2A to 2G A schematic diagram of a centering device (centerer) according to an embodiment of the present invention is provided. Figure 2A This is a side view of the centering device, where the arm assembly of the centering device is in a radially outward position corresponding to the larger wellbore diameter. Figure 2B The arm assembly is shown in a radially inward position corresponding to a smaller wellbore diameter. Figure 2C and 2D This is an end view, showing the arm assembly in both radially outward and radially inward positions. Figure 2E and 2F This is again an isometric view of the arm assembly in radially outward and radially inward positions. Figure 2G Is Figure 2A A cross-sectional view on line AA of the centering device, along the centerline (longitudinal axis), with the arm assembly in a radially outward position.

[0079] Figures 2H to 2J Provided separately in such Figure 2A A schematic cross-sectional view along lines DD, CC, and BB.

[0080] Figures 3A to 3G It shows Figures 2A to 2GThe centering device is shown, but only one arm assembly is shown to highlight the relative position of the pivot axis of the arm's pivot joint. Figure 3A It is a side view. Figure 3B It is orthogonal to Figure 3A The other side view of the view. Figure 3C yes Figure 3B A cross-sectional view of the center line (longitudinal axis) of the centering device on line EE. Figures 3D to 3F They are respectively in such Figure 3A The cross-sectional views shown are along lines FF, GG, and HH. Figure 3G It is an isometric view.

[0081] Figure 4A and 4B Two centerers containing radially acting springs are shown.

[0082] Figure 5A and 5B It shows the relationship with Figure 2A and 2G A centering device similar to the centering device, but in which the rotation axis of the wheel of each arm assembly is offset from the third pivot joint. Figure 5A It is a side view, and Figure 5B It is an isometric view.

[0083] Figure 6 A diagram is provided showing the mechanical advantage (leverage) and the angles of the arm assembly of the centering device, where the angles are the angles between the arm of the centering device's arm assembly and the center axis or longitudinal axis of the centering device. Figure 2A and 2B The middle is angle A.

[0084] Figure 7 A graph is provided showing the mechanical advantage (lever force), spring force, and the resulting radial force exerted on the wellbore wall by the arm assembly of the centering device according to the invention, versus the radial deflection of the arm assembly.

[0085] Figures 8A to 8C This is a schematic diagram that provides a comparison between the centering device constructions. Figure 8A The configuration is shown such that all three pivot joints and pivot axes of each arm assembly are on one side of a plane coinciding with the longitudinal axis of the centerer. Figure 8B The diagram shows the construction of an arm assembly in which the third or intermediate pivot joint and pivot axis are located on the first side of a plane coinciding with the longitudinal axis of the centerer, and the first and second pivot joints and pivot axes are located on the opposite second side of the plane at their respective ends. Figure 8CA construction according to one aspect of the invention is shown, the construction having a first pivot joint and pivot axis at a first end of the arm assembly, a third or intermediate pivot joint and pivot axis of the arm assembly located on a first side of a plane coinciding with the longitudinal axis of the centerer, and a second pivot joint and pivot axis at a opposite second end of the arm assembly located on a opposite second side of a plane.

[0086] Figure 9 A comparative diagram of radial force and radial deflection characteristics is provided for three centering device assemblies; a centering device with a "proximal" pivot configuration ( Figure 8A A centering device with a "distal" pivot structure ( Figure 8B ) and a centering device with a "hybrid side" pivot configuration ( Figure 8C ).

[0087] Figures 10A to 10E An alternative centering device with a “distal” pivot configuration is shown. Figure 10A This is a side view of the centering device, where the arm assembly of the centering device is in a radially outward position corresponding to the larger wellbore diameter. Figure 10B The arm assembly is shown in a radially inward position corresponding to a smaller wellbore diameter. Figure 10C yes Figure 10A A cross-sectional view on line II of the centering device, along the center line (longitudinal axis). Figure 10D and 10E This is again an isometric view of the arm assembly in radially outward and radially inward positions.

[0088] Figures 10F to 10H Provided separately in such Figure 10A Schematic cross-sectional views of the lines LL, KK, and JJ shown.

[0089] Figure 11A and 11B It shows Figures 10A to 10D The centering device is shown, but only one arm assembly is shown to highlight the relative position of the pivot axis of the arm's pivot joint. Figure 11A It is a side view, and Figure 11B It is an isometric view.

[0090] Figure 12A and 12B An alternative centering device with a “distal” pivot configuration is shown. Figure 12A This is a side view of the centering device, where the arm assembly of the centering device is in a radially outward position corresponding to the larger wellbore diameter. Figure 12B This is again an isometric view of the arm assembly in a radially outward position.

[0091] Figures 13A to 13CAn alternative centering device with a “distal” pivot configuration is shown. Figure 13A This is an isometric view showing the arm assembly in a radially outward position. Figure 13B It is also an isometric view, but a spring is omitted to show the mandrel of the polygon. Figure 13C It is a sectional view along the longitudinal axis of the device, through the supporting members and the spindle.

[0092] Figures 14A to 14F An alternative centering device with five arms and a “distal” pivot configuration is shown. Figure 14A This is a side view of the centering device, where the arm assembly of the centering device is in a radially outward position corresponding to the larger wellbore diameter. Figure 14B End view, and Figure 14C This is again an isometric view of the arm assembly in a radially outward position. Figure 14D This is a side view of the centering device, where the arm assembly of the centering device is in a radially inward position corresponding to the smaller wellbore diameter. Figure 14E End view, and Figure 14F This is again an isometric view of the arm assembly in a radially inward position.

