Physical simulation test system and method for reservoir forming and filling rule of heterogeneous reservoir

Abstract

The invention provides a physical simulation test system and method for a reservoir forming and filling rule of a heterogeneous reservoir, and the system comprises a displacement pump, a first intermediate container, a second intermediate container, a first core holder, a second core holder, a third core holder, a first recovery metering container, a second recovery metering container, and a third recovery metering container. The output end of the displacement pump is respectively connected to the first intermediate container and the second intermediate container, and the outlets of the first intermediate container and the second intermediate container are connected to the first core holder, the second core holder and the third core holder through pipelines; and the output ends of the first core holder, the second core holder and the third core holder are respectively connected to the first recovery metering container, the second recovery metering container and the third recovery metering container corresponding to the output ends of the first core holder, the second core holder and the third core holder. According to the method, the inter-layer heterogeneity and oil source evaluation of the reservoir can be considered, the understanding of crude oil reservoir formation is deepened, and conditions are provided for oil and gas development.

Description

Technical Field

[0001] The present invention relates to the technical field of physical simulation of reservoir hydrocarbon accumulation and filling, and particularly to a physical simulation test system and method for the law of hydrocarbon accumulation and filling in heterogeneous reservoirs. Background Art

[0002] With the increasing discovery of low oil saturation reservoirs in oilfields at home and abroad, petroleum workers have carried out comprehensive research on such reservoirs and summarized and generalized the common characteristics shown by each reservoir. At present, petroleum workers generally believe that a low oil saturation reservoir is a reservoir with a coexisting water saturation higher than that of general reservoirs, with obvious mobile water, no water-free production period during the development process, but with certain economic value. Domestic and foreign scholars have carried out extensive research on the causes of low oil saturation reservoirs, and there are many different views on the causes of low oil saturation reservoirs. However, most views believe that the main factors causing the low oil saturation in the reservoir are structural factors, reservoir and fluid factors, and hydrocarbon accumulation factors. At the same time, a large number of such reservoirs represented by the Moxizhuang Oilfield in the central part of the Junggar Basin in China also have interlayer heterogeneity, which further increases the difficulty of studying the causes of such reservoirs.

[0003] In recent years, the research on interlayer interference in heterogeneous reservoirs has mainly focused on the interlayer interference during the oil and gas resource development stage, and mainly uses numerical simulation methods for research. At present, there is no public report on systematically studying the interlayer interference during the hydrocarbon accumulation process of reservoirs by physical simulation means. However, reasonable physical simulation experiments are helpful to understand the hydrocarbon accumulation mechanism of reservoirs more deeply and provide guidance for the subsequent development stage.

[0004] In the Chinese patent application with the application number: CN202210998231.0, it relates to an oil and gas accumulation physical simulation device and experimental method. The oil and gas accumulation physical simulation device includes a simulation box, a booster pump, a heating device, at least 4 thrusters and a plurality of push rod mechanisms. The heating device is arranged in the simulation box, the booster pump is communicated with the simulation box, and at least 4 thrusters are respectively arranged at both ends of the simulation box in the horizontal direction, including a first thruster, a second thruster, a third thruster and a fourth thruster. The first thruster and the second thruster are located at the left end and the first thruster is arranged above the second thruster, and the third thruster and the fourth thruster are located at the right end and the third thruster is arranged above the fourth thruster. By applying different stresses to the formation in the simulation box, the stress deformation of the formation with complex structures is simulated, and the oil and gas accumulation mechanism under complex structural deformation is clarified, solving the technical problem that the simulation experiments in the prior art cannot accurately reflect the actual situation of oil and gas accumulation. This application has made certain progress in the oil and gas accumulation simulation device, and proposes to simulate the stress deformation of the formation with complex structures by applying different stresses to the formation in the simulation box, but only relates to the accumulation simulation device and does not provide a complete physical simulation method for simulating the accumulation process.

[0005] In the Chinese patent application with the application number: CN202210052045.8, it relates to a physical simulation device for hydrocarbon source rock hydrocarbon expulsion, oil and gas migration, and reservoir formation, belonging to the technical field of petroleum and natural gas geology teaching experiment simulation research equipment. It includes a bracket, on which a flipping mechanism is connected to support and connect the model body and rotate to adjust the inclination angle. The model body is filled with a formation model, and injection points are arranged on the outer periphery of the model body. A simulated injection tube is connected through the injection points. At one end of the simulated injection tube inserted into the formation model, there is a simulated blasting grenade. The formation model is pre-compacted by a compaction piece and then covered with a visualization structure. Different injection points are selected to connect the simulated injection tubes until the pressure accumulated at the simulated blasting grenade reaches the breakthrough pressure value, and then breakthrough injection is carried out into the formation model. During the process, the oil and gas simulated migration is observed and recorded through the visualization structure to realize the simulation of hydrocarbon generation, hydrocarbon expulsion of hydrocarbon source rocks, and the migration and reservoir formation laws under different geological configurations. The main advantage of this application is that it can visually and intuitively observe the oil and gas migration laws in different formation models and under different pressure distributions. This device can be applied to qualitative analysis and intuitive observation, but lacks a quantitative evaluation method.

