Hydraulic lifting multi-gradient drilling experiment device and testing method

Abstract

The invention relates to a hydraulic lifting multi-gradient drilling experiment device and a testing method, the experiment device comprises a drilling fluid circulation system, a power fluid circulation system, an experiment bench main body and an underground complex simulation system, and a central channel, an annular channel and a shaft channel are sequentially arranged in the experiment bench main body from inside to outside; the two ends of the drilling fluid circulation system are communicated with the other end of the center channel and the other end of the shaft channel through pipelines respectively, the two ends of the power fluid circulation system are communicated with one end of the annular channel through pipelines respectively, and the two ends of the underground complex simulation system are communicated with one end of the shaft channel through pipelines respectively. According to the invention, an experimental basis is provided for the development and test of a hydraulic lifting multi-gradient drilling technology for land and ocean complex formations, assistance can be provided for the development and improvement of the hydraulic lifting multi-gradient drilling technology, and a basic support is provided for solving accidents such as well collapse, jamming of a drilling tool, well kick, blowout and leakage of the complex formations on a simulation site of the technology.

Description

Technical Field

[0001] The present invention relates to the technical fields of oil and gas drilling and completion and gas hydrate drilling and production, and particularly relates to a hydraulic lift multi-gradient drilling experimental device and a testing method. Background Art

[0002] With the continuous exploitation of oil and gas resources, oil and gas exploration and development are moving towards deep, low-permeability, and unconventional oil and gas. However, in some areas with complex geological conditions such as Xinjiang and Sichuan-Chongqing in China, there are problems such as encountering multiple pressure systems during drilling, and an extremely narrow drilling fluid density window. The existence of the narrow safety density window problem increases the number of casing strings and greatly increases the drilling cost.

[0003] However, due to the difficulty of pre-drilling prediction, the optimization margin of wellbore structure design is limited, and the high-pressure layer and the weak layer restrict each other, and even cannot be balanced. Conventional methods can only respond passively, with low efficiency and poor safety, and the existing number of casing strings is difficult to continue.

[0004] To solve the problem of narrow safety density window on land, based on the dual-gradient implementation principle of offshore dual-gradient drilling and combined with the characteristics of narrow wellbore space in onshore drilling, a hydraulic lift multi-gradient drilling technology has been proposed in China. The hydraulic lift multi-gradient drilling uses downhole tools such as a top drive adapter, multi-channel drill pipe, annulus isolation tool, and downhole lift pump sub. The high-pressure power fluid is driven by a ground hydraulic pump. After passing through the top drive adapter and multi-channel drill pipe, the power fluid enters the downhole lift pump, drives the turbine motor to work, and at the same time, the power fluid enters the annulus isolation tool. Under the push of the power fluid pressure, the annulus isolation tool works and isolates the annulus. When the turbine motor works, it converts power into the annulus fluid lift force to assist in lifting the bottom-hole drilling fluid, reducing the bottom-hole pressure, and forming multiple pressure gradients with the annulus isolation tool as the interval, that is, the hydraulic lift multi-gradient drilling technology. Different from offshore dual-gradient drilling, the hydraulic lift multi-gradient drilling technology does not have additional risers and subsea devices, and realizes multi-gradient drilling through downhole tools such as a top drive adapter, three-channel drill pipe, downhole lift pump sub, and annulus isolation tool. The process is simple, occupies little space, and the bottom-hole pressure regulation is accurate and stable, with high flexibility and reliability. At present, there are only performance monitoring experimental devices for double-wall drill pipes and dual-gradient drilling experimental devices applicable to offshore riser gas injection at home and abroad. There is no report on experimental devices for multi-gradient drilling technology, and it is still in a blank state.

[0005] In order to carry out technical research in aspects such as the core theoretical principles, operation process flow, parameter regulation measures, and reliability of equipment and tools of the new technology of hydraulic lift multi-gradient drilling, further improve and perfect this cutting-edge technology, and provide assistance for China to gain an international leading advantage in the field of wellbore pressure control technology, it is necessary to fully combine the authenticity of drilling conditions in complex formations and the convenience of indoor regulation, establish a set of experimental devices and testing methods for hydraulic lift multi-gradient drilling, and provide platform support for the shaping and improvement of this technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an experimental device and testing method for hydraulic lift multi-gradient drilling, aiming to solve the problems in the prior art.

[0007] The technical solution of the present invention to solve the above technical problems is as follows:

[0008] An experimental device for hydraulic lift multi-gradient drilling includes a drilling fluid circulation system, a power fluid circulation system, a main experimental bench frame, and a downhole complex simulation system. Inside the main experimental bench frame, a central channel, an annular channel, and a wellbore channel are sequentially arranged from the inside to the outside. One end of the central channel is communicated with one end of the wellbore channel, and an opening communicated with the wellbore channel is provided on the central channel;

[0009] Both ends of the drilling fluid circulation system are respectively communicated with the other end of the central channel and the other end of the wellbore channel through pipelines. Both ends of the power fluid circulation system are respectively communicated with one end of the annular channel through pipelines. Both ends of the downhole complex simulation system are respectively communicated with one end of the wellbore channel through pipelines.

[0010] The beneficial effect of the present invention is that during the operation process, the function of the main experimental bench frame is to simulate the downhole operation environment of the hydraulic lift multi-gradient drilling site, including providing a simulated wellbore for the experimental test string, constructing a wellbore channel, and providing a wellbore space for the circulation of drilling fluid;

[0011] The function of the drilling fluid circulation system is to simulate the circulation process of the injection and return of drilling fluid. The drilling fluid is injected into the experimental wellbore from the drilling fluid tank and then returns through the wellbore channel and enters the drilling fluid tank again for standby;

[0012] The function of the power fluid circulation system is to simulate the circulation process of the injection and return of power fluid. The power fluid is injected into the multi-channel drill pipe from the power fluid tank, drives the downhole lift pump short joint, and then returns from the multi-channel drill pipe and enters the power fluid tank again for standby;

[0013] The function of the downhole complex simulation system is to simulate complex processes such as downhole overflow and loss during the hydraulic lift multi-gradient drilling process.

[0014] The present invention provides an experimental basis for the development and testing of the hydraulic lift multi-gradient drilling technology in complex land and marine formations, can contribute to the development and improvement of the hydraulic lift multi-gradient drilling technology, and also provides basic support for simulating on-site the solution of accidents such as wellbore collapse, stuck pipe, well kick, blowout, and coexistence of leakage and blowout in complex formations by using this technology.

[0015] Based on the above technical solutions, the present invention can also be further improved as follows.

[0016] Further, the main body of the test bench includes a multi-channel drill pipe, an outer wellbore, and at least one short joint assembly. The multi-channel drill pipe is installed inside the outer wellbore, one end of which is located inside the outer wellbore and the other end extends outside the outer wellbore. The short joint assembly is installed at one end of the multi-channel drill pipe. The central channel and the annular channel are distributed from the inside to the outside in the multi-channel drill pipe and the short joint assembly, and a wellbore channel is formed between the outer wellbore and the multi-channel drill pipe.

