Oil and gas cased well tool string displacement measurement system and method

Abstract

The invention belongs to the technical field of oil and gas tool string displacement measurement, and relates to an oil and gas cased well tool string displacement measurement system and method. The method comprises the following steps: after a first communication transmission unit at an underground end receives a ground data acquisition instruction, a motion acceleration acquisition unit acquires inertial acceleration data of an underground tool string and transmits the inertial acceleration data to a first data processing unit; the first data processing unit performs quadratic integration on the inertial acceleration data to obtain first motion displacement data; and the displacement measurement unit measures the motion displacement of the armored cable to obtain second motion displacement data, and corrects the first motion displacement data to obtain real-time displacement data. According to the invention, the underground clamping and cable accumulation conditions in the process of conveying the pipe string by the cable can be detected in time, more accurate real-time displacement data of the underground tool string can be obtained, and the actual operation state of the underground tool string can be safely monitored; the underground real-time displacement of the current tool string can be directly calculated, and the underground real-time displacement measuring device has the advantages of high measuring precision, visual result, simple structure and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas tool string displacement measurement, and in particular, relates to an oil and gas casing well tool string displacement measurement system and method. Background Art

[0002] Unconventional oil and gas reservoirs such as shale gas and tight oil and gas are adsorbed or free in mudstone interlayers rich in organic matter. The reserves are very rich. Compared with conventional oil and gas resources, unconventional oil and gas resources have poor reservoir conditions and often require horizontal well drilling and volume fracturing to achieve effective development. During the horizontal well drilling process, the wellbore extends horizontally toward the formation for a distance to increase the contact area of ​​the formation, thereby increasing production capacity.

[0003] In the cased well, the cable conveying multi-stage cluster perforation and bridge plug tool string needs to provide a certain external force through pumping or traction to push the pipe string to the target section. If the thrust is too small, the tool string will not be able to move smoothly in the deflection and horizontal sections; if the thrust is too large, it will easily cause a sudden increase in the wellhead pumping pressure, increase the risk of failure of the wellhead cable dynamic seal, and may increase the risk of the pipe string falling into the well or cause it to get stuck in the well. During the transportation process, it is necessary to accurately monitor the operating status of the downhole tool string so that the thrust size can adapt to the changes in different layers in the oil and gas well.

[0004] At present, the method of monitoring the operation status of downhole tool strings in the oil and gas well industry is mostly to indirectly judge the slack of the cable through the surface or downhole force-bearing device to guide the setting of the thrust size. However, this type of method has the problem that the measurement accuracy of the force-bearing device is not high; and as the depth below the cable increases, the corresponding increase in cable gravity will also interfere with the measurement of the force-bearing device; the force-bearing device cannot detect the accumulation of cables in the process below in time. Therefore, this type of method cannot safely monitor the actual operation status of the downhole tool string.

[0005] In addition, based on the classic inertial prediction algorithm, it is necessary to provide measurement information corresponding to the calculated data in real time. In the narrow space of oil and gas wells, real-time measurement of displacement data is difficult to achieve, and relying solely on calculated data cannot suppress error diffusion and propagation.

[0006] Therefore, a monitoring instrument and method with higher reliability and safety is needed to monitor the operating status of oil and gas well tool strings in oil and gas wells with limited space, so as to overcome the application limitations of traditional measurement methods such as low accuracy and monitoring blind spots. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a system and method for measuring displacement of a tool string in an oil and gas casing well.