[0093] Figure 15 A variable pitch coil spring is shown, which is configured to provide a variable spring rate. Detailed Implementation

[0094] Figure 1 A schematic diagram of well site 100 is provided. A logging tool string 101 descends along the wellbore 102 on a cable 103. Well site surface equipment typically includes pulleys 104 suspended from the derrick and a winch unit 105 for unwinding and rewinding the cable to and from the wellbore to deploy and retrieve the logging tool 101 into and from the wellbore for wellbore cable logging operations. The logging tool string 101 may include one or more logging tools, each carrying one or more sensors 106, which are coupled together to form the logging tool string 101. The cable 102 includes multiple conductors or cables to provide power to the one or more sensors 106 and to transmit sensor data to the well site surface. One or more alignment devices 1 are provided to the logging tool 101 to align the logging tool 101 within the wellbore 102.

[0095] Figures 2A to 2GThis is a schematic diagram of a centering device 1, which will be provided with or as part of a tool string 101. The centering device (or centerer) includes a coupling 2 or interface at each end for connecting the centerer 1 to other components of the tool string 101. The coupling may include an electrical or hydraulic connection to provide electrical and hydraulic communication from the cable to the cable logging tool and / or the wireline tool. Alternatively, the centerer device may be integrated with the cable logging tool; for example, the outer housing of the logging tool may form the central mandrel of the centerer. Alternatively, the centerer device may slide on the outside of the cable logging tool (housing), thereby avoiding any electrical or hydraulic connection to the tool string and cable. The coupling or interface may be any suitable coupling or interface known in the art. Multiple arm assemblies (linkages) 3 are circumferentially spaced around a longitudinal axis 4 of the device 1. In the illustrated embodiment, four arm assemblies 3 are present; however, the centerer may have three or more arm assemblies, such as five or six arm assemblies. The arm assembly 3 is configured to move axially and radially to engage the wellbore wall 102a, thereby providing a centering force to keep the tool string 101 centered in the wellbore 102.

[0096] Each arm assembly or linkage 3 includes a first arm or link 5 and a second arm or link 6. The first arm 5 is pivotally connected to a first support member 7 via a first pivot joint 9, while the second arm 6 is pivotally connected to a second support member 8 via a second pivot joint 10. The first arm 5 and the second arm 6 are pivotally attached together via a third pivot joint 11. Each pivot joint 9, 10, 11 has a pivot pin or shaft on which the arms 5, 6 pivot about pivot axes 9a, 10a, 11a, which are the axes of the pin or shaft. One or both support members 7, 8 are adapted to move axially such that each arm assembly 3 moves radially to engage the wellbore wall 102 via pivoting of the first pivot joint 9, the second pivot joint 10, and the third pivot joint 11. One or both support members 7, 8 can slide axially on the center member or mandrel 12 of the centering device 1. For example, support members 7 and 8 may include a hoop or annular member that is collinear with and received on the spindle 12 for sliding thereon. Each support member 7 or 8 may include multiple components assembled together around the spindle 12.

[0097] Support members 7 and 8 can be keyed to the mandrel to rotatably secure the support member to the mandrel, allowing axial movement of the support member on the mandrel without relative rotation between the support member and the mandrel. For example, one of the mandrel and support member may include a longitudinal "track" or protrusion to engage with a corresponding longitudinal channel or slot of the other of the mandrel and support member (see, for example, described below). Figure 12A and 12B (Example).

[0098] The centering device 1 has one or more spring elements 13 to provide force to the arm assembly 3, thereby forcing the arm assembly against the wellbore wall 102a to provide a centering force, thereby centrally holding the centering device 1 and the associated tool string 101 within the wellbore 102. In the illustrated embodiment, both the first support member 7 and the second support member 8 are axially movable, and the centering device 1 has axial springs 13 acting on each support member 7, 8 to axially bias the support members 7, 8 together, thereby radially outwardly biasing the arm assembly 3 against the wellbore wall 102a. When one of the support members 7, 8 is fixed, the centering device 1 has no spring acting on the fixed support member. The axial springs 13 may be coil springs, as shown in the illustrated embodiment, which are collinear with the mandrel 12, or may also include a plurality of coil springs (spaced apart in azimuth) arranged circumferentially around the mandrel. Those skilled in the art will understand that other types of springs and spring structures may be used to power the centering device, such as torsion springs, leaf springs, and Belleville washers. A combination of two or more spring assemblies can also be used; for example, one or more springs can be provided end-to-end to impart a nonlinear spring rate to the combination. Alternatively, the pitch of the coil spring can be varied over its length to provide a nonlinear spring stiffness. The centerer may additionally or alternatively have spring elements that apply a radially outward force directly to the arm assembly. For example, a coil spring or leaf spring may be located between the first arm and the spindle and / or between the second arm and the spindle to provide a radial force, such as... Figure 4A (Leaf spring 15) and Figure 4B (Spring 16) is shown. The centering device according to the invention may have only an axial spring, only a radial spring, or a combination of axial and radial springs. A combination of axial and radial acting springs can be used to provide a relatively constant radial force.

[0099] Preferably, each arm assembly 3 includes a roller or wheel 14 located at or near the third pivot joint 11 to contact the wellbore wall 102a, thereby reducing friction between the wellbore wall 102a and the tool string 101 as it passes through the wellbore 102. Figure 2A As shown, the roller 14 may have a rotation axis that is collinear with the pivot axis 11a of the third pivot joint 11, or it may be located near the third pivot joint 11, for example, the roller may be rotatably mounted to the first arm or the second arm near the third pivot joint. Figure 5A and 5B It shows having with Figures 2A to 2G An embodiment with a similar configuration to the centering device, but with roller 14 mounted to the first arm 5 adjacent to the third pivot axis 11a, wherein the axis of rotation of roller 14 is parallel to the third pivot axis.

