Reservoir damage simulation system and reservoir damage measurement method

Abstract

This application discloses a reservoir damage simulation system and reservoir damage measurement method, wherein the reservoir damage simulation system includes a clamping device, a displacement device, a mud circulation device, and a target core. The clamping device includes a spacer and a core clamp, the spacer being located outside the target core and clamped by the core clamp via the spacer. The displacement device is connected to the core clamp and is configured to deliver a displacement medium into the spacer layer where the spacer is located. The target core has a hollow damage portion, which is connected to the mud circulation device, which is configured to inject drilling fluid into the hollow damage portion. The reservoir damage simulation system and reservoir damage measurement method disclosed in this application can more comprehensively and scientifically simulate the reservoir damage process during drilling and accurately measure the extent of reservoir damage.

Description

Technical Field

[0001] The present application relates to the technical field of oil drilling engineering research, and in particular to a reservoir damage simulation system and a reservoir damage measurement method. Background Art

[0002] The reservoir damage process during drilling refers to the process in which the drilling fluid undergoes various physical and chemical reactions with the surrounding reservoir rocks during circulation, resulting in a decrease in the permeability of the reservoir surrounding the wellbore. Studying the reservoir damage process during drilling is of great significance for the scientific evaluation of reservoir damage during drilling.

[0003] Regarding reservoir damage assessment methods, the industry standard SY / T6540-2002, "Indoor Evaluation Method for Damaged Reservoirs Caused by Drilling and Completion Fluids," assesses the extent of reservoir damage by measuring the change in axial permeability of standard cores before and after immersion in damaging fluids. Current domestic reservoir damage assessment methods are largely based on this principle.

[0004] However, whether drilling fluid intrudes into the wellbore and damages the reservoir during drilling, or formation oil and gas seeps into the wellbore during gas (oil) production, the downhole fluid flows radially. Evaluating reservoir damage using axial permeability differs from the radial flow patterns of drilling fluid and formation oil and gas during actual drilling. Therefore, the measured reservoir damage level is inaccurate and of limited reference value. Summary of the Invention

[0005] In view of this, the present application provides a reservoir damage simulation system and a reservoir damage measurement method, which can measure the extent of reservoir damage more accurately and scientifically.

[0006] This application specifically adopts the following technical solutions:

[0007] On the one hand, the present application provides a reservoir damage simulation system, which includes a clamping device, a displacement device, a mud circulation device and a target core.

[0008] The clamping device includes a spacer and a core clamp, wherein the spacer is located outside the target core, and the core clamp clamps the target core through the spacer;

[0009] The displacement device is connected to the core holder, and the displacement device is configured to deliver a displacement medium into the spacer layer where the spacer is located;

[0010] The target core has a hollow damaged portion, the hollow damaged portion is communicated with the mud circulation device, and the mud circulation device is configured to inject drilling fluid into the hollow damaged portion.

[0011] Preferably, the hollow damage portion is a groove opened on the target core, and the open end of the groove has a sealing plug;

[0012] The mud circulation device is communicated with the inner cavity of the groove.

[0013] Preferably, the mud circulation device includes a mud circulation pipeline, and a mud circulation pump and a mud pressure gauge sequentially connected to the mud circulation pipeline along the flow direction of the drilling fluid;

[0014] The mud circulation pipeline is configured to penetrate the sealing plug and communicate with the inner cavity of the groove;

[0015] The inlet of the mud circulation pipeline is close to the open end of the groove, and the outlet of the mud circulation pipeline is close to the closed end of the groove, and the closed end is opposite to the open end.

[0016] Preferably, the mud circulation device further includes a mud pressure stabilizing container and a mud preheating temperature control unit.

[0017] The mud pressure stabilizing container is arranged between the inlet of the mud circulation pipeline and the mud circulation pump;

[0018] The mud preheating temperature control unit is connected to the mud pressure stabilizing container and is configured to heat the drilling fluid in the mud circulation pipeline.

[0019] Preferably, the displacement device comprises a gas permeation circulation unit, and the gas permeation circulation unit comprises a gas pressurization pipeline and a gas back-pressure pipeline;

[0020] The gas boosting pipeline is connected to the core holder and the outlet end of the gas boosting pipeline is communicated with the spacer layer. Along the gas flow direction, the gas boosting pipeline is sequentially provided with a gas storage bottle, a gas boosting pump, a gas injection pressure gauge and a gas injection valve;

[0021] The gas back-pressure pipeline is connected to the core clamp and the inlet end of the gas back-pressure pipeline is communicated with the hollow damaged part. Along the gas flow direction, the gas back-pressure pipeline is sequentially provided with an outlet valve, a gas flow meter and a gas back-pressure valve. The outlet end of the gas back-pressure pipeline is connected to the gas boosting pipeline and is located between the gas boosting pump and the gas injection pressure gauge.

[0022] Preferably, the gas boosting pipeline is further provided with a first gas pressure-stabilizing container, the first gas pressure-stabilizing container is located between the gas boosting pump and the gas injection pressure gauge, the outlet end of the gas back-pressure pipeline is connected to the first gas pressure-stabilizing container, and the first gas pressure-stabilizing container is connected to a high-pressure reducing valve; and / or,

[0023] A second gas pressure-stabilizing container is further provided on the gas back-pressure pipeline. The second gas pressure-stabilizing container is located between the gas outlet valve and the gas back-pressure valve. The gas flow meter is connected to the second gas pressure-stabilizing container.

[0024] Preferably, the displacement device further comprises a liquid permeation circulation unit, and the liquid permeation circulation unit comprises a liquid pressurization pipeline and a liquid back-pressure pipeline;

[0025] The liquid boosting pipeline is connected to the core holder and the outlet end of the liquid boosting pipeline is communicated with the spacer layer. Along the liquid flow direction, the liquid boosting pipeline is sequentially provided with a liquid storage tank, a liquid boosting pump and a liquid injection valve;

[0026] The liquid back-pressure pipeline is connected to the core holder and the inlet end of the liquid back-pressure pipeline is in communication with the hollow damaged part. Along the direction of liquid flow, the liquid outlet valve, the liquid back-pressure unit and the liquid back-pressure valve are sequentially arranged on the liquid back-pressure pipeline. The outlet end of the liquid back-pressure pipeline is connected to the liquid pressurization pipeline and is located between the injection valve and the outlet end of the liquid pressurization pipeline. The liquid back-pressure unit is connected to a liquid metering device, and the liquid metering device is configured to obtain the liquid flow rate seeping from the hollow damaged part.