[0008] In a first aspect, the present invention provides a displacement measurement system for a tool string in an oil and gas casing well, comprising a downhole end and a surface end;

[0009] The downhole end includes a motion acceleration acquisition unit, a first data processing unit and a first communication transmission unit; the first data processing unit and the first communication transmission unit are electrically connected; the motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit are arranged inside the first housing;

[0010] The motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit are all arranged on the downhole tool string;

[0011] The ground end includes a displacement measuring unit, a second data processing unit and a second communication transmission unit; the displacement measuring unit is arranged on the armored cable for measuring the displacement of the armored cable, and the displacement measuring unit, the second data processing unit and the second communication transmission unit are all arranged inside the second shell; the displacement measuring unit, the second communication transmission unit and the second data processing unit are connected by electrical signals;

[0012] The second data processing unit sends the surface data acquisition instruction to the first communication transmission unit at the downhole end through the second communication transmission unit;

[0013] After the first communication transmission unit at the downhole end receives the ground data acquisition instruction, the motion acceleration acquisition unit acquires the inertial acceleration data of the downhole tool string and transmits it to the first data processing unit; the first data processing unit performs a second integration on the inertial acceleration data to obtain the first motion displacement data;

[0014] The displacement measuring unit measures the movement displacement of the armored cable to obtain second movement displacement data, and the second data processing unit corrects the first movement displacement data according to the second movement displacement data to obtain corrected real-time displacement data of the downhole tool string.

[0015] In a second aspect, the present invention provides a method for measuring displacement of a tool string in an oil and gas casing well based on a tool string displacement measurement system for an oil and gas casing well, comprising:

[0016] The second data processing unit sends the surface data acquisition instruction to the first communication transmission unit at the downhole end through the second communication transmission unit;

[0017] After the first communication transmission unit at the downhole end receives the ground data acquisition instruction, the motion acceleration acquisition unit acquires the inertial acceleration data of the downhole tool string and transmits it to the first data processing unit;

[0018] The first data processing unit performs a second integration on the inertial acceleration data to obtain first motion displacement data;

[0019] The displacement measuring unit measures the movement displacement of the armored cable to obtain second movement displacement data;

[0020] The second data processing unit corrects the first motion displacement data according to the second motion displacement data to obtain corrected real-time displacement data of the downhole tool string.

[0021] Based on the above technical solution, the present invention can also be improved as follows.

[0022] Furthermore, the motion acceleration acquisition unit includes an inertial acceleration sensor and a signal conditioning circuit; the inertial acceleration sensor is electrically connected to the first data processing unit through the signal conditioning circuit; the inertial acceleration sensor, the signal conditioning circuit, the first data processing unit and the first communication transmission unit are all arranged on an integrated circuit board at the downhole end; the integrated circuit board is arranged on the downhole tool string.

[0023] Furthermore, the signal conditioning circuit includes a preamplifier, a filter, a main amplifier and a voltage sampling circuit; the inertial acceleration sensor, the preamplifier, the filter, the main amplifier and the voltage sampling circuit are connected in sequence; and the output end of the voltage sampling circuit is electrically connected to the first data processing unit.

[0024] Furthermore, the displacement measuring unit is a roller encoder arranged on the armored cable; the roller encoder is electrically signal connected to the second data processing unit.

[0025] Furthermore, the ground data acquisition instructions are reduced using Huffman coding, and the carrier is coupled to the armored cable in a differential Huffman coding format for communication. The downhole end receives the reduced ground data acquisition instructions and decodes them according to the preset Huffman tree nodes, and parses the decoded ground data acquisition instructions.

[0026] Furthermore, the first data processing unit numbers the current motion data, and the inertial acceleration data is valid only when the amplitude of the inertial acceleration data is greater than a set threshold, and the inertial acceleration data is sent to the first communication transmission unit and uploaded to the ground end.

[0027] Furthermore, after receiving the inertial acceleration data, the second data processing unit extracts the serial number of the inertial acceleration data, obtains the integral time of the integral calculation according to the difference between the serial numbers of two adjacent inertial acceleration data and the acquisition period of the downhole inertial acceleration data, performs a second integral calculation on the inertial acceleration data to obtain the first motion displacement data; compares the first motion displacement data with the second motion displacement data of the armored cable to obtain the difference value; calculates the covariance according to the error propagation function; minimizes the covariance calculated by the error propagation function using the linear least squares method; iteratively calculates, and after a set number of iterations, the covariance finally converges to the set threshold value, and obtains the corrected real-time displacement data of the downhole tool string.

