Method for evaluating four-chamber pressure simulation of capillary design kettle body, platform and shaft

Abstract

The application provides a four-cavity pressure simulation evaluation method with a capillary design kettle body, a platform and a wellbore. The kettle body is internally and externally provided with a tool pipe column, a packer rubber tube and a test casing, a capillary injection port is arranged on the upper end of the kettle body, and the capillary passes through the space between the test casing and the kettle body and is connected with the lower end of the test casing. The platform comprises the kettle body. The method is realized based on the kettle body. When the high-temperature and high-pressure downhole tool detection and evaluation is carried out, the strength of the test casing tooling is not additionally increased due to the limited structure, and the overall cost of the test is saved. After the four cavities are independently realized, the leakage of each cavity can be judged in the test process, and the test working condition of the downhole tool sample can be more accurately judged. The system pump injection pressurization efficiency is improved, and the detection precision and speed are improved. The internal cooling is realized at the same time as the pressure maintenance in the casing and outside the casing, and the interference on the test working condition during the cooling period is reduced.

Description

Technical Field

[0001] This invention relates to the field of fracturing operations in oil and gas development and extraction technology, and more specifically, to a method for simulating and evaluating the pressure of a four-chamber system consisting of a capillary-designed vessel, platform, and wellbore. Background Technology

[0002] The main function of the high-temperature and high-pressure downhole tool testing platform is to conduct testing and evaluation of various well tools used in oil and gas exploration.

[0003] Unlike surface pressure testing and tensile strength testing, high-temperature and high-pressure downhole tool testing platforms can more realistically reproduce the complex underground environment. The simulated parameters include wellbore temperature, pressure, and tubing axial force. The testing and evaluation standards mainly refer to industry-recognized API 11D1 and API 19TT. In the past decade, domestic oilfields have actively carried out the construction of related platforms, and the comprehensive simulated temperature and pressure indicators have reached 260℃ and 210MPa, basically covering all dimensions of oil and gas exploration wellbores. With my country's increased exploration and development efforts in deep-earth oil and gas energy, the existing testing platform parameters are gradually becoming insufficient to meet evaluation needs. Domestic oilfields and private enterprises are planning to construct several testing platforms with increasingly higher requirements for the simulated environment, such as simulated temperature reaching 350℃, simulated pressure reaching 300MPa, and simulated loading force reaching 4000KN.

[0004] Currently, there are two main methods for establishing a simulated environment on the test platform: one is a vessel body + casing, and the other is casing + casing. Regardless of the method, both have certain shortcomings in simulating wellbore pressure, including:

[0005] (1) External pressure, formation pressure, oil pressure, and rubber sleeve pressure cannot be simulated separately.

[0006] (2) The volume of the test vessel has a significant impact on the accuracy and efficiency of zero-bubble detection.

[0007] (3) It cannot be separated from the internal circulation channel.

[0008] Regarding the aforementioned defects (1), the current method mainly involves increasing the internal and external extrusion resistance of the test casing to the point that the external balance pressure can be completely ignored during this test. For example, when the pressure difference is 105 MPa in the test, the lower space can be kept at 0 MPa. Alternatively, the lower end of the tool string or test casing can be sealed to achieve hard isolation between oil pressure and formation pressure. This method uses stronger test casing tooling, and the tooling processing cost will increase the overall cost of the test. At the same time, if there is a leak when the lower end of the tool string or test casing is sealed, it will cause pressure to flow between the two sides, increasing the difficulty of judging the pressure leak point.