[0006] In the Chinese patent application with the application number: CN201420850965.5, it relates to a tight sandstone reservoir formation simulation device including an oil pressure pump, a closed container, a clamping device, an automatic meter, and a PC. An oil circuit inlet and an oil circuit outlet are provided on the upper end surface of the closed container, and tight sandstone is installed in the closed container. The clamping device clamps the tight sandstone; the oil pressure pump is connected to the oil circuit inlet on the closed container through a oil pipe, the oil circuit outlet on the closed container is connected to the clamping device, one end of the automatic meter is electrically connected to the clamping device, and the other end is electrically connected to the PC. The utility model has a simple structure and is easy to operate. The oil pressure pump is used to provide oil pressure to the closed container. By continuously pressurizing, the pressure continuously increases. After the oil pressure in the closed container is stable, it is then transported to the clamping device. The relationship between the pressure magnitude and the oil saturation can be quantitatively calculated, and the measured data is displayed in real time through the connected PC.

[0007] In the Chinese patent application with the application number CN201310098490.9, it involves a comprehensive simulation experimental device for reservoir heterogeneity, belonging to the simulation experimental device in the fields of petroleum geology and development geology. It mainly solves the problems of simple simulation geological models, single simulation functions, and the disconnection between hydrocarbon accumulation and development simulation in the past. The characteristics of this experimental device are the realization of the integrated simulation of the hydrocarbon accumulation and development processes, especially the influence of reservoir heterogeneity on hydrocarbon accumulation, water injection development, and the formation and distribution of remaining oil. This device mainly consists of a fluid injection system, a geological model establishment system, and an experimental acquisition and control system, and corresponding connection devices are equipped inside each system and between systems. This experimental device system is comprehensive, highly integrated, flexible in design, reasonable in structure, convenient to operate, and highly automated. It can not only directly observe the movement of reservoir fluids but also dynamically monitor the changes of fluids in various parts of the reservoir. Therefore, it can achieve a variety of experimental functions and has a wide range of uses.

[0008] At the same time, during the hydrocarbon accumulation process of crude oil, during the primary migration of the oil generated in the source rock (oil source area) from the source rock to the reservoir, with a certain oil source, the crude oil stops migrating after the pressure in the oil source area is released. However, in all the physical simulation systems for hydrocarbon accumulation designed in existing research, the physical simulation of the hydrocarbon accumulation filling process in a reservoir with a certain oil source and unlimited oil injection has not been publicly reported. The crude oil reservoir is not a homogeneous system, and its interlayer heterogeneity exists, which will affect the migration of crude oil. At present, there are few relevant studies on the influence of interlayer heterogeneity on the hydrocarbon accumulation process. In particular, there is no public report on systematically studying the interlayer interference during the hydrocarbon accumulation process of an oil reservoir using physical simulation means. A reasonable physical simulation experiment helps to understand the hydrocarbon accumulation mechanism of the oil reservoir more deeply. To sum up, the common problem of the existing technology is that it does not fully consider the influence of reservoir interlayer heterogeneity and a certain oil source on the reservoir hydrocarbon accumulation process. At the same time, the lack of a systematic method for quantitatively evaluating the hydrocarbon accumulation filling law of the reservoir also restricts the development of related research.

[0009] All the above existing technologies are quite different from the present invention and cannot solve the technical problems we want to solve. Therefore, we have invented a new physical simulation test system and method for the hydrocarbon accumulation filling law of heterogeneous reservoirs. Summary of the Invention

[0010] The object of the present invention is to provide a physical simulation test system for the filling law of a reservoir that can take into account the interlayer heterogeneity of the reservoir and the evaluation of a certain oil source, and combine nuclear magnetic resonance analysis means to form a method that can effectively and quantitatively characterize the occurrence law of fluids in heterogeneous reservoirs during the hydrocarbon accumulation process of an oil reservoir, deepen the relevant understanding of crude oil hydrocarbon accumulation, and provide conditions for the efficient development of oil and gas resources.

[0011] The object of the present invention can be achieved by the following technical measures: a physical simulation test system for the accumulation and filling law of heterogeneous reservoirs. The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs includes a displacement pump, a first intermediate container, a second intermediate container, a first core holder, a second core holder, a third core holder, a first recovery and metering container, a second recovery and metering container, and a third recovery and metering container. The output end of the displacement pump is respectively connected to the first intermediate container and the second intermediate container. The outlets of the first intermediate container and the second intermediate container are connected to the first core holder, the second core holder, and the third core holder through pipelines. The output ends of the first core holder, the second core holder, and the third core holder are respectively connected to the corresponding first recovery and metering container, the second recovery and metering container, and the third recovery and metering container.

[0012] The object of the present invention can also be achieved by the following technical measures:

[0013] The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a manual pump, which is respectively connected to the first core holder, the second core holder, and the third core holder for applying confining pressure.

[0014] The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a second pressure gauge, which is located between the manual pump and the first core holder, the second core holder, and the third core holder.

[0015] The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a constant temperature box, and the manual pump, the first intermediate container, the second intermediate container, the first core holder, the second core holder, the third core holder, the first recovery and metering container, the second recovery and metering container, and the third recovery and metering container are all located in the constant temperature box.

[0016] The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a first valve. The inlet ends of the first core holder, the second core holder, and the third core holder are connected in parallel and connected to one end of the first valve, and the other end of the first valve is connected to the outlets of the first intermediate container and the second intermediate container.