[0027] Preferably, a liquid pressure stabilizing container is further provided on the liquid boosting pipeline, and the liquid pressure stabilizing container is located between the liquid boosting pump and the liquid injection valve.

[0028] Preferably, the outlet end of the liquid pressurizing pipeline is connected to the gas pressurizing pipeline and is located between the gas injection valve and the outlet end of the gas pressurizing pipeline; and / or,

[0029] The inlet end of the liquid back-pressure pipeline is connected to the gas back-pressure pipeline and is located between the inlet end of the gas back-pressure pipeline and the gas outlet valve; and / or,

[0030] The outlet end of the liquid back-pressure pipeline is connected to the first gas pressure-stabilizing container.

[0031] Another aspect of the present application is to provide a reservoir damage determination method, which is implemented by the above-mentioned reservoir damage simulation system, and comprises:

[0032] Obtaining a target rock core, and clamping the target rock core with a clamping device;

[0033] delivering a displacement medium into the spacer layer where the spacer of the clamping device is located by a displacement device to obtain the initial permeability of the target core;

[0034] delivering drilling fluid to the hollow damaged portion of the target core through a mud circulation device, and circulating the drilling fluid in the hollow damaged portion for a set time to obtain the damaged target core;

[0035] delivering the displacement medium into the spacer layer through the displacement device to obtain the damaged permeability of the damaged target core;

[0036] The degree of reservoir damage is determined based on the initial permeability and the damaged permeability.

[0037] The beneficial effects of the embodiments of the present application are at least:

[0038] The reservoir damage simulation system provided by the embodiment of the present application uses a target core having a hollow damage portion, a clamping device that can clamp the target core, and the clamping device and the target core are not in direct contact, and there is a spacer layer between the two that can accommodate the displacement medium. During the simulation, the displacement device can be used to first transport the displacement medium into the spacer layer to determine the initial permeability of the target core, and then the mud circulation device can be started to inject drilling fluid into the hollow damage portion to damage the target core. After the damage is completed, the displacement device can be used again to transport the displacement medium into the spacer layer to determine the damage permeability of the target core after the damage, so that the damage degree of the target core can be obtained based on the permeability of these two displacements, and then the damage degree of the reservoir where the target core is located can be obtained. The reservoir damage simulation system provided by the embodiment of the present application more comprehensively, scientifically and objectively simulates the damage process of the reservoir during the drilling process, so that a more accurate degree of reservoir damage can be determined, providing an important reference basis for decision-making during the drilling construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 This is a schematic structural diagram of a clamping device provided in an embodiment of the present application;

[0041] Figure 2 This is a schematic structural diagram of a displacement device provided in an embodiment of the present application;

[0042] Figure 3 This is a schematic structural diagram of a mud circulation device provided in an embodiment of the present application;

[0043] Figure 4 This is a schematic structural diagram of a confining pressure device provided in an embodiment of the present application;

[0044] Figure 5 It is a structural schematic diagram of a temperature control device provided in an embodiment of the present application.

[0045] Reference numerals:

[0046] 100, clamping device; 110, spacer; 120, core clamp;

[0047] 200. Displacement device;

[0048] 210. Gas booster pipeline; 211. Gas storage cylinder; 212. Gas booster pump; 213. Gas injection pressure gauge; 214. Gas injection valve; 215. First gas pressure-stabilizing container; 216. High-pressure pressure reducing valve;

[0049] 220, gas back-pressure pipeline; 221, gas outlet valve; 222, gas flow meter; 223, gas back-pressure valve; 224, second gas pressure-stabilizing container;

[0050] 230. Liquid booster pipeline; 231. Liquid storage tank; 232. Liquid booster pump; 233. Liquid injection valve; 234. Liquid pressure stabilizing container;

[0051] 240. Liquid back-pressure pipeline; 241. Liquid outlet valve; 242. Liquid back-pressure unit; 243. Liquid back-pressure valve; 244. Liquid metering equipment;

[0052] 300, mud circulation device; 310, mud circulation pipeline; 311, inlet; 312, outlet; 320, mud circulation pump; 330, mud pressure gauge; 340, mud pressure stabilizing container; 350, mud preheating temperature control unit;

[0053] 400, target core; 410, hollow lesion; 420, sealing plug;

[0054] 500, confining pressure device;

[0055] 510, confining pressure boosting pipeline; 511, confining pressure boosting valve; 512, confining pressure gauge;

[0056] 520, confining pressure and back pressure pipeline; 521, back pressure boosting valve;

[0057] 530. Confining pressure safety pipeline; 531. Confining pressure safety valve;

[0058] 600. Temperature control device; 610. Temperature control instrument; 620. Heating temperature control unit; 630. Heater.

[0059] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0061] The present invention provides a reservoir damage simulation system, which includes a clamping device 100, a displacement device 200, a mud circulation device 300, and a target core 400. The clamping device 100 includes a core clamp 120 and a spacer 110. The spacer 110 is located outside the target core 400, and the core clamp 120 clamps the target core 400 through the spacer 110. The displacement device 200 is connected to the core clamp 120 and is configured to deliver a displacement medium into the spacer layer where the spacer 110 is located. The target core 400 has a hollow damage portion 410, which is connected to the mud circulation device 300.

