A new mechanical device and technique for borehole caliper while drilling

Abstract

A new mechanical arm caliper developed. Mechanically flexible and compressible arms eliminate push-out systems and expand applications. Dual sensors monitor mechanical arm position during drilling, reaming, and tripping. Minimum six mechanical arms in a non-rotating collar for high-quality data. When considering arms, the caliper's outside diameter exceeds the bore hole. The arms stay in contact with the bore wall. Each arm has a fixed and guided free end to keep the caliper in contact with the drilled hole wall. The sensor measures axial movement and may be a linear resistor at the arm's free end. On the non-rotating collar opposite each arm, another EDM sensor measures arm position relative to the tool body. Electrical boards translate sensor readings of arm positions. At least two sealed bearings are required to keep the collar non-rotating and transfer drill string torque and rotation downhole to the bit.

Description

DescriptionTitle of the InventionA new mechanical device and technique for borehole caliper while drilling operations.Technical Field

[0001] This invention pertains to drilling equipment, specifically a device and technique for measuring the diameter of a well borehole while drilling, tripping, or reaming.Background Art

[0002] Drill rigs are typically equipped with a rotary table or top drive system to rotate the drill string. The drill string consists of drill pipes and a bottom hole assembly (BHA). During drilling operation, the drill string's axial load and surface rotation can be transferred to the drill bit at the bottom, causing the drill bit to penetrate subsurface rock formations. Mud pumps located close to the rig are responsible for pumping drilling fluid called drilling mud through drill string and down to the bit. Mud exits via drill bit nozzles. Drilling fluids have many functions, including cooling and lubricating the drill bit, helping to suspend rock cuttings, controlling well pressure, stabilizing exposed rocks, and providing buoyancy. It also cools and lubricates the wellbore, allowing rock cuttings to move smoothly to the surface.

[0003] Measurement while drilling (MWD) tools are part of the drill string, and they include sensors that measure geodetic trajectory and mechanical parameters. Logging while drilling (LWD) tools are also part of the drill string, but they are responsible for measuring petrophysical parameters of the surrounding rock formation. The present invention is considered part of these systems and responsible for the wellbore caliper.

[0004] The MLWD systems use a data process to convert sensors’ measurements into telemetry format, which is then applied to either the valve assembly part of the drill string controlling the mud flow, called Mud Pulse Telemetry, or an electromagnetic transmitter called an EM tool. The mud pulser telemetry could be negative or positive or a continuous pulse system depending on the mechanism of thefluctuating pressure. A pressure transducer located in the standpipe records these fluctuations and translates them to digital bits and then to data using the surface measurement device and computers. In the EM system, many rods are inserted on the ground and close to the BOP stack to receive the electromagnetic waves sent from the downhole and translate them to digital bits and then to data using the surface measurement device and computers.

[0005] The drilled wellbore through the formations usually spirals. The rotation action of the drill bit creates the spiral wellbore. However, a change in the formation's structure can also deflect the drill bit, causing the wellbore to change shape. Even a straight wellbore deviates and changes directions. Steerable drilling equipment extensively uses extremely deviated and horizontal wellbores to increase reservoir production. These variations create substantial difficulties for the drilling, completion, and production processes. Therefore, it was essential when evaluating the wellbore caliper.

[0006] Many applications require borehole size and geometry data. Knowing the distance between sensors (such as acoustic, neutron, and density sensors) and the wellbore wall is critical. Data quality assessment and environmental corrections for formation evaluation sensors require knowledge of borehole size and geometry.

[0007] Running the casing string within a wellbore can be challenging, and the stresses can cause damage to the casing string. So, borehole calipers are required to place casing devices like centralizers and calculate cement volume during wellbore completion. It is necessary to measure the borehole to find out the regional directional stress and see if the drilling mud system is right for clay swelling or filter cake buildup.