[0009] Regarding the aforementioned defect (2), the current methods for pressurizing large-volume spaces mainly involve opening larger pressure injection holes in the vessel body and increasing the injection capacity and pressure of the booster pump to improve pumping pressurization efficiency. However, opening larger pressure injection holes in the vessel body is limited by the pressure rating of the vessel body. Opening holes in ultra-high pressure vessels will reduce the rated working pressure of the vessel body unless parameters such as increasing the vessel body wall thickness are compensated for, which will lead to a sharp increase in the manufacturing cost of the vessel body. Increasing the injection capacity and pressure of the booster pump requires purchasing a more expensive pumping system. Therefore, both of the above methods will increase the overall cost of system construction. Due to the large detection volume leading to reduced detection accuracy and increased detection time, the current main research direction is to mix helium into nitrogen to improve detectability. However, there are no standards for helium detection in such test platforms, and there is a phenomenon that the detection accuracy is too high, which makes the tools unable to meet the requirements. Therefore, it is difficult to promote.

[0010] Regarding the aforementioned defect (3), the current main method used is external circulation cooling of the vessel body to achieve isolation from the internal flow channels. Although this method can further achieve pressure holding and cooling, the cooling efficiency is lower than that of internal injection circulation cooling. In this example, the platform uses external cold air cooling to reduce the temperature from 200℃ to room temperature, which takes 8-12 hours. If the heat transfer oil is used for cooling, it only takes 3-6 hours. This results in the inability to simultaneously achieve both the isolation of the flow channels (cooling flow channels and internal flow channels) and the cooling efficiency of the currently built platform. At the same time, since the newly built test platforms in China are aimed at my country's deep-earth oil and gas exploration, the target has been raised to a simulated temperature of 350℃. For temperatures exceeding 260℃, only more expensive ultra-high temperature heat transfer oil can be selected. The new generation of platform heat transfer technology tends to be more efficient and environmentally friendly technologies such as electrothermal heat transfer or even electromagnetic heating. Taking electromagnetic heating as an example, the external vessel body is limited by the induction distance of the electromagnetic coil, and there is not enough space to set up a cooling circulation channel. Therefore, the current method is outdated and cannot meet the above-mentioned new requirements. Summary of the Invention

[0011] The purpose of this invention is to address at least one of the aforementioned shortcomings of the prior art. For example, one objective of this invention is to address the problem of high testing costs in existing test platforms; another objective is to address the problem that the three-chamber structure cannot accurately reproduce the actual working conditions of wellbore pressure; a third objective is to address the problem of low accuracy and efficiency in gas seal testing; and a fourth objective is to address the defect that internal cooling easily interferes with the test conditions.

[0012] To achieve the above objectives, the present invention provides a vessel for testing downhole tools.

[0013] The vessel body is equipped with a capillary structure.

[0014] Furthermore, a capillary tube is provided inside the vessel, with the injection port of the capillary tube located at the upper end of the vessel, and the capillary pore is also connected to the lower end of the test sleeve.

[0015] Furthermore, the vessel body is provided with a tool column, a packer sleeve, and a test sleeve from the inside out.

[0016] Furthermore, the capillary tube inside the vessel passes through the space between the test sleeve and the vessel body.

[0017] Another aspect of the present invention provides a downhole tool testing platform.

[0018] The platform includes the wellbore testing vessel as described above.

[0019] In another aspect, the present invention provides a method for simulating and evaluating the pressure of four chambers in a wellbore during downhole tool testing.

[0020] The method is based on the well tool testing vessel described above.

[0021] Furthermore, the evaluation method is capable of independently simulating the oil, casing, formation, and external casing equilibrium pressures.

[0022] Furthermore, when conducting zero-bubble gas seal testing on downhole tools, the evaluation method requires injecting gas into the two spaces separated by the packer sleeve.

[0023] Furthermore, the gas includes nitrogen.

[0024] Furthermore, the evaluation method is able to maintain the pressure in the lower space of the packer sleeve during the cooling process, based on the capillary tube.

[0025] Compared with existing technologies, this invention achieves the following effects in the construction of high-temperature and high-pressure downhole tool testing platforms:

[0026] (1) When conducting testing and evaluation of high-temperature and high-pressure downhole tools, the strength of the test casing tooling is not increased due to the limited structure, thus saving the overall cost of the test;

[0027] (2) After the four chambers are independent, it is easier to judge the leakage of each chamber during the test, and thus more accurately judge the test conditions of the test downhole tool sample.