[0017] The beneficial effect of adopting the above further solution is that the structure is simple and the design is reasonable. The multi-channel drill pipe, the outer wellbore, and the short joint assembly are used to simulate the downhole operation environment of the hydraulic lift multi-gradient drilling site, construct the wellbore channel, and provide a wellbore space for the circulation of the drilling fluid.

[0018] Further, each short joint assembly includes a hydraulic drive short joint and a fluid lift short joint. The hydraulic drive short joint is fixedly installed at one end of the multi-channel drill pipe, and the fluid lift short joint is fixedly connected to the hydraulic drive short joint.

[0019] The beneficial effect of adopting the above further solution is that the structure is simple and the design is reasonable. The functions of the above-mentioned hydraulic drive short joint and the fluid lift short joint are to simulate a full-scale downhole lift pump on-site, and after being driven by the power fluid, they provide an additional lift driving force for the drilling fluid in the wellbore channel.

[0020] Further, each short joint assembly also includes an annulus isolation tool. The annulus isolation tool is fixedly installed on the corresponding fluid lift short joint and is used to divide the annular cavity in the wellbore channel into two parts.

[0021] The beneficial effect of adopting the above further solution is that the function of the annulus isolation tool is to simulate a full-scale annulus isolation tool on-site, which is driven by the power fluid to realize the isolation and opening of the wellbore channel.

[0022] Further, upper and lower plugs are respectively fixedly installed at both ends of the outer wellbore. Two lower joints are provided opposite to one end of the outer wellbore, and the two lower joints are respectively communicated with both ends of the downhole complex simulation system through pipelines. An upper joint is provided at the other end of the outer wellbore, and the upper joint is communicated with one end of the drilling fluid circulation system through a pipeline.

[0023] The beneficial effect of adopting the above further solution is that the upper plug is connected to the drilling fluid circulation system to provide an outlet for the return of the drilling fluid; the lower plug is connected to the bottom end of the downhole lifting pump nipple to close the power fluid flow path and achieve the closed circulation of the power fluid.

[0024] In addition, the function of the upper and lower connectors is to be connected to the downhole complex simulation system to provide channels and sources for downhole overflow or lost fluids.

[0025] Furthermore, a top drive adapter is fixedly installed at the other end of the multi-channel drill pipe. A cavity communicating with the annular channel is provided inside the top drive adapter, and an inlet and an outlet respectively communicating with the cavity are further provided on the top drive adapter. The inlet and the outlet are respectively communicated with the power fluid circulation system through pipelines.

[0026] The beneficial effect of adopting the above further solution is that the function of the top drive adapter is to simulate a full-size top drive adapter adapted to the top drive on site, provide a drilling fluid injection port and a power fluid inflow and return outlet, and separate the circulation channels of the drilling fluid and the power fluid.

[0027] Furthermore, the drilling fluid circulation system includes a drilling pump and a drilling fluid pit. The drilling pump, the drilling fluid pit, the other end of the wellbore channel, and the other end of the central channel are sequentially communicated through pipelines.

[0028] The beneficial effect of adopting the above further solution is that the function of the drilling fluid circulation system is to simulate the circulation process of the injection and return of the drilling fluid. The drilling fluid is injected from the drilling fluid pit into the experimental wellbore by the drilling pump and then returns through the wellbore channel and enters the drilling fluid pit again for standby.

[0029] Furthermore, the power fluid circulation system includes a drive pump and a power fluid pit. One side of one end of the annular channel, the drive pump, the power fluid pit, and the other side of one end of the annular channel are sequentially communicated through pipelines.

[0030] The beneficial effect of adopting the above further solution is that the function of the power fluid circulation system is to simulate the circulation process of the injection and return of the power fluid. The power fluid is injected from the power fluid pit into the multi-channel drill pipe by the drive pump to drive the downhole lifting pump nipple and then returns from the multi-channel drill pipe and enters the power fluid pit again for standby.

[0031] Furthermore, the downhole complex simulation system includes a formation fluid hydraulic pump and a fluid storage tank. One side of one end of the wellbore channel, the formation fluid hydraulic pump, the fluid storage tank, and the other side of one end of the wellbore channel are sequentially communicated through pipelines.

[0032] The beneficial effect of adopting the above further solution is that the function of the downhole complex simulation system is to simulate complex processes such as downhole overflow and leakage during the process of hydraulic-lift multi-gradient drilling.

[0033] The present invention also relates to a testing method for hydraulic-lift multi-gradient drilling, which is realized by using the above-mentioned experimental device for hydraulic-lift multi-gradient drilling, and includes the following specific steps:

[0034] S1: Start the drilling fluid circulation system and the power fluid circulation system, and record the relevant pressure parameters.

[0035] S2: Change the flow rate and pressure of the drilling fluid circulation system and the power fluid circulation system, and record the pressure parameters under different operating conditions after the circulation is stable.

[0036] S3: Start the downhole complex simulation system, simulate the downhole overflow condition, repeat steps S1 - S3, and record the experimental data during the simulated overflow; meanwhile, simulate the downhole leakage condition, repeat steps S1 - S3, and record the experimental data during the simulated leakage.

[0037] S4: Replace fluid systems such as the power fluid, drilling fluid, and simulated formation fluid, repeat the experiment, and the test is completed.

[0038] The beneficial effect of adopting the above further solution is that the present invention provides a testing method, which provides an experimental basis for the development and testing of the hydraulic-lift multi-gradient drilling technology in complex land and marine formations, can contribute to the development and improvement of the hydraulic-lift multi-gradient drilling technology, and also provides a basic support for simulating on-site to solve accidents such as wellbore collapse, stuck pipe, well kick, blowout, and coexistence of leakage and blowout in complex formations for this technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic structural diagram of the first embodiment in the present invention;

[0040] Figure 2 is a schematic structural diagram of the second embodiment in the present invention.