[0100] Each linkage or arm assembly 3 provides a mechanical advantage (mechanical leverage) between axial and radial displacement to engage the axial spring element 13 in providing a radial force to the wellbore wall 102a. Since the support members 7 and 8 are linked by multiple arm assemblies 3, the displacement of each arm assembly is equal to the axial displacement of the support member, thereby aligning the centering device and tool string within the wellbore. The mechanical advantage varies with the axial and radial position of the arm assembly 3. The mechanical advantage of the arm assembly 3 can be expressed as Fr / Fa, where Fa is the axial force provided by the axial spring element(s) 13 on the arm assembly, and Fr is the resulting radial force applied to the wellbore wall 102a. As the mechanical advantage increases, the radial force transferred from the axial spring force to the wellbore wall also increases. The mechanical advantage depends on the angle between each arm and the centerline of the device (…). Figure 2A and 2B The angle A in the equation increases with the increase of angle A, such as... Figure 6 The graph showing the mechanical advantage versus angle A is shown. Therefore, the mechanical advantage of arm assembly 3 increases with increasing wellbore diameter. In balance with this mechanical advantage, the force provided by spring 13 decreases as the wellbore diameter increases because support members 7 and 8 slide axially as the wellbore diameter increases, thus reducing spring pressure. Conversely, as the wellbore diameter decreases, the mechanical advantage decreases, and the axial spring force increases as the spring is further compressed by the sliding support members.

[0101] It should be understood that the angle between the arm and the central axis is defined as the angle between the line extending through the respective ends of the arm's pivot axis and the longitudinal axis. For example, the angle A between the second arm 6 and the longitudinal axis 4 is the angle A between the line extending through the second pivot axis 10a and the third pivot axis 11a and the longitudinal axis 4.

[0102] Preferably, the centering device 1 provides a relatively constant centering force within the wellbore diameter range. The radial force applied by the centering device 1 is a product of the axial spring force provided by one or more springs 13 and the mechanical advantage of the arm assembly 3. Since the axial force increases as the mechanical advantage decreases, a relatively constant radial force can be achieved for a range of wellbore diameter sizes by balancing the spring force and mechanical advantage through optimizing the spring stiffness, spring preload, and geometry of the arm assembly. Figure 7 The radial force of an axial spring centering device is shown, designed to operate in sleeve sizes varying between 224 mm and 130 mm in diameter (a diameter range of 94 mm, corresponding to a radial range of 47 mm for each arm assembly from 112 mm to 65 mm). Within this diameter range, the radial force remains in the range of approximately 1000 to 1500 N (224 to 336 psi). Figure 7The centering force is approximately 1250N ± 250N, which is considered relatively constant for the actual function of centering the tool string 101 in the wellbore 102.

[0103] To achieve a relatively constant radial force against the wellbore wall 102a, the angle A between arms 5 and 6 of arm assembly 3 and the central axis 4 of device 1 should be limited to avoid very large and very small angles. At large angles (approaching 90 degrees) between the longitudinal axis 4 and arms 5 and 6 of arm assembly 3, small axial spring forces will result in high radial forces applied to the wellbore wall 102a. As the logging tool string passes through the wellbore, high radial forces lead to greater friction. High friction can prevent the tool string from descending under gravity and may cause stick-slip, where the tool moves upwards along the wellbore at a series of sudden, rather than constant, velocities, affecting the accuracy of the collected data. When the arms are at large angles, even greater radial forces are required to cause the centering device to collapse. This makes it difficult to descend the centering device into smaller diameter casing (e.g., from 9 5 / 8 inch casing to 7 inch liner). The arms of the centering device may even become stuck by the wellhead control assembly, which consists of a stack of hydraulic plungers and valves for wellhead control and safety (closing in case of a blowout).

[0104] Conversely, at small angles (close to 0 degrees) between the longitudinal axis and arms 5 and 6 of arm assembly 3, a large axial spring force is required to provide sufficient radial force for tool string alignment. Furthermore, the axial displacement of (one or more) support members 7 and 8 is very small relative to the radial displacement (outer diameter of centerer 1), causing centerer device 1 to fail to align tool string 101 in small-diameter wellbore. For example, at a 10-degree arm angle, a 10 mm change in centerer diameter (5 mm radial displacement) results in less than 1 mm of axial displacement. With such small axial movement of support members 7 and 8, gaps in pivot points 9, 10, and 11, bearings, and sliding support members 7 and 8 prevent centerer device from aligning the tool string because the radial displacement of one arm assembly is not sufficiently accurately transmitted to the other arm assemblies via support members 7 and 8 and pivot points 9 and 10. This causes device 1 to de-center, which in turn causes tool string sensor 106 to return erroneous data. At the forearm angle, radial force can be transmitted via, as referenced above... Figure 4A and 4B The radial reinforcement spring is used to increase centering; however, this does not correct the fundamental problem of centering. The logging tool will deviate from the center by a distance determined by the tool weight acting perpendicular to the wellbore wall and the stiffness of the radial spring.

[0105] Additionally or alternatively, variable stiffness springs may be applied axially to the sliding support members 7, 8 and / or radially to each arm assembly to provide increased spring force at small angles between the longitudinal axis of the arm assembly with reduced mechanical advantage and arms 5, 6, and decreased spring force at large angles between the longitudinal axis of the arm assembly with increased mechanical advantage and arms 5, 6. For example, variable pitch coil springs may be provided axially to the sliding support members 7, 8 and / or radially disposed between arms 5, 6 and the spindle, such that the spring stiffness increases as the coil spring is compressed. Variable pitch springs, such as... Figure 15 As shown. Variable stiffness springs can be designed to achieve a constant radial force for a range of wellbore diameters by combining the variable spring stiffness with the variable mechanical advantages provided by the arm assemblies. However, even with variable stiffness springs, alignment at small angles presents challenges. At small angles, large changes in the wellbore diameter cause only very small changes in the axial displacement of the support members 7 and 8. Therefore, deflection of one arm assembly is difficult to transmit to other arm assemblies via axial deflection of the support members, and the arms do not deflect uniformly. When this occurs, the device is no longer used for tool alignment, and the arms act independently of each other. Extremely high precision tolerances are required between components to ensure that all arms deflect uniformly for alignment. The machining tolerances required to achieve alignment at arm angles may be impractical.