[0062] The reservoir damage simulation system provided by the embodiment of the present application uses a target core 400 having a hollow damaged portion 410. The clamping device 100 can clamp the target core 400, and the clamping device 100 and the target core 400 are not in direct contact. There is a spacer layer between the two that can accommodate the displacement medium. During the simulation, the displacement device 200 can be used to first deliver the displacement medium into the spacer layer to determine the initial permeability of the target core 400, and then the mud circulation device 300 can be started to inject drilling fluid into the hollow damaged portion 410 to damage the target core 400. After the damage is completed, the displacement device 200 is used again to deliver the displacement medium into the spacer layer to determine the damage permeability of the target core 400 after the damage. Therefore, the damage degree of the target core 400 can be obtained based on the permeability of these two displacements, and then the damage degree of the reservoir where the target core 400 is located can be obtained. The reservoir damage simulation system provided in the embodiment of the present application simulates the reservoir damage process during drilling in a more comprehensive, scientific and objective manner, thereby being able to determine a more accurate degree of reservoir damage and providing an important reference basis for decision-making during drilling construction.

[0063] In order to make the technical solutions and advantages of this application clearer, Figure 1-5, a reservoir damage simulation system provided in an embodiment of the present application is further introduced and explained.

[0064] The reservoir damage simulation system provided in the embodiment of the present application includes a clamping device 100 , a displacement device 200 , a mud circulation device 300 and a target core 400 .

[0065] like Figure 1 As shown, the clamping device 100 includes a spacer 110 and a core clamp 120. The spacer 110 is located outside the target core 400, and the core clamp 120 can clamp the target core 400 through the spacer 110. The spacer 110 is used to form a spacer layer. Due to the presence of the spacer layer, the core clamp 120 does not directly contact the target core 400 when clamping the target core 400, and the spacer layer can accommodate the displacement medium.

[0066] In the embodiment of the present application, the spacer 110 may be, for example, a steel mesh or a partition plate, and has a high pressure-bearing strength, and can withstand the high-pressure clamping of the core clamp 120 .

[0067] like Figure 2 As shown, the displacement device 200 is connected to the core holder 120 and is configured to deliver a displacement medium into the spacer layer where the spacer 110 is located. The displacement medium in the spacer layer can directly contact the outer wall of the target core 400, thereby penetrating the target core 400 under pressure, simulating the gas (oil) production process of reservoir oil and gas radially penetrating into the wellbore.

[0068] like Figure 3 As shown, target core 400 has a hollow lesion 410, which is used to simulate a drilling wellbore. Hollow lesion 410 is connected to a mud circulation device 300, which is configured to circulate drilling fluid into hollow lesion 410, thereby simulating the circulation process of drilling fluid in the wellbore. The drilling fluid injected into hollow lesion 410 can penetrate the periphery of target core 400, simulating the radial seepage process of actual drilling reservoir damage.

[0069] Therefore, the reservoir damage simulation system provided in the embodiment of the present application can simulate the process of drilling fluid radially invading the wellbore to damage the reservoir and the gas (oil) production process of formation oil and gas radially penetrating into the wellbore. At the same time, it simulates the process of drilling fluid circulating in the wellbore. The simulation is more comprehensive, objective and scientific, and can help determine the degree of reservoir damage in a more scientific, reasonable and accurate manner.

[0070] like Figure 1As shown, in some implementations of the present invention, the hollow lesion 410 can be a groove formed in the target core 400, with a sealing plug 420 disposed at the open end of the groove. The sealing plug 420 is used to isolate the inner cavity of the groove from the spacer layer, preventing the displacement medium from directly entering the inner cavity of the groove through the open end of the groove and affecting the permeation measurement. No displacement medium can penetrate through the sealing plug 420.

[0071] In some embodiments, the target core 400 may be a cylindrical structure, and the groove may be a cylindrical groove. The axis of the target core 400 coincides with the axis of the groove, so that the displacement medium in the spacer layer can evenly penetrate the interior of the groove. For example, the target core 400 may be a cylindrical structure with a diameter of 105 mm and a height of 100 to 200 mm. A blind hole is drilled axially on the top surface of the cylindrical target core 400 to form a cylindrical groove. The axis of the cylindrical groove coincides with the axis of the cylindrical target core 400. The diameter of the cylindrical groove may be 34 mm. The closed end of the groove is 20 to 50 mm away from the bottom surface of the cylindrical target core 400. The closed end of the groove refers to the end opposite the open end located on the top surface of the target core 400.

[0072] like Figure 3 As shown, the mud circulation device 300 is communicated with the inner cavity of the groove, so that drilling fluid can be injected into the inner cavity of the groove and circulated.

[0073] In the embodiment of the present application, the mud circulation device 300 may include a mud circulation pipeline 310, and a mud circulation pump 320 and a mud pressure gauge 330 sequentially connected to the mud circulation pipeline 310 along the flow direction of the drilling fluid.

[0074] The mud circulation line 310 is configured to penetrate the sealing plug 420 and communicate with the inner cavity of the groove. Thus, the inner cavity of the groove is connected to the outlet 312 and inlet 311 of the mud circulation line 310. The outlet 312 of the mud circulation line 310 is located near the closed end of the groove, while the inlet 311 of the mud circulation line 310 is located near the open end of the groove. During circulation, drilling fluid flows out of the outlet 312 of the mud circulation line 310 and enters the bottom of the inner cavity of the groove. As the amount of drilling fluid injected increases, the liquid level of the drilling fluid gradually rises to near the open end and flows back into the mud circulation line 310 through the inlet 311 located at the open end.

[0075] The mud circulation pump 320 provides driving force for the drilling fluid, allowing it to circulate in a set direction at a set circulation pressure. A mud pressure gauge 330 is located near the outlet 312 of the mud circulation pipeline 310 to measure and display the mud circulation pressure in the mud circulation pipeline 310, facilitating pressure control by technicians.

[0076] In other embodiments of the present application, the mud circulation pipeline 310 may further include a mud pressure stabilizing container 340 and a mud preheating temperature control unit 350 .

[0077] After the drilling fluid enters the mud circulation pipeline 310, the presence of air in the pipeline creates resistance to the flow of the drilling fluid. The magnitude of this resistance varies with the flow rate of the drilling fluid. Therefore, a mud pressure stabilizing vessel 340 can be installed between the inlet 311 of the mud circulation pipeline 310 and the mud circulation pump 320. This vessel can compensate for the flow of the drilling fluid and ensure a uniform flow rate.