[0028] The beneficial effects of the present invention are:

[0029] (1) The present invention can timely detect the downhole jam and cable accumulation during the cable transmission process, obtain more accurate real-time displacement data of the downhole tool string, and safely monitor the actual operating status of the downhole tool string;

[0030] (2) The present invention uses inertial acceleration data based on perforating operation information to directly calculate the real-time displacement of the current tool string in the well. Compared with the traditional indirect measurement method, it has the advantages of high measurement accuracy, intuitive results and simple structure;

[0031] (3) The present invention uses a simplified electronic circuit structure, which improves the anti-seismic performance of perforation, reduces the volume of the measurement system, and is reusable, which can reduce the cost of each use and facilitate long-term use and maintenance;

[0032] (4) The present invention does not require presetting of parameters related to well conditions, has higher applicability, simplifies the operation process, and improves the portability of operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a displacement measurement system for a tool string in an oil and gas casing well provided in Example 1 of the present invention;

[0034] Figure 2 This is the principle block diagram of the downhole end;

[0035] Figure 3 This is a schematic diagram of a displacement measurement system for a tool string in an oil and gas casing well provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0037] Example 1

[0038] As an example, Figure 1 As shown, in order to solve the above technical problems, this embodiment provides an oil and gas casing well tool string displacement measurement system, including a downhole end and a surface end;

[0039] The downhole end includes a motion acceleration acquisition unit, a first data processing unit and a first communication transmission unit; the first data processing unit and the first communication transmission unit are electrically connected; the motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit are arranged inside the first housing;

[0040] The motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit are all arranged on the downhole tool string;

[0041] The ground end includes a displacement measuring unit, a second data processing unit and a second communication transmission unit; the displacement measuring unit is arranged on the armored cable for measuring the displacement of the armored cable, and the displacement measuring unit, the second data processing unit and the second communication transmission unit are all arranged inside the second shell; the displacement measuring unit, the second communication transmission unit and the second data processing unit are connected by electrical signals;

[0042] The second data processing unit sends the surface data acquisition instruction to the first communication transmission unit at the downhole end through the second communication transmission unit;

[0043] After the first communication transmission unit at the downhole end receives the ground data acquisition instruction, the motion acceleration acquisition unit acquires the inertial acceleration data of the downhole tool string and transmits it to the first data processing unit; the first data processing unit performs a second integration on the inertial acceleration data to obtain the first motion displacement data;

[0044] The displacement measuring unit measures the movement displacement of the armored cable to obtain second movement displacement data, and the second data processing unit corrects the first movement displacement data according to the second movement displacement data to obtain corrected real-time displacement data of the downhole tool string.

[0045] In actual application, the shell of the oil and gas well tool string displacement measurement system provides mechanical protection for the internal module and can withstand the liquid pressure in the oil and gas well.

[0046] Optionally, the motion acceleration acquisition unit includes an inertial acceleration sensor and a signal conditioning circuit; the inertial acceleration sensor is electrically connected to the first data processing unit through the signal conditioning circuit; the inertial acceleration sensor, the signal conditioning circuit, the first data processing unit and the first communication transmission unit are all arranged on an integrated circuit board at the downhole end; the integrated circuit board is arranged on the downhole tool string.

[0047] Optionally, the signal conditioning circuit includes a preamplifier, a filter, a main amplifier and a voltage sampling circuit; the inertial acceleration sensor, the preamplifier, the filter, the main amplifier and the voltage sampling circuit are connected in sequence; and the output end of the voltage sampling circuit is electrically connected to the first data processing unit.