[0041] In the drawings, the list of components represented by each reference numeral is as follows:

[0042] 1. Top drive adapter; 2. Upper plug; 3. Upper sub; 4. Multi-channel drill pipe; 5. Outer wellbore; 6. Hydraulic drive sub; 7. Annular packoff tool; 8. Fluid lift sub; 9. Bottom hole pressure gauge 1; 10. Lower plug; 11. Power fluid pump-in pressure gauge; 12. Power fluid flowmeter; 13. Drive pump; 14. Power fluid tank; 15. Power fluid return pressure gauge; 16. Drilling fluid pump-in pressure gauge; 17. Drilling fluid pump-in flowmeter; 18. Relief valve 1; 19. Drilling pump; 20. Drilling fluid tank; 21. Throttle valve; 22. Drilling fluid return flowmeter; 23. Drilling fluid return pressure gauge; 24. Formation pressure gauge; 25. Relief valve 2; 26. Fluid reserve tank; 27. Formation fluid hydraulic pump; 28. Check valve; 29. Bottom hole pressure gauge 2; 30. Leak-off valve; 31. Lower sub. Detailed implementation manners

[0043] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0044] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0046] The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0047] Embodiment 1

[0048] AsFigure 1 and Figure 2 As shown in Figure 2 , this embodiment provides a hydraulic lifting multi-gradient drilling experimental device, which includes a drilling fluid circulation system, a power fluid circulation system, a main experimental bench frame, and a downhole complex simulation system. Inside the main experimental bench frame, there are a central channel, an annular channel, and a wellbore channel in sequence from inside to outside. One end of the central channel is communicated with one end of the wellbore channel, and there is an opening on the central channel that is communicated with the wellbore channel;

[0049] Both ends of the drilling fluid circulation system are respectively communicated with the other end of the central channel and the other end of the wellbore channel through pipelines. Both ends of the power fluid circulation system are respectively communicated with one end of the annular channel through pipelines. Both ends of the downhole complex simulation system are respectively communicated with one end of the wellbore channel through pipelines.

[0050] During the operation process, the function of the main experimental bench frame is to simulate the downhole operation environment of the hydraulic lifting multi-gradient drilling site, including providing a simulated wellbore for the experimental test string, constructing a wellbore channel, and providing a wellbore space for the circulation of the drilling fluid;

[0051] The function of the drilling fluid circulation system is to simulate the circulation process of the injection and return of the drilling fluid. The drilling fluid is injected into the experimental wellbore from the drilling fluid tank and then returns through the wellbore channel, and then enters the drilling fluid tank again for standby;

[0052] The function of the power fluid circulation system is to simulate the circulation process of the injection and return of the power fluid. The power fluid is injected into the multi-channel drill pipe from the power fluid tank, drives the downhole lifting pump sub-section, and then returns from the multi-channel drill pipe, and then enters the power fluid tank again for standby;

[0053] The function of the downhole complex simulation system is to simulate the complex processes such as downhole overflow and loss during the hydraulic lifting multi-gradient drilling process.

[0054] This embodiment provides an experimental basis for the development and testing of the hydraulic lifting multi-gradient drilling technology in land and marine complex formations, can provide assistance for the development and improvement of the hydraulic lifting multi-gradient drilling technology, and also provides basic support for simulating on-site to solve accidents such as wellbore collapse, sticking, well kick, blowout, and coexistence of leakage and blowout in complex formations by this technology.

[0055] Embodiment 2

[0056] On the basis of Embodiment 1, in this embodiment, the test bench main body includes a multi-channel drill pipe 4, an outer wellbore 5, and at least one short joint assembly. The multi-channel drill pipe 4 is installed in the outer wellbore 5, one end of which is located inside the outer wellbore 5 and the other end extends outside the outer wellbore 5. The short joint assembly is installed at one end of the multi-channel drill pipe 4. The central channel and the annular channel are distributed from the inside to the outside in the multi-channel drill pipe 4 and the short joint assembly, and a wellbore channel is formed between the outer wellbore 5 and the multi-channel drill pipe 4.

[0057] This solution has a simple structure and reasonable design. It uses the multi-channel drill pipe 4, the outer wellbore 5, and the short joint assembly to simulate the downhole operation environment of the hydraulic lift multi-gradient drilling site, construct a wellbore channel, and provide a wellbore space for the circulation of drilling fluid.

[0058] Preferably, in this embodiment, the function of the multi-channel drill pipe 4 is to simulate a full-size multi-channel drill pipe on-site and provide a flow circulation channel for the drilling fluid and the power fluid.

[0059] In addition, the above-mentioned outer wellbore 5 preferably has a cylindrical structure.

[0060] Preferably, in this embodiment, the number of short joint assemblies can preferably be multiple, and multiple short joint assemblies are distributed in series in sequence, and the number thereof is appropriately set according to the size of the outer wellbore 5.

[0061] Embodiment 3

[0062] On the basis of Embodiment 2, in this embodiment, each short joint assembly includes a hydraulic drive short joint 6 and a fluid lift short joint 8. The hydraulic drive short joint 6 is fixedly installed at one end of the multi-channel drill pipe 4, and the fluid lift short joint 8 is fixedly connected to the hydraulic drive short joint 6.

[0063] This solution has a simple structure and reasonable design. The functions of the above-mentioned hydraulic drive short joint 6 and the fluid lift short joint 8 are to simulate a full-size downhole lift pump on-site, and after being driven by the power fluid, provide an additional lift driving force for the drilling fluid in the wellbore channel.

[0064] Preferably, in this embodiment, the above-mentioned hydraulic drive short joint 6 and the fluid lift short joint 8 can be multiple pairs, and multiple pairs of hydraulic drive short joints 6 and fluid lift short joints 8 can be arranged in series in sequence. Here, the number of the hydraulic drive short joint 6 and the fluid lift short joint 8 can be selected and designed according to the size of the outer wellbore 5.

[0065] Embodiment 4

[0066] On the basis of Embodiment 3, in this embodiment, each short joint assembly further includes an annulus packoff tool 7. The annulus packoff tool 7 is fixedly installed on the corresponding fluid lift short joint 8 and is used to divide the annular cavity in the wellbore channel into two parts.

[0067] The function of the annulus packoff tool 7 is to simulate the full-size annulus packoff tool on-site, which is driven by power fluid to achieve the isolation and opening of the wellbore passage.

[0068] Based on the above solution, the number of the annulus packoff tools 7 is the same as that of the hydraulic drive sub 6 and the fluid lift sub 8.

[0069] In addition, the annulus packoff tool 7 can be fixedly sleeved on the fluid lift sub 8, or the annulus packoff tool 7 is fixedly connected to the fluid lift sub 8.

[0070] Embodiment 5

[0071] Based on any one of Embodiments 2 to 4, in this embodiment, an upper plug 2 and a lower plug 10 are respectively and fixedly installed at both ends of the outer wellbore 5. Two lower connectors 31 are oppositely arranged at one end of the outer wellbore 5, and the two lower connectors 31 are respectively communicated with both ends of the downhole complex simulation system through pipelines; an upper connector 3 is arranged at the other end of the outer wellbore 5, and the upper connector 3 is communicated with one end of the drilling fluid circulation system through a pipeline.

[0072] The function of the upper plug 2 is to be connected to the drilling fluid circulation system to provide an outlet for the return of the drilling fluid; the function of the lower plug 10 is to be connected to the bottom end of the downhole lift pump sub to close the power fluid flow path and achieve the closed circulation of the power fluid.

[0073] In addition, the function of the upper and lower connectors is to be connected to the downhole complex simulation system to provide a channel and source for downhole overflow or lost fluid.