[0106] The inventors have determined that the angle between at least one arm of the arm assembly and the longitudinal axis should ideally be in the range of approximately 30° to 60°. For angles much below 30°, the mechanical advantage requiring high spring loads is reduced, and centering becomes impossible due to practical component tolerances. For angles much above 60°, the mechanical advantage is too great, resulting in increased sensitivity and high wellbore wall loads. Furthermore, at angles much above 60°, the tool string may fail to transfer from a larger diameter casing to a smaller diameter casing because the centerer arm 3 may "hook" on the flange formed between the larger and smaller diameter casings. This angle is preferably much greater than 10 degrees and much less than 75 degrees. For example, Figure 7 The radial deflection involves an arm angle of 26° to 57°. This angle is preferably limited to the range of 20 to 70 degrees, or more preferably to the range of 25 to 65 degrees.

[0107] An improved range of radial motion can be achieved by positioning the first and second pivots on opposite sides of a plane that coincides with the longitudinal axis of the centerer and is opposite to the third pivot, while keeping the angle between the arm assembly 3 and the longitudinal axis 4 within available limits, such as 30 degrees and 60 degrees, to obtain a relatively constant radial force.

[0108] Figure 8AA schematic diagram of the centering device is provided, in which the first pivot 9 and the second pivot 10, like the third pivot 11, are located on the same side of the plane coinciding with the longitudinal axis 4 (this configuration is referred to herein as a "proximal" pivot). In contrast, Figure 8C A schematic diagram of the centering device is provided, wherein the third pivot 11 is located on the first side of a plane coinciding with the longitudinal axis 4 of the centering device, and the first pivot 9 and the second pivot 10 are located on the opposite second side of the plane (this configuration is referred to herein as the “far-side” pivot). Figure 8A and 8C This comparison between the arrangements illustrates that when the angle between the arm assembly 3 and the longitudinal axis 4 is limited to between 30 and 60 degrees, Figure 8C The distal pivot configuration achieves a greater radial range, thus providing a centering device suitable for a wider range of wellbore diameters. Therefore, the distal pivot configuration is preferable to the proximal pivot configuration in providing a centering device suitable for a wider range of wellbore diameters. Furthermore, to achieve arm angles ranging from 30 to 60 degrees, Figure 8A The arms in the proximal configuration must be relatively short. Shorter arms result in smaller axial displacement, thus requiring very stiff springs to generate the radial force needed to align the tool string, which complicates the engineering design of the device.

[0109] The inventors have determined that the benefits, such as..., can be achieved by positioning only one of the first pivot joint 9 and the second pivot joint 10 on opposite second sides of a plane coinciding with the longitudinal axis of the centering device. Figure 8B As shown in the schematic diagram, and as in Figures 2A to 2G The centering device incorporates a hybrid side pivot (this configuration is referred to herein as a "hybrid" side pivot). The inventors determined that a relatively constant radial force can be achieved to gain useful mechanical advantages by keeping the angle between only one of the arms 5, 6 of the arm assembly 3 and the longitudinal axis 4 within a usable range. Figure 8C As shown, the angle between the longitudinal axis 4 and the second arm 6 of the pivot 10, which has a "far side" pivot joint, i.e., located on the opposite side of the plane coinciding with the longitudinal axis and opposite to the third pivot joint 11, is ( Figure 2A Angle A) is kept within a useful range to achieve a sufficiently constant radial force within the improved radial range and therefore within the cylinder diameter range. Figure 8B and 8C The comparison between them shows Figure 8B Mixed-side pivot arrangement and Figure 8CThe distal pivot arrangement has the same radial extent. However, compared to the distal pivot arrangement, the radial extent of the hybrid side arrangement is achieved over a shorter axial length variation. Since the axial displacement of the hybrid side arrangement is less compared to the distal arrangement, the hybrid side arrangement can be designed with a shorter, stiffer spring. The axial travel of the support member 7 is denoted by L2 in Figure 8B and by L3 in Figure 8C , where L2 < L3. Thus, the hybrid side arrangement achieves a shorter centralizer length and hence a shorter tool string length, which is a significant benefit for guiding the tool string down the wellbore. Additionally, this shorter length characteristic enables the hybrid side centralizer to be retrofitted to replace existing centralizers integral with tool strings having a proximal arrangement with a housing space too small for a distal arrangement. Centralizers with a proximal pivot configuration in the prior art are typically integral with logging tools, where the body of the logging tool forms the mandrel 12 of the centralizer, or in other words, the arm assembly 3 and support members 7, 8 of the centralizer 1 are assembled to the body of the slender logging tool assembly. The support members 7, 8 can be assembled to a reduced diameter section of the logging tool. By removing the existing proximal centralizer and retrofitting the hybrid side centralizer spring(s) 13, support members 7, 8, and arm assembly 3, the hybrid side arrangement can be designed to be assembled to a logging tool string designed for a proximal arrangement to achieve improved centering over a greater radial extent (wellbore diameter range).

[0110] Figure 9 Presents a comparison of the radial force versus radial deflection characteristics of three centralizer devices; a centralizer with a "proximal" pivot configuration ( Figure 8A ), a centralizer with a "distal" pivot configuration ( Figure 8B ), and a centralizer with a "hybrid side" pivot configuration ( Figure 8C ). For a given radial force band, the distal pivot configuration achieves the greatest radial deflection or extent, whereas the hybrid side achieves a radial deflection or extent significantly superior to the proximal configuration while achieving a reduction in the axial length of the centralizer compared to the distal configuration.

[0111] Figures 2A to 2G The centralizer of Figure 8BThe first pivot joint 9 and the third pivot joint 11 are located on a first side of a plane coinciding with the longitudinal axis 4 of the centering device 1, and the second pivot joint 10 is located on the opposite second side of the same plane. The first pivot joint 9 has a first pivot axis 9a, the second pivot joint 10 has a second pivot axis 10a, and the third pivot joint 11 has a third pivot axis 11a. Axial movement of the support members 7 and 8 causes the arms 5 and 6 to pivot about the first pivot axis, the second pivot axis, and the third pivot axis. The pivot joints 9, 10, and 11 are arranged such that the first pivot axis 9a and the third pivot axis 11a are located on a first side of a plane P1 coinciding with the longitudinal axis 4 of the centering device 1, and the second pivot axis 10a is located on the opposite second side of the same plane P1.

