Sand control medium blocking and unblocking evaluation device and method

Abstract

The application discloses a device and method for evaluating plugging and unplugging of sand control medium, which comprises a three-phase mixed displacement kettle, a gas storage tank, a one-way variable hydraulic pump, a sand mixing tank, a multi-interface connector, a plugging remover power mechanism, a sand settling tank, a test fluid channel, a sleeve, a plugging remover, a screen pipe, a temperature measuring system, a pressure measuring system and a control terminal. The device and method can master the plugging law and mechanism in the hydrate mining process, and the optimal unplugging process suitable for the hydrate mining will become an important support means for maintaining long-term and efficient mining of the hydrate, and has extremely important significance for promoting the industrialization process of the hydrate.

Description

TECHNICAL FIELD

[0001] The present application relates to hydrate and oil and gas experimental equipment, and particularly relates to a sand control medium plugging and unblocking evaluation device and method. BACKGROUND

[0002] Whether it is the development of marine oil and gas or the trial production of natural gas hydrates, the problem of yield decline caused by the decrease of permeability of the production channel is faced in the production cycle. Therefore, quickly analyzing the plugging reason, determining the plugging area, and selecting the unblocking process, can provide support for ensuring the stable production of the wellbore and realizing the maximum development of energy.

[0003] The hydrate reservoir in the South China Sea area is characterized by high clay content and fine particle size. Under the action of production pressure difference, large-scale sand production is easily formed, and long-term sand production is not conducive to the long-term stable operation of ESP, sand remover, separator and other equipment. To some extent, the screen pipe and the packed gravel solve the problems of sand production and sand blocking, but as the natural gas hydrate production cycle is prolonged, different well materials will form a structure type blockage mainly composed of inorganic substances such as mud and sand, and containing a small amount of microorganisms and oil sludge in the near wellbore. At the same time, long-term production causes the temperature of the natural gas hydrate decomposition zone to decrease, and secondary hydrate is easily formed around the wellbore, causing ice blockage. The plugging forms include coarse component selection bridge, local sand group and overall sand bridge. In order to prolong the natural gas hydrate production cycle and improve the recovery rate, after a period of development of the natural gas hydrate well, appropriate unblocking measures need to be taken to dredge the gas production channel in the near wellbore zone, so as to restore the permeability of the tubing, screen pipe, gravel layer or near wellbore zone formation, and reduce the friction along the way. See the literature “Shi Haoxian, Xie Wenwei, Yu Yanjiang, et al. Feasibility analysis of application of compound unblocking technology in natural gas hydrate development [J]. Drilling Engineering, 2022, 49(1): 5-15”.

[0004] Patent CN113062713A can prepare natural gas hydrate deposit samples, simulate the depressurization of natural gas hydrate in the near-well reservoir, and determine the plugging degree of the reservoir, but can only be used to evaluate the effect of acid injection for plugging removal, and cannot effectively evaluate the physical, biological, and composite plugging removal effects. Patent CN113216902A provides a comprehensive utilization of mechanical crushing method, heating method, and injection of hydrate inhibitor method to remove hydrate plugging in deep water gas wells. However, it cannot simulate the plugging degree and biological plugging removal effect of different regions of horizontal wells and vertical wells under the influence of gravity. Patent CN112710450A builds a hydraulic pulse plugging removal experimental system for particle plugging in fractures, which can study the migration law of particle plugging in fractures under hydraulic pulse, but the evaluation of plugging removal process is single. Patent CN214997580U provides a hydraulic impact plugging removal device for oilfield injection wells, which can generate liquid force oscillation through an oscillator to improve the injection plugging removal effect of low permeability reservoirs, but the evaluation of plugging removal process is single. Patent CN110018101B provides a mechanical experimental system for evaluating shock wave plugging removal, which studies the plugging removal effect of liquid force oscillation such as shock wave and electric explosion, but the evaluation of plugging removal process is single. In addition, many devices and systems still focus on the evaluation of commonly used single plugging removal process, and the experimental scale is small.

[0005] In summary, the influence of sand plugging on productivity during hydrate production due to formation sand production and secondary hydrate generation has not been thoroughly studied. At the same time, there are many plugging removal technologies in the oil and gas industry, such as physical, chemical, biological, and composite methods, but their applicability in hydrate plugging removal has not been thoroughly evaluated

[0006] The current stage is the most critical period of natural gas hydrate industrialization, and ensuring long-term stable production of hydrate production will be an important guarantee for industrialization. How to quickly remove the plugging of the sand blocking medium and restore the productivity will be one of the key technologies in the near future. The current common problem is:

[0007] ① Most devices or systems only evaluate single plugging removal technology or process, and cannot evaluate multiple plugging removal processes, which cannot meet the needs of efficient and rapid evaluation.