[0028] (3) The system pumping pressurization efficiency can be easily improved without opening a larger injection hole on the vessel body or purchasing a pumping system with higher performance parameters.

[0029] (4) No need to add easily detectable gases such as helium to nitrogen. The capillary tube shortens the gas volume occupied in the test well, thereby improving the detection accuracy and speed.

[0030] (5) It realizes the isolation of internal circulation cooling and internal pressure systems, which provides the possibility for the platform to adopt more efficient and environmentally friendly heating methods such as electromagnetic heating. The cooling efficiency can be improved through internal circulation, and pressure is maintained inside and outside the jacket while cooling inside, reducing the interference to the test conditions during cooling.

[0031] (6) This invention is of great benefit in saving test construction costs and operating costs, improving detection accuracy and efficiency, and improving the realism of environmental simulation, and has broad application prospects. Attached Figure Description

[0032] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0033] Figure 1 A schematic diagram of the structure of the vessel body of the present invention is shown.

[0034] Explanation of key figure labels:

[0035] 1-Tool column, 11-Lower end of tool column; 2-Packer sleeve; 3-Test sleeve, 31-Lower end of test sleeve; 4-Bottle body, 5-Capillary tube, 51-Capillary injection port. Detailed Implementation

[0036] The following will describe in detail the pressure simulation and evaluation method of the present invention, which has a capillary-designed vessel body, platform, and wellbore, with reference to exemplary embodiments.

[0037] Exemplary Example 1

[0038] This exemplary embodiment provides a test vessel for downhole tools. The test vessel is capable of independently simulating oil, casing, formation, and external casing pressure balance.

[0039] The vessel body contains, from the inside out, a tool column, a packer sleeve, and a test sleeve. A capillary tube is installed inside the vessel body, with its inlet located at the upper end and its capillary orifice connected to the lower end of the test sleeve. The capillary tube passes through the space between the test sleeve and the vessel body.

[0040] Exemplary Example 2

[0041] This exemplary embodiment provides a downhole tool testing platform.

[0042] The platform includes the test vessel for downhole tools as described in Exemplary Example 1.

[0043] Exemplary Example 3

[0044] This exemplary embodiment provides a method for simulating and evaluating the pressure in the four chambers of a wellbore during downhole tool testing.

[0045] The method is implemented based on the downhole tool testing vessel in Exemplary Example 1 or the downhole tool testing platform in Exemplary Example 2.

[0046] In this embodiment, the evaluation method is capable of independently simulating the oil, casing, formation, and external casing equilibrium pressures.

[0047] In this embodiment, the evaluation method, when conducting zero-bubble gas seal testing on downhole tools, requires injecting gas into the two spaces separated by the packer sleeve. The gas may include nitrogen.

[0048] In this embodiment, the evaluation method is able to maintain the pressure in the lower space of the packer sleeve during the cooling process based on the capillary tube.

[0049] To better understand the exemplary embodiments described above, further explanation will be provided below with reference to specific examples.

[0050] Example 1

[0051] This invention incorporates a capillary structure inside the vessel body, as shown in the following diagram. Figure 1 As shown, Figure 1 In this embodiment, 11 is the lower end of the tool column, 31 is the lower end of the test sleeve, and 51 is the capillary injection port. The vessel body 4 contains the tool column 1, the packer sleeve 2, the test sleeve 3, and the capillary tube 5. Specifically, this embodiment adds a pressure-transmitting injection hole (i.e., capillary injection port 51) to the upper part of the vessel body 4. This hole connects to the upper sleeve head, enters the original P3 space, and is connected to the lower end 31 of the test sleeve via the capillary tube 5.

[0052] The advantages of this technical solution are:

[0053] (1) Each pressure system is isolated and independent.