[0017] The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a first pressure gauge, which is connected to the other end of the first valve.

[0018] The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a second valve, which is located between the first core holder and the first recovery and metering container.

[0019] The object of the present invention can also be achieved by the following technical measures: a physical simulation test method for the accumulation and filling law of heterogeneous reservoirs, which adopts a physical simulation test system for the accumulation and filling law of heterogeneous reservoirs, including:

[0020] Step 1, prepare experimental cores and experimental oils;

[0021] Step 2, test and calculate the gas-measured permeability of the cores;

[0022] Step 3, measure the porosity of the cores by the weighing method;

[0023] Step 4, test the nuclear magnetic resonance T2 spectrum of the cores in the state of saturated simulated formation water to characterize the total pore volume;

[0024] Step 5, put the cores with high permeability, medium permeability and low permeability into the first core holder, the second core holder and the third core holder respectively, turn on the constant temperature oven to simulate the original reservoir temperature, apply confining pressure to simulate the original effective stress state of the formation, and then evacuate the front end of the cores;

[0025] Step 6, use nuclear magnetic resonance to test the occurrence state of crude oil in the cores;

[0026] Step 7, conduct the filling of the medium-permeability cores and low-permeability cores;

[0027] Step 8, calculate the oil saturation at different displacement stages.

[0028] In Step 1, prepare experimental cores and experimental oils. Fill the first intermediate container with simulated formation water and fill the second intermediate container with simulated formation crude oil.

[0029] This physical simulation test method for the accumulation and filling law of heterogeneous reservoirs also includes, after Step 1, wash the experimental cores with oil and dry them, and test the diameter and length of the cores.

[0030] In Step 2, use a confining pressure pore permeability test system to test and calculate the gas-measured permeability of the cores according to the stable gas flow rate under different pressures.

[0031] In Step 3, evacuate, fully saturate the cores with simulated formation water, and then pressurize and saturate to make the cores fully saturated, and measure the porosity of the cores by the weighing method.

[0032] In Step 4, use a nuclear magnetic resonance core analyzer to test the nuclear magnetic resonance T2 spectrum of the cores in the state of saturated simulated formation water to characterize the total pore volume.

[0033] The physical simulation test method for the accumulation and injection law of heterogeneous reservoirs also includes that after step 4, the core is immersed in an MnCl₂ aqueous solution with a certain concentration until there is no nuclear magnetic signal in the core. For cores with relatively low permeability, the MnCl₂ aqueous solution needs to be used for displacement to shield the nuclear magnetic signal of water.

[0034] In step 6, close the first valve, use the displacement pump to increase the displacement pressure to the designed displacement pressure, then open the first valve for displacement until the first pressure gauge drops to a certain pressure, close the first valve, and use nuclear magnetic resonance to test the occurrence state of crude oil in the core.

[0035] In step 7, displace to a certain number of PVs (pore volume multiples). When the high-permeability core is fully saturated, close the second valve and conduct the injection of the medium-permeability core and the low-permeability core.

[0036] In step 8, calculate the oil saturation at different displacement stages according to the ratio of the nuclear magnetic resonance signal amount of crude oil in the core to the signal amount of water in the saturated water state.

[0037] In step 8, the formula for calculating the oil saturation So at different displacement stages is:

[0038]

[0039] In the formula: Mw represents the T2 signal amplitude in the saturated water state, Mo represents the T2 signal amplitude in the bound water state, and the subscript i represents the T2 relaxation time range.

[0040] The physical simulation test system and method for the accumulation and injection law of heterogeneous reservoirs in the present invention, compared with the prior art, have the following beneficial effects:

[0041] (1) During the process of crude oil accumulation, during the primary migration of petroleum generated in the source rock (oil source area) from the source rock to the reservoir, the oil source is certain. After the pressure in the oil source area is released, the crude oil stops migrating. However, in the existing physical simulation systems designed for reservoir formation, the crude oil is injected infinitely. The fixed oil source and the infinite injection of crude oil have a key impact on the distribution of crude oil in the pores. Therefore, the existing reservoir formation simulation systems cannot effectively simulate the actual crude oil accumulation process. The present invention proposes to transform the physical simulation experiment process, combine nuclear magnetic resonance analysis means, and establish an experimental method that can effectively and quantitatively simulate the actual injection process of the reservoir during the crude oil accumulation process under the condition of a fixed oil source, which is very helpful for deeply understanding the injection process of the reservoir.

[0042] (2) Crude oil reservoirs are not homogeneous systems. There is interlayer heterogeneity in them, which will affect the migration of crude oil. The interlayer interference during the development stage of crude oil resources has been widely concerned in recent years. Numerical simulation methods are mainly used for research. At present, there are few studies on the influence of interlayer heterogeneity on the hydrocarbon accumulation process. In particular, there is no public report on systematically studying the interlayer interference in the hydrocarbon accumulation process of oil reservoirs by physical simulation means. Reasonable physical simulation experiments help to understand the hydrocarbon accumulation mechanism of oil reservoirs more deeply. Based on the improved physical simulation experimental process, the present invention establishes an experimental method that can simulate the injection process of heterogeneous reservoirs, and combined with nuclear magnetic resonance analysis means, it can effectively and quantitatively reveal the injection law of heterogeneous reservoirs. Description of the Drawings