[0008] ② Hydrate is a new energy, and many conventional oil and gas technologies cannot be directly applied, but need to be adapted and improved. Due to the characteristics of high mud content and strong plugging in ultra-deep water, the technology for restoring the permeability of the near-well zone has not been thoroughly developed, therefore, a device and experimental method that can meet this research need is urgently needed. SUMMARY

[0009] The present application aims to overcome the deficiencies of the prior art, and provides a sand control medium plugging and unblocking evaluation device and method, which can master the plugging law and mechanism in the hydrate exploitation process, and optimally select the unblocking process suitable for hydrate exploitation, thus becoming an important support for maintaining long-term and efficient exploitation of hydrates, and having extremely important significance for promoting the industrialization process of hydrates. The device and method can also be used for plugging and unblocking mechanism research in the oil and gas industry.

[0010] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0011] In the first aspect, the present application provides a sand control medium plugging and unblocking evaluation device, which comprises a three-phase mixed displacement still, a gas storage tank, a one-way variable hydraulic pump, a sand mixing tank, a multi-interface connector, an unblocking device power mechanism, a sand settling tank, a test fluid channel, a casing, an unblocking device, a screen pipe, a temperature measurement system, a pressure measurement system, and a control terminal.

[0012] The sand mixing tank is used for mixing solid-liquid substances.

[0013] The gas storage tank is connected to the three-phase mixed displacement still, so as to input gas into the three-phase mixed displacement still.

[0014] The one-way variable hydraulic pump is connected to the sand mixing tank, so as to pump the solid-liquid substances in the sand mixing tank to the three-phase mixed displacement still.

[0015] The three-phase mixed displacement still is used for mixing the solid-liquid substances and the gas, and transmitting the mixed gas-liquid-solid three-phase to the test fluid channel.

[0016] The test fluid channel is connected to the casing, and the casing is bored to serve as an injection channel for the gas-liquid-solid three-phase.

[0017] The screen pipe is arranged in the casing, and the screen pipe and the casing constitute a test main still body.

[0018] The unblocking device is inserted into the screen pipe and reciprocally moves in the screen pipe under the driving of the unblocking device power mechanism. The unblocking device is connected to the multi-interface connector, and the multi-interface connector is used for connecting to different unblocking devices.

[0019] The sand settling tank is used for collecting the solid-containing liquid flowing out from the inside of the screen pipe and flowing out from the annulus of the screen pipe and the casing.

[0020] The gas-liquid flow meter is used for monitoring the flow of the fluid and the gas injected by the test fluid channel.

[0021] The temperature measurement system is used for monitoring the temperature in the casing.

[0022] The pressure measuring system is used for monitoring the pressure condition in the casing;

[0023] The control terminal is connected with the gas-liquid flow meter, the temperature measuring system and the pressure measuring system respectively.

[0024] Further, the plugging removal device is an electric pulse plugging removal device, which provides a liquid force pulse generated by electric explosion, and the pulse acts on the screen pipe through the plugging removal device to remove the plugging on the screen pipe.

[0025] Further, the plugging removal device is a microbial enzyme culture tank, which provides a microorganism capable of decomposing silt particles in a deep-sea seawater environment, and the microorganism enters the plugging removal device through the multi-interface connector to act on the screen pipe, so that the original plugging is dredged and the permeability is restored after a period of microbial plugging removal reaction.

[0026] Further, the plugging removal device is an oscillation generator, which generates liquid force oscillation through a piston, and the liquid force enters the plugging removal device through the multi-interface connector and the test fluid passage, and acts on the screen pipe to achieve a physical method of plugging removal.

[0027] Further, a gate valve is installed on the pipeline connected between the test fluid passage and the casing opening.

[0028] Further, the sand control medium plugging and deplugging evaluation device further comprises a sliding seal, which is arranged at the plug-in position of the plugging removal device and the screen pipe.

[0029] Further, the sand control medium plugging and deplugging evaluation device further comprises a sealing end cover, which is arranged at the other end of the screen pipe without plugging the plugging removal device.

[0030] Further, gravel is filled in the annular gap between the casing and the screen pipe.

[0031] Further, the sand control medium plugging and deplugging evaluation device further comprises a support frame to provide support for the entire test main kettle body.

[0032] In the second aspect, the present application provides a sand control medium plugging and deplugging evaluation method, which is based on the above-mentioned device, and the method comprises the following steps:

[0033] Step one:

[0034] The test evaluation device is built, and each component is debugged to ensure that it can work normally.