[0078] The mud preheating temperature control unit 350 is connected to the mud pressure-stabilizing container 340 and is configured to heat the drilling fluid in the mud circulation pipeline 310. During the drilling process, the drilling fluid is typically heated by the formation to the corresponding formation temperature. Therefore, to more realistically simulate the bottomhole environment, the system is also equipped with a mud preheating temperature control unit 350 to heat the drilling fluid. Before circulating the drilling fluid, the mud preheating temperature control unit 350 can heat the drilling fluid to a set temperature, thereby more realistically and objectively simulating the drilling fluid circulation process. The set temperature is equal to the formation temperature of the target core 400.

[0079] At this point, the mud circulation device 300 can comprehensively and objectively simulate the circulation temperature, mud circulation pressure, circulation path and reservoir damage mode of the drilling fluid, basically restoring the process of drilling fluid circulation in the wellbore, and the damage to the target core 400 in the simulation experiment is more scientific and accurate.

[0080] Figure 2 The structure of a displacement device 200 is shown. The displacement device 200 includes a gas permeation circulation unit, which may include a gas pressurization pipeline 210 and a gas back-pressure pipeline 220.

[0081] like Figure 2 As shown, a gas booster line 210 is connected to the core holder 120, and the outlet of the gas booster line 210 is in communication with the spacer layer. Along the direction of gas flow, the gas booster line 210 is sequentially provided with a gas cylinder 211, a gas booster pump 212, a gas injection pressure gauge 213, and a gas injection valve 214. After the gas injection valve 214 is opened and the gas booster pump 212 is started, the gas in the gas cylinder 211 can be injected into the spacer layer under the drive of the gas booster pump 212. Under the gas displacement pressure, the gas penetrates from the outer wall of the target core 400 into the hollow damaged portion 410 of the target core 400. The gas injection pressure gauge 213 can measure and display the pressure at the outlet of the gas booster line 210 (i.e., the inlet pressure of the spacer layer), facilitating technicians to adjust the gas displacement pressure.

[0082] In some embodiments of the present application, the gas medium used for gas displacement may be nitrogen with good stability. Accordingly, the gas storage cylinder 211 on the gas boosting pipeline 210 may be a nitrogen cylinder, and the gas boosting pump 212 may be a nitrogen booster.

[0083] Continue to see Figure 2 The gas back-pressure pipeline 220 is connected to the core clamp 120 and the inlet end of the gas back-pressure pipeline 220 is communicated with the hollow damaged part 410. Along the gas flow direction, the gas back-pressure pipeline 220 is sequentially provided with an outlet valve 221, a gas flow meter 222 and a gas back-pressure valve 223. The outlet end of the gas back-pressure pipeline 220 is connected to the gas boosting pipeline 210 and is located between the gas boosting pump 212 and the gas injection pressure gauge 213.

[0084] After the outlet valve 221 and the gas back-pressure valve 223 are opened, the gas that has penetrated the hollow lesion 410 can be back-pressurized through the gas back-pressure pipeline 220. The outlet of the gas back-pressure pipeline 220 is connected to the gas booster pipeline 210, forming a circulation path, simulating the gas displacement process during drilling. The gas flowmeter 222 can detect the gas flow in the gas back-pressure pipeline 220. This gas flow reflects the amount of gas permeation, which can be used to calculate the gas permeability.

[0085] When the gas circulates in the gas boosting pipeline 210 and the gas back-pressure pipeline 220, it is also necessary to compensate the gas flow through the pressure-stabilizing container to make the gas flow uniform. Therefore, in some embodiments of the present application, a first gas pressure-stabilizing container 215 is further provided on the gas boosting pipeline 210. The first gas pressure-stabilizing container 215 is located between the gas boosting pump 212 and the gas injection pressure gauge 213, and the outlet end of the gas back-pressure pipeline 220 is connected to the first gas pressure-stabilizing container 215. The first gas pressure-stabilizing container 215 is used to compensate for the gas flow in the gas boosting pipeline 210. In order to improve the safety of the gas permeation circulation unit, a high-pressure pressure-reducing valve 216 can also be connected to the first gas pressure-stabilizing container 215. When the pressure value detected by the gas injection pressure gauge 213 is higher than the safety threshold, the high-pressure pressure-reducing valve 216 can be opened to release part of the pressure to avoid danger.

[0086] Similarly, a second gas pressure-stabilizing container 224 can also be provided on the gas back-pressure pipeline 220. The second gas pressure-stabilizing container 224 is located between the gas outlet valve 221 and the gas back-pressure valve 223 and is used to compensate for the gas flow in the gas back-pressure pipeline 220. The gas flow meter 222 can be connected to the second gas pressure-stabilizing container 224, so that the flow measured by the gas flow meter 222 is more stable and accurate.

[0087] The aforementioned gas permeation circulation unit can be used in reservoir damage simulations for gas wells to measure the gas permeability of target core 400 before and after damage. Furthermore, the aforementioned gas permeation circulation unit can also be used to measure the gas permeability of target core 400 in oil wells before and after damage. Measuring the liquid permeability of target core 400 in oil wells before and after damage requires the use of a corresponding liquid permeation circulation unit.

[0088] Continue to see Figure 2 In some other implementations of the embodiment of the present application, the displacement device 200 may further include a liquid permeation circulation unit, and the liquid permeation circulation unit may include a liquid pressurization pipeline 230 and a liquid back-pressure pipeline 240.

[0089] like Figure 2 As shown, the liquid boosting pipeline 230 is connected to the core holder 120, and the outlet end of the liquid boosting pipeline 230 is in communication with the spacer layer. Along the direction of liquid flow, the liquid boosting pipeline 230 is sequentially provided with a liquid storage tank 231, a liquid boosting pump 232, and a liquid injection valve 233. After the liquid injection valve 233 is opened and the liquid boosting pump 232 is started, the liquid in the liquid storage tank 231 can be injected into the spacer layer under the drive of the liquid boosting pump 232, and then penetrate from the outer wall of the target core 400 into the hollow damaged portion 410 of the target core 400 under the liquid displacement pressure.

[0090] In some embodiments of the present application, the liquid medium used in liquid displacement may be kerosene, and accordingly, the liquid storage tank 231 on the liquid pressurization pipeline 230 may be a kerosene tank.