[0074] Moreover, the upper plug 2 plays a sealing role, and the lower plug 10 connects the central channel and the wellbore channel.

[0075] Embodiment 6

[0076] Based on Embodiment 5, in this embodiment, a top drive adapter 1 is fixedly installed at the other end of the multi-channel drill pipe 4. A cavity communicating with the annular channel is provided in the top drive adapter 1, and an inlet and an outlet communicating with the cavity are further provided on the top drive adapter 1. The inlet and the outlet are respectively communicated with the power fluid circulation system through pipelines.

[0077] The function of the top drive adapter 1 is to simulate the full-size top drive adapter 1 adapted to the top drive on-site, provide a drilling fluid injection port and a power fluid inflow and return outlet, and separate the circulation channels of the drilling fluid and the power fluid.

[0078] Embodiment 7

[0079] Based on the above embodiments, in this embodiment, the drilling fluid circulation system includes a drilling pump 19 and a drilling fluid tank 20, and the drilling pump 19, the drilling fluid tank 20, the other end of the wellbore channel, and the other end of the central channel are sequentially connected through pipelines.

[0080] The function of the drilling fluid circulation system is to simulate the circulation process of the injection and return of the drilling fluid. The drilling fluid is injected from the drilling fluid tank 20 into the experimental wellbore through the drilling pump 19 and then returns through the wellbore channel, and then enters the drilling fluid tank again for standby.

[0081] Preferably, in this embodiment, a first overflow valve 18 is installed in parallel with the above-mentioned drilling pump 19.

[0082] In addition, a drilling fluid inlet pressure gauge 16 and a drilling fluid inlet flowmeter 17 are fixedly installed on the pipeline between the drilling pump 19 and the other end of the central channel.

[0083] Moreover, a throttle valve 21, a drilling fluid return flowmeter 22, and a drilling fluid return pressure gauge 23 are fixedly installed on the pipeline between the drilling fluid tank 20 and the other end of the wellbore channel.

[0084] The function of the drilling fluid inlet pressure gauge is to measure and display the liquid pressure of the drilling fluid pumped out by the drilling pump, which is convenient for monitoring the drilling fluid pressure and adjusting the experimental parameters; the function of the drilling fluid inlet flowmeter is to measure and display the liquid flow of the drilling fluid pumped out by the drilling pump, which is convenient for monitoring the drilling fluid flow and adjusting the experimental parameters; the function of the overflow valve 1 is to set a fixed pressure when simulating the overflow condition. When the pipeline pressure exceeds the fixed pressure, the drilling fluid overflowing from the drilling fluid injection port can return to the drilling fluid tank through the overflow valve without damaging the drilling pump; the function of the drilling pump is to provide power for the circulation of the drilling fluid; the function of the drilling fluid tank is to store the drilling fluid system for experiments, provide the injected drilling fluid and store the returned drilling fluid; the function of the throttle valve is to regulate the return flow rate and return pressure parameters of the drilling fluid in the wellbore channel by adjusting the opening of the throttle valve; the function of the drilling fluid return flowmeter is to measure and display the liquid flow of the drilling fluid returned from the wellbore channel, which is convenient for monitoring the drilling fluid flow and adjusting the experimental parameters; the function of the drilling fluid return pressure gauge is to measure and display the liquid pressure of the drilling fluid returned from the wellbore channel, which is convenient for monitoring the drilling fluid pressure and adjusting the experimental parameters.

[0085] Embodiment 8

[0086] Based on the above embodiments, in this embodiment, the power fluid circulation system includes a driving pump 13 and a power fluid tank 14, and one side of one end of the annular channel, the driving pump 13, the power fluid tank 14, and the other side of one end of the annular channel are sequentially connected through pipelines.

[0087] The function of the power fluid circulation system is to simulate the circulation process of the injection and return of the power fluid. The power fluid is injected from the power fluid pool 14 into the multi-channel drill pipe 4 by the driving pump 13, then the downhole lifting pump sub-section is driven, and then it returns from the multi-channel drill pipe and enters the power fluid pool again for standby.

[0088] Preferably, in this embodiment, a power fluid inlet pressure gauge 11 and a power fluid flowmeter 12 are fixedly installed on the pipeline between the driving pump 13 and one end of the annular channel.

[0089] In addition, a power fluid return pressure gauge 15 is fixedly installed on the pipeline between the power fluid pool 14 and one end of the annular channel.

[0090] The function of the power fluid inlet pressure gauge is to measure and display the liquid pressure of the power fluid pumped out by the driving pump, which is convenient for monitoring the power fluid pressure and adjusting the experimental parameters; the function of the power fluid flowmeter is to measure and display the liquid flow of the power fluid pumped out by the driving pump, which is convenient for monitoring the power fluid flow and adjusting the experimental parameters; the function of the driving pump is to provide power for the circulation of the power fluid; the function of the power fluid pool is to store the power fluid system for experiments, provide the injected power fluid and store the returned power fluid; the function of the power fluid return pressure gauge is to measure and display the liquid pressure of the power fluid returned from the multi-channel drill pipe, which is convenient for monitoring the power fluid pressure and adjusting the experimental parameters.

[0091] Based on the above scheme, the above annular channel can be divided into an upper annular channel and a lower annular channel (or left and right annular channels, arranged oppositely), and the two ports connected to the power fluid return pressure gauge 15 and the power fluid inlet pressure gauge 11 respectively correspond to one side of the annular channel, one for injection and one for return, forming a closed circulation path.

[0092] Embodiment 9

[0093] On the basis of the above embodiments, in this embodiment, the downhole complex simulation system includes a formation fluid hydraulic pump 27 and a fluid storage pool 26. One side of one end of the wellbore channel, the formation fluid hydraulic pump 27, the fluid storage pool 26, and the other side of one end of the wellbore channel are sequentially connected through pipelines.

[0094] The function of the downhole complex simulation system is to simulate complex processes such as downhole overflow and loss during the process of hydraulic lift multi-gradient drilling.

[0095] Preferably, in this embodiment, a second overflow valve 25 and a formation pressure gauge 24 are installed in parallel with the formation fluid hydraulic pump 27.

[0096] In addition, a bottom hole pressure gauge one 9 and a check valve 28 are fixedly installed on the pipeline between the formation fluid hydraulic pump 27 and one end of the wellbore channel.

[0097] Moreover, a bottom-hole pressure gauge II 29 and a leakage valve 30 are fixedly installed on the pipeline between the fluid reserve tank 26 and one end of the wellbore passage.