[0035] Step two:

[0036] Step 2.1: The metered solid-liquid material, including mass and particle size distribution, is mixed by a sand mixing tank, and gas is provided by a gas storage tank. After entering the three-phase mixing displacement kettle, the mixture is fully mixed, pumped into the casing by a single variable hydraulic pump, and monitored for flow rate, temperature and pressure data by a gas-liquid flow meter, pressure measurement system and temperature measurement system, and transmitted to the control terminal.

[0037] Step 2.2: Start the plugging test. The three-phase material is continuously pumped into the casing by a single variable hydraulic pump. The slurry flows through the casing opening into the annulus between the casing and the screen pipe, passes through the screen pipe, and is discharged to the sand settling tank. The data displayed on the control terminal is observed. Due to the plugging of the slurry, the seepage channel inside and outside the screen pipe decreases, and the annular pressure between the casing and the screen pipe gradually increases. When the pressure slowly increases to a certain value, the pumping is stopped, and the plugging test is completed. Within T time, the annular pressure between the casing and the screen pipe reaches P1.

[0038] Step 2.3: Start the unblocking test. The plugging structure in the screen pipe is maintained stable. The output part of the oscillation generator is connected to the unblocking device and inserted into the screen pipe through a sliding seal. The external generator of the oscillation generator is connected to the unblocking device through a multi-interface connector. The oscillation generator generates hydraulic oscillation. The oscillation effect generates pressure excitation and oscillation of the liquid in the screen pipe through the output part of the oscillation generator connected to the unblocking device. The pressure excitation and oscillation are transmitted to the screen pipe through the liquid and act on the plugging material in the screen pipe. Through continuous oscillation, the plugging material gradually loosens and collapses, and is eventually washed away. The channel inside and outside the screen pipe increases, and the annular pressure between the casing and the screen pipe gradually decreases. However, the influence of plugging cannot be completely eliminated, so the pressure will decrease to P2, and the unblocking test is completed.

[0039] Step 2.4: Re-plugging test after unblocking. Repeat step 2.2 to conduct a new plugging test. The test process is the same as step 2.2, but the initial plugging pressure of the screen pipe is changed to P2 due to the influence of plugging. The time for the plugging to stabilize is T1, and the stable pressure is P3. The time for the plugging pressure to reach P1 is T2.

[0040] Step 2.5: Unblocking effect evaluation. Through the plugging-unblocking-re-plugging test process, the screen pipe plugging characteristic curve under two plugging conditions is obtained. The unblocking effect is evaluated through the P1=f1(t) and P2=f2(t) analytical curves. The better the unblocking effect, the closer the plugging curve of the re-plugging to the original screen pipe plugging curve, the smaller the pressure difference, and the smaller the difference between the integral results of the same pressure time of the plugging and the re-plugging. Set K and K1 as the integral values of the plugging and re-plugging to the same pressure time, and the formula is as follows:

[0041]

[0042]

[0043] Wherein, when the screen pipe is used for the first time, the time T reaches the plugging pressure P1, the process is considered that the screen pipe or the sand control medium has a better sand control effect, the plugging process is slow, the analytical equation of the curve is time-integrated to obtain K, and K is defined as the initial sand control effect value;

[0044] After the plugging removal operation is implemented, the screen pipe has been worn and cannot present the plugging curve in the first use, and the initial plugging removal operation starts at a higher pressure starting point P2 and reaches the same plugging pressure P1 in a shorter time T2, the analytical equation of the curve is time-integrated to obtain K1, and K1 is defined as the sand control effect value after the plugging removal operation;

[0045] Q is defined as the plugging removal effect value, and the calculation formula is:

[0046] Q=K-K1

[0047] In the experimental process of different plugging removal modes, the same P1 pressure is reached, the same method is used to evaluate the plugging removal effect, and finally the plugging removal effect is evaluated through the Q value; wherein, the larger the Q value is, the worse the plugging removal effect is, and the smaller the Q value is, the better the plugging removal effect is;

[0048] Step three:

[0049] Through a plurality of horizontal comparison tests, the plugging mechanism and law of the screen pipe with different shale contents and different particle sizes are analyzed, and the plugging removal effects of different plugging removal processes are also obtained. By filling gravel between the casing and the screen pipe, the plugging and plugging removal mechanism of the gravel packing layer can also be studied.