[0112] Figures 2A to 2G The relative positions of the first pivot joint 9, the second pivot joint 10, and the third pivot joint 11 in the embodiment are as follows: Figures 2H to 2J Further shown in the sectional view. Arm assembly 3 in Figure 2E and 2F The components are labeled as arm assemblies 3A, 3B, 3C, and 3D (arm assembly 3C is in...). Figure 2F (Obstructed in the middle). Figures 2H to 2J In the sectional view, the first pivot joint, the second pivot joint, and the third pivot joint of arm assembly 3A are identified by reference numerals 3A-9, 3A-10, and 3A-11, and arm assemblies 3B, 3C, and 3D are subject to the same numbering convention.

[0113] like Figures 2H to 2JAs shown and referring to arm assembly 3A, the first pivot joint 3A-9 and the second pivot joint 3A-10 are circumferentially spaced (i.e., offset in azimuth) by 180 degrees around the longitudinal axis 4 of the centering device. The first pivot axis 9a, the second pivot axis 10a, and the third pivot axis 11a are parallel. Preferably, the first pivot axis 9a, the second pivot axis 10a, and the third pivot axis 11a are perpendicular to the longitudinal axis 4 of the centering device 1. The first pivot joint 3A-9 and the second pivot joint 3A-10 are aligned on a plane P2 that coincides with the longitudinal axis 4 of the centering device. Plane P2 is orthogonal to plane P1. The first pivot joint 3A-9 and the third pivot joint 3A-11 and / or the wheel 14 can be aligned on plane P2. For example, the first arm 5 can be straight or other shapes such that the first pivot joint 3A-9 and the third pivot joint 3A-11 and / or the wheel 14 are located on plane P2 and aligned circumferentially or in azimuth. First pivot joints 3A-9 and third pivot joints 3A-11 are located on a first side of plane P1, and second pivot joint 10 is located on the opposite second side of plane P1. Pivot joints 9, 10, and 11 are arranged such that first pivot axis 9a and third pivot axis 11a are located on the first side of plane P1, and second pivot axis 10a is located on the opposite second side of plane P1. A second arm 6 extends circumferentially around and along the longitudinal axis or bends to position the second pivot joint 3A-10 and axis 10a on opposite sides of plane P1. For example, the second arm may extend helically around and along the longitudinal axis.

[0114] Lateral alignment of pivot joints 9, 10, 11 and wheel 14 on plane P2 reduces mechanical stress on the pivot joints, for example by reducing bending moment and thrust loads on joints 9, 10, and 11.

[0115] like Figure 2A and 2B As shown in the optimal configuration, the arm assembly 3 is arranged such that the first pivot joint 9 and the pivot axis line 9a of the arm assembly 3 are axially aligned. That is, the first pivot joint 9 and the axis 9a of all arm assemblies 3 are aligned in the transverse plane (a plane orthogonal to the longitudinal axis 4, for example, in...). Figure 2A Alignment is achieved on the first plane extending through line DD. Similarly, the second pivot 10 and axis 10a are aligned in the transverse plane (e.g., in the first plane extending through line DD). Figure 2A The second plane extends through line BB. Preferably, the third pivot 11 and axis 11a are also aligned in the transverse plane (e.g., in the middle). Figure 2A The middle extends through the third plane of line CC.

[0116] With the first and second pivot joints and their respective axes axially aligned, the arm assemblies are nested together circumferentially around the spindle, or in other words, the arm assemblies 3 are wound together around the spindle 12, much like threads wound together in a multi-start thread. This arrangement achieves a shorter centering device compared to arm assemblies or arm assemblies that are diametrically opposed and spaced apart along the axial direction of the centering device.

[0117] The first arm can be of a different length than the second arm, such that the distance between the second pivot axis and the third pivot axis is different from the distance between the first pivot axis and the third pivot axis. For example, the distance between the first pivot axis 9a and the third pivot axis 11a can be shorter than the distance between the second pivot axis 10a and the third pivot axis 11a, such as... Figure 2A and 3A As shown. Alternatively, the distance between the first pivot axis 9a and the third pivot axis 11a may be longer than the distance between the second pivot axis 10a and the third pivot axis 11a.

[0118] refer to Figure 3A The angle between the line extending between the first pivot axis 9a and the third pivot axis 11a and the longitudinal axis 4 is smaller than the angle between the line extending between the second pivot axis 10a and the third pivot axis 11a and the longitudinal axis 4. Angle B decreases as the length of the first arm increases. However, as mentioned above, angle A should be kept within a preferred range (25 to 65 degrees).

[0119] In an alternative arrangement, the first arm 5 may extend or bend (e.g., spirally) circumferentially around the longitudinal axis 4, such that the first pivot joint 9 and the third pivot joint 11 are circumferentially spaced apart, i.e., misaligned in azimuth. The first pivot joint 9 may be located on a first side of plane P2, and the second pivot joint 10 may be located on the opposite second side of plane P2. Other configurations are also possible, for example, where the first pivot joint 9 and the second pivot joint 10 may be located on a first side of plane P2, wherein the first arm 5 and the second arm 6 extend circumferentially around the longitudinal axis to position the wheel 14 on a plane coinciding with the longitudinal axis 4 (e.g., plane P2).