[0091] Continue to see Figure 2 The liquid back-pressure pipeline 240 is connected to the core holder 120, and the inlet end of the liquid back-pressure pipeline 240 is in communication with the hollow damaged portion 410. Along the liquid flow direction, the liquid back-pressure pipeline 240 is sequentially provided with a liquid outlet valve 241, a liquid back-pressure unit 242, and a liquid back-pressure valve 243. The outlet end of the liquid back-pressure pipeline 240 is connected to the liquid pressurization pipeline 230 and is located between the injection valve 233 and the outlet end of the liquid pressurization pipeline 230. The liquid back-pressure unit 242 is connected to a liquid metering device 244, and the liquid metering device 244 is configured to obtain the liquid flow rate seeping out of the hollow damaged portion 410.

[0092] After the liquid outlet valve 241 and the liquid back-pressure valve 243 are opened, the liquid that has penetrated the hollow lesion 410 can be back-pressurized through the liquid back-pressure pipeline 240 under the control of the liquid back-pressure unit 242. The outlet of the liquid back-pressure pipeline 240 can be connected to the liquid boosting pipeline 230 to form a circulation path, simulating the liquid displacement process during drilling. The liquid metering device 244 can obtain the liquid in the liquid back-pressure pipeline 240 and measure the liquid flow rate in the liquid back-pressure pipeline 240. This liquid flow rate reflects the amount of liquid penetration, which can then be calculated to obtain the liquid permeability.

[0093] In some embodiments, the liquid back pressure unit 242 has a fluid outlet, and the liquid metering device 244 can be a liquid metering electronic balance, which can be connected to the fluid outlet of the liquid back pressure unit 242 to obtain the mass of the liquid that penetrates into the hollow damage part 410, and then obtain the volume flow rate and liquid permeability of the liquid by calculation.

[0094] Similar to gas compensation, when the liquid circulates in the liquid boosting pipeline 230 and the liquid back pressure pipeline 240, it is also necessary to compensate the liquid flow through the pressure stabilizing container to make the liquid flow uniform. Therefore, in some embodiments of the present application, such as Figure 2 As shown, a liquid pressure stabilizing container 234 is further provided on the liquid pressurizing pipeline 230 , and the liquid pressure stabilizing container 234 is located between the liquid pressurizing pump 232 and the liquid injection valve 233 . The liquid pressure stabilizing container 234 is used to compensate for the liquid flow in the liquid pressurizing pipeline 230 .

[0095] In some implementations of the embodiments of the present application, the pipelines in the gas permeation circulation unit and the liquid permeation circulation unit may be simplified to make the structure of the entire displacement device 200 simpler and more efficient.

[0096] like Figure 2 As shown, in some embodiments, the liquid boost line 230 can be connected to the spacer layer using the same pipe section as the gas boost line 210. For example, the outlet end of the liquid boost line 230 can be connected to the gas boost line 210 and located between the gas injection valve 214 and the outlet end of the gas boost line 210.

[0097] In other embodiments, the liquid back-pressure line 240 may also be connected to the spacer layer using the same pipe section as the gas back-pressure line 220. For example, the inlet end of the liquid back-pressure line 240 may be connected to the gas back-pressure line 220 and located between the inlet end of the gas back-pressure line 220 and the outlet valve 221.

[0098] In some other embodiments, the outlet end of the liquid back-pressure pipeline 240 can also be connected to the gas boosting pipeline 210 and use the same pipe section for circulation. For example, the outlet end of the liquid back-pressure pipeline 240 can be connected to the first gas pressure stabilizing container 215. At this time, the liquid back-pressure unit 242 can control the liquid back pressure based on the first gas pressure stabilizing container 215.

[0099] At this point, the displacement device 200 can comprehensively and objectively simulate the gas displacement process of the gas well and the oil displacement process of the oil well, basically restoring the gas and oil production processes of the reservoir, and making the measurement of gas permeability and liquid permeability in the simulation experiment more scientific and accurate.

[0100] At the same time, in order to more realistically simulate the formation environment where the target core 400 is located, in some implementations of the embodiments of the present application, the reservoir damage simulation system also includes a confining pressure device 500 and a temperature control device 600 loaded onto the core clamp 120, and the confining pressure device 500 and the temperature control device 600 respectively provide high pressure and high temperature conditions for the target core 400.

[0101] like Figure 4 As shown, the confining pressure device 500 includes a confining pressure pressurization pipeline 510 and a confining pressure back-pressure pipeline 520 .

[0102] The confining pressure and pressurization pipeline 510 is connected to the core holder 120. The inlet end of the confining pressure and pressurization pipeline 510 is connected to the liquid boosting pipeline 230 and is located between the liquid boosting pump 232 and the injection valve 233. For example, it can be located before or after the liquid pressure-stabilizing container 234. The outlet end of the confining pressure and pressurization pipeline 510 is connected to the spacer layer. A confining pressure and pressurization valve 511 and a confining pressure gauge 512 are arranged in sequence on the confining pressure and pressurization pipeline 510 along the pressure driving direction. After the confining pressure and pressurization valve 511 is opened, the liquid in the liquid storage tank 231 enters the spacer layer through the confining pressure and pressurization pipeline 510 under the drive of the liquid boosting pump 232, and applies confining pressure to the target core 400 to simulate the formation pressure of the actual reservoir. The confining pressure gauge 512 is used to detect the confining pressure applied to the target core 400 by the confining pressure device 500.

[0103] One end of the confining pressure back-pressure pipeline 520 is connected to the liquid storage tank 231, and the other end is connected to the confining pressure pressurization pipeline 510 and is located between the confining pressure gauge 512 and the outlet end of the confining pressure pressurization pipeline 510. A back-pressure pressurization valve 521 is provided on the confining pressure back-pressure pipeline 520. By adjusting the back-pressure pressurization valve 521, the confining pressure of the target core 400 can be adjusted.