[0048] In actual applications, the signal output by the acceleration sensor is usually weak. The main function of the preamplifier is to amplify the weak signal and increase the signal amplitude. The function of the filter is to suppress the noise signal in the process of inertial acceleration data acquisition and improve the signal quality. The main amplifier further amplifies the signal after preamplification and filtering to meet the signal amplitude requirements of the first data processing unit. Figure 2 As shown, the inertial acceleration sensor, the signal conditioning circuit, the first data processing unit and the first communication transmission unit are all arranged on an integrated circuit board at the downhole end, and the integrated circuit board is arranged in the first shell.

[0049] Optionally, the oil and gas casing well tool string displacement measurement system further includes a power management module disposed at the downhole end, and the power management module is electrically connected to the motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit.

[0050] Optionally, the displacement measuring unit is a roller encoder arranged on the armored cable; the roller encoder is electrically connected to the second data processing unit.

[0051] In actual application, when measuring the movement displacement of the armored cable, the characteristic of the encoder generating pulses when the armored cable passes through the roller encoder is utilized. For example, the roller encoder generates 768 pulses per circle, and the circumference of the roller encoder is 0.6 meters. The pulses are captured and counted, and then converted into distance values, thereby realizing the movement displacement measurement of the armored cable.

[0052] The present invention has the following advantages:

[0053] (1) The present invention can timely detect the downhole jam and cable accumulation during the cable transmission process, obtain more accurate real-time displacement data of the downhole tool string, and safely monitor the actual operating status of the downhole tool string;

[0054] (2) The present invention uses inertial acceleration data based on perforating operation information to directly calculate the real-time displacement of the current tool string in the well. Compared with the traditional indirect measurement method, it has the advantages of high measurement accuracy, intuitive results and simple structure;

[0055] (3) The present invention uses a simplified electronic circuit structure, which improves the anti-seismic performance of perforation, reduces the volume of the measurement system, and is reusable, which can reduce the cost of each use and facilitate long-term use and maintenance;

[0056] (4) The present invention does not require presetting of parameters related to well conditions, has higher applicability, simplifies the operation process, and improves the portability of operations.

[0057] Example 2

[0058] Based on the same principle as the system shown in Example 1 of the present invention, as shown in the attached Figure 3 As shown, an embodiment of the present invention also provides a method for measuring displacement of a tool string in an oil and gas casing well, comprising:

[0059] The second data processing unit sends the surface data acquisition instruction to the first communication transmission unit at the downhole end through the second communication transmission unit;

[0060] After the first communication transmission unit at the downhole end receives the ground data acquisition instruction, the motion acceleration acquisition unit acquires the inertial acceleration data of the downhole tool string and transmits it to the first data processing unit;

[0061] The first data processing unit performs a second integration on the inertial acceleration data to obtain first motion displacement data;

[0062] The displacement measuring unit measures the movement displacement of the armored cable to obtain second movement displacement data;

[0063] The second data processing unit corrects the first motion displacement data according to the second motion displacement data to obtain corrected real-time displacement data of the downhole tool string.

[0064] Optionally, the ground data acquisition instructions are reduced using Huffman coding, and the carrier is coupled to the armored cable in a differential Huffman coding format for communication. The downhole end receives the reduced ground data acquisition instructions and decodes them according to the preset Huffman tree nodes, and parses the decoded ground data acquisition instructions.

[0065] Optionally, the first data processing unit numbers the current motion data, and the inertial acceleration data is valid only when the amplitude of the inertial acceleration data is greater than a set threshold, and the inertial acceleration data is sent to the first communication transmission unit and uploaded to the ground end.

[0066] Optionally, after receiving the inertial acceleration data, the second data processing unit extracts the serial number of the inertial acceleration data, obtains the integral time of the integral calculation based on the difference in the serial numbers of two adjacent inertial acceleration data and the acquisition period of the downhole inertial acceleration data, performs a secondary integral calculation on the inertial acceleration data to obtain the first motion displacement data; compares the first motion displacement data with the second motion displacement data of the armored cable to obtain a difference value; calculates the covariance according to the error propagation function; minimizes the covariance calculated by the error propagation function using the linear least squares method; and iterates the calculation, and after a set number of iterations, the covariance finally converges to a set threshold value, thereby obtaining the corrected real-time displacement data of the downhole tool string.