[0050] Compared with the prior art, the present application has the beneficial effects that:

[0051] ① It can be used for studying and evaluating the plugging process and law of the sand and mud in the hydrate production process to the near wellbore, causing the plugging of the sand control gravel packing layer and the sand control screen pipe pores;

[0052] ② It can be used for studying and evaluating the application effect of different plugging removal processes under the condition of high shale content and strong plugging, and carrying out adaptability evaluation, and optimizing the high-efficiency plugging removal process suitable for hydrate development;

[0053] ③ It can be used for evaluating the applicability of new plugging removal technology and to-be-developed plugging removal technology in the field of hydrate development, reserving a plugging removal multi-interface connector in the device, such as connecting a chemical agent plugging removal tank, and providing support for subsequent development of new plugging removal processes;

[0054] ④ It can be used for studying the plugging and plugging removal mechanism of the sand control medium under different well types, mainly including horizontal wells and vertical wells.

[0055] At the same time, the sand blocking medium permeability change rule and the plugging mechanism research can be used for the oil and gas industry, and provides support for long-term stable production of the oil and gas industry. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 The structure schematic view of the sand control medium plugging and unblocking evaluation device provided by the embodiment is shown in the figure.

[0057] Figure 2 The top view of the test main kettle body is shown in the figure.

[0058] Figure 3 The sectional view of the test main kettle body is shown in the figure.

[0059] Figure 4 The curve schematic view of the plugging rule is shown in the figure.

[0060] Figure 4 The curve schematic view of the unblocking process is shown in the figure.

[0061] Figure 5 The curve schematic view of the repeated plugging experiment after unblocking is shown in the figure.

[0062] Figure 5 The schematic view of the unblocking effect evaluation is shown in the figure.

[0063] In the figure, 1 is a data transmission channel, 2 is a gas-liquid flow meter, 3 is a three-phase mixed displacement kettle, 4 is a gas storage tank, 5 is a one-way variable hydraulic pump, 6 is a sand mixing tank, 7 is a multi-interface connector, 8 is an electric pulse unblocker, 9 is a biological enzyme culture tank, 10 is a sliding seal, 11 is an unblocker power mechanism, 12 is an oscillation generator, 13 is a sand settling tank, 14 is a gate valve, 15 is a test fluid channel, 16 is a sleeve, 17 is an unblocker, 18 is a sealing end cover, 19 is a screen pipe, 20 is a temperature measurement system, 21 is a pressure measurement system, 22 is a control terminal, and 23 is a support frame. DETAILED DESCRIPTION

[0064] Embodiment:

[0065] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection" should be understood broadly, for example, can be fixed connection, or detachable connection, or integrally connected, can be mechanical connection, or electrical connection, signal connection, can be directly connected, or indirectly connected through an intermediate medium, can be said to be connected inside two elements. For ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. The technical solutions of the present application are further described below in combination with the drawings and embodiments.

[0066] Reference Figure 1As shown, the sand control medium blocking and unblocking evaluation device provided by the embodiment mainly comprises a data transmission channel 1, a gas-liquid flowmeter 2, a three-phase mixed displacement kettle 3, a gas storage tank 4, a one-way variable hydraulic pump 5, a sand mixing tank 6, a multi-interface connector 7, an electric pulse unblocking device 8, a biological enzyme culture tank 9, an unblocking device power mechanism 11, an oscillation generator 12, a sand settling tank 13, a test fluid channel 15, a casing 16, an unblocking device 17, a screen pipe 19, a temperature measurement system 20, a pressure measurement system 21 and a control terminal 22.

[0067] The sand mixing tank 6 is used for mixing solid-liquid substances, so that the solid phase and the liquid phase are uniformly mixed according to the designed proportion; the gas storage tank 4 is connected with the three-phase mixed displacement kettle 3, so as to input gas into the three-phase mixed displacement kettle 3; specifically, the gas storage tank 4 can store different types of gas, such as methane gas and carbon dioxide gas.

[0068] The one-way variable hydraulic pump 5 is connected with the sand mixing tank 6, so as to pump the solid-liquid substances in the sand mixing tank 6 into the three-phase mixed displacement kettle 3; the three-phase mixed displacement kettle 6 is used for mixing the solid-liquid substances and the gas, and transmitting the mixed gas-liquid-solid three-phase into the test fluid channel 15; the test fluid channel 15 is a channel of test fluid of the whole device; through the test fluid channel 15, the gas-liquid flowmeter 2, the three-phase mixed displacement kettle 3, the gas storage tank 4, the one-way variable hydraulic pump 5, the sand mixing tank 6, the multi-interface connector 7, the electric pulse unblocking device 8, the biological enzyme culture tank 9, the oscillation generator 12, the sand settling tank 13, the gate valve 14, the casing 16, the unblocking device 17 and the screen pipe 19, the flow of the test fluid between each other is realized, and the displacement and flow rate of the fluid are controlled.