[0043] Figure 1 It is a structural diagram of a specific embodiment of the physical simulation test system for the hydrocarbon accumulation and injection law of heterogeneous reservoirs of the present invention;

[0044] Figure 2 It is a schematic diagram of the nuclear magnetic resonance test results of the first group of cores in different states in a specific embodiment of the present invention;

[0045] Figure 3 It is a curve graph of the injection process of the first group of cores in a specific embodiment of the present invention;

[0046] Figure 4 It is a schematic diagram of the nuclear magnetic resonance test results of the second group of cores in different states in a specific embodiment of the present invention;

[0047] Figure 5 It is a curve graph of the injection process of the second group of cores in a specific embodiment of the present invention;

[0048] Figure 6 It is a schematic diagram of the nuclear magnetic resonance test results of the third group of cores in different states in a specific embodiment of the present invention;

[0049] Figure 7 It is a curve graph of the injection process of the third group of cores in a specific embodiment of the present invention;

[0050] Figure 8 It is a schematic diagram of the nuclear magnetic resonance test results of the fourth group of cores in different states in a specific embodiment of the present invention;

[0051] Figure 9 It is a curve graph of the injection process of the fourth group of cores in a specific embodiment of the present invention;

[0052] Figure 10 It is a schematic diagram of the nuclear magnetic resonance test results of the fifth group of cores in different states in a specific embodiment of the present invention;

[0053] Figure 11 It is a curve graph of the injection process of the fifth group of cores in a specific embodiment of the present invention. Detailed implementation mode

[0054] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0055] It should be noted that the terms used herein are only for describing the specific implementation mode and are not intended to limit the exemplary implementation mode according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0056] As Figure 1 shown, Figure 1 is a structural diagram of a physical simulation test system for the accumulation and injection law of heterogeneous reservoirs of the present invention. The physical simulation test system for the accumulation and injection law of heterogeneous reservoirs includes a displacement pump (1) and recovery and metering containers (8.1, 8.2, 8.3), and also includes a manual pump (2), valves (3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8), intermediate containers (4.1, 4.2), pressure gauges (5.1, 5.2), a constant temperature box (6), and core holders (7.1, 7.2, 7.3). The output ends of the displacement pump (1) are respectively connected to the intermediate container (4.1) and the second intermediate container (4.2). The outlets of the intermediate container (4.1) and the intermediate container (4.2) are connected to the core holders (7.1), the core holders (7.2), and the core holders (7.3) through pipelines. The output ends of the core holders (7.1), the core holders (7.2), and the core holders (7.3) are respectively connected to the recovery and metering containers (7.1), the recovery and metering containers (7.2), and the recovery and metering containers (7.3);

[0057] The core holders (7.1), the core holders (7.2), and the core holders (7.3) are provided with a manual pump (2) for confining pressure pressurization.

[0058] Preferably, the output ends of the above displacement pump (1) are respectively connected to the intermediate container (4.1) and the intermediate container (4.2) through valves (3.7) and valves (3.8); the output ends of the intermediate container (4.1) and the intermediate container (4.2) are respectively provided with valves (3.5) and valves (3.6); the valves (3.5) and valves (3.6) are connected to the valve (3.1).

[0059] Preferably, valves (3.2), valve (3.3) and valve (3.4) are respectively provided on the outlet pipelines of the above-mentioned core holders (7.1), core holders (7.2) and core holders (7.3).

[0060] Preferably, the pipelines on one side of the inlet ends of the above-mentioned core holders (7.1), core holders (7.2) and core holders (7.3) are in parallel and connected to the valve (3.1).

[0061] Preferably, a pressure gauge (5.2) is installed at the outlet end of the above-mentioned manual pump (2), and a pressure gauge (5.1) is installed at the left end of the valve (3.1).

[0062] The using method of the physical simulation test system for the injection law of heterogeneous reservoirs mentioned in the present invention includes the following steps:

[0063] (1) Prepare experimental cores and experimental oils, fill the intermediate container (4.1) with simulated formation water, and fill the intermediate container (4.2) with simulated formation crude oil;

[0064] (2) Wash and dry the experimental cores, and measure the diameter and length of the cores;

[0065] (3) Use the overburden porosity and permeability test system to test and calculate the gas permeability of the core according to the stable gas flow rate under different pressures;

[0066] (4) Evacuate, fully saturate the core with simulated formation water, then pressurize and saturate to make the core fully saturated, and measure the porosity of the core by the weighing method;

[0067] (5) Use the nuclear magnetic resonance core analyzer to test the nuclear magnetic resonance T2 spectrum of the core in the state of being saturated with simulated formation water to characterize the total pore volume;

[0068] (6) Immerse the core in an aqueous solution of MnCl2 with a certain concentration until there is no nuclear magnetic signal in the core. For cores with lower permeability, it is necessary to displace with the aqueous solution of MnCl2 to shield the nuclear magnetic signal of water;

[0069] (7) Put cores with high permeability, medium permeability and low permeability into the core holders (7.1), core holders (7.2) and core holders (7.3) respectively, turn on the constant temperature oven to simulate the original reservoir temperature, apply confining pressure to simulate the original effective stress state of the formation, and then evacuate the front end of the core;

[0070] (8) Close the valve 3.1, use the displacement pump to increase the displacement pressure to the designed displacement pressure, then open the valve 3.1 for displacement until the pressure gauge (5.1) drops to a certain pressure, close the valve 3.1, and use nuclear magnetic resonance to test the occurrence state of crude oil in the core;

[0071] (9) Displace to a certain PV number. When the high-permeability core is fully saturated, close valve 3.2 and conduct the injection for the medium-permeability core and the low-permeability core.