[0098] The function of the bottom-hole pressure gauge is to measure and display the bottom-hole pressure, facilitating the monitoring of the bottom-hole pressure and the adjustment of experimental parameters; the function of the check valve is to control the flow direction of the overflow or leakage fluid; the function of the formation pressure gauge is to measure and display the liquid pressure of the simulated formation fluid pumped out by the formation fluid hydraulic pump, facilitating the monitoring of the simulated formation fluid pressure and the adjustment of experimental parameters; the function of the overflow valve is to set the simulated formation pressure when simulating the overflow condition. When the bottom-hole pressure is lower than the set simulated formation pressure, the simulated formation fluid is pumped out by the formation fluid hydraulic pump, the check valve is opened and pumped into the wellbore. When the bottom-hole pressure is higher than the set simulated formation pressure, the simulated formation fluid is pumped out by the formation fluid hydraulic pump, passes through the formation pressure gauge and the overflow valve, and returns to the fluid reserve tank; the function of the formation fluid hydraulic pump is to provide pressure for the formation fluid and simulate the formation pressure; the function of the fluid reserve tank is to store the simulated formation fluid system for experiments, provide the simulated formation fluid for overflow and store the lost drilling fluid. The function of the leakage valve is to set the simulated well leakage pressure when simulating the leakage condition. When the bottom-hole pressure is lower than the simulated well leakage pressure, the leakage valve closes. When the bottom-hole pressure is higher than the simulated well leakage pressure, the leakage valve opens, and the drilling fluid in the wellbore passes through the bottom-hole pressure gauge and the leakage valve and enters the fluid reserve tank.

[0099] Embodiment 10

[0100] Based on the above embodiments, this embodiment further provides a hydraulic lift multi-gradient drilling test method, which is implemented by using the hydraulic lift multi-gradient drilling experimental device as described above, and includes the following specific steps:

[0101] S1: Start the drilling fluid circulation system and the power fluid circulation system, and record the relevant pressure parameters;

[0102] S2: Change the flow rate and pressure of the drilling fluid circulation system and the power fluid circulation system, and record the pressure parameters under different operating conditions after the circulation is stable;

[0103] S3: Start the downhole complex simulation system, simulate the downhole overflow condition, repeat steps S1 - S3, and record the experimental data during the simulated overflow; at the same time, simulate the downhole leakage condition, repeat steps S1 - S3, and record the experimental data during the simulated leakage;

[0104] S4: Replace the fluid systems such as the power fluid, drilling fluid, and simulated formation fluid, repeat the experiment, and the test is completed.

[0105] This embodiment provides a testing method, which provides an experimental basis for the development and testing of the hydraulic lifting multi-gradient drilling technology in land and marine complex formations, can contribute to the development and improvement of the hydraulic lifting multi-gradient drilling technology, and also provides basic support for simulating on-site accidents such as well collapse, stuck pipe, well kick, blowout, and simultaneous leakage and blowout in complex formations with this technology.

[0106] The testing process of the present invention is as follows:

[0107] Step 1: Install and connect the hydraulic lifting multi-gradient drilling experimental device.

[0108] Step 2: Turn on the drilling pump and adjust the displacement and pressure of the drilling fluid.

[0109] Step 3: Turn on the drive pump and adjust the displacement and pressure of the power fluid.

[0110] Step 4: Record the pressure data such as the bottom hole pressure gauge, the drilling fluid inlet pressure gauge, the drilling fluid return pressure gauge, the power fluid inlet pressure gauge, and the power fluid return pressure gauge.

[0111] Step 5: Change parameters such as the power fluid displacement, power fluid pressure, drilling fluid displacement, and drilling fluid pressure. After the circulation is stable, record the experimental data under different operating parameters.

[0112] Step 6: Start the downhole complex simulation system to simulate the downhole overflow condition, repeat Steps 4 - 6, and record the experimental data during the simulated overflow.

[0113] Step 7: Start the downhole complex simulation system to simulate the downhole loss condition, repeat Steps 4 - 6, and record the experimental data during the simulated loss.

[0114] Step 8: Replace fluid systems such as the power fluid, drilling fluid, and simulated formation fluid, and repeat the experiment.

[0115] Step 9: The testing is completed.

[0116] A hydraulic lifting multi-gradient drilling experimental device and testing method proposed by the present invention have certain innovation, provide an experimental basis for the development and testing of the hydraulic lifting multi-gradient drilling technology in land and marine complex formations. General designers and R & D personnel in the oil and gas industry can build the experimental device and carry out experimental tests according to the device structure and testing method of the present invention based on the actual experimental conditions. It can contribute to the development and improvement of the hydraulic lifting multi-gradient drilling technology, and also provides basic support for simulating on-site accidents such as well collapse, stuck pipe, well kick, blowout, and simultaneous leakage and blowout in complex formations with this technology.

[0117] A hydraulic lifting multi-gradient drilling experimental device and testing method proposed by the present invention have the following

[0118] Beneficial effects:

[0119] 1. The experimental device has a simple structure, convenient control, and low experimental cost, filling the gaps in the experimental test device and test method of this technology in China;

[0120] 2. The hydraulic lift multi-gradient drilling experimental device proposed by the present invention can simulate the technological process and control measures of hydraulic lift multi-gradient drilling, providing a reference for on-site operation and control;

[0121] 3. By regulating parameters such as the displacement of drilling fluid, the displacement of power fluid, and the opening of throttle valves, the control effect of bottom-hole pressure is tested, which has a certain reference value for the testing of hydraulic lift multi-gradient drilling technology and the formation of control software;

[0122] 4. The experimental device can simulate complex working conditions such as downhole leakage and overflow, providing a reference for the hydraulic lift multi-gradient drilling technology to deal with downhole complexity;

[0123] 5. The experimental device can be used simultaneously for the performance and working reliability testing of hydraulic lift multi-gradient drilling equipment, providing conditions for the testing of key equipment tools.

[0124] It should be noted that all the electronic components involved in the present invention adopt existing technologies, and the above-mentioned components are electrically connected to the controller, and the control circuit between the controller and each component is an existing technology.

[0125] As the latest achievement of wellbore pressure control technology, the hydraulic lift multi-gradient drilling technology plays a positive role in efficient drilling operations in deep and complex formations and other difficult-to-drill wells, and is expected to lead the high-end technology revolution in the field of international wellbore pressure control drilling. However, at present, no systematic standard experimental device and test method have been proposed for this technology, which brings inconvenience to the indoor experimental research and equipment improvement of this technology. The present invention innovatively designs a hydraulic lift multi-gradient drilling experimental device with a simple structure and complete test functions, and at the same time proposes a hydraulic lift multi-gradient drilling experimental test method around this device, which can be used to test the operation ability of hydraulic lift multi-gradient drilling and the reliability of pressure control measures, laying an experimental test foundation for the improvement and enhancement of hydraulic lift multi-gradient drilling technology.

[0126] The present invention mainly makes up for the gaps in the experimental device and test method of the new hydraulic lift multi-gradient drilling technology, and proposes a hydraulic lift multi-gradient drilling experimental device and test method. Relying on this device, the wellbore pressure can be regulated by adjusting the test string structure, the displacement of the drilling pump, the displacement of the drive pump, the opening of the throttle valve, etc., so that the experimental wellbore pressure is within a safe pressure window range.