[0069] The test fluid channel 15 is connected with the casing 16, the casing 16 simulates the casing or well wall after reservoir reconstruction in actual production, the casing 16 is provided with an opening, so as to serve as an injection channel of the gas-liquid-solid three-phase; the screen pipe 19 is arranged in the casing 16, the screen pipe 19 and the casing 16 form a test main kettle body, and the test main kettle body is supported by a support frame 23; the screen pipe 19 is a test object, which is a tubular object with a porous structure, has the characteristics that the porous structure will be blocked under the action of a fluid containing mud, and the blockage will collapse under the action of liquid force and microorganisms, and the porous channel is partially or completely dredged, and the annular gap between the casing 16 and the screen pipe 19 can be filled with gravel as another sand control medium, which is used for test evaluation.

[0070] The plug remover 17 is inserted into the screen pipe 19 and reciprocally moves in the screen pipe 19 under the drive of the plug remover power mechanism 11, and the plug remover 17 is mainly a tubular structure; the plug remover power mechanism 11 provides power and support for the reciprocating movement of the screen pipe 19 and can meet the set moving speed of entering or extracting the screen pipe 19. At the same time, the whole test main kettle body can be changed from a horizontal state to a vertical state to simulate the plugging and plug removal mechanism of different flow states such as horizontal wells and vertical wells under the influence of gravity.

[0071] The plug remover 17 is connected with the multi-interface connector 7, and the multi-interface connector 7 is used for different plug removal devices, so that quick connection and replacement of different plug removal modes can be provided, and the application feasibility of different plug removal modes in hydrate exploitation can be met. Different plug removal devices include an electric pulse plug remover 8, a biological enzyme culture tank 9, and an oscillation generator 12; the electric pulse plug remover 8 provides a liquid pulse generated by electric explosion, and the high-pressure pulse acts on the screen pipe 19 through the plug remover 17 to produce a plug removal effect on the plug in the screen pipe 19; the microbial enzyme culture tank 9 provides a microorganism that can decompose silt particles in a deep-sea water environment, enters the plug remover 17 through the multi-interface connector 7, and acts on the screen pipe 19. After a period of microbial plug removal reaction, the original plug is dredged, and the permeability is restored; the oscillation generator 12 generates liquid oscillation through a piston, and the liquid enters the plug remover 17 through the multi-interface connector 7, the test fluid channel 15, etc. and acts on the screen pipe 19 to achieve a physical plug removal.

[0072] The sand tank 13 is used for collecting solid-phase liquid flowing out from the inside of the screen pipe 19 and flowing out from the annulus between the screen pipe 19 and the casing 16; and the sand is collected by sedimentation for subsequent test analysis and evaluation.

[0073] The gas-liquid flowmeter 2 is used for monitoring the flow of the fluid and gas injected through the test fluid channel; the temperature measurement system 20 is used for monitoring the temperature in the casing to provide a temperature change curve in the test process; the pressure measurement system 22 is used for monitoring the pressure in the casing to provide a pressure change curve in the test process; the control terminal 22 is connected with the gas-liquid flowmeter 2, the temperature measurement system 20, and the pressure measurement system 21 through the data transmission channel 1 respectively; in addition, the control terminal 22 is also connected with the three-phase mixed displacement kettle 3, the one-way variable hydraulic pump 5, the electric pulse plug remover 8, the biological enzyme culture tank 9, the plug remover power mechanism 11, the oscillation generator 12, and other electrical elements through the data transmission channel 1 to form a circuit control of the whole device, realize software control on each control unit, and display, process, and store the collected data of pressure, temperature, etc. in real time.

[0074] As a preferred embodiment of the sand control medium plugging and unblocking evaluation device, a gate valve 14 is installed on the pipeline connecting the test fluid passage 15 and the casing 16 opening, and the flow state of the test fluid in the test fluid passage can be controlled by the switch, which can meet the research of the plugging and unblocking mechanism under different flow states

[0075] As another preferred embodiment of the sand control medium plugging and unblocking evaluation device, a sliding seal 10 is further included, which is arranged at the insertion position of the unblocking device 17 and the screen pipe 19 to ensure that the unblocking device 17 reciprocates under the action of the unblocking device power mechanism 11, and the seal between the inside and outside of the test kettle body is not leaked.

[0076] As a further preferred embodiment of the sand control medium plugging and unblocking evaluation device, a sealing end cover 18 is further included, which is arranged at the other end of the screen pipe 19 without inserting the unblocking device 17. By arranging the sealing end cover 18, fluid can be injected and discharged from one side, and the demand for rapid replacement of the screen pipe after a group of tests can be met, which is conducive to repeated development of lateral comparison experiments and systematic study of the plugging and unblocking characteristics of hydrate reservoirs with fine particle size and high mud content.