[0072] (10) According to the ratio of the nuclear magnetic resonance signal amount of crude oil in the core to the signal amount of water in the saturated water state, use formula (1) to calculate the oil saturation at different displacement stages.

[0073]

[0074] In the formula: Mw represents the T2 signal amplitude in the saturated water state, Mo represents the T2 signal amplitude in the bound water state, and the subscript i represents the T2 relaxation time range.

[0075] Preferably, the simulated oil mentioned in step (1) includes: simulated oils for different target blocks.

[0076] The following are several specific embodiments of applying the present invention

[0077] Embodiment 1

[0078] In a specific embodiment 1 of applying the present invention, the designed displacement pressure is 0.1 MPa. The high-permeability, medium-permeability, and low-permeability cores used in the experiment are Core 94-1 (permeability 121.50 mD), Core 39 (permeability 14.08 mD), and Core 71 (permeability 1.83 mD) respectively.

[0079] It can be seen from the nuclear magnetic resonance test results that when the displacement pressure is 0.1 MPa, the high-permeability core 94-1 can be well injected. As the injected PV increases, the crude oil first enters the large pores, and then the nuclear magnetic resonance T2 spectrum gradually moves upward and leftward, indicating that the crude oil advances towards the core outlet end and gradually enters the smaller pores. When reaching state 4, the core injection process is mainly for oil production, and the oil saturation increases slowly; but when the displacement pressure is increased to 0.2 MPa, the oil saturation of the core increases.

[0080] The medium-permeability core 39 can also be injected to a certain extent. As the PV number increases, the oil saturation gradually increases, but its saturation speed is slow. When reaching states 4 and 5, for Core 94-1, the oil production is the main process, and the crude oil forms a preferential channel in the core. The crude oil injected into Core 39 has not broken through the core outlet end yet. At this time, the injected crude oil mainly flows through the high-permeability core, and the seepage capacity of the high-permeability core is 70 times that of the medium-permeability core.

[0081] During the entire injection process of the low-permeability core 71, the seepage resistance is large, the injection is insufficient, and the oil saturation is low. When the valve before the high-permeability core is closed, the medium-permeability core can be well injected, and the low-permeability core can also be injected to a certain extent, and the oil saturation increases by a certain margin. After the medium-permeability core is injected with a certain number of PVs, the crude oil forms a preferential channel in the core, the oil saturation increases slowly, and the seepage velocity is relatively high. While the low-permeability core is injected slowly, and the seepage capacity of the medium-permeability core reaches 140 times that of the low-permeability core, as shown in Table 1 below and Figure 2 , 3 shown.

[0082] Table 1 Law of oil-water production during displacement of the first group of cores

[0083]

[0084]

[0085] Example 2

[0086] In the specific Example 2 of applying the present invention, the displacement pressure is designed to be 0.2 MPa. The high-permeability, medium-permeability, and low-permeability cores used in the experiment are Core No. 17-3 (permeability 94.65 mD), Core No. 74 (permeability 11.72 mD), and Core No. 49-6 (permeability 1.67 mD), respectively.

[0087] It can be seen from the nuclear magnetic resonance test results that when the displacement pressure is 0.2 MPa, the high-permeability core 17-3 can be well injected. As the injected PV increases, the oil saturation gradually increases. When it reaches 0.26 PV, the crude oil has broken through the core. At the same time, as the PV increases, the medium-permeability core can also be injected to a certain extent. Initially, the difference in seepage velocity between the high-permeability core and the medium-permeability core is relatively small. As the displacement multiple increases, the difference in their seepage capacity becomes larger and larger. It is analyzed that in the initial stage of injection, the crude oil quickly enters the high-permeability core, and the high-permeability core becomes an oil-water two-phase, and the seepage resistance gradually increases. While the medium-permeability core has a high water saturation, and the seepage resistance in the core is mainly that of water, and its seepage resistance is small, so the difference in their seepage capacity is small. As the displacement multiple increases, the crude oil in the high-permeability core forms a preferential channel, and the seepage resistance decreases. While the medium-permeability core, as the oil saturation increases, the seepage resistance of the oil-water two-phase increases. Therefore, the difference in seepage velocity between the high-permeability core and the medium-permeability core becomes larger and larger. In States 5 and 6, after the high-permeability core is well injected with crude oil, its seepage capacity is 20-50 times that of the medium-permeability core.

[0088] During the entire injection process of the low-permeability core 71, the seepage resistance is large, the injection is insufficient, and the oil saturation is low. When the displacement pressure is increased to 0.4 MPa, the oil saturation of the high-permeability core increases slightly, that of the medium-permeability core increases significantly, and that of the low-permeability core also increases slightly. When the valve before the high-permeability core is closed, the medium-permeability core can be well injected, and the low-permeability core can also be injected to a certain extent, and the oil saturation increases to a certain extent. After the medium-permeability core is injected with a certain number of PVs, the crude oil forms a preferential channel in the core, and the seepage velocity is relatively high, while the injection of the low-permeability core is slow, and the seepage capacity of the medium-permeability core reaches nearly 20 times that of the low-permeability core. As shown in Table 2 and Figure 4 and 5 shown below.