[0008] As mentioned above, the geometry and orientation of the wellbore, as well as how a completion string sits in it, have an impact on its effectiveness during cleanup, treatment, cementing / isolation, and production. Because of that, wireline calipers are used as conventional measurements after drilling operations. The conventional wireline caliper is a mechanical device with extending contact arms that are pushed against the borehole wall. It is described in US patent number 4407157A for measuring the borehole caliper. Before running the wireline into theborehole, it is necessary to trip out the drill string. This may require extra time and expenses on the rig. Furthermore, the use of these wireline calipers can lead to a reduction in the condition of the holes throughout logging, as well as a higher probability of becoming stuck. In addition, directional drilling often leads to significant deviations from vertical boreholes, making wireline equipment ineffective.

[0009] Using a caliper while drilling can effectively address the previously mentioned problems associated with traditional wireline calipers. Furthermore, it has the potential to improve real-time drilling techniques and mitigate issues associated with downhole operations. At present, there are multiple typical logging while drilling calipers available for accurately measuring the diameter of a borehole. However, existing LWD calipers have certain limitations. Certain caliper measures are considered secondary as they deal with minor variations in other values, which act as the principal characteristic being measured. For example, a common type of LWD instrument uses 2 MHz electromagnetic waves to gauge the resistivity of rock formations. The resistivity caliper utilizes minor variations in the phases and amplitudes of electromagnetic waves. However, it is not successful when used in oil-based mud, as it can only provide an average diameter measurement. The LWD tool utilizes gamma-rays to evaluate the density of rock formations, which are able to penetrate through the drilling mud. The space between the density sensors and the borehole wall influences the count rates at two detectors, as the densities of the mud and rock formation differ. Only during the drilling process can you obtain the density caliper, which can only measure relatively minor washouts, such as those smaller than 1 inch in size. The ultrasonic caliper sends pulses towards the borehole wall and measures the time it takes for the pulses to travel back and forth. Fluid chemistry, viscosity, and particles can affect the accuracy or effectiveness of ultrasonic borehole imaging (UBI) measurements. In other words, UBI has a restricted capability to operate effectively in thick mud. Furthermore, these intricate instruments are costly and susceptible to failure under the challenging conditions of the borehole. Mechanical calipers, on the other hand, have the capability to directly and precisely measure the borehole's diameter, and they can even measure boreholes that are not perfectly round. Moreover, these mechanicalcalipers possess the capacity to gauge the diameters of various formations, including those with irregular shapes and curves. This facilitates a deeper understanding of the borehole dimensions and guarantees the acquisition of accurate measurement data. Furthermore, the specific composition of the mud does not limit the mechanical wireline calipers, making them a highly flexible and reliable choice for measuring borehole diameters.Summary of Invention

[0010] A new design for a mechanical arm caliper that can be used while drilling operations has been developed. It relies on mechanically flexible, compressible arms eliminating the need for push-out systems and expanding the range of applications. This design includes dual sensors that measure the change in position of the mechanical arms during drilling, reaming, and tripping. The system positions at least six mechanical arms within a non-rotating collar for accurate measurements. When considering the arms, the mechanical arm caliper's outside diameter exceeds the bore hole's size. This will allow the arms to compress and expand maintaining constant contact with the wellbore wall. Each arm features a fixed end and a guided free end, allowing the calipers’ arms to be in contact with the drilled hole wall. The free end of the arm connects to a sensor which measures the change in the axial movement of the free end which could be a linear resistor. An electrical board is responsible for converting the change in the sensor reading into a reading that indicates the location of each arm. On the non-rotating collar, opposite each arm, there is another EDM sensor that is responsible for measuring the change in the arm position relative to the tool body. These measurements are used to determine the total outer diameter of the borehole. It is the responsibility of at least two sealed bearings to maintain the non-rotating collar without rotation and transfer the necessary torque and rotation of the drill string downhole to the bit.Technical Problem

[0011] The borehole caliper plays a crucial role during the drilling, completion, and production phases. Different equipment and techniques have been invented to achieve this goal.

[0012] The mechanical device known as the conventional wireline caliper, with its extending contact arms, presses against the borehole wall. The mechanical caliper is considered the more accurate caliper due to the direct contact with the wellbore wall, but it requires stopping drilling, pulling the drilling equipment out of the hole, and running wireline tools. This process can be time-consuming and costly.