[0127] The specific embodiments of the present invention are as follows:

[0128] (1) Embodiment 1

[0129] In one embodiment, as Figure 1 shown, a hydraulic lift multi-gradient drilling experimental device includes a drilling fluid circulation system, a power fluid circulation system, a test bench main body, and a downhole complex simulation system.

[0130] The drilling fluid circulation system includes a drilling fluid inlet pressure gauge, a drilling fluid inlet flowmeter, an overflow valve, a drilling pump, a drilling fluid tank, a throttle valve, a drilling fluid return flowmeter, and a drilling fluid return pressure gauge; the overflow valve is connected in parallel with the drilling pump, and the drilling fluid inlet pressure gauge, the drilling fluid inlet flowmeter, the overflow valve, the drilling pump, the drilling fluid tank, the throttle valve, the drilling fluid return flowmeter, and the drilling fluid return pressure gauge are connected in sequence.

[0131] The power fluid circulation system includes a power fluid inlet pressure gauge, a power fluid flowmeter, a drive pump, a power fluid tank, and a power fluid return pressure gauge; the power fluid inlet pressure gauge, the power fluid flowmeter, the drive pump, the power fluid tank, and the power fluid return pressure gauge are connected in sequence.

[0132] The test bench main body includes a top drive adapter, a multi-channel drill pipe, a hydraulic drive sub, an annulus packer tool, a fluid lift sub, an upper plug, an upper joint, a lower plug, an outer wellbore, and a lower joint; the top drive adapter, the multi-channel drill pipe, the hydraulic drive sub, the annulus packer tool, the fluid lift sub, and the lower plug are connected in sequence, and the three-channel drill pipe, the hydraulic drive sub, the annulus packer tool, the fluid lift sub, and the lower plug are placed in the wellbore. The upper plug is installed on the left side of the outer wellbore to achieve the seal between the outer wellbore and the multi-channel drill pipe. The upper joint is connected to the drilling fluid circulation system, the lower joint is connected to the downhole complex simulation system, and the top drive adapter is installed outside one end of the simulated wellbore and connected to the power fluid circulation system.

[0133] The downhole complex simulation system mainly includes a bottom hole pressure gauge, a check valve, a formation pressure gauge, an overflow valve, a formation fluid hydraulic pump, a fluid reserve tank, and a leakage valve. The bottom hole pressure gauge is connected to the lower joint, and the check valve, the formation fluid hydraulic pump, the fluid reserve tank, and the leakage valve are connected in sequence. The formation pressure gauge and the overflow valve are connected in parallel with the formation fluid hydraulic pump.

[0134] Specifically, a test method for a hydraulic lift multi-gradient drilling experimental device includes the following steps:

[0135] Step 1: Install and connect the land dual-gradient drilling experimental device;

[0136] Step 2: Turn on the drilling pump and adjust the drilling fluid displacement to 15 L / s;

[0137] Step 3: Turn on the drive pump and adjust the power fluid displacement to 15 L / s;

[0138] Step 4: Record the data of the bottom hole pressure gauge, the drilling fluid injection pressure gauge, the drilling fluid return pressure gauge, the power fluid injection pressure gauge, and the power fluid return pressure gauge.

[0139] Step 5: Adjust the power fluid displacement to 15 L / s, 13 L / s, 11 L / s, 9 L / s, and 7 L / s in sequence. After circulating for 5 minutes, repeat Step 4 and record the pressure gauge data at different power fluid displacements.

[0140] Step 6: Adjust the drilling fluid displacement to 15 L / s, 13 L / s, 11 L / s, 9 L / s, and 7 L / s in sequence. At different drilling fluid displacements, repeat Steps 4 and 5.

[0141] Step 7: Adjust the leak-off valve to 5 MPa, completely close the second overflow valve, and adjust the drilling fluid displacement and pressure to control the wellbore pressure at 7 MPa.

[0142] Step 8: Continuously increase the power fluid displacement to increase the lifting force of the downhole lift pump until the wellbore pressure drops to less than 5 MPa, and record the experimental data at different times.

[0143] Step 9: The test is completed.

[0144] (2) Embodiment 2

[0145] In one embodiment, as Figure 1 shown, a hydraulic lift multi-gradient drilling experimental device includes a drilling fluid circulation system, a power fluid circulation system, a test bench main body, and a downhole complex simulation system.

[0146] The drilling fluid circulation system includes a drilling fluid injection pressure gauge, a drilling fluid injection flowmeter, an overflow valve, a drilling pump, a drilling fluid tank, a throttle valve, a drilling fluid return flowmeter, and a drilling fluid return pressure gauge; the overflow valve is connected in parallel with the drilling pump, and the drilling fluid injection pressure gauge, the drilling fluid injection flowmeter, the overflow valve, the drilling pump, the drilling fluid tank, the throttle valve, the drilling fluid return flowmeter, and the drilling fluid return pressure gauge are connected in sequence.

[0147] The power fluid circulation system includes a power fluid injection pressure gauge, a power fluid flowmeter, a drive pump, a power fluid tank, and a power fluid return pressure gauge; the power fluid injection pressure gauge, the power fluid flowmeter, the drive pump, the power fluid tank, and the power fluid return pressure gauge are connected in sequence.

[0148] The main body of the test bench includes a top drive adapter, multi-channel drill pipes, a hydraulic drive sub, an annulus packer tool, a fluid lift sub, an upper plug, an upper joint, a lower plug, an outer wellbore, and a lower joint. The top drive adapter, multi-channel drill pipes, hydraulic drive sub, annulus packer tool, fluid lift sub, and lower plug are connected in sequence. The three-channel drill pipes, hydraulic drive sub, annulus packer tool, fluid lift sub, and lower plug are placed in the wellbore. The upper plug is installed on the left side of the outer wellbore to achieve the seal between the outer wellbore and the multi-channel drill pipes. The upper joint is connected to the drilling fluid circulation system, and the lower joint is connected to the downhole complex simulation system. The top drive adapter is installed outside one end of the simulated wellbore and is connected to the power fluid circulation system.

[0149] The downhole complex simulation system mainly includes a bottom hole pressure gauge, a check valve, a formation pressure gauge, a relief valve, a formation fluid hydraulic pump, a fluid storage tank, and a leakage valve. The bottom hole pressure gauge is connected to the lower joint, and the check valve, formation fluid hydraulic pump, and fluid storage tank, and leakage valve are connected in sequence. The formation pressure gauge and the relief valve are connected in parallel to the formation fluid hydraulic pump.