[0104] In some embodiments of the present application, the confining pressure device 500 further includes a confining pressure safety line 530 and a confining pressure safety valve 531 disposed on the confining pressure safety line 530. One end of the confining pressure safety line 530 is connected to the liquid storage tank 231, and the other end is connected to the confining pressure pressurization line 510 and is located between the confining pressure pressurization valve 511 and the confining pressure gauge 512. When the confining pressure device 500 is applying confining pressure, the confining pressure safety valve 531 is usually closed. If the confining pressure displayed by the confining pressure gauge 512 exceeds the normal range, the confining pressure safety valve 531 is opened to release pressure and avoid danger.

[0105] For example, the confining pressure boosting valve 511 and the back pressure boosting valve 521 may be manual valves, which are manually opened and closed by technicians to improve safety.

[0106] like Figure 5 As shown, the temperature control device 600 includes a temperature control instrument 610, a heating and temperature control unit 620, and a heater 630. The temperature control instrument 610 is connected to the heating and temperature control unit 620, which is further connected to the heater 630. The heater 630 is connected to the core holder 120. The temperature control instrument 610 is used to receive an external heating temperature input and transmit the heating temperature to the heating and temperature control unit 620. The heating and temperature control unit 620 can control the heater 630 to perform heating. The heat generated by the heater 630 is transmitted to the target core 400 through the core holder 120 and the spacer 110. For example, the heater 630 can be a heating rod. The core holder 120 can be provided with a placement slot, and the heating rod can be inserted into the placement slot.

[0107] In some embodiments of the present application, the heating temperature control unit 620 and the mud preheating temperature control unit 350 can control heating based on the same temperature control instrument 610 .

[0108] At this point, the confining pressure device 500 and the temperature control device 600 can simulate the formation environment where the reservoir is located, providing a high temperature and high pressure environment for the target core 400, making the damage and permeability measurement of the target core 400 in this environment more scientific and accurate.

[0109] In some embodiments of the present application, the reservoir damage simulation system may also include a data acquisition and control device, which can receive data such as core parameters, pressure parameters, temperature parameters, etc., and at the same time connect various valves, booster pumps and circulation pumps, detection instruments and other components, thereby realizing automatic control and intelligent detection of the entire system.

[0110] In summary, the reservoir damage simulation system provided by the embodiment of the present application takes the target core 400 having the hollow damage portion 410 as the research object, and is connected to the core clamp 120 of the target core 400 with a confining pressure device 500 and a temperature control device 600, which can simulate the high temperature and high pressure formation conditions of the reservoir; the system is equipped with a mud circulation device 300 for injecting drilling fluid into the hollow damage portion 410 to simulate the circulation process of the drilling fluid in the wellbore under high temperature and high pressure conditions and the radial seepage process of actual drilling reservoir damage; the system is also equipped with a displacement device 200, which can use gas or liquid for displacement to simulate the gas (oil) production process of radial infiltration of gas (oil) into the wellbore during drilling. At the same time, the entire system can also be automatically controlled through a data acquisition and control device to improve simulation efficiency. Therefore, the reservoir damage simulation system provided in the embodiment of the present application more comprehensively, scientifically and objectively simulates the reservoir damage process during drilling, thereby being able to determine a more accurate degree of reservoir damage, and providing an important reference basis for decision-making during drilling construction.

[0111] The present application also provides a reservoir damage determination method, which can be implemented by the reservoir damage simulation system described above. The method may include the following steps:

[0112] Step 101: Obtain a target core and clamp the target core using a clamping device;

[0113] Step 102: delivering a displacement medium to the spacer layer of the clamping device via the displacement device to obtain the initial permeability of the target core;

[0114] Step 103: Drilling fluid is delivered to the hollow damaged portion of the target core through a mud circulation device, and the drilling fluid is circulated in the hollow damaged portion for a set time to obtain the damaged target core;

[0115] Step 104: delivering a displacement medium into the spacer layer through a displacement device to obtain the damaged permeability of the target core after damage;

[0116] Step 105: Determine the reservoir damage degree based on the initial permeability and the damaged permeability.

[0117] The reservoir damage determination method provided in the embodiments of the present application first uses a displacement medium to determine the radial initial permeability of the target core, then circulates drilling fluid to damage the hollow damaged portion of the target core, and then uses a displacement medium again to determine the radial damaged permeability of the target core. The damage degree of the target core can then be determined based on the initial permeability and damaged permeability of the target core, thereby obtaining the damage degree of the reservoir in which the target core is located. The reservoir damage determination method provided in the embodiments of the present application is performed under a comprehensive, scientific, and objective simulation of the reservoir damage process during drilling. It can quantitatively measure the damage degree of the target core, thereby obtaining a more accurate reservoir damage degree, providing an important reference basis for decision-making during drilling construction.

[0118] The technical solution of the present application will be further described below through specific embodiments.

[0119] Example 1

[0120] For example, the measurement of reservoir damage during drilling at a specific depth in a gas well was performed. The target core sampled at this depth had the following parameters: 200 mm in height and 102 mm in diameter. Drilling of this target core revealed a hollow damaged portion with an inner diameter of 38 mm and a hole depth of 170 mm. Based on the actual operating parameters at this depth in the gas well, the experimental conditions were determined to be a gas displacement pressure of 1 MPa, a confining pressure of 15 MPa, a temperature of 90°C, and a mud circulation pressure of 3.5 MPa.

[0121] This embodiment provides a reservoir damage determination method, which includes:

[0122] Step 1: Experimental preparation.

[0123] After drying the target core, wrap it in steel mesh and seal it in a core holder. Input experimental parameters corresponding to actual operating conditions, such as core length, core diameter, atmospheric pressure, gas viscosity, set confining pressure, gas displacement pressure, and core temperature, into the data acquisition and control device. Keep all valves in the system closed.

[0124] Turn on the liquid booster pump, confining pressure boosting valve and back pressure boosting valve, keep the confining pressure safety valve closed, and adjust the opening of the back pressure boosting valve by observing the confining pressure gauge so that the confining pressure applied by the core holder to the target core is maintained at 15 MPa.

[0125] The heating temperature of 90°C is input to the temperature control instrument. The heating temperature control unit controls the heater to start preheating the target core. The mud preheating temperature control unit controls the drilling fluid in the mud circulation pipeline to start preheating. The preheating time is 10 minutes.

[0126] Step 2: Determine the initial permeability of the target core.