[0013] Different inventions have been introduced to calipers while drilling to overcome previously stated conventional wireline caliper issues. The resistivity caliper relies on minute variations in the phases and amplitudes of electromagnetic waves, and it is ineffective in oil-based mud, providing only an average diameter. Ultrasonic borehole imaging (UBI) measurements have a relatively limited range in heavy muds. Research has demonstrated the limitations and ineffectiveness of secondary caliper measurements, leading to the introduction of various inventions designed to provide mechanical calipers during drilling. The use of a pad mechanical caliper while drilling, with at least one pad open to contact the wellbore wall, may affect the borehole trajectory. Additionally, its position within the bottom hole assembly is limited, particularly when using rotary steerable system pads as a caliper. Another contribution is that when a caliper arm is connected to a sleeve, the sleeve moves relative to the collar, causing the arms to move outward towards the inner diameter of a bore. This movement allows for the recording of caliper data. The caliper arm using sleeve can only be used during the retrieval of drill pipes not during drilling or reaming operations.Solution to Problem

[0014] The present invention solves the problems brought up in the technical problem discussion. It specifically deals with the use of direct mechanical measurement, making sure the position is reliable within the bottom hole assembly, and improving the reliability of the application.

[0015] A mechanically flexible compressible arm adapts to the shape of the hole, eliminating the need for a push-out system and expanding its range of applications. The arms are mounted to a non-rotating collar using bearings, which stabilize the caliper measurements, record oriented reference data, and enhance data qualityand application during drilling, reaming, running in the hole, or pulling out of the hole.Advantageous Effects of Invention

[0016] The current mechanical arm caliper is designed to be in mechanical direct contact with the wellbore wall for accurate measurements. The flexibility to position the caliper within the bottom hole assembly was also considered. It was also considered to ensure the drilling process remains unaffected, enabling the transfer of drilling mud, weight and rotation to the below BHA components and subsequently to the drilling bit. It operates either in real-time mode linked to the drilling measurement while drilling system or in memory mode and during all drilling operations, including drilling, reaming, and running in or pulling out the hole.InventionBrief Description of Drawings

[0017] The figures are not perfectly scaled. Alternatively, the design can be modified by increasing the thickness of the layers or areas. In addition, the design can be modified by adding any electrical parts responsible for data processing or data transferring to the MWD surface unit.

[0018] Figure 1 represents a diagram illustrating drilling systems components.

[0019] Figure 2 represents a diagram illustrating the full 3D of the mechanical arm caliper attached to a rock bit using a bit sub.

[0020] Figure 3 represents a top view of the mechanical arm caliper before running in hole showing a full expansion of the arms.

[0021] Figure 4 represents a bottom view of the mechanical arm caliper from bit side showing the bit size is smaller than the arms outside diameter.

[0022] Figure 5 represents the full tool cross section area showing the internal parts of the mechanical arm caliper.

[0023] Figure 6 represents the full tool cross section area of the mechanical arm caliper showing the direction of the forces exerted on the arms and its effect on the force of the free end of the arm.

[0024] Figure 7 represents the dual sensor mounted on the non-rotating collar of the mechanical arm caliper.

[0025] Figure 8 represents the rotation direction of the mandrel and the forces effect of the arms’ cutters.

[0026] Figure 9 represent a flow chart describing the process for configuring the mechanical arm caliper.Detailed Description