[0067] Each collected data point has a unique number to identify the collection order. The difference in the numbers of two adjacent data reflects how many data collection units have been experienced between the two collections. For example, if the number increases from 100 to 105, the difference is 5, which means that there are 5 data collection intervals in between. The collection cycle of downhole inertial acceleration data refers to the collection time of each downhole inertial acceleration data. For example, the collection cycle is 1 second, which means that the inertial acceleration data will be recorded once every 1 second. The integration time is the time interval for performing secondary integration operations on the inertial acceleration data. This integration time can be obtained by multiplying the difference in the numbers of two adjacent data by the collection cycle. For example, if the number difference is 5 and the collection cycle is 1 second, then the integration time is 5 seconds.

[0068] Displacement is the integral of velocity over time, and velocity is the integral of acceleration over time. If the acceleration changes with time, the change in velocity can be obtained by performing a second integral operation on the acceleration within the integral time (usually using numerical integration methods such as trapezoidal integration method and Simpson integration method, etc.); and the displacement can be obtained by integrating the velocity once more.

[0069] The first motion displacement data and the second motion displacement data are subtracted at the same time point or at the corresponding position, and the difference obtained is the difference value. This difference value reflects the inconsistency between the displacement calculation result based on acceleration integration and the armored cable displacement measured by other methods.

[0070] The error propagation function describes how the measurement error propagates during the calculation process and affects the final result. In the scenario of the present invention, the error propagation function takes into account the influence of the acceleration measurement error, the integral calculation covariance and other related factors (such as sensor noise, etc.) on the displacement calculation result.

[0071] In order to find an error propagation function that minimizes the covariance calculated by the basis, the linear least squares method is used to calculate the minimum value of the covariance, which can better correct the real-time displacement data obtained based on the acceleration integration.

[0072] During the iteration process, each time the motion displacement data is calculated, it is compared with the reference armored cable displacement data, the difference value is calculated, and then the covariance is optimized by the linear least squares method. Then, the new coefficient is applied to the next displacement calculation. This process is repeated continuously, and each iteration can make the calculation results of the motion displacement data more accurate.

[0073] As the number of iterations increases, the covariance will gradually stabilize. When it changes to a certain extent and meets the set threshold requirements (for example, the change in covariance is less than the set threshold), it is considered to have converged, which means that through multiple iterations, a relatively stable covariance that can effectively reduce the error is obtained.

[0074] When the covariance converges, the calculated displacement data is the corrected real-time displacement data of the downhole tool string. Compared with the first motion displacement data initially obtained based on acceleration integration, this data has higher accuracy and can more truly reflect the position change of the downhole tool string in actual work.

[0075] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A displacement measurement system for a tool string in an oil and gas casing well, characterized in that: Including downhole end and surface end; The downhole end includes a motion acceleration acquisition unit, a first data processing unit and a first communication transmission unit; the first data processing unit and the first communication transmission unit are electrically connected; the motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit are arranged inside the first housing; The motion acceleration acquisition unit, the first data processing unit and the first communication transmission unit are all arranged on the downhole tool string; The ground end includes a displacement measuring unit, a second data processing unit and a second communication transmission unit; the displacement measuring unit is arranged on the armored cable for measuring the displacement of the armored cable, and the displacement measuring unit, the second data processing unit and the second communication transmission unit are all arranged inside the second shell; the displacement measuring unit, the second communication transmission unit and the second data processing unit are connected by electrical signals; The second data processing unit sends the surface data acquisition instruction to the first communication transmission unit at the downhole end through the second communication transmission unit; After the first communication transmission unit at the downhole end receives the ground data acquisition instruction, the motion acceleration acquisition unit acquires the inertial acceleration data of the downhole tool string and transmits it to the first data processing unit; the first data processing unit performs a second integration on the inertial acceleration data to obtain the first motion displacement data; The displacement measuring unit measures the movement displacement of the armored cable to obtain second movement displacement data, and the second data processing unit corrects the first movement displacement data according to the second movement displacement data to obtain corrected real-time displacement data of the downhole tool string.