[0127] The gas storage bottle is opened and the gas booster pump is started so that the gas pressure in the first gas pressure stabilizing container (215) is maintained at 1 MPa.

[0128] Open the gas injection valve, observe and record the inlet pressure of the spacer layer displayed on the gas injection pressure gauge.

[0129] Open the gas outlet valve and the gas back pressure valve (the back pressure here is 0), and measure the gas flow rate Q0 using a gas flow meter.

[0130] The permeability calculation formula (1) of the target core is:

[0131]

[0132] Where K is the permeability, μm 2 ; Q is flow rate, cm 3 / s; μ is gas viscosity, μPa·S; P0 is atmospheric pressure, Pa; r e is the outer diameter of the target core, m; r w represents the inner diameter of the hollow lesion, m; π is the circumference of a circle; h is the height of the target core, m; P e Indicates displacement pressure, Pa; P w Indicates gas back pressure, Pa.

[0133] The initial permeability K0 of the target core is calculated by the data acquisition and control device according to the above calculation formula (1) and recorded in the system.

[0134] Step 3: Damage the target core and record the flow rate changes during the damage process.

[0135] While maintaining the current status of each component in step 2, start the mud circulation pump and adjust the displacement of the mud circulation pump by observing the reading displayed on the mud pressure gauge to maintain the mud circulation pressure at 3.5 MPa. The drilling fluid circulates into the mud pressure stabilization container and continues to circulate for the set time, which is 125 minutes.

[0136] At the same time, the data acquisition and control device records the gas flow data during the drilling fluid circulation process through the gas flow meter. The series of gas flow data recorded during the drilling fluid circulation process reflects the reservoir damage process.

[0137] When the set time is reached, the circulation ends, the mud circulation pump is stopped, and all the drilling fluid in the hollow damaged part is discharged through the drainage pipe connected to the hollow damaged part.

[0138] Step 4: Determine the damaged permeability of the target core.

[0139] Continue to obtain the gas flow data measured by the gas flow meter, and after the gas flow measured by the gas flow meter stabilizes, record the gas flow Q1.

[0140] Stop the experiment and close the gas injection valve, gas booster pump, gas storage cylinder, gas outlet valve and gas back-pressure valve.

[0141] The damaged permeability K1 of the target core is calculated according to the above formula (1) by the data acquisition and control device and recorded in the system.

[0142] Step 5: Determine the extent of damage to the gas-producing reservoir.

[0143] The calculation formula (2) for reservoir damage degree is:

[0144]

[0145] Where S is the damage degree. The larger S is, the more serious the reservoir damage is. K0 is the initial permeability, μm 2 ; K1 is the damage permeability, μm 2 .

[0146] The data acquisition and control device calculates the damage degree of the gas-producing reservoir where the target core is located according to the above calculation formula (2).

[0147] Example 2

[0148] For example, the measurement of reservoir damage during drilling at a specific depth in an oil well was performed. The target core sampled at a specific depth in the gas well had the following parameters: a height of 200 mm and a diameter of 105 mm. Drilling of the target core revealed a hollow damaged portion with an inner diameter of 34 mm and a hole depth of 150 mm. Based on the actual operating parameters at a specific depth in the oil well, the experimental conditions were determined to be a liquid displacement pressure of 1 MPa, a confining pressure of 15 MPa, a temperature of 90°C, and a mud circulation pressure of 3.5 MPa.

[0149] This embodiment provides a reservoir damage determination method, which includes:

[0150] Step 1: Experimental preparation.

[0151] After drying the target core, wrap it in steel mesh and seal it in a core holder. Input experimental parameters corresponding to actual operating conditions, such as core length, core diameter, atmospheric pressure, gas viscosity, set confining pressure, gas displacement pressure, and core temperature, into the data acquisition and control device. Keep all valves in the system closed.

[0152] Turn on the liquid booster pump, confining pressure boosting valve and back pressure boosting valve, keep the confining pressure safety valve closed, and adjust the opening of the back pressure boosting valve by observing the confining pressure gauge so that the confining pressure applied by the core holder to the target core is maintained at 15 MPa.

[0153] The heating temperature of 90°C is input to the temperature control instrument. The heating temperature control unit controls the heater to start preheating the target core. The mud preheating temperature control unit controls the drilling fluid in the mud circulation pipeline to start preheating. The preheating time is 10 minutes.

[0154] Step 2: Determine the initial permeability of the target core.

[0155] Open the injection valve, start the liquid booster pump, and adjust the liquid pressure stabilizing container to keep the inlet pressure of the spacer layer at 1MPa.

[0156] Open the liquid outlet valve, adjust the liquid back pressure unit through the liquid back pressure valve (the back pressure here is 0), turn on the liquid metering electronic balance, record the liquid mass increment, and convert the liquid mass increment into liquid volume flow rate Q0'.

[0157] The initial permeability K0' of the target core is calculated according to the above calculation formula (1) by the data acquisition and control device and recorded in the system.

[0158] Step 3: Damage the target core and record the flow rate changes during the damage process.

[0159] Close the injection valve, liquid booster pump, liquid outlet valve and liquid back pressure valve.

[0160] Start the mud circulation pump and adjust the displacement of the mud circulation pump by observing the reading displayed on the mud pressure gauge to keep the mud circulation pressure at 3.5MPa. The drilling fluid circulates into the mud pressure stabilizing container and continues to circulate for the set time, which is 125 minutes.

[0161] After the circulation is completed, stop running the mud circulation pump and drain all the drilling fluid in the hollow damaged part through the drainage pipe connected to the hollow damaged part.

[0162] Step 4: Determine the damaged permeability of the target core.

[0163] Open the injection valve, start the liquid booster pump, and adjust the liquid pressure stabilizing container to keep the inlet pressure of the spacer layer at 1MPa.

[0164] Open the liquid outlet valve, adjust the liquid back pressure unit through the liquid back pressure valve (the back pressure here is 0), turn on the liquid metering electronic balance, record the liquid mass increment, and convert the liquid mass increment into liquid volume flow Q1'.

[0165] The data acquisition and control device calculates the damage permeability K1' of the target core according to the above calculation formula (1) and records it in the system.