[0027] The mechanical arm caliper 1 is part of the bottom hole assembly (BHA) 1 1 . It has box threaded connection 12 and pin threaded connection 25, which could be any type of oilfield connection based on the size of the drilled section and the size of the tool. To clarify the working method of the device, the mechanical arm caliper 1 made up to the drill bit 13 using a bit sub 26, Figure 2. As described above, the drill bit 13 is responsible for drilling the hole through the underground formations. After making up the bit 13 with the required bottom hole assembly (BHA) 1 1 components based on the profile of the wells, which could be vertical, directional, or horizontal. The mechanical arm caliper 1 can be placed in any part of the bottom hole assembly (BHA) 1 1 . In case the bottom hole assembly (BHA) 1 1 includes other measurements while drilling collars 14, the mechanical arm caliper 1 will be made up with the measurement while drilling downhole tools 14 to get the benefit of the real-time caliper data transfer and analysis during drilling. In case the bottom hole assembly (BHA) 1 1 will not include the measurement while drilling downhole tools (MWD) 14, the mechanical arm caliper 1 will be run in memory mode. In this case, the mechanical arm caliper tool 1 can be placed in any part of the bottom hole assembly (BHA) 1 1. During drilling or reaming operations, drilling mud 15, which is stored in surface tanks 16, will be pumped using the rig pumps 17 from surface to downhole through the drill pipes 18 and the BHA components 11. The mechanical arm caliper tool 1 is designed to have a mandrel 27 which has an internal bore 19 to allow the drilling mud 15 to pass through it to the downhole andso to the drill bit 13. The drilling mud 15 flows through the bit nozzles 20 to carry out the drilling cuttings, and this requires the presence of a space between the drill string 28 and the borehole wall called an Annulus 21. The present mechanical caliper 1 is designed to allow the drilling mud 15 to pass around it without effecting the circulation process. The drilling mud 15 reaches the surface carrying the drilling cuttings and passes through different sequences for cleaning, starting from the shale shaker 22, settling tanks 23, and solid control equipment 24 before pumping back to the downhole, Figure 1 . The drilling mud 15 can be used as a telemetry for measurement while drilling communication, as described in the background art section.

[0028] In the present caliper while drilling tool, the mechanical arm caliper 1 for high quality data includes minimum six flexible compressible arms 2 mounted to a nonrotating collar 3. The non-rotating collar 3 helps in stabilization and orientation of caliper measurements. To achieve this, a minimum of two sealed bearings 4 are required, as illustrated in Figure 2 and Figure 5. The bearings 4 are responsible for transferring the required drill string 28 rotation and torque downhole to the bit 13 and, at the same time, sealing the internal parts of the caliper system. Each arm 2 is configured to have another arm 2 on the opposite side, i.e., a 180-degree difference, so the hole outside diameter is calculated from each caliber reading as described in Figure 3. With the six-arm tool, we will have three readings from each pair of arms 2. With conjunction with the tool face orientation from the measurement while drilling downhole tools (MWD) 14, the reading can be displaced relative to the bore hole and also have a continuous average number of the bore hole size.Borehole Diameter one arm set 1&4 — Tool StZC “F DistcUlCC Reading Arm 1 "I" Distance reading Arm 4Avarge Borehole Size at Depth of reading = Borehole Diameter k) / kk=iK = N / 2Where;N is the total number of arms 2k is the total number of arm sets

[0029] In this design, it is mandatory to have the mechanical arm caliper 1 outside diameter, including the arms 2, be bigger than the plan drill section size, i.e., for a 6 in hole size, the total outside diameter of the mechanical arm caliper 1 , including the arms 2, should be around 7.5 to 8 in depending on the expected wash out size, Figure 4. Varied sizes of arms 2 should be available for the same hole section size. This will allow the tool to measure the borehole size in all cases, i.e., washout or tight sections. The caliper arms 2 are mounted with the non-rotating collar 3 in a manner that allows the arms to compress and expand with the borehole shape and size Figure 2 and Figure 5. Each arm has a fixed end 5 and a free guided end 6; this provides the arms 2 to compress and expand with the hole size, and the free end of the arm can be moved with the axis of the non-rotating collar 3 based on the actual hole size, Figure 6.

[0030] Figure 7, the mechanical arm caliper 1 includes two different sensor locations, allowing to analyze data from two different sensors for better correlation and reliability. The arm's free end 6 connects to the first sensor 7. It gauges the shift in axial movement. This sensor 7 is equipped to measure the axial movement of the free end 6, it could be a based liner resistor sensor 7. The second sensor 8, an electronic distance measuring device (EDM) 8, is located in front of the maximum curvature of the arm 2. This sensor could be any distance measuring sensor; an ultrasonic, laser, or electromagnetic wave sensor. For accurate measurements, use the arm 2 as a reflecting device or as a receiver of the signals.