[0120] According to one aspect of the invention, the centering device described above provides one or more of the following benefits. Compared to prior art centering devices, this centering device achieves a relatively constant radial force over a larger wellbore diameter range, with all its pivot points on the same side of the longitudinal axis of the wheel in contact with the wellbore. The wellbore diameter range achieved by this centering device is comparable to that of devices where the arm assembly pivot joint is located on the opposite side of the centering device's longitudinal axis relative to the wheel; however, the diameter range is achieved with a device of reduced axial length. The pivot joint configuration allows the centering device to provide a radial centering force that is not high enough to cause excessive friction in smaller diameter wellbore within the desired wellbore range, but still provides sufficient radial force to centrally hold the centering device and associated tool string in larger diameter wellbore. By balancing the practical mechanical advantages and axial spring force, the centering device allows the tool string to be centered even in skewed wellbore, where the weight of the tool string and centering device resists the centering radial force provided by the centering device. Furthermore, the centering device is a passive device, powered solely by a mechanical spring component 13. No other power input is required, such as electrical or hydraulic power supplied by a power unit located in the service area. Therefore, this invention provides a low-cost, efficient, and simplified device that offers better operational reliability and accuracy of logging data.

[0121] Figures 10A to 10E Centering devices with a "distal" pivot configuration, as referenced above. Figure 8B The features discussed are the same as or similar to those in the embodiments described above. Figures 10A to 10E Features of the embodiments are referenced in the drawings using the same reference numerals that appear in the previous drawings, and are not specifically referenced in the figures. Figures 10A to 10E To describe it in detail again.

[0122] exist Figures 10A to 10E In one embodiment, the centering device 20 includes a first support member 7 and a second support member 8, and a plurality of arm assemblies 3 connected between the first and second support members. Under the action of one or more springs 13, axial movement of one or two support members 7, 8 causes radial movement of the arm assemblies 3 to engage the wellbore wall 102 by pivoting the first pivot joint 9, the second pivot joint 10, and the third pivot joint 11, as described above for the previous embodiment.

[0123] However, in Figures 10A to 10EIn this configuration, each arm assembly 3, including the first arm 5 and the second arm 6, is configured such that the third pivot joint 11 is located on a first side of plane P1 coinciding with the longitudinal axis 4 of the device, and the first pivot joint 9 and the second pivot joint 10 are located on opposite second sides of plane P1. The positioning of the pivot joints 9, 10, and 11, as described and illustrated, positions the third pivot axis 11a on the first side of plane P1 and the first pivot axis 9a and the second pivot axis 10a on opposite second sides of plane P1 (“far-side” pivot arrangement). The longer arm length achieves a greater radial range under relatively constant radial forces, as referenced above. Figures 8A to 8C and 9.

[0124] like Figures 10F to 10H As shown, the first and second pivot joints are aligned in azimuth. The first and second pivot joints are circumferentially spaced (misaligned in azimuth) from the third pivot joint around the longitudinal axis 4, preferably by 180 degrees, as shown. The first pivot axis 9a, the second pivot axis 10a, and the third pivot axis 11a are parallel. Preferably, the first pivot axis 9a, the second pivot axis 10a, and the third pivot axis 11a are perpendicular to the longitudinal axis 4 of the centering device 20. The first pivot joint 3A-9 and the second pivot joint 3A-10 are aligned on a plane P2 that coincides with the longitudinal axis 4 of the centering device. Plane P2 is orthogonal to plane P1. The first pivot joint 3A-9, the second pivot joint 3A-10, and the third pivot joint 3A-11 and / or the wheel 14 are aligned on plane P2. The third pivot joint 3A-11 is located on the first side of plane P1, and the first pivot joint 9 and the second pivot joint 10 are located on the opposite second side of plane P1. The pivot joints 9, 10, and 11 are arranged such that the third pivot axis 11a is located on the first side of plane P1, and the first pivot axis 9a and the second pivot axis 10a are located on the opposite second side of plane P1. Figure 11A and 11B The positions of pivot joints 9, 10, 11 and pivot axis lines 9a, 10a, 11a are further clarified, with only one arm assembly 3 shown.

[0125] exist Figures 10A to 10E In the embodiments, the lateral alignment of pivot joints 9, 10, 11 and wheel 14 on plane P2 reduces mechanical stress on the pivot joints, for example by reducing bending moment and thrust loads on joints 9, 10 and 11.

[0126] The arm assembly extends or bends circumferentially around and along the longitudinal axis 4 of the centerer 20. The first arm 5 extends or bends circumferentially around and along the longitudinal axis 4 between the first pivot axis 9 and the third pivot axis 11a, while the second arm 6 extends or bends circumferentially around and along the longitudinal axis 4 between the third pivot axis 11a and the second pivot axis 10a to position the first pivot joint 9 and the second pivot joint 10 on the side of plane P1 opposite to the third pivot joint 11. For example, the first and second arms, and thus the arm assembly 3, may extend helically around and along the longitudinal axis.

[0127] exist Figures 10A to 10E In the embodiments, the arm assembly 3 is arranged such that the first pivot joint 9 and the pivot axis 9a of the arm assembly 3 are axially aligned, that is, the first pivot joint 9 and the axis 9a of all arm assemblies 3 are aligned in the transverse plane (orthogonal to the plane of the longitudinal axis 4, which, for example, is in the plane of the longitudinal axis 4). Figure 10A The second pivot 10 and the axis 10a are aligned in the first plane extending through line LL, and similarly, the second pivot 10 and the axis 10a are aligned in the transverse plane (e.g., in...). Figure 10A Alignment is made on the second plane extending through line JJ. Preferably, the third pivot joint 11 and the axis 11a are also aligned in the transverse plane (e.g., in...). Figure 10A Align the middle extension through the third plane of line KK.

[0128] With the first and second pivot joints and their respective axes axially aligned, the arm assemblies are nested together circumferentially around the spindle, or in other words, the arm assemblies 3 are wound together around the spindle 12, much like threads wound together in a multi-start thread. This arrangement achieves a shorter centering device compared to arm assemblies or arm assemblies that are diametrically opposed and spaced apart along the axial direction of the centering device.