[0089] Table 2 Displacement oil and water production law table of the second group of cores

[0090]

[0091] Example 3

[0092] In a specific Example 3 of applying the present invention, the designed displacement pressure is 1 MPa. The high-permeability, medium-permeability, and low-permeability cores used in the experiment are Core No. 94-4 (permeability 136.98 mD), Core No. 67 (permeability 15.10 mD), and Core No. 49-5 (permeability 2.11 mD), respectively.

[0093] Since the seepage velocity of the high-permeability core is extremely high when the displacement pressure reaches 1 MPa, which is likely to cause velocity sensitivity to the core. Therefore, during this experimental process, first close Valve 3.1, start the pump to increase the pressure. When it reaches 1 MPa, turn off the displacement pump, and at the same time open Valve 3.1 to simulate a certain amount of crude oil injection process. After opening the valve, the crude oil rapidly injects into the high-permeability core, and the pressure drops significantly. After several rounds of injection, the high-permeability core is well injected, while the injection volume of the medium- and low-permeability cores is extremely small, indicating that the heterogeneity seriously affects the injection of the medium- and low-permeability cores.

[0094] From the nuclear magnetic resonance test results, it can be seen that when the displacement pressure is 1 MPa, the high-permeability core 94-4 can be well injected. As the injected PV increases, the oil saturation gradually increases. When it reaches 0.22 PV, the crude oil has broken through the core. At the same time, as the PV increases, when it reaches the injection state 4, the oil saturation of the core is relatively high, reaching 55.36%. Continuing the injection, the increase in the oil saturation of the core is less. As the injection pore volume multiple increases, the oil saturation of the medium-permeability core 67 gradually increases, and the medium-permeability core can also be injected to a certain extent. Initially, the seepage velocities of the high-permeability core and the medium-permeability core are relatively small, and their injection rates differ by 3-5 times. As the displacement multiple increases, the difference in their seepage capacities becomes larger and larger. At state 5, the crude oil forms a dominant channel in the high-permeability core, and the seepage resistance is small. While for the medium-permeability core, as the oil saturation increases, the seepage resistance of the oil-water two-phase flow increases. At this time, the seepage capacity during the injection process of the high-permeability core reaches 47 times that of the medium-permeability core, indicating that it is increasingly difficult to inject the medium-permeability core.

[0095] The seepage resistance of the low-permeability core 49-5 is large throughout the injection process, the injection is insufficient, and the oil saturation is low. Only some large pores can be injected with a small amount of crude oil. When the valve before the high-permeability core is closed at state 6, the oil saturation of the medium-permeability core increases significantly, and it can be well injected. The low-permeability core can also be injected to a certain extent, and the oil saturation increases to a certain extent. After the medium-permeability core is injected with a certain number of PVs, the crude oil forms a dominant channel in the core, and the seepage velocity is relatively high. While the injection of the low-permeability core is slow, and the seepage capacity of the medium-permeability core reaches nearly 70 times that of the low-permeability core. As shown in Table 3 below and Figure 6 、 7 shown.

[0096] Table 3 Displacement oil-water production law table of the third group of cores

[0097]

[0098] Example 4

[0099] In a specific Example 4 of applying the present invention, the displacement pressure is designed to be 5 MPa. The high-permeability, medium-permeability, and low-permeability cores used in the experiment are core 17-4 (permeability 213.91 mD), core 63 (permeability 21.43 mD), and core 49-2 (permeability 2.52 mD) respectively.

[0100] When the displacement pressure reaches 5 MPa, the seepage velocity of the high-permeability core is very high, which affects the measurement of the experiment and causes certain damage to the core. Therefore, for this group of cores, valve 3.1 is also closed, the displacement pump is turned on, and valve 3.1 is opened when it reaches 5 MPa to simulate a certain amount of crude oil injection process. After the valve is opened, the crude oil rapidly injects into the high-permeability core, and the pressure drops significantly. After several rounds of injection, the high-permeability core is well injected, while the injection volume of the medium- and low-permeability cores is extremely small.

[0101] It can be seen from the nuclear magnetic resonance test results that when the displacement pressure is 5 MPa, the high-permeability core 17-4 can be well injected. As the injection PV increases, the oil saturation gradually increases, and the injected crude oil quickly breaks through the core. When the injection state reaches 4, the oil saturation of the core is relatively high, reaching 64.03%. Continuing the injection, the increase in the oil saturation of the core is less. As the injection pore volume multiple increases, the oil saturation of the medium-permeability core 63 gradually increases, and the medium-permeability core can also be injected to a certain extent. At state 4, the oil saturation of the core reaches 31.93%. When reaching state 5, the change in the oil saturation of the core is small. It is analyzed that when reaching state 5, the crude oil in the high-permeability core is fully injected to form a preferential channel, and the seepage resistance is small. While for the medium-permeability core, as the oil saturation increases, the seepage resistance of the oil-water two-phase increases. At this time, the seepage capacity during the injection process of the high-permeability core reaches 36 times that of the medium-permeability core, indicating that it is increasingly difficult to inject the medium-permeability core.