[0031] The tool material should be built with a drilling environment convenient material such as steel material. However, it could be built with non-magnetic material (P540), which is a special non-mag, austenitic Mn-Cr-N-Steel with a nickel content of less than 2%. This option allows for the addition of a directional sensor, such as a magnetometer and accelerometer, which can record the orientation of the nonrotating collar 3 and monitor its rotation, thereby enhancing the tool's performance. Some wells exhibit extremely soft formation and significant washout, which can impact the non-rotating collar 3 rotation and prevent the arms 2 from contacting the borehole wall. In this case, larger external diameter arms 2 will be required. Forthis reason, the caliper arms 2 have been designed to have cutters 10 in each arm in a direction to engage with the formation wall and so reduce or prevent the accidental rotation of the non-rotating collar 3, as shown in Figure 8.

[0032] As with any downhole logging while drilling tools, for real-time monitoring and measurements, the mechanical arm caliper 1 will be built in a matter to have communication with the measurement while drilling system the measurement while drilling downhole tools (MWD) 14. This can be down-wire configuration or wireless connection, Figure 9. The data will be transmitted to the MWD surface unit 10 using any of the measurement while drilling (MWD) telemetry systems, which could be:• Mud pulse telemetry system, including negative, positive, or continuing system.• Electromagnetic telemetry system.• Wired drill pipe connection system.Industrial Applicability

[0033] The present mechanical arm caliper is primarily designed for usage in water, oil, and gas field applications, specifically for drilling and completing wells. It can also be utilized for measuring the internal diameter of any tubular object.Citation ListPatent Literature

[0034] The International Patent Documents - PCT2014 / 047537 A1 03 / 2014 Brian Oliver.99 / 36801 07 / 1999 Manfred et al.U.S. Patent Documents6,467,341 B1 10 / 2002 Boucher et al.8.484.858 B2 07 / 2013 Brannigan et al.7,389,828 B2 06 / 2008 Ritter et al.1 1 ,536,130 B2 12 / 2022 Nakajima et al.

Claims

Claims

1. A mechanical arm caliper 1 is an apparatus for describing the borehole caliper, comprising:A non-rotating collar 3;A minimum two mechanically flexible, compressible arms 2 mounted to the non-rotating collar 3;A sealed bearing 4 to support the non-rotating collar 3;A minimum one sensor 7 or 8 mounted on the non-rotating collar 3 to define the position of the arm 2; andA mandrel 27 including a bore 19.

2. The mechanical arm caliper 1 of claim 1 , wherein the arms 2 have a fixed end 5 and a free guided end 6.

3. The mechanical arm caliper 1 of claim 1 , characterized in that, the outside diameter, including the arms 2, bigger than the required caliper section size.

4. The mechanical arm caliper 1 of claim 1 , wherein the arms 2 include cutters 10 configured to prevent rotation of the non-rotating collar 3.

5. The mechanical arm caliper 1 of claim 1 , wherein the improvement comprises reliable to be positioned within the bottom hole assembly 1 1 .

6. A method comprising: the mechanically flexible compressible arm 2 adapts to the shape of the hole, eliminating the need for a push-out systems and expanding the range of applications.

7. The method of claim 6, further the arm 2 compress in and expand out with the shape of the hole causing the free guided end 6 to move in / out with the axis of the non-rotating collar 3.

8. The method of claim 7, whereby the sensor 7 measures the axial change of the free guided end 6 of each arm 2.

9. The method of claim 8, wherein the measurements of the axial change of the free guided end 6 of each arm 2 define the position of the arm 2 relative to the non-rotating collar 3.

10. The method of claim 7, whereby the sensor 8 measures the arm position relative to the non-rotating collar 3.

11. The method of claim 6, further the mandrel 27 including the bore 19 mounted to the non-rotating collar 3 using the seal bearings 4 such that transfer drilling mud 15, and drill string 28 torque and rotation downhole to the bit 13.

12. The method of claim 6, The mechanical arm caliper 1 operates either in real-time mode linked to the drilling measurement while drilling system or in memory mode.

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