[0129] By positioning the first pivot joint 9 and the second pivot joint 10 (and their respective axes 9a, 10a) radially outside the outer diameter of the center mandrel 12 of the centering device, the first and second pivot axes are positioned as far away as possible from the longitudinal axis 4 and the third pivot axis, further achieving a greater radial range. This provides longer arms 5, 6 and a greater radial range (wellbore diameter range) for a given angular range (A) between the first arm 5 and the second arm 6 and the longitudinal axis 4 of the device. Figure 10C As best shown in the cross-sectional view, the first pivot axis 9a and the second pivot axis 10a do not intersect the mandrel 12. The third pivot joint is also located radially outside the outer diameter of the mandrel to allow for the full radial range of motion of the arm assembly, i.e., even when the arm assembly is in a position such as... Figure 10BAt the radially innermost position shown, the third pivot joint is also outside the outer diameter of the mandrel. Even at the radially innermost position, the third pivot joint does not intersect with mandrel 12.

[0130] Similarly, such as Figure 2A , 2B As shown in 2G, in the previously described embodiment, the second pivot joint 10 and axis 10a are located radially outside the outer diameter of the center mandrel 12 of the centerer. The second pivot axis does not intersect the mandrel 12. The first pivot joint 9 and axis 9a are also located outside the outer diameter of the mandrel 12. The first pivot axis does not intersect the mandrel 12.

[0131] Figure 12A and 12B Another embodiment of the centering device 21 is shown, which has a "distal" pivot configuration similar to that described above. Figures 10A to 10E Similar to embodiment 20, however, additionally includes support members 7, 8 keyed to the mandrel 12 to rotatably secure the support members 7, 8 to the mandrel 12 such that the support members 7, 8 can move axially on the mandrel 12 without relative rotation between the support members 7, 8 and the mandrel 12. The mandrel 12 includes longitudinal "tracks" or protrusions 17 to engage corresponding longitudinal channels or slots in the respective support members 7, 8. Figure 12B 18). Those skilled in the art will understand that the male / female aspects of the keyway arrangements 17, 18 between the support members 7, 8 and the spindle 12 can be reversed, i.e., the support members 7, 8 may include longitudinal “tracks” or protrusions 17 to engage corresponding longitudinal channels or slots 18 in the spindle 12. The keyway arrangements 17, 18 ensure that the first pivot joint 9, the second pivot joint 10, and the third pivot joint 11 and the wheel 14 are in a plane coinciding with the longitudinal axis of the centerer (e.g., 18). Figures 2H to 2J and Figures 10F to 10H Keep aligned on plane P2).

[0132] Figure 12A and 12B Embodiment 21 also includes mechanical stops 19 to set the maximum diameter of the centering device 21. Each stop 19 restricts the axial movement of the corresponding support member 7, 8 to limit the radial outward movement of the arm assembly 3. When the centering device 21 enters a large-diameter section of the wellbore, such as a flushing section, the mechanical stops 19 prevent the arm assembly 3 from extending radially beyond the desired range to avoid difficulties, for example, when the centering device 21 enters a small-diameter (or nominal diameter) section of the wellbore from a large-diameter flushing section. Those skilled in the art will understand that other methods can be used to limit the maximum diameter of the centering device 21. For example, each support member 7, 8 may include a "buffer" such that contact between the buffers of the support members spaces the support members apart by a distance corresponding to the maximum radial position of the arm assembly.

[0133] Figure 13A Another embodiment of the centering device 22 is shown, which has a "distal" pivot configuration similar to that described above. Figures 10A to 10E Similar to embodiment 20, but additionally includes support members 7, 8 keyed to mandrel 12 to rotatably secure the support members 7, 8 to mandrel 12 such that the support members 7, 8 can move axially on mandrel 12 without relative rotation between the support members 7, 8 and mandrel 12. The mandrel 12 of the centerer is typically hollow to accommodate wiring, and the external wellbore pressure in the wellbore can be very high, for example, 30,000 psi (pounds per square inch). Keyways and grooves on the mandrel will cause a “stress rise” (localized stress increase) on mandrel 12, which may cause the mandrel to collapse under pressure. To reduce the increased stress in the mandrel, the support members 7, 8 can be provided with keyways, while the mandrel has features such as Figure 12A and 12B The corresponding key or track in the embodiments. However, the necessary radial height of the keyway may be difficult to meet in the support members 7, 8, and / or the radial height of the key on the mandrel requires a significant amount of additional machining of the material during the manufacture of the mandrel. To address these issues, in some embodiments and as in... Figure 13A As shown, the keying of the support member to the mandrel is provided by a mandrel having multiple facets (flat surfaces) spaced apart around the outer surface of the mandrel. Each facet extends at least a portion of the mandrel length, allowing the first and / or second support members to move on the mandrel. Support members 7 and 8 have corresponding multiple spaced facets around their inner surfaces to allow the support members to be rotatably keyed to the mandrel, thereby preventing rotation and allowing the support members to slide or move axially on the mandrel. Each facet may be tangent to an arc centered on the central longitudinal axis of the mandrel / device.

[0134] Providing a multi-faceted surface for the mandrel avoids stress rise caused by keyways on the mandrel and reduces the radial height required to accommodate the keyways on the support member.

[0135] exist Figure 13A In the illustrated embodiment, the cross-sections are arranged to provide a polygonal outer surface to the mandrel, while the support members 7 and 8 have corresponding polygonal inner surfaces to rotatably key the support members to the mandrel, thereby preventing rotation and allowing the support members to slide or move axially on the mandrel. Figure 13B Centering device 22 is shown, with a spring 13 omitted to show the cross-section and polygonal outer surface of mandrel 12, on which support member 8 slides. Figure 13C The cross-section of the mandrel and its polygonal outer surface, as well as the corresponding polygonal inner surface of the support member 8, are shown. The mandrel also has a polygonal outer surface for the first support member 7, which is partially obscured by the spring. Figure 13A In the embodiments described, the polygon is octagonal; however, those skilled in the art will understand that other polygons are possible, with more or fewer facets. It is conceivable that the mandrel and(one or more) support members may have at least two facets (e.g., diametrically opposed) to key the mandrel and(one or more) support members together. However, in a preferred embodiment, the outer surface of the mandrel has facets azimuthally aligned with adjacent first or second pivot joints at the first or second support member. Alternatively or additionally, the mandrel may have facets extending between adjacent first or second pivot joints such that the number of facets is equal to or twice the number of arm assemblies. For example, in the illustrated embodiment including four arms, the mandrel includes eight facets, or an octagonal outer shape. For example, a centerer including three arm assemblies may have a mandrel with a hexagonal outer surface, wherein the first and / or second support members have corresponding hexagonal inner surfaces.