[0102] During the entire injection process of the low-permeability core 49-5, the seepage resistance is large, the injection is not sufficient, the oil saturation is low, and only some large pores can be injected with crude oil. As the displacement multiple increases, the oil saturation increases to a certain extent. When the valve before the high-permeability core is closed at state 6, the oil saturation of the medium-permeability core increases significantly and can be well injected, and the low-permeability core can also be injected to a certain extent, and the oil saturation increases to a certain extent. After the medium-permeability core is injected with a certain PV number, the crude oil forms a preferential channel in the core, and the seepage velocity is relatively high, while the injection of the low-permeability core is slow. The seepage capacity of the medium-permeability core reaches more than 20 times that of the low-permeability core. As shown in Table 4 and Figure 8 、 9 shown.

[0103] Table 4 Displacement oil-water production law table of the fourth group of cores

[0104]

[0105]

[0106] Example 5

[0107] In a specific embodiment 5 of the application of the present invention, the displacement pressure is designed to be 10 MPa. The high-permeability, medium-permeability, and low-permeability cores used in the experiment are Core No. 17-2 (permeability 259.64 mD), Core No. 40 (permeability 32.62 mD), and Core No. 79 (permeability 4.04 mD), respectively.

[0108] Since the seepage velocity of the high-permeability core is very high when the displacement pressure reaches 10 MPa, which affects the measurement of the experiment and causes certain damage to the core. Therefore, for this group of cores, valve 3.1 is also closed, the displacement pump is turned on, and valve 3.1 is opened when it reaches 10 MPa to simulate a certain amount of crude oil injection process. After the valve is opened, the crude oil quickly injects from the high-permeability core, and the pressure drops rapidly. After several rounds of injection, the high-permeability core is well injected, while the injection volume of the medium- and low-permeability cores is extremely small.

[0109] It can be seen from the nuclear magnetic resonance test results that when the displacement pressure is 10 MPa, the high-permeability core 17-4 can be well injected, and the crude oil quickly breaks through the core. Then, as the displacement PV number increases, the oil saturation rises relatively slowly. When it reaches state 5, the oil saturation of the core reaches 67.51%. As the injection pore volume multiple increases, the oil saturation of the medium-permeability core 40 gradually increases, and the medium-permeability core can also be injected to a certain extent. At state 4, the oil saturation of the core reaches 36.57%. When it reaches state 5, the change in the oil saturation of the core is small, reaching 38.18%. It is analyzed that when it reaches state 5, the crude oil in the high-permeability core is fully injected to form a preferential channel, and the seepage resistance is small. While for the medium-permeability core, as the oil saturation increases, the seepage resistance of the oil-water two-phase increases. At this time, the seepage capacity during the injection process of the high-permeability core reaches 36 times that of the medium-permeability core, indicating that it is increasingly difficult to inject the medium-permeability core.

[0110] The entire injection process of the low-permeability core 79 has a large seepage resistance and is not fully injected, but the oil saturation increases to a certain extent as the displacement multiple increases. When the valve before the high-permeability core is closed at state 6, the oil saturation of the medium-permeability core increases significantly and can be well injected, and the low-permeability core can also be injected to a certain extent, and the oil saturation increases to a certain extent. When it is in state 7, since the medium-permeability core has been well injected, its oil saturation increases less, while the oil saturation of the low-permeability core increases to a certain extent and saturates into smaller pores. At this time, after the medium-permeability core is injected with a certain PV number, the crude oil forms a preferential channel in the core and the seepage velocity is relatively high, while the injection of the low-permeability core is slow, and the seepage capacity of the medium-permeability core reaches 30 times that of the low-permeability core. As shown in Table 5 below and Figure 10 、 11 shown.

[0111] Table 5 Displacement oil-water production law table of the fifth group of cores

[0112]

[0113]

[0114] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0115] Except for the technical features described in the specification, the rest are well-known technologies to those skilled in the art.

Claims

1. Physical simulation test system for the accumulation and filling law of heterogeneous reservoirs, characterized in that, The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs includes a displacement pump, a first intermediate container, a second intermediate container, a first core holder, a second core holder, a third core holder, a first recovery and measurement container, a second recovery and measurement container, and a third recovery and measurement container. The output end of the displacement pump is respectively connected to the first intermediate container and the second intermediate container. The outlets of the first intermediate container and the second intermediate container are connected to the first core holder, the second core holder, and the third core holder through pipelines. The output ends of the first core holder, the second core holder, and the third core holder are respectively connected to their corresponding first recovery and measurement container, second recovery and measurement container, and third recovery and measurement container.

2. The physical simulation test system for the hydrocarbon accumulation and charging law of heterogeneous reservoirs according to claim 1, characterized in that The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a manual pump, which is respectively connected to the first core holder, the second core holder, and the third core holder for confining pressure pressurization.

3. The physical simulation test system for the hydrocarbon accumulation and charging law of heterogeneous reservoirs according to claim 2, characterized in that, The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a second pressure gauge, which is located between the manual pump and the first core holder, the second core holder, and the third core holder.