[0077] Taking the oscillation unblocking as an example, a sand control medium plugging and unblocking evaluation method is provided, and the evaluation methods of other unblocking modes are similar.

[0078] Step one:

[0079] The test device is built, and each part is debugged to ensure normal operation. The test materials and test supplies, personnel, etc. are prepared, and the pre-test preparation work is done;

[0080] Step two:

[0081] Step 2.1: The mixed and metered solid-liquid material, including mass, particle size distribution, etc., is mixed in the sand mixing tank 6, the gas is provided by the gas storage tank 4, and after entering the three-phase mixing displacement kettle 3, it is fully mixed, pumped into the casing 16 by the single variable hydraulic pump 5, and the flow rate, temperature and pressure, etc. Data are monitored by the gas-liquid flow meter 2, pressure measurement system 21 and temperature measurement system 20, and transmitted to the control terminal 22.

[0082] Step 2.2: Start the plugging test, continuously pump the three-phase material into the casing 16 by the single variable hydraulic pump 5, and the mud sand fluid passes through the casing 16 opening into the annulus between the casing 16 and the screen pipe 19, and then passes through the screen pipe 19 and is discharged to the sand settling tank 13 through the outlet. Observe the data displayed by the control terminal 22. Due to the plugging of the mud sand, the seepage channel inside and outside the screen pipe 19 is reduced, the annular pressure between the casing 16 and the screen pipe 19 gradually rises, and finally reaches a slow growth state. When the pump is stopped, the plugging test is completed. In T time, the annular pressure between the casing 16 and the screen pipe 19 reaches P1, and the test time-pressure curve is shown inFigure 4 a shown;

[0083] Step 2.3: Start the unblocking test, maintain the solid-liquid material in the screen pipe 19, connect the output part of the oscillation generator 12 with the unblocking device 17, and insert it into the screen pipe 19 through the sliding seal 10, and connect the external generator of the oscillation generator 12 with the unblocking device 17 through the multi-interface connector 7. Through the oscillation generator 12, liquid force oscillation is generated, and the oscillation effect generates pressure excitation and oscillation of the liquid in the 19 through the output part of the oscillation generator 12 connected with the unblocking device 17, and the pressure excitation and oscillation are transmitted to the 19 through the liquid, and act on the blockage in the pores inside the screen pipe 19, and through continuous oscillation, the blockage gradually loosens and collapses, and is finally washed away, and the pressure in the annulus between the casing 16 and the screen pipe 19 will gradually decrease, but the effect of the blockage cannot be eliminated, so the pressure will decrease to P2, and the unblocking test is ended, and the unblocking process is shown in Figure 4 b.

[0084] Step 2.4: Re-blocking test after unblocking, in order to evaluate the unblocking effect, the step 2.2 process needs to be repeated to conduct a re-blocking test, and the test process is the same as step 2.2, but due to the influence of the blockage, the initial blocking pressure of the screen pipe becomes P2, the time for the final blocking to stabilize is T1, and the stable pressure is P3. The time for the blocking pressure to reach P1 is T2. The re-blocking test is shown in Figure 5 a.

[0085] Step 2.5: Unblocking effect evaluation, through the test process of blocking-unblocking-re-blocking, the screen pipe blocking characteristic curve under the condition of twice blocking can be obtained, as shown in Figure 5 b. Through the P1=f1(t), P2=f2(t) analysis curve, the unblocking effect evaluation is conducted. The better the unblocking effect is, the closer the blocking curve of the re-blocking to the blocking curve of the original screen pipe is, the smaller the pressure difference is, and the smaller the difference of the integral result of the same pressure time is, so K and K1 are set as the integral values of the blocking and re-blocking to the same pressure time, and the formula is as follows:

[0086]

[0087]

[0088] Wherein, when the screen pipe is used for the first time, the time T reaches the blocking pressure P1, and this process is considered that the screen pipe or the sand retaining medium has a good sand retaining effect, and the blocking process is slow, and the time integral of the analysis equation of the curve is obtained, and K is defined as the initial sand control effect value.

[0089] After the unblocking operation is implemented, the screen tube has been worn out and can no longer show the clogging curve when it was first used. Initially, it will start at a higher pressure starting point P2 and reach the same clogging pressure P1 in a shorter time T2. The analytical equation of the curve is integrated over time to obtain K1, which is defined as the sand control effect value after unblocking.