2. The oil and gas casing well tool string displacement measurement system according to claim 1, characterized in that: The motion acceleration acquisition unit includes an inertial acceleration sensor and a signal conditioning circuit; the inertial acceleration sensor is electrically connected to the first data processing unit through the signal conditioning circuit; the inertial acceleration sensor, the signal conditioning circuit, the first data processing unit and the first communication transmission unit are all arranged on an integrated circuit board at the downhole end; the integrated circuit board is arranged on the downhole tool string.

3. The oil and gas casing well tool string displacement measurement system according to claim 1, characterized in that: The signal conditioning circuit includes a preamplifier, a filter, a main amplifier and a voltage sampling circuit; the inertial acceleration sensor, the preamplifier, the filter, the main amplifier and the voltage sampling circuit are connected in sequence; and the output end of the voltage sampling circuit is electrically connected to the first data processing unit.

4. The oil and gas casing well tool string displacement measurement system according to claim 1, characterized in that: The displacement measuring unit is a roller encoder arranged on the armored cable; the roller encoder is connected with the second data processing unit via electrical signals.

5. A method for measuring displacement of a tool string in a casing well of oil and gas based on the tool string displacement measuring system in casing well of oil and gas according to claim 1, characterized in that: include: The second data processing unit sends the surface data acquisition instruction to the first communication transmission unit at the downhole end through the second communication transmission unit; After the first communication transmission unit at the downhole end receives the ground data acquisition instruction, the motion acceleration acquisition unit acquires the inertial acceleration data of the downhole tool string and transmits it to the first data processing unit; The first data processing unit performs a second integration on the inertial acceleration data to obtain first motion displacement data; The displacement measuring unit measures the movement displacement of the armored cable to obtain second movement displacement data; The second data processing unit corrects the first motion displacement data according to the second motion displacement data to obtain corrected real-time displacement data of the downhole tool string.

6. The method for measuring displacement of a tool string in a casing well of oil and gas according to claim 5, characterized in that: The ground data acquisition instructions are reduced using Huffman coding, and the carrier is coupled to the armored cable in a differential Huffman coding format for communication. The downhole end receives the reduced ground data acquisition instructions and decodes them according to the preset Huffman tree nodes, and parses the decoded ground data acquisition instructions.

7. The method for measuring displacement of a tool string in a casing well of oil and gas according to claim 5, characterized in that: The first data processing unit numbers the current motion data, and the inertial acceleration data is valid only when the amplitude of the inertial acceleration data is greater than a set threshold value, and sends the inertial acceleration data to the first communication transmission unit and uploads it to the ground end.

8. The method for measuring displacement of a tool string in a casing well of oil and gas according to claim 5, characterized in that: After receiving the inertial acceleration data, the second data processing unit extracts the serial number of the inertial acceleration data, obtains the integral time of the integral calculation according to the difference between the serial numbers of two adjacent inertial acceleration data and the acquisition period of the downhole inertial acceleration data, performs a second integral calculation on the inertial acceleration data to obtain the first motion displacement data; compares the first motion displacement data with the second motion displacement data of the armored cable to obtain the difference value; calculates the covariance according to the error propagation function; minimizes the covariance calculated by the error propagation function by using the linear least squares method; performs iterative calculation, and after a set number of iterations, the covariance finally converges to the set threshold value, and obtains the corrected real-time displacement data of the downhole tool string.

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