4. The physical simulation test system for the accumulation and charging law of heterogeneous reservoirs according to claim 2, characterized in that, The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a constant temperature oven, and the manual pump, the first intermediate container, the second intermediate container, the first core holder, the second core holder, the third core holder, the first recovery and measurement container, the second recovery and measurement container, and the third recovery and measurement container are all located in the constant temperature oven.

5. The physical simulation test system for the hydrocarbon accumulation and charging law of heterogeneous reservoirs according to claim 1, characterized in that The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a first valve. The inlet ends of the first core holder, the second core holder, and the third core holder are in parallel and connected to one end of the first valve, and the other end of the first valve is connected to the outlets of the first intermediate container and the second intermediate container.

6. The physical simulation test system for the accumulation and charging law of heterogeneous reservoirs according to claim 5, characterized in that, The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a first pressure gauge, which is connected to the other end of the first valve.

7. The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs according to claim 1, characterized in that The physical simulation test system for the accumulation and filling law of heterogeneous reservoirs further includes a second valve, which is located between the first core holder and the first recovery and measurement container.

8. Physical simulation test method for the law of hydrocarbon accumulation and filling in heterogeneous reservoirs, characterized in that, The physical simulation test method for the accumulation and filling law of heterogeneous reservoirs uses the physical simulation test system for the accumulation and filling law of heterogeneous reservoirs described in claim 1, and includes: Step 1, prepare experimental cores and experimental oils. Step 2, test and calculate the gas permeability of the cores. Step 3, measure the porosity of the cores by the weighing method. Step 4, test the nuclear magnetic resonance T2 spectrum of the cores in the state of saturated simulated formation water to characterize the total pore volume. Step 5, respectively place the cores with high permeability, medium permeability, and low permeability into the first core holder, the second core holder, and the third core holder. Open the constant temperature oven to simulate the original reservoir temperature, apply confining pressure to simulate the original effective stress state of the formation, and then evacuate the front end of the cores. Step 6, use nuclear magnetic resonance to test the occurrence state of crude oil in the cores. Step 7, conduct the filling of the medium-permeability core and the low-permeability core. Step 8, calculate the oil saturation at different displacement stages.

9. The physical simulation test method for the hydrocarbon accumulation and filling law of heterogeneous reservoirs according to claim 8, characterized in that In Step 1, prepare the experimental core and experimental oil, fill the first intermediate container with simulated formation water, and fill the second intermediate container with simulated formation crude oil.

10. The physical simulation test method for the hydrocarbon accumulation and charging law of heterogeneous reservoirs according to claim 8, characterized in that, This physical simulation test method for the accumulation and filling law of heterogeneous reservoirs also includes, after Step 1, washing the experimental core with oil and drying it, and measuring the diameter and length of the core.

11. The physical simulation test method for the accumulation and charging law of heterogeneous reservoirs according to claim 8, characterized in that In Step 2, use the overburden pore pressure and permeability test system to measure and calculate the gas permeability of the core according to the stable gas flow rate under different pressures.

12. The physical simulation test method for the accumulation and filling law of heterogeneous reservoirs according to claim 8, characterized in that In Step 3, evacuate, fully saturate the core with simulated formation water, and then pressurize and saturate it to make the core fully saturated, and measure the porosity of the core by the weighing method.

13. The physical simulation test method for the hydrocarbon accumulation and filling law of heterogeneous reservoirs according to claim 8, characterized in that In Step 4, use the nuclear magnetic resonance core analyzer to measure the nuclear magnetic resonance T2 spectrum of the core in the state of being saturated with simulated formation water to characterize the total pore volume.

14. The physical simulation test method for the hydrocarbon accumulation and charging law of heterogeneous reservoirs according to claim 13, characterized in that, This physical simulation test method for the accumulation and filling law of heterogeneous reservoirs also includes, after Step 4, soaking the core in an aqueous solution of MnCl2 with a certain concentration until there is no nuclear magnetic resonance signal in the core. For cores with lower permeability, it is necessary to displace with an aqueous solution of MnCl2 to shield the nuclear magnetic resonance signal of water.

15. The physical simulation test method for the hydrocarbon accumulation and charging law of heterogeneous reservoirs according to claim 8, characterized in that, In Step 6, close the first valve, use the displacement pump to increase the displacement pressure to the designed displacement pressure, then open the first valve for displacement until the first pressure gauge drops to a certain pressure, close the first valve, and use nuclear magnetic resonance to measure the occurrence state of crude oil in the core.

16. The physical simulation test method for the hydrocarbon accumulation and filling law of heterogeneous reservoirs according to claim 8, characterized in that, In Step 7, displace to a certain PV number. The high-permeability core is fully saturated. Close the second valve and carry out the filling of the medium-permeability core and the low-permeability core.

17. The physical simulation test method for the hydrocarbon accumulation and filling law of heterogeneous reservoirs according to claim 8, wherein In Step 8, calculate the oil saturation at different displacement stages according to the ratio of the nuclear magnetic resonance signal amount of crude oil in the core to the signal amount of water in the saturated water state.

18. The physical simulation test method for the accumulation and filling law of heterogeneous reservoirs according to claim 17, characterized in that In Step 8, the formula for calculating the oil saturation So at different displacement stages is: Where: Mw represents the T2 signal amplitude in the saturated water state, Mo represents the T2 signal amplitude in the bound water state, and the subscript i represents the T2 relaxation time range.

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