[0090] Then Q is defined as the unblocking effect value, and its calculation formula is:

[0091] Q = K - K1

[0092] In all experiments involving different unblocking methods, the same P1 pressure was achieved, and the same method was used to evaluate the unblocking effect. The final evaluation was based on the Q value. A larger Q value indicates a worse unblocking effect, while a smaller Q value indicates a better unblocking effect.

[0093] Step 3:

[0094] Through multiple sets of comparative experiments, the clogging mechanism and patterns of screens with different mud contents and particle sizes can be analyzed, and the unclogging effects of different unclogging processes can also be obtained. By filling the space between the casing 16 and the screen 19 with gravel, the clogging and unclogging mechanisms of the gravel-filled layer can also be studied. This provides support for the long-term stable production of hydrates.

[0095] In summary, compared with the prior art, the present invention has the following technical features:

[0096] ① It can be used to study and evaluate the process and regularity of mud and sand transport to the vicinity of the wellbore during hydrate production, resulting in the filling of the sand-blocking gravel layer and the blockage of the sand-control screen pores;

[0097] ② It can be used to study and evaluate the application effects of different unblocking processes under high mud content and strong clogging conditions, and to conduct adaptability evaluations to select the most efficient unblocking processes suitable for hydrate development;

[0098] ③ It can be used to evaluate the applicability of new unblocking technologies and unblocking technologies to be developed in the field of hydrate development. The device is equipped with multi-interface connectors for unblocking, such as connecting chemical unblocking tanks, to support the subsequent development of new unblocking processes.

[0099] ④ It can be used to study the blockage and unblocking mechanisms of sand-blocking media under different well types, mainly including horizontal wells and vertical wells.

[0100] ⑤ It can also be used to study the permeability variation law and unblocking mechanism of sand-blocking media in the oil and gas industry, providing support for the long-term stable production of the oil and gas industry.