[0150] A specific test method for a hydraulic lift multi-gradient drilling experimental device includes the following steps:

[0151] Step 1: Install and connect the land dual-gradient drilling experimental device;

[0152] Step 2: Open the drilling pump and adjust the drilling fluid displacement to 20 L / s;

[0153] Step 3: Open the drive pump and adjust the power fluid displacement to 20 L / s;

[0154] Step 4: Record the data of the bottom hole pressure gauge, the drilling fluid inlet pressure gauge, the drilling fluid outlet pressure gauge, the power fluid inlet pressure gauge, and the power fluid outlet pressure gauge;

[0155] Step 5: Adjust the power fluid displacement to 18 L / s, 16 L / s, 14 L / s, 12 L / s, and 10 L / s in sequence. After circulating for 5 minutes, repeat Step 4 and record the pressure gauge data at different power fluid displacements;

[0156] Step 6: Adjust the drilling fluid displacement to 18 L / s, 16 L / s, 14 L / s, 12 L / s, and 10 L / s in sequence. At different drilling fluid displacements, repeat Steps 4 and 5;

[0157] Step 7: Adjust the second relief valve to 10 MPa, completely close the leakage valve, adjust the drilling fluid displacement and pressure to control the wellbore pressure at 8 MPa, and start the formation fluid hydraulic pump;

[0158] Step 8: Continuously reduce the displacement of the power fluid and the lifting force of the downhole lifting pump until the wellbore pressure increases to more than 10 MPa, and record the experimental data at different times;

[0159] Step 9: The test is completed.

[0160] (3) Example 3

[0161] In one embodiment, as Figure 2 shown, a hydraulic lifting multi-gradient drilling experimental device includes a drilling fluid circulation system, a power fluid circulation system, a test bench main body, and a downhole complex simulation system.

[0162] The drilling fluid circulation system includes a drilling fluid inlet pressure gauge, a drilling fluid inlet flowmeter, an overflow valve, a drilling pump, a drilling fluid tank, a throttle valve, a drilling fluid return flowmeter, and a drilling fluid return pressure gauge; the overflow valve is connected in parallel with the drilling pump, and the drilling fluid inlet pressure gauge, the drilling fluid inlet flowmeter, the overflow valve, the drilling pump, the drilling fluid tank, the throttle valve, the drilling fluid return flowmeter, and the drilling fluid return pressure gauge are connected in sequence.

[0163] The power fluid circulation system includes a power fluid inlet pressure gauge, a power fluid flowmeter, a drive pump, a power fluid tank, and a power fluid return pressure gauge; the power fluid inlet pressure gauge, the power fluid flowmeter, the drive pump, the power fluid tank, and the power fluid return pressure gauge are connected in sequence.

[0164] The test bench main body includes a top drive adapter, two multi-channel drill pipes, two hydraulic drive short joints, two annulus packoff tools, two fluid lifting short joints, an upper plug, an upper joint, a lower plug, an outer wellbore, and a lower joint; the top drive adapter, the first multi-channel drill pipe, the first hydraulic drive short joint, the first annulus packoff tool, the first fluid lifting short joint, the second multi-channel drill pipe, the second hydraulic drive short joint, the second annulus packoff tool, the second fluid lifting short joint, and the lower plug are connected in sequence and placed in the wellbore after connection. The upper plug is installed on the left side of the outer wellbore to achieve the seal between the outer wellbore and the multi-channel drill pipe. The upper joint is connected to the drilling fluid circulation system, the lower joint is connected to the downhole complex simulation system, and the top drive adapter is installed outside one end of the simulated wellbore and connected to the power fluid circulation system.

[0165] The downhole complex simulation system mainly includes a bottom hole pressure gauge, a check valve, a formation pressure gauge, an overflow valve, a formation fluid hydraulic pump, a fluid storage tank, and a leakage valve. The bottom hole pressure gauge is connected to the lower joint, and the check valve, the formation fluid hydraulic pump, the fluid storage tank, and the leakage valve are connected in sequence. The formation pressure gauge and the overflow valve are connected in parallel with the formation fluid hydraulic pump.

[0166] Specifically, a test method for a hydraulic lifting multi-gradient drilling experimental device includes the following steps:

[0167] Step 1: Install and connect the land dual-gradient drilling experimental device;

[0168] Step 2: Do not start the drilling pump, and only keep the drilling fluid circulation channel unblocked;

[0169] Step 3: Turn on the drive pump and adjust the displacement of the power fluid to 25 L / s;

[0170] Step 4: Record the data of the bottom hole pressure gauge, the drilling fluid injection pressure gauge, the drilling fluid return pressure gauge, the power fluid injection pressure gauge, and the power fluid return pressure gauge;

[0171] Step 5: Adjust the displacement of the power fluid to 24 L / s, 22 L / s, 20 L / s, 18 L / s, and 16 L / s in sequence. After circulating for 5 minutes, repeat Step 4 and record the pressure gauge data at different power fluid displacements;

[0172] Step 6: Adjust the leakage valve to 6 MPa, completely close the second overflow valve, and adjust the drilling fluid displacement and pressure to control the wellbore pressure to 8 MPa;

[0173] Step 8: Continuously increase the displacement of the power fluid to increase the lifting force of the downhole lift pump until the wellbore pressure drops to less than 6 MPa, and record the experimental data at different times;

[0174] Step 9: The test is completed.

[0175] (4) Example 4

[0176] In one embodiment, as Figure 2 shown, a hydraulic lift multi-gradient drilling experimental device includes a drilling fluid circulation system, a power fluid circulation system, a main experimental bench, and a downhole complex simulation system.

[0177] The drilling fluid circulation system includes a drilling fluid injection pressure gauge, a drilling fluid injection flowmeter, an overflow valve, a drilling pump, a drilling fluid tank, a throttle valve, a drilling fluid return flowmeter, and a drilling fluid return pressure gauge; the overflow valve is connected in parallel with the drilling pump, and the drilling fluid injection pressure gauge, the drilling fluid injection flowmeter, the overflow valve, the drilling pump, the drilling fluid tank, the throttle valve, the drilling fluid return flowmeter, and the drilling fluid return pressure gauge are connected in sequence.

[0178] The power fluid circulation system includes a power fluid injection pressure gauge, a power fluid flowmeter, a drive pump, a power fluid tank, and a power fluid return pressure gauge; the power fluid injection pressure gauge, the power fluid flowmeter, the drive pump, the power fluid tank, and the power fluid return pressure gauge are connected in sequence.

[0179] The main body of the test bench includes a top drive adapter, two multi-channel drill pipes, two hydraulic drive subsections, two annulus packoff tools, two fluid lift subsections, an upper plug, an upper joint, a lower plug, an outer wellbore, and a lower joint; the top drive adapter, the first multi-channel drill pipe, the first hydraulic drive subsection, the first annulus packoff tool, the first fluid lift subsection, the second multi-channel drill pipe, the second hydraulic drive subsection, the second annulus packoff tool, the second fluid lift subsection, and the lower plug are connected in sequence, and after connection, they are placed in the wellbore. The upper plug is installed on the left side of the outer wellbore to achieve the seal between the outer wellbore and the multi-channel drill pipe. The upper joint is connected to the drilling fluid circulation system, the lower joint is connected to the downhole complex simulation system, and the top drive adapter is installed outside one end of the simulated wellbore and connected to the power fluid circulation system.