[0136] In the illustrated embodiment, a portion of the mandrel located between the first and second support members has a larger outer cross-section than the section with a cross-section, to provide mechanical stops that set the maximum diameter for the centering device. Each stop restricts the axial movement of the corresponding support member 7, 8 to limit the radial outward movement of the arm assembly.

[0137] The faceted surfaces of the mandrel and one or more support members enable keying between the support members and the mandrel, while also increasing rigidity and requiring less material to be machined from the blank material during mandrel manufacturing. Those skilled in the art will understand that centerers with the above-described hybrid side construction, or any other lever arm type, can also have reference... Figures 13A to 13C The described faceted mandrel and support member are used to key (one or more) support members to the mandrel.

[0138] Those skilled in the art will understand that a mandrel with a polygonal outer surface has a cross-section having a constant polygonal outer profile extending for at least a portion of the mandrel's length. Similarly, a support member with a polygonal inner surface also has a cross-section having a constant polygonal inner shape extending for a certain length of the support member.

[0139] Figures 14A to 14F Another embodiment of the centering device 23 is shown, whose "distal" pivot configuration is the same as described above. Figures 10A to 10E Similar to embodiment 20, but with five arm assemblies 3, these arm assemblies in Figure 14C and 14FThe terminator is referred to as 3A to 3E. The centering device must have at least three arm assemblies to center the tool string. However, preferably, the number of arm assemblies is increased to the maximum number that can be practically mounted around the mandrel 12. The inventors have determined that five arm assemblies are the optimal number of robotic arm assemblies, which is the maximum number that can be practically mounted around the mandrel for applications involving tool string centering in wellbore.

[0140] The invention has already been described in relation to aligning a tool string in the wellbore during wireline logging operations. However, the alignment device according to the invention can be used to align sensor assemblies in the wellbore in other applications, such as aligning a camera in a pipe for inspection purposes.

[0141] Although the invention has been described by way of example and with reference to its possible implementations, it should be understood that changes or modifications may be made thereto without departing from the spirit or scope of the appended claims.

Claims

1. An apparatus for aligning a sensor assembly in a cylinder, the apparatus comprising: A first support member and a second support member are axially spaced apart along the central longitudinal axis of the device, and one or both of the first support member and the second support member are adapted to move axially along the central longitudinal axis; A plurality of arm assemblies, circumferentially spaced around the central longitudinal axis of the device and connected between the first support member and the second support member, each arm assembly comprising: The first arm is pivotally connected to the first support member via a first pivot joint having a first pivot axis. The second arm is pivotally connected to the second support member via a second pivot joint having a second pivot axis, and the first and second arms are pivotally connected together via a third pivot joint having a third pivot axis. The first pivot axis and the third pivot axis are located on the first side of a plane that coincides with the central longitudinal axis of the device, while the second pivot axis is located on the second side of the plane that is opposite to the first side.

2. The apparatus as claimed in claim 1, characterized in that, The first pivot joint is circumferentially aligned with the third pivot joint.

3. The apparatus as described in claim 1, characterized in that, The plane is a first plane, and the first pivot joint and the third pivot joint, or the wheel carried by the arm assembly to contact the cylinder, are aligned on a second plane that coincides with the central longitudinal axis, the second plane being orthogonal to the first plane.

4. The apparatus as claimed in claim 1, characterized in that, The first pivot joint and the second pivot joint are offset by 180 degrees in azimuth around the central longitudinal axis of the device.

5. The apparatus as claimed in claim 1, characterized in that, The plane is a first plane, and the first pivot joint and the second pivot joint are aligned on a second plane that coincides with the central longitudinal axis, the second plane being orthogonal to the first plane.

6. The apparatus as claimed in claim 1, characterized in that, The device includes a spindle, one or both of the first support member and the second support member being adapted to move axially along the spindle, wherein neither the first pivot axis nor the second pivot axis intersects the spindle.

7. The apparatus as claimed in claim 1, characterized in that, The second arm circumferentially surrounds and extends circumferentially along the central longitudinal axis to position the second pivot axis and the third pivot axis on opposite sides of the plane, respectively.

8. The apparatus as claimed in claim 1, characterized in that, The second arm of the arm assembly is circumferentially nested or entangled around the central longitudinal axis.

9. The apparatus as claimed in claim 1, characterized in that, The angle between the line extending between the first pivot axis and the third pivot axis and the central longitudinal axis is smaller than the angle between the line extending between the second pivot axis and the third pivot axis and the central longitudinal axis.

10. The apparatus as claimed in claim 1, characterized in that, Each arm assembly includes a roller or wheel to contact the wall of the cylinder, and wherein the wheel is rotatably coupled to the first arm or the second arm on a rotation axis perpendicular to the central longitudinal axis and offset from the third pivot joint.

11. The apparatus as claimed in claim 1, characterized in that, The device includes one or more spring elements to radially outward bias the arm assembly.

12. The apparatus as claimed in claim 11, characterized in that, The spring element includes one or more leaf springs, which are mounted to apply a radially outward force to the first arm of one or more arm assemblies.

13. The apparatus as claimed in claim 1, characterized in that, The angle between the line extending through the second pivot axis and the third pivot axis and the central longitudinal axis is maintained within the range of greater than 10 degrees and less than 75 degrees.

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