[0101] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for evaluating the blockage and unblocking of sand-controlling media, the method being based on a device for evaluating the blockage and unblocking of sand-controlling media, characterized in that, The sand-controlling medium blockage and unblocking evaluation device includes a gas-liquid flow meter, a three-phase mixing displacement vessel, a gas storage tank, a unidirectional variable hydraulic pump, a sand mixing tank, a multi-port connector, an unblocking device power mechanism, a settling tank, a test fluid channel, a sleeve, an unblocking device, a sieve tube, a temperature measurement system, a pressure measurement system, and a control terminal; wherein... The mixing tank is used to mix solid and liquid substances; The gas storage tank is connected to the three-phase mixing and displacement vessel for inputting gas into the three-phase mixing and displacement vessel; The unidirectional variable hydraulic pump is connected to the sand mixing tank to pump the solid-liquid substances in the sand mixing tank to the three-phase mixing displacement vessel. The three-phase mixing displacement vessel is used to mix solid-liquid substances and gases, and to transfer the mixed gas-liquid-solid three-phase mixture to the test fluid channel; The test fluid channel is connected to the sleeve, and the sleeve has an opening to serve as an injection channel for the gas-liquid-solid three phases. The sieve tube is installed inside the sleeve; the sieve tube and the sleeve together form the main experimental vessel body; The unblocking device is inserted into the screen tube and reciprocates within the screen tube under the drive of the unblocking device power mechanism; the unblocking device is connected to the multi-interface connector, which is used to connect to different unblocking devices; The settling tank is used to collect solid-phase liquid flowing out from inside the screen tube and from the annulus of the screen tube and sleeve. The gas-liquid flow meter is used to monitor the flow rate of the fluid and gas injected into the test fluid channel; The temperature measurement system is used to monitor the temperature inside the sleeve; The pressure measurement system is used to monitor the pressure inside the casing; The control terminal is connected to the gas-liquid flow meter, the temperature measurement system, and the pressure measurement system, respectively. The unblocking device is an oscillation generator. The oscillation generator generates hydraulic oscillation through a piston. The hydraulic force enters the unblocking device through the multi-port connector and the test fluid channel, and acts on the sieve tube to achieve unblocking in a physical way. The method includes: Step 1: Set up the testing and evaluation equipment and debug each component to ensure that it can work properly; Step Two: Step 2.1: The metered solid and liquid substances are mixed in a sand mixing tank, including mass and particle size distribution. Gas is supplied by a gas storage tank and enters a three-phase mixing displacement vessel for thorough mixing. The mixture is then pumped into the casing by a one-way variable hydraulic pump. The flow rate, temperature and pressure data are monitored by a gas-liquid flow meter, a pressure measurement system, and a temperature measurement system and transmitted to the control terminal. Step 2.2: Begin the blockage test. Use a unidirectional variable hydraulic pump to continuously pump in three-phase material. The muddy and sandy fluid enters the annulus between the casing and the screen pipe through the casing opening. After passing through the screen pipe, it is discharged to the sedimentation tank through the outlet. Observe the data displayed on the control terminal. Due to the blockage of mud and sand, the seepage channels inside and outside the screen pipe are reduced, and the annulus pressure between the casing and the screen pipe gradually increases. When it finally reaches a slow growth state, stop pumping and the blockage test ends. Within time T, the pressure of the annulus between the casing and the screen pipe reaches P1. Step 2.3: Begin the unblocking test. To maintain the stability of the blockage structure inside the screen tube, connect the output part of the oscillator to the unblocker and insert it into the screen tube through a sliding seal. The external generator of the oscillator is connected to the unblocker through a multi-port connector. The oscillator generates hydraulic oscillations. The oscillation effect generates pressure excitation and oscillation of the liquid inside the screen tube through the output part of the oscillator connected to the unblocker. The pressure excitation and oscillation are transmitted to the screen tube through the liquid and act on the blockage in the pores inside the screen tube. Through continuous oscillation, the blockage gradually loosens and collapses, and is eventually flushed away. The channels inside and outside the screen tube increase, and the pressure in the sleeve screen tube ring space will gradually decrease. However, the effect of the blockage cannot be completely eliminated. Therefore, the pressure will decrease to P2, and the unblocking test will end. Step 2.4: After unblocking, conduct a re-blocking test. Repeat step 2.2 to conduct a re-blocking test. The test process is the same as in step 2.2, but due to the influence of blockage, the initial blockage pressure of the screen tube becomes P2, the final blockage stabilization time is T1, and the stabilization pressure is P3; the time when the blockage pressure reaches P1 is T2. Step 2.5: Evaluation of Unblocking Effect. Through a test process of creating blockage, unblocking, and re-creating blockage, the characteristic curves of screen tube blockage under two blockage-creating conditions are obtained. The unblocking effect is evaluated using the analytical curves P1 = f1(t) and P2 = f2(t). The better the unblocking effect, the closer the re-created blockage curve is to the original screen tube blockage curve, and the smaller the pressure difference. This results in a smaller difference in the integral of the time from blockage to the same pressure. K and K1 are set as the integral values ​​of the time from blockage to re-creating blockage to the same pressure, as shown in the following formula: When the screen tube is used for the first time, it takes time T to reach the clogging pressure P1. This process is considered to have a good sand-blocking effect. The clogging process is slow. The analytical equation of the curve is integrated over time to obtain K, which is defined as the initial sand control effect value. After the unblocking operation is implemented, the screen tube has been worn out and can no longer show the clogging curve when it was first used. Initially, it will start at a higher pressure starting point P2 and reach the same clogging pressure P1 in a shorter time T2. The analytical equation of the curve is integrated over time to obtain K1, which is defined as the sand control effect value after unblocking. Then Q is defined as the unblocking effect value, and its calculation formula is: Q = K - K1 In the experiments with different unblocking methods, the same P1 pressure was achieved, and the same method was used to evaluate the unblocking effect. Finally, the unblocking effect was evaluated by the Q value; the larger the Q value, the worse the unblocking effect, and the smaller the Q value, the better the unblocking effect. Step 3: Through multiple sets of comparative experiments, the clogging mechanism and regularity of screen tubes with different mud contents and different particle sizes were analyzed, and the unclogging effect of different unclogging processes was also obtained. By filling the space between the casing and the screen tube with gravel, the clogging and unclogging mechanism of the gravel filling layer can also be studied.

2. The method for evaluating sand-controlling medium blockage and unblocking as described in claim 1, characterized in that, A gate valve is installed on the pipeline connecting the test fluid channel and the sleeve opening.

3. The method for evaluating sand-controlling medium blockage and unblocking as described in claim 1, characterized in that, The sand control medium blockage and unblocking evaluation device also includes a sliding seal, which is located at the insertion position of the unblocker and the screen tube.

4. The method for evaluating sand-controlling medium blockage and unblocking as described in claim 1, characterized in that, The sand control medium blockage and unblocking evaluation device also includes a sealing end cap, which is located at the other end of the screen tube where the unblocking device is not inserted.

5. The method for evaluating sand-controlling medium blockage and unblocking as described in claim 1, characterized in that, Gravel can be filled in the annular space between the sleeve and the screen tube.

6. The method for evaluating sand-controlling medium blockage and unblocking as described in claim 1, characterized in that, The sand control medium blockage and unblocking evaluation device also includes a support frame to provide support for the entire test vessel.

Images