[0166] Stop the experiment and turn off the corresponding valves, pumps, heaters, etc.

[0167] The damaged permeability K1 of the target core is calculated according to the above formula (1) by the data acquisition and control device and recorded in the system.

[0168] Step 5: Determine the extent of damage to the oil-producing reservoir.

[0169] The data acquisition and control device calculates the damage degree of the oil-producing reservoir where the target core is located according to the above calculation formula (2).

[0170] In this application, it should be understood that the terms "first", "second", "third", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0171] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the present invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only.

[0172] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A reservoir damage simulation system, characterized in that: The system includes a clamping device, a displacement device, a mud circulation device and a target core. The clamping device includes a spacer and a core clamp, wherein the spacer is located outside the target core, and the core clamp clamps the target core through the spacer; The displacement device is connected to the core holder, and the displacement device is configured to deliver a displacement medium into the spacer layer where the spacer is located; The target core has a hollow damaged portion, the hollow damaged portion is in communication with the mud circulation device, and the mud circulation device is configured to inject drilling fluid into the hollow damaged portion; Wherein, the displacement device includes a gas permeation circulation unit and a liquid permeation circulation unit, the gas permeation circulation unit includes a gas pressurization pipeline and a gas back-pressure pipeline, and the liquid permeation circulation unit includes a liquid pressurization pipeline and a liquid back-pressure pipeline; The gas booster pipeline is connected to the core holder, and the outlet end of the gas booster pipeline is in communication with the spacer layer. Along the gas flow direction, the gas booster pipeline is sequentially provided with a gas storage bottle, a gas booster pump, a gas injection pressure gauge, and a gas injection valve; the gas back-pressure pipeline is connected to the core holder, and the inlet end of the gas back-pressure pipeline is in communication with the hollow damaged part. Along the gas flow direction, the gas back-pressure pipeline is sequentially provided with a gas outlet valve, a gas flow meter, and a gas back-pressure valve. The outlet end of the gas back-pressure pipeline is connected to the gas booster pipeline and is located between the gas booster pump and the gas injection pressure gauge. The liquid boosting pipeline is connected to the core holder and the outlet end of the liquid boosting pipeline is communicated with the spacer layer. Along the liquid flow direction, the liquid boosting pipeline is sequentially provided with a liquid storage tank, a liquid boosting pump and a liquid injection valve; The liquid back-pressure pipeline is connected to the core clamp, and the inlet end of the liquid back-pressure pipeline is communicated with the hollow damaged part. Along the direction of liquid flow, the liquid outlet valve, the liquid back-pressure unit and the liquid back-pressure valve are sequentially arranged on the liquid back-pressure pipeline; the outlet end of the liquid back-pressure pipeline is connected to the liquid boosting pipeline and is located between the injection valve and the outlet end of the liquid boosting pipeline. The liquid back-pressure unit is connected to a liquid metering device, and the liquid metering device is configured to obtain the liquid flow rate seeping out of the hollow damaged part.

2. The reservoir damage simulation system according to claim 1, characterized in that: The hollow damage portion is a groove formed on the target core, and an open end of the groove is provided with a sealing plug; The mud circulation device is communicated with the inner cavity of the groove.

3. The reservoir damage simulation system according to claim 2, characterized in that: The mud circulation device includes a mud circulation pipeline, and a mud circulation pump and a mud pressure gauge connected in sequence along the flow direction of the drilling fluid on the mud circulation pipeline; The mud circulation pipeline is configured to penetrate the sealing plug and communicate with the inner cavity of the groove; The inlet of the mud circulation pipeline is close to the open end of the groove, and the outlet of the mud circulation pipeline is close to the closed end of the groove, and the closed end is opposite to the open end.

4. The reservoir damage simulation system according to claim 3, characterized in that: The mud circulation device also includes a mud pressure stabilizing container and a mud preheating temperature control unit. The mud pressure stabilizing container is arranged between the inlet of the mud circulation pipeline and the mud circulation pump; The mud preheating temperature control unit is connected to the mud pressure stabilizing container and is configured to heat the drilling fluid in the mud circulation pipeline.

5. The reservoir damage simulation system according to claim 1, characterized in that: The gas boosting pipeline is further provided with a first gas pressure stabilizing container, the first gas pressure stabilizing container is located between the gas boosting pump and the gas injection pressure gauge, the outlet end of the gas back-pressure pipeline is connected to the first gas pressure stabilizing container, and the first gas pressure stabilizing container is connected to a high-pressure pressure reducing valve; and / or, A second gas pressure-stabilizing container is further provided on the gas back-pressure pipeline. The second gas pressure-stabilizing container is located between the gas outlet valve and the gas back-pressure valve. The gas flow meter is connected to the second gas pressure-stabilizing container.

6. The reservoir damage simulation system according to claim 1, characterized in that: The liquid boosting pipeline is further provided with a liquid pressure stabilizing container, and the liquid pressure stabilizing container is located between the liquid boosting pump and the liquid injection valve.

7. The reservoir damage simulation system according to claim 6, characterized in that: The outlet end of the liquid pressurizing pipeline is connected to the gas pressurizing pipeline and is located between the gas injection valve and the outlet end of the gas pressurizing pipeline; and / or, The inlet end of the liquid back-pressure pipeline is connected to the gas back-pressure pipeline and is located between the inlet end of the gas back-pressure pipeline and the gas outlet valve; and / or, The outlet end of the liquid back-pressure pipeline is connected to the first gas pressure-stabilizing container.

8. A reservoir damage determination method, characterized in that: The method is implemented by the reservoir damage simulation system according to any one of claims 1 to 7, and the method comprises: Obtaining a target rock core, and clamping the target rock core with a clamping device; delivering a displacement medium into the spacer layer where the spacer of the clamping device is located by a displacement device to obtain the initial permeability of the target core; delivering drilling fluid to the hollow damaged portion of the target core through a mud circulation device, and circulating the drilling fluid in the hollow damaged portion for a set time to obtain the damaged target core; delivering the displacement medium into the spacer layer through the displacement device to obtain the damaged permeability of the damaged target core; The degree of reservoir damage is determined based on the initial permeability and the damaged permeability.

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