[0180] The downhole complex simulation system mainly includes a bottom hole pressure gauge, a check valve, a formation pressure gauge, a relief valve, a formation fluid hydraulic pump, a fluid storage tank, and a leak-off valve. The bottom hole pressure gauge is connected to the lower joint, and the check valve, the formation fluid hydraulic pump, the fluid storage tank, and the leak-off valve are connected in sequence. The formation pressure gauge and the relief valve are connected in parallel to the formation fluid hydraulic pump.

[0181] A specific test method for a hydraulic lift multi-gradient drilling experimental device includes the following steps:

[0182] Step 1: Install and connect the land dual-gradient drilling experimental device;

[0183] Step 2: Do not start the drilling pump, and only keep the drilling fluid circulation channel unblocked;

[0184] Step 3: Open the drive pump and adjust the power fluid displacement to 30 L / s;

[0185] Step 4: Record the data of the bottom hole pressure gauge, the drilling fluid injection pressure gauge, the drilling fluid return pressure gauge, the power fluid injection pressure gauge, and the power fluid return pressure gauge;

[0186] Step 5: Adjust the power fluid displacement to 28 L / s, 26 L / s, 24 L / s, 22 L / s, and 20 L / s in sequence. After circulating for 5 minutes, repeat Step 4 and record the pressure gauge data at different power fluid displacements;

[0187] Step 6: Adjust the second relief valve to 12 MPa, completely close the leak-off valve, adjust the drilling fluid displacement and pressure to control the wellbore pressure to 10 MPa, and start the formation fluid hydraulic pump;

[0188] Step 7: Continuously reduce the power fluid displacement and the lifting force of the downhole lift pump until the wellbore pressure increases to more than 12 MPa, and record the experimental data at different times;

[0189] Step 8: The test is completed.

[0190] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0191] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0192] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydraulic lifting multi-gradient drilling experimental device, characterized in that: It includes a drilling fluid circulation system, a power fluid circulation system, a main experimental bench frame, and a downhole complex simulation system. Inside the main experimental bench frame, a central channel, an annular channel, and a wellbore channel are sequentially arranged from inside to outside. One end of the central channel is communicated with one end of the wellbore channel, and an opening communicating with the wellbore channel is provided on the central channel; Both ends of the drilling fluid circulation system are respectively communicated with the other end of the central channel and the other end of the wellbore channel through pipelines. Both ends of the power fluid circulation system are respectively communicated with one end of the annular channel through pipelines. Both ends of the downhole complex simulation system are respectively communicated with one end of the wellbore channel through pipelines.

2. The hydraulic lifting multi-gradient drilling experimental device according to claim 1, characterized in that: The main experimental bench frame includes a multi-channel drill pipe (4), an outer wellbore (5), and at least one short joint assembly. The multi-channel drill pipe (4) is installed inside the outer wellbore (5). One end is located inside the outer wellbore (5), and the other end extends outside the outer wellbore (5). The short joint assembly is installed at one end of the multi-channel drill pipe (4); the central channel and the annular channel are distributed inside the multi-channel drill pipe (4) from inside to outside, and the wellbore channel is formed between the outer wellbore (5) and the multi-channel drill pipe (4).

3. The hydraulic lifting multi-gradient drilling experimental device according to claim 2, characterized in that: Each short joint assembly includes a hydraulic drive short joint (6) and a fluid lifting short joint (8). The hydraulic drive short joint (6) is fixedly installed at one end of the multi-channel drill pipe (4), and the fluid lifting short joint (8) is fixedly connected to the hydraulic drive short joint (6).

4. The hydraulic lifting multi-gradient drilling experimental device according to claim 3, characterized in that: Each short joint assembly also includes an annulus packoff tool (7). The annulus packoff tool (7) is fixedly installed on the corresponding fluid lifting short joint (8) and is used to divide the annular cavity in the wellbore channel into two parts.

5. The hydraulic lifting multi-gradient drilling experimental device according to claim 2, characterized in that: Upper plugs (2) and lower plugs (10) are respectively fixedly installed at both ends of the outer wellbore (5). Two lower joints (31) are oppositely arranged at one end of the outer wellbore (5). The two lower joints (31) are respectively communicated with both ends of the downhole complex simulation system through pipelines; an upper joint (3) is provided at the other end of the outer wellbore (5), and the upper joint (3) is communicated with one end of the drilling fluid circulation system through a pipeline.

6. The hydraulic lifting multi-gradient drilling experimental device according to claim 5, characterized in that: A top drive adapter (1) is fixedly installed at the other end of the multi-channel drill pipe (4). A cavity communicated with the annular channel is provided inside the top drive adapter (1), and an inlet and an outlet respectively communicated with the cavity are also provided on the top drive adapter (1). The inlet and the outlet are respectively communicated with the power fluid circulation system through pipelines.

7. The hydraulic lifting multi-gradient drilling experimental device according to any one of claims 1-6, characterized in that: the drilling fluid circulation system includes a drilling pump (19) and a drilling fluid tank (20), and the drilling pump (19), the drilling fluid tank (20), the other end of the wellbore passage and the other end of the central passage are sequentially connected through pipelines.

8. The hydraulic lifting multi-gradient drilling experimental device according to any one of claims 1-6, characterized in that: the power fluid circulation system includes a driving pump (13) and a power fluid tank (14), and one side of one end of the annular passage, the driving pump (13), the power fluid tank (14) and the other side of one end of the annular passage are sequentially connected through pipelines.

9. The hydraulic lifting multi-gradient drilling experimental device according to any one of claims 1-6, characterized in that: the downhole complex simulation system includes a formation fluid hydraulic pump (27) and a fluid storage tank (26), and one side of one end of the wellbore passage, the formation fluid hydraulic pump (27), the fluid storage tank (26) and the other side of one end of the wellbore passage are sequentially connected through pipelines.

10. A hydraulic lifting multi-gradient drilling test method, characterized in that: it is realized by using the hydraulic lifting multi-gradient drilling experimental device according to any one of claims 1-9, and includes the following specific steps: S1: Start the drilling fluid circulation system and the power fluid circulation system, and record the relevant pressure parameters; S2: Change the flow rate and pressure of the drilling fluid circulation system and the power fluid circulation system, and record the pressure parameters under different operating conditions after the circulation is stable; S3: Start the downhole complex simulation system, simulate the downhole overflow condition, repeat steps S1-S3, and record the experimental data during the simulated overflow; at the same time, simulate the downhole leakage condition, repeat steps S1-S3, and record the experimental data during the simulated leakage; S4: Replace fluid systems such as the power fluid, drilling fluid, and simulated formation fluid, repeat the experiment, and the test is completed.

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