[0054] Previous technical solutions could only achieve independent simulation of three pressure systems: oil, casing, and formation. With the addition of capillary tube 5, an independent simulation of the fourth chamber, P4, was added, realizing independent simulation of oil, casing, formation, and external casing pressure balance. This expands the functionality of the test platform and can more realistically reproduce the pressure conditions of the tool string downhole.

[0055] (2) Solved the problems of low pressurization efficiency and low detection accuracy in gas seal testing.

[0056] When conducting zero-bubble gas seal testing on downhole tools, nitrogen is only injected into the P2 and P4 spaces, which greatly reduces the volume occupied by nitrogen. Without additional investment to improve pumping capacity, the gas pressurization efficiency is improved. At the same time, due to the reduction in the volume occupied by gas, if the rubber sleeve fails to seal under pressure difference, the leaked gas can be detected quickly, improving the detection accuracy.

[0057] (3) Solve the problem of isolating the cooling and internal flow channels and achieve pressure holding and cooling.

[0058] Based on the capillary tube 5 structure, if electromagnetic induction heating is used, pressure holding (external pressure) cyclic cooling can be achieved through the P3 channel. At the same time, since Pm and P3 are independent, the pressure in the P4 space can still be maintained during the pressure change and cooling process in the P3 channel, thus achieving pressure holding and cooling inside the sleeve.

[0059] Example 2 (Application Example)

[0060] This invention takes the high-temperature and high-pressure downhole tool testing platform under construction by one of the applicants, Sichuan Qingyuan Company, as an example. This platform simulates wellbore temperatures exceeding 300℃ and wellbore pressures reaching 300MPa. It can conduct various downhole tool evaluation tests according to API 11D1 and 19TT standards, with a maximum testing level of V0-H. Using the results in Example 1 of this invention, it is estimated that 50 sets of various downhole tool tests will be conducted annually. The cost of casing alone is expected to be reduced by more than 1 million yuan. In the zero-bubble gas seal testing process, the method of this invention not only significantly improves accuracy but also saves testing time. Each day saved can save nearly 100,000 yuan in water, electricity, and gas costs. Most importantly, it more realistically recreates the complex pressure scenarios of downhole tools in the wellbore, resulting in a significant improvement in the overall performance of the platform.

[0061] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A test vessel for downhole tools, characterized in that, The vessel body is equipped with a capillary structure.

2. The test vessel for downhole tools according to claim 1, characterized in that, The vessel body is equipped with a capillary tube, the injection port of which is located at the upper end of the vessel body, and the capillary pore is also connected to the lower end of the test sleeve.

3. The test vessel for downhole tools according to claim 2, characterized in that, The reactor body is equipped with a tool column, a packer sleeve, and a test sleeve from the inside out.

4. The test vessel for downhole tools according to claim 3, characterized in that, The capillary tube inside the vessel passes through the space between the test sleeve and the vessel body.

5. A downhole tool testing platform, characterized in that, The platform includes the test vessel for downhole tools as described in any one of claims 1 to 4.

6. A method for simulating and evaluating the pressure in a four-chamber wellbore during downhole tool testing, characterized in that, The method is implemented based on the test vessel for downhole tools according to any one of claims 1 to 4.

7. The method for simulating and evaluating the pressure of a four-chamber wellbore during downhole tool testing according to claim 6, characterized in that, The evaluation method can independently simulate the oil, casing, formation, and external casing equilibrium pressures.

8. The method for simulating and evaluating the pressure of a four-chamber wellbore during downhole tool testing according to claim 6, characterized in that, The evaluation method requires injecting gas into the two spaces separated by the packer sleeve when conducting zero-bubble gas seal testing on downhole tools.

9. The method for simulating and evaluating the pressure of a four-chamber wellbore during downhole tool testing according to claim 8, characterized in that, The gas includes nitrogen.

10. The method for simulating and evaluating the pressure of a four-chamber wellbore during downhole tool testing according to claim 6, characterized in that, The evaluation method is able to maintain the pressure in the lower space of the packer sleeve during the cooling process based on the capillary tube.

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