Device and method for simulating recovery of thickened oil by viscosity-reducing composite flooding under low-efficiency water flooding

Abstract

The application provides a device and method for simulating low-efficiency water drive thick oil viscosity reduction composite drive enhanced oil recovery, which comprises an injection system, a three-dimensional large-size sand filling model, a multi-well back pressure measurement and control system and a multi-well flow metering system. The injection system is connected to the three-dimensional large-size sand filling model, and fluid is injected into the three-dimensional large-size sand filling model which can simulate well pattern mode. The multi-well back pressure measurement and control system is connected to the three-dimensional large-size sand filling model, and the formation pressure is set. The multi-well flow metering system is connected to the three-dimensional large-size sand filling model, and the output fluid is metered. The device and method for simulating low-efficiency water drive thick oil viscosity reduction composite drive enhanced oil recovery can meet the enhanced oil recovery experiments of water drive, polymer drive, viscosity reduction drive, viscosity reduction composite drive and the like of three-dimensional large-scale heterogeneous reservoir models under different well pattern modes, and has important significance for the enhanced oil recovery of low-efficiency water drive thick oil reservoirs.

Description

Technical Field

[0001] This invention relates to the field of oilfield production technology, and in particular to a device and method for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to improve oil recovery. Background Technology

[0002] Heavy oil accounts for a significant proportion of global oil and gas resources. my country has abundant heavy oil resources, accounting for approximately 20% of its total oil resources, with a predicted resource volume of 198 × 10⁻⁶. 8 Heavy oil reserves are mainly distributed in the Liaohe, Shengli, and Karamay oilfields.

[0003] Taking Shengli Oilfield as an example, the recoverable reserves of heavy oil through water-driven flooding are 890 million tons, with nearly half of the reservoirs having a recovery rate of less than 20%, currently in a stage of extremely high water cut (93.2%) and low oil production rate (0.4%). How to further improve development efficiency and increase recovery rate is the main technical challenge currently faced. To address this, field tests of viscosity-reducing composite flooding have been conducted, achieving good oil production enhancement effects. However, research on the oil displacement laws under different reservoir conditions lacks simulation methods, and the understanding of relevant laws and mechanisms is insufficient.

[0004] Therefore, researching devices and methods for simulating the combined flooding of inefficient water-driven heavy oil to reduce viscosity and enhance oil recovery is of great significance for improving the development effect and enhancing the recovery rate of inefficient water-driven heavy oil reservoirs.

[0005] Chinese patent application CN202110770054.6 discloses a three-dimensional physical simulation method for viscosity-reducing flooding of ordinary heavy oil reservoirs. The method includes: sampling reservoir cores and analyzing their physical properties; mixing epoxy resin with different mesh sizes of natural river sand; CNC sculpting a cubic cemented model to create a scaled-down reservoir model; applying high-temperature sealant to the scaled-down reservoir model; 3D printing a pressure chamber model; filling a 3D aluminum pressure chamber halfway with high-temperature sealant and placing the sealed three-dimensional scaled-down reservoir model inside; calculating the regular and irregular well patterns and spacings in the three-dimensional scaled-down reservoir model; and predicting the actual reservoir's recovery rate. This three-dimensional physical simulation method for viscosity-reducing flooding of ordinary heavy oil reservoirs simulates regular and irregular well patterns based on the actual well layout of the reservoir, detects the production of different single wells (such as fluid and oil production), and predicts the actual reservoir's recovery rate. This method provides a novel approach to three-dimensional modeling, but the wettability, capillary force, and other properties of this model differ significantly from those of actual reservoirs.

[0006] Chinese patent application CN201510628714.1 discloses a three-dimensional physical simulation device and method for bottom-water reservoir water energy. This device includes a model body, a water intermediate container, a gas intermediate container, a displacement pump, a high-pressure gas cylinder, a first six-way valve, and a second six-way valve. The top and bottom of the displacement pump, high-pressure gas cylinder, water intermediate container, and gas intermediate container are respectively connected to one valve of the first six-way valve. The bottom of the water intermediate container is connected to the bottom of the model body via the second six-way valve. The displacement pump pumps external water into the water intermediate container through the first six-way valve. The high-pressure gas cylinder injects external gas into the gas intermediate container through the first six-way valve. The model body contains the bottom-water oil layer to simulate the bottom-water reservoir. This invention significantly reduces the size of the three-dimensional physical simulation equipment, and the equipment used is simple and easy to operate, enabling the three-dimensional physical simulation of bottom-water reservoir water energy to be achieved indoors. However, it does not involve experimental methods for viscosity-reducing composite flooding.

[0007] Chinese patent application CN201310062915.0 discloses a three-dimensional physical simulation experimental device. This device involves placing multiple layers of rock cores within a model body. The contact surfaces between the model body and the sand are specially roughened, and the model cover plate is fixed to the outer support of the model body via an upper pressure plate. The sand used to simulate geological formations is actually under compression, providing a good seal. Sufficient saturation points and pressure measuring points are evenly arranged on the model's base plate. These saturation points and other measuring points can be interchanged using different connector methods, ensuring effective monitoring of the saturation and pressure field within the model during the experiment, and ensuring that the system's operating parameters meet experimental requirements. This invention effectively solves the problems of existing three-dimensional models, such as low working pressure, lack of an overburden pressure system, poor sealing, and the absence of saturation and pressure measuring points within the model. However, this invention only provides a three-dimensional physical model experimental device and does not involve related experimental methods.

[0008] The existing technologies mentioned above involve three-dimensional physical simulation devices, which focus on the production of the three-dimensional model body and do not involve the simulation of the actual oil reservoir viscosity reduction composite process. They are all quite different from the present invention and fail to solve the technical problem we want to solve. Therefore, we have invented a new device and method for simulating inefficient water-driven heavy oil viscosity reduction composite flooding to improve recovery rate. Summary of the Invention

[0009] The purpose of this invention is to provide an apparatus and method for improving oil recovery by simulating inefficient water-driven heavy oil viscosity reduction combined flooding based on actual reservoir characteristics.

[0010] The objective of this invention can be achieved through the following technical measures: a device for simulating inefficient water-driven heavy oil viscosity reduction composite flooding to enhance oil recovery. This device includes an injection system, a three-dimensional large-scale sand-filled model, a multi-well backpressure monitoring and control system, and a multi-well flow metering system. The injection system is connected to the three-dimensional large-scale sand-filled model and injects fluid into the model, which can simulate well network patterns. The multi-well backpressure monitoring and control system is connected to the three-dimensional large-scale sand-filled model and sets the formation pressure. The multi-well flow metering system is connected to the three-dimensional large-scale sand-filled model and measures the produced fluid.

[0011] The objective of this invention can also be achieved through the following technical measures:

[0012] The injection system includes a first constant-pressure constant-flow pump, a second constant-pressure constant-flow pump, a formation water intermediate container, a crude oil intermediate container, a plugging agent intermediate container, a water-soluble viscosity reducer intermediate container, an oil-soluble viscosity reducer intermediate container, a tracer intermediate container, and a drain valve. The first constant-pressure constant-flow pump is connected to the formation water intermediate container, the crude oil intermediate container, the plugging agent intermediate container, the water-soluble viscosity reducer intermediate container, and the tracer intermediate container through the drain valve, so as to inject formation water, crude oil, plugging agent, water-soluble viscosity reducer, and tracer into the injection well of the three-dimensional large-scale sand-filled model. The second constant-pressure constant-flow pump is connected to the oil-soluble viscosity reducer intermediate container and the water-soluble viscosity reducer intermediate container, so as to inject oil-soluble viscosity reducer and water-soluble viscosity reducer into the production well of the three-dimensional large-scale sand-filled model.

[0013] The injection system also includes a six-way valve, a gas cylinder, a booster pump, and an air compressor. The crude oil intermediate container, the formation water intermediate container, the plugging agent intermediate container, the tracer intermediate container, the water-soluble viscosity reducer intermediate container, and the booster pump are connected to the injection well of the three-dimensional large-scale sand-filled model through the six-way valve. The gas cylinder and the air compressor are respectively connected to the booster pump. The booster pump pressurizes the gas in the gas cylinder and provides a gas source for the experiment as needed.

[0014] The device for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery also includes an oven, in which the intermediate container for formation water, the intermediate container for crude oil, the intermediate container for plugging agent, the intermediate container for water-soluble viscosity reducer, the intermediate container for oil-soluble viscosity reducer, the intermediate container for tracer, and the three-dimensional large-scale sand-filled model are all located.

[0015] The large-scale three-dimensional sand-filled model includes a three-dimensional model body, a pressure inspection and acquisition module, a resistivity measurement and acquisition module, and a well network module. The three-dimensional model body is used to fill the homogeneous model, interlayer heterogeneous model, and planar interlayer heterogeneous model required for the experiment. The sides and bottom of the three-dimensional model body are provided with holes that connect to the pressure inspection and acquisition module, the resistivity measurement and acquisition module, and the well network module. The pressure inspection and acquisition module collects the pressure data of the three-dimensional model body, the resistivity measurement and acquisition module collects the resistivity data of the three-dimensional model body, and the well network module simulates the well network pattern of the actual well group in the reservoir.

[0016] The pressure inspection and acquisition module includes a pressure sensor and a pressure acquisition module. The pressure sensor is connected to the 3D model body, the pressure sensor is connected to the pressure acquisition module, and the pressure acquisition module is connected to a computer. The pressure data of the 3D model body acquired by the pressure sensor is transmitted to the computer through the pressure acquisition module.

[0017] The resistivity measurement and acquisition module includes a resistivity probe and a resistivity acquisition device. The resistivity probe is connected to the three-dimensional model body, the resistivity probe is connected to the resistivity acquisition device, and the resistivity acquisition device is connected to a computer. The resistivity data of the three-dimensional model body acquired by the resistivity probe is transmitted, converted, and displayed on the computer through the resistivity acquisition device.

[0018] The multi-well backpressure monitoring and control system includes a backpressure valve, a constant pressure pump, and a multi-well backpressure monitoring and control system. The backpressure valve is connected to the production well of the three-dimensional large-scale sand-filled model through a pipeline. The constant pressure pump is connected to the backpressure valve. The pump's inlet or outlet action on the backpressure valve increases or decreases the formation pressure. The multi-well backpressure monitoring and control system is connected to a computer to control the production pressure difference between the injection and production wells.

[0019] The multi-well flow metering system includes an electronic balance and a gas flow meter. The electronic balance and the gas flow meter are connected to a computer. The data collection container of the electronic balance is connected to the outlet of the back pressure valve. The electronic balance is used to measure the amount of produced fluid, and the gas flow meter is used to measure the gas flow rate.

[0020] The objective of this invention can also be achieved through the following technical measures: a method for simulating inefficient water-driven heavy oil viscosity-reducing combined flooding to enhance oil recovery, wherein the method employs an apparatus for simulating inefficient water-driven heavy oil viscosity-reducing combined flooding to enhance oil recovery, comprising:

[0021] Step 1: Determine the reservoir physical properties and derive the similarity criteria;

[0022] Step 2: Prepare a three-dimensional large-scale sand-filled model;

[0023] Step 3: Using the prepared three-dimensional large-scale sand-filled model, conduct a simulation experiment of inefficient water-driven heavy oil viscosity reduction composite flooding.

[0024] Step 4: Collect pressure, resistivity, and temperature data of the large-scale three-dimensional sand-filled model during the experiment;

[0025] Step 5: After the experiment, test the oil saturation of the samples at different locations to correct the collected saturation.

[0026] Step 6: Construct a three-dimensional numerical model of viscosity-reducing composite drive based on the three-dimensional large-scale sand-filling model, and use numerical methods to invert the flow field evolution characteristics during the development process.

[0027] The objective of this invention can also be achieved through the following technical measures:

[0028] In step 1, the target block and target well group are selected, and the reservoir characteristics and production dynamics of the well group are analyzed. Parameters such as well pattern, well spacing, layer thickness, crude oil viscosity, permeability, porosity, saturation, and temperature are determined. The similarity criteria for water drive and viscosity-reducing composite drive are derived using the integral analogy method, the main similarity criteria number for viscosity-reducing composite drive is determined, and the parameters of the three-dimensional physical simulation between the reservoir well group prototype and the scale model are converted.

[0029] In step 2, based on the physical property parameters, sedimentary rhythm and interlayer characteristics determined by the similarity criterion, and combined with the core grain size analysis results, homogeneous models, interlayer heterogeneous models and planar interlayer heterogeneous models required for the experiment are prepared; at the same time, resistivity acquisition devices are evenly arranged according to the actual well pattern during the model making process.

[0030] Step 3 includes:

[0031] Step 31: Perform an airtightness test. Connect the experimental device according to the procedure. Use a gas testing device to check the airtightness. Inject gas into the three-dimensional model body. If the pressure remains stable, the model has good airtightness.

[0032] Step 32: Saturate the sand-filled model. Use a vacuum pump to evacuate the model. Inject produced formation water into the model at multiple points and at low speed to saturate the formation water. Inject formation crude oil into the model at multiple points and at low speed to saturate the formation crude oil. Check the pressure sensor and resistivity acquisition device to ensure that they are in normal operating condition. Aging is carried out for a set time under reservoir temperature and pressure conditions.

[0033] Step 33, water drive: According to the injection parameters determined by the similarity criteria, open the formation water intermediate container to inject water from the central well, start production, and drive water drive until the actual reservoir water cut is reached.

[0034] Step 34: Inject plugging agent. According to the designed injection volume, open the intermediate container of plugging agent and inject the plugging agent with the set PV number from the central well to seal the high-permeability channel between the injection wells.

[0035] Step 35: Inject viscosity reducer, close the plugging agent valve, open the intermediate viscosity reducer container valve, and inject the water-soluble viscosity reducer with the set PV number;

[0036] Step 36, proceed with subsequent water drive; close the viscosity reducer injection valve, open the water drive valve and continue water drive;

[0037] Step 37: Perform production well inflow and outflow to induce production effect; based on experimental requirements, for inefficient production wells, use an injection pump to inject a set amount of oil-soluble viscosity reducer into the production well, and inject a set amount of water-soluble viscosity reducer to further expand the effect. After the well is shut down for a period of time, start production.

[0038] Step 38: Adjust the flow field; based on the characteristics of the well network, implement measures such as converting production wells into injection wells, densifying the well network, and adjusting the fluid volume of injection and production wells to change the flow line of the well group and further improve the recovery rate of the well group;

[0039] Step 39, tracer drive: Close the water drive valve, open the tracer injection valve, and inject water-soluble tracer into the model.

[0040] In step 5, the produced liquid is processed and separated, the instantaneous production of oil and water is calculated, and samples are taken and photographed in different areas. The oil saturation of samples at different locations is tested to correct the collected saturation.

[0041] The apparatus and method for simulating low-efficiency water-driven heavy oil viscosity-reducing composite flooding to enhance oil recovery in this invention are reasonably conceived, simple to operate, and closely resemble the actual reservoir development process. They can simulate the well network pattern of actual well groups, mimicking the three-dimensional spatial variations in sedimentary rhythm, interlayer characteristics, reservoir space, and heterogeneity of permeable properties. They can also simulate the fluid flow characteristics of heavy oil under formation conditions, simulate well network flow field adjustments, and invert the evolution characteristics of the well network flow field. This invention can meet the needs of large-scale three-dimensional heterogeneous reservoir models under different well network patterns for enhancing oil recovery through water-driven oil recovery, polymer flooding, viscosity-reducing flooding, and viscosity-reducing composite flooding. It is of great significance for enhancing the oil recovery of low-efficiency water-driven heavy oil reservoirs. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structural connection of the device for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery according to the present invention.

[0043] Figure 2 This is a schematic diagram of the structure and connection of the multi-well backpressure monitoring and control system of the present invention;

[0044] Figure 3This is a flowchart of the experimental method for improving oil recovery by inefficient water-driven heavy oil viscosity reduction combined flooding according to the present invention;

[0045] Figure 4 This is a recovery rate and pressure curve diagram in a specific embodiment of the present invention;

[0046] Figure 5 This is a pressure field distribution diagram in a specific embodiment of the present invention;

[0047] Figure 6 This is a concentration field distribution diagram of the viscosity reducer in a specific embodiment of the present invention;

[0048] Figure 7 This is a water saturation field distribution diagram in a specific embodiment of the present invention;

[0049] Figure 8 This is a streamline field distribution diagram in a specific embodiment of the present invention;

[0050] Figure 9 This is a streamline diagram of the reverse nine-point well network to the row-shaped injection-production well network in a specific embodiment of the present invention. Detailed Implementation

[0051] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0052] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should 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.

[0053] The device for simulating low-efficiency water-driven heavy oil reservoir viscosity reduction and combined flooding to enhance oil recovery of the present invention includes an injection system for injecting fluid into a three-dimensional sand-filled model, a three-dimensional large-scale sand-filled model for simulating well pattern, a multi-well backpressure measurement and control system for setting formation pressure, a multi-well flow rate measurement system for measuring produced fluid, and a temperature control system for adjusting temperature.

[0054] The injection system includes a first constant-pressure constant-flow pump, a second constant-pressure constant-flow pump, intermediate containers for formation water, crude oil, plugging agent, water-soluble viscosity reducer, oil-soluble viscosity reducer, and tracer, as well as drain valves. The first constant-pressure constant-flow pump is connected to the intermediate containers for formation water, crude oil, plugging agent, water-soluble viscosity reducer, and tracer via drain valves, so as to inject formation water, crude oil, plugging agent, water-soluble viscosity reducer, and tracer from the intermediate containers into the injection well of the 3D model. The second constant-pressure constant-flow pump is connected to the intermediate containers for oil-soluble and water-soluble viscosity reducers, so as to inject oil-soluble and water-soluble viscosity reducers into the production well of the 3D model.

[0055] The injection system also includes a gas cylinder, a booster pump, and an air compressor. The gas cylinder is connected to the booster pump and the air compressor. The booster pump is connected to the three-dimensional model system to pressurize the gas and provide a gas source for the experiment as needed.

[0056] The large-scale three-dimensional sand-filled model includes a three-dimensional model body, a pressure inspection and acquisition module, a resistivity measurement and acquisition module, and a well network module. The three-dimensional model has holes on its sides and bottom that connect to the pressure inspection and acquisition module, the resistivity measurement and acquisition module, and the well network module. The pressure inspection and acquisition module collects pressure data from the three-dimensional model body, and the resistivity measurement and acquisition module collects resistivity data from the three-dimensional model body. The well network module simulates the well network pattern of the actual well group in the oil reservoir.

[0057] The device for improving oil recovery by viscosity reduction and combined flooding of inefficient water-driven heavy oil reservoirs also includes an oven, and intermediate containers for formation water, crude oil, plugging agent, water-soluble viscosity reducer, oil-soluble viscosity reducer, tracer, and the three-dimensional large-scale sand-filled model are all located in the oven.

[0058] The pressure inspection and acquisition module includes a pressure sensor and a pressure acquisition module. The pressure sensor is connected to the 3D model body, the pressure sensor is connected to the pressure acquisition module, and the pressure acquisition module is connected to a computer. The pressure data is transmitted through the pressure acquisition module and displayed on the computer acquisition software.

[0059] The resistivity measurement and acquisition module includes a resistivity probe and a resistivity acquisition device. The resistivity probe is connected to the three-dimensional model body, the resistivity probe is connected to the resistivity acquisition device, and the resistivity acquisition device is connected to a computer. The resistivity data is transmitted, converted, and displayed on the computer acquisition software through the resistivity acquisition device.

[0060] The multi-well backpressure monitoring and control system includes a backpressure valve, a constant pressure pump, and the system itself. The backpressure valve is connected to the production well via pipeline. The constant pressure pump is connected to the backpressure valve; by pumping in or out of the constant pressure pump, the formation pressure is increased or decreased. The multi-well backpressure monitoring and control system is connected to a computer, enabling control of the production pressure differential. This production pressure differential is the pressure difference between the injection and production wells; the injection well has a higher pressure, while the production well has a lower pressure, with fluid flowing from the high-pressure well to the low-pressure well.

[0061] The multi-well flow metering system includes an electronic balance and a gas flow meter. The electronic balance and the gas flow meter are connected to a computer. The data collection container of the electronic balance is connected to the outlet of the back pressure valve. The electronic balance is used to measure the amount of produced fluid, and the flow meter is used to measure the gas flow.

[0062] Methods to improve oil recovery by simulating inefficient water-driven heavy oil viscosity reduction combined flooding, such as... Figure 3 As shown, this method for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery employs a device for enhancing oil recovery through inefficient water-driven heavy oil reservoir viscosity reduction combined flooding, including:

[0063] Step 1: Determining reservoir physical properties. Select the target block and target well group, analyze the reservoir characteristics and production dynamics of the well group, and determine parameters such as well pattern, well spacing, layer thickness, crude oil viscosity, permeability, porosity, saturation, and temperature;

[0064] Step 2, Derivation of Similarity Criteria. The similarity criteria for waterflooding and viscosity-reducing composite flooding are derived using the integral analogy method. The main similarity criterion numbers for viscosity-reducing composite flooding are determined, and parameter conversion between the reservoir well group prototype and the scale model in three-dimensional physical simulation is performed.

[0065] Step 3: Preparation of a large-scale three-dimensional sand-filled model. Based on the physical properties, sedimentary rhythm, and interlayer characteristics determined by the similarity criterion, and combined with the core grain size analysis results, homogeneous models, interlayer heterogeneous models, and planar interlayer heterogeneous models required for the experiment are prepared. Simultaneously, resistivity acquisition devices are uniformly arranged according to the actual well pattern during model construction.

[0066] Step 4, airtightness test. Connect the experimental apparatus according to the procedure, and use a gas testing device to check the airtightness. Inject gas into the three-dimensional physical simulation closed device. If the pressure remains stable, the model has good airtightness.

[0067] Step 5, Saturate the sand-filled model. Use a vacuum pump to evacuate the model, inject produced formation water into the model at multiple points and low speed to saturate the formation water, and inject formation crude oil into the model at multiple points and low speed to saturate the formation crude oil. Check the pressure sensor and resistivity acquisition device to ensure that they are in normal operating condition, and age them for the set time under reservoir temperature and pressure conditions.

[0068] Step 6, Water Drive. Following the injection parameters determined by the similarity criteria, open the intermediate formation water container and inject water from the central well. Start production and drive water up to the actual reservoir water cut to end the water drive process.

[0069] Step 7, Injecting and Adjusting Agent. According to the designed injection volume, open the intermediate container of the adjusting agent and inject the set PV number of the adjusting agent from the central well to seal the high-permeability channels between the injection wells;

[0070] Step 8, inject viscosity reducer. Close the plugging agent valve, open the intermediate viscosity reducer container valve, and inject the water-soluble viscosity reducer with the set PV number;

[0071] Step 9, subsequent water drive. Close the viscosity reducer injection valve and open the water drive valve to continue water drive;

[0072] Step 10, production well induction effect. Based on experimental requirements, for inefficient production wells, a set amount of oil-soluble viscosity reducer is injected using an injection pump, and a set amount of water-soluble viscosity reducer is injected to further expand the effect. After the well is shut down for a period of time, production is started.

[0073] Step 11, Flow field adjustment. Based on the characteristics of the well network, the flow lines of the well group are changed by converting production wells to injection wells, densifying the well network, and adjusting the fluid volume of injection and production wells to further improve the recovery rate of the well group;

[0074] Step 12, tracer flooding. Close the water flooding valve, open the tracer injection valve, and inject water-soluble tracer into the model;

[0075] Step 13: Use computer monitoring software to record and monitor data such as pressure, resistivity, and temperature during the experiment.

[0076] Step 14, experiment ends. The produced liquid is processed and separated, the instantaneous oil-water production is calculated, and samples are taken and photographed in different areas. The oil saturation of samples at different locations is tested to correct the collected saturation.

[0077] Step 15, Numerical Inversion. Based on the experimental model, a three-dimensional numerical model of viscosity-reducing composite drive is constructed, and the flow field evolution characteristics during the development process are inverted using numerical methods.

[0078] The apparatus and method for simulating low-efficiency water-driven heavy oil viscosity-reducing composite flooding to enhance oil recovery in this invention are reasonably conceived, simple to operate, and closely resemble the actual reservoir development process. They can simulate the well network pattern of actual well groups, mimicking the three-dimensional spatial variations in sedimentary rhythm, interlayer characteristics, reservoir space, and heterogeneity of permeable properties. They can also simulate the fluid flow characteristics of heavy oil under formation conditions, simulate well network flow field adjustments, and invert the evolution characteristics of the well network flow field. This invention can meet the needs of large-scale three-dimensional heterogeneous reservoir models under different well network patterns for enhancing oil recovery through water-driven oil recovery, polymer flooding, viscosity-reducing flooding, and viscosity-reducing composite flooding. It is of great significance for enhancing the oil recovery of low-efficiency water-driven heavy oil reservoirs.

[0079] The following are several specific embodiments of the application of the present invention.

[0080] Example 1

[0081] In a specific embodiment 1 of the present invention, such as Figure 1 and Figure 2 As shown, a device for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to improve oil recovery includes an injection system, a three-dimensional large-scale sand-filled model, a multi-well backpressure monitoring and control system, and a multi-well flow metering system.

[0082] The injection system includes a constant pressure and constant flow pump 1, a constant speed and constant flow pump 2, an intermediate crude oil container 4, an intermediate formation water container 5, an intermediate plugging agent container 6, an intermediate tracer container 7, an intermediate water-soluble viscosity reducer container 8, an intermediate oil-soluble viscosity reducer container 9, a nitrogen cylinder 10, a booster pump 11, an air compressor 12, a drain valve 3, and a six-way valve 13. The constant pressure and constant flow pumps 1 and 2 are connected to the intermediate containers via the drain valve 3. The intermediate crude oil container 4, intermediate formation water container 5, intermediate plugging agent container 6, intermediate tracer container 7, intermediate water-soluble viscosity reducer container 8, nitrogen cylinder 10, booster pump 11, and air compressor 12 are connected to the injection well of the 3D model body via the six-way valve 13. The intermediate water-soluble viscosity reducer containers 8 and 9 are connected to the production well of the 3D model body via pipelines.

[0083] The three-dimensional model system comprises a three-dimensional model body 14, a pressure measurement and acquisition module, and a resistivity measurement and acquisition module. The model body 14 is placed in an oven 24.

[0084] The three-dimensional model body has an inner cavity that is 30cm long, 30cm wide, and 20cm high, with a wall thickness of 8cm. The model body can withstand a maximum pressure of 30MPa. The sides and bottom of the model are provided with holes that connect to the pressure sensor and resistivity probe.

[0085] The pressure measurement and acquisition module includes a pressure sensor 15, a pressure acquisition module 16, a digital display, and pressure acquisition and display software. The pressure sensor 15 is connected to the three-dimensional model body 14, the pressure sensor 15 is connected to the pressure acquisition module 16, and the pressure acquisition module 16 is connected to the computer 18.

[0086] The resistivity measurement and acquisition module includes a resistivity probe 25 and a resistivity acquisition device 17. The resistivity probe 25 is connected to the three-dimensional model body 14, the resistivity probe 25 is connected to the resistivity acquisition device 17, and the resistivity acquisition device 17 is connected to the computer 18.

[0087] The multi-well backpressure monitoring and control system includes a backpressure valve 20, a constant pressure pump 21, and a multi-well backpressure monitoring and control system. The backpressure valve 20 is connected to the production well in the three-dimensional model through a pipeline. The backpressure valve 20 is connected to the constant pressure pump 21 through a drain valve 23. The constant pressure pump 21 is connected to a computer 18.

[0088] The multi-well flow metering system includes an electronic balance 22 and a gas flow meter 23. The electronic balance's collection container 22 is connected to the outlet end of the back pressure valve 20. The electronic balance 22 and the gas flow meter 23 are connected to a computer.

[0089] The device for improving oil recovery by viscosity reduction composite flooding in inefficient water-driven heavy oil reservoirs also includes an oven 24, an intermediate container for crude oil 4, an intermediate container for formation water 5, an intermediate container for plugging agent 6, an intermediate container for tracer 7, an intermediate container for water-soluble viscosity reducer 8, an intermediate container for oil-soluble viscosity reducer 9, and a three-dimensional model body 14, all of which are located in the oven.

[0090] Example 2

[0091] In a specific embodiment 2 of the present invention, the present invention discloses a method for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to improve oil recovery. The experimental method includes the following steps:

[0092] Step 1: Determination of reservoir physical parameters. The target block well pattern is an inverse five-point well pattern with a well spacing of 200×300m; the oil layer thickness ranges from 2.2 to 5m; under formation conditions, the crude oil viscosity is between 300 and 500 mPa·s, the average reservoir permeability is 432 mD, the porosity is 28%, and the oil saturation is 56%; the formation temperature is 54℃, and the injection rate is 40-80 m³ / s. 3 / d;

[0093] Step 2, Derivation of Similarity Criteria. The main similarity criteria for viscosity-reducing composite flooding are: production time, production pressure differential, permeability, interfacial tension, and injection rate. The converted model parameters are: well spacing 21.2 cm; reservoir thickness 5 cm; crude oil viscosity between 300-500 mPa·s under formation conditions, reservoir permeability 432 mD, porosity 28%, oil saturation 56%; formation temperature 54℃; and injection rate 3-6 mL / min.

[0094] Step 3, preparation of a three-dimensional large-scale sand-filled model. For homogeneous thick layers, a homogeneous model required for the experiment is prepared. The sand particle ratio is 40-60 mesh: 60-100 mesh: 100-150 mesh = 1:5:4. The sand particles are mixed evenly, filled into the model and compacted. Nine sets of resistivity probes are evenly arranged on the plane.

[0095] Step 4, airtightness test. Connect the experimental apparatus according to the procedure, inject nitrogen into the three-dimensional physical simulation sealed device, and pressurize it to 3MPa. If the pressure remains stable, the model has good airtightness.

[0096] Step 5: Saturate the sand-filled model. Use a vacuum pump to evacuate the model, then inject produced formation water at multiple points and at low speed into the model to saturate the formation water, calculating the saturation water volume. Inject crude oil at multiple points and at low speed into the model to saturate it, recording the injected oil volume and the volume of water displaced. Check the initial values ​​of the pressure sensor and resistivity acquisition device to ensure they are in normal operating condition. Aging is performed for 48 hours under reservoir temperature and pressure conditions.

[0097] Step 6, water drive. Based on the calculation results according to the similarity criterion, the injection rate is set to 3 ml / min. Water is injected from the central well through the intermediate formation water container, and production is started. Water drive ends when the actual water cut reaches 80%.

[0098] Step 7, inject viscosity reducer. Close the water drive valve, open the valve of the intermediate viscosity reducer container, and inject 0.3 PV of water-soluble viscosity reducer into the stopcock;

[0099] Step 8, subsequent water drive. Close the viscosity reducer injection valve and open the water drive valve to continue water drive;

[0100] Step 9, tracer flooding. Close the water flooding valve, open the tracer injection valve, and inject water-soluble tracer into the model;

[0101] Step 10: Use computer monitoring software to record and monitor data such as pressure, resistivity, and temperature during the experiment.

[0102] Step 11, experiment complete. The produced fluid is processed and separated; instantaneous oil-water production, water cut, and recovery rate are calculated, such as... Figure 4 As shown. Sectional photography and sampling were conducted, and the oil saturation of samples at different locations was tested to correct the collected saturation.

[0103] Example 3

[0104] In a specific embodiment 3 of the present invention, the method for improving oil recovery by simulating inefficient water-driven heavy oil viscosity reduction combined flooding includes:

[0105] Step 1: Determination of reservoir physical parameters. The target block well pattern is an inverted nine-point well pattern with a well spacing of 300m; the effective oil layer thickness is 100m; the formation crude oil viscosity is 90mPa·s, the reservoir permeability is 1500-3000mD, the porosity is 32%, and the oil saturation is 65%; the formation temperature is 64℃, the formation pressure is 15MPa, and the injection rate is 500-3000m³. 3 / d, production time 25a;

[0106] Step 2, Derivation of Similarity Criteria. The main similarity criteria for viscosity-reducing composite flooding are: production time, production pressure differential, permeability, interfacial tension, injection rate, and time to full production. The converted model parameters are: well spacing 13cm; effective thickness 20cm; crude oil viscosity 90mPa.s, permeability 1500-3000mD, porosity 32%, oil saturation 65%; formation temperature 64℃, formation pressure 15MPa, injection rate 0.5-2mL / min, and production time 1-3d.

[0107] Step 3: Preparation of a three-dimensional large-scale model. For multi-layered heterogeneous positive rhythmic reservoirs, a heterogeneous model was prepared. The sand particle ratio for 1000-2000mD was 40-60 mesh: 60-100 mesh: 100-150 mesh = 3:5:2, and the sand particle ratio for 2000-4000mD was 40-60 mesh: 60-100 mesh: 100-150 mesh = 3:5:1. The sand particles with different ratios were mixed evenly, loaded into the model, and compacted. 27 sets of resistivity probes were evenly arranged in 9 groups in the plane and 3 layers in the vertical direction.

[0108] Step 4, airtightness test. Connect the experimental device according to the procedure, inject nitrogen into the three-dimensional physical simulation sealed device, and pressurize it to 15MPa. If the pressure remains stable, the model has good airtightness.

[0109] Step 5: Saturate the sand-filled model. Use a vacuum pump to evacuate the model, then inject produced formation water at multiple points and at low speed into the model to saturate the formation water, recording the saturation water volume. Inject crude oil at multiple points and at low speed into the model to saturate the crude oil, recording the injected oil volume and the volume of water displaced. Check the initial values ​​of the pressure sensor and resistivity acquisition device to ensure they are in normal operating condition. Aging is performed for 48 hours under reservoir temperature and pressure conditions.

[0110] Step 6, water drive. Based on the calculation results according to the similarity criterion, the injection rate is set to 2 ml / min. Water is injected from the central well through the intermediate formation water container, and production is started. Water drive ends when the actual water cut reaches 98%.

[0111] Step 7, Inject plugging agent. Open the intermediate plugging agent container and inject 0.3PV of plugging agent from the central well to seal the high-permeability channel between the injection wells;

[0112] Step 8, inject viscosity reducer. Close the plugging agent valve, open the valve of the intermediate container for water-soluble viscosity reducer, and inject 0.3 PV of water-soluble viscosity reducer;

[0113] Step 9, subsequent water drive. Close the water-soluble viscosity reducer injection valve, open the water drive valve to continue water drive;

[0114] Step 10, production well induction. For inefficient production wells, inject 10 mL of oil-soluble viscosity reducer using an injection pump, close the oil-soluble viscosity reducer injection valve, open the water-soluble viscosity reducer valve, and inject 10 mL of water-soluble viscosity reducer to further expand the effect. After simmering the well for 10 hours, start production.

[0115] Step 11, Flow Field Adjustment. Convert side wells into injection wells to form a row-shaped injection-production well network, such as... Figure 9 As shown, the production fluid volume of high water-cut production wells is reduced, the fluid volume of inefficient wells is increased, and the well group streamline is adjusted to further improve the well group recovery rate.

[0116] Step 12, tracer flooding. Close the water flooding valve, open the tracer injection valve, and inject water-soluble tracer into the model;

[0117] Step 13: Use computer monitoring software to record and monitor data such as pressure, resistivity, and temperature during the experiment.

[0118] Step 14, experiment ends. The produced liquid is processed and separated, the instantaneous oil-water production is calculated, and samples are taken and photographed in different areas. The oil saturation of samples at different locations is tested to correct the collected saturation.

[0119] Step 15, Numerical Inversion. Based on the experimental model, a three-dimensional numerical model of viscosity-reducing composite drive is constructed, and the flow field evolution characteristics during the development process are inverted using numerical methods. Figure 5 This is a pressure field diagram derived from the inversion of pressure data. Figure 6 For the inverted viscosity reducer concentration field diagram, Figure 7 For the inverted water saturation field map, Figure 8 This is the streamline field diagram after inversion.

[0120] The flow chart can reflect the dynamic changes in reservoir pressure, viscosity reducer, crude oil, and water throughout the experiment, providing a basis for the dynamic adjustment of viscosity-reducing composite flooding.

[0121] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended 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 make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0122] Except for the technical features described in the specification, all other technologies are known to those skilled in the art.

Claims

1. A device for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery, characterized in that, The device for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery includes an injection system, a three-dimensional large-scale sand-filled model, a multi-well backpressure monitoring and control system, and a multi-well flow metering system. The injection system is connected to the three-dimensional large-scale sand-filled model and injects fluid into the model, which can simulate well network patterns. The multi-well backpressure monitoring and control system is connected to the three-dimensional large-scale sand-filled model and sets the formation pressure. The multi-well flow metering system is connected to the three-dimensional large-scale sand-filled model and measures the produced fluid.

2. The apparatus for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 1, characterized in that, The injection system includes a first constant-pressure constant-flow pump, a second constant-pressure constant-flow pump, a formation water intermediate container, a crude oil intermediate container, a plugging agent intermediate container, a water-soluble viscosity reducer intermediate container, an oil-soluble viscosity reducer intermediate container, a tracer intermediate container, and a drain valve. The first constant-pressure constant-flow pump is connected to the formation water intermediate container, the crude oil intermediate container, the plugging agent intermediate container, the water-soluble viscosity reducer intermediate container, and the tracer intermediate container through the drain valve, so as to inject formation water, crude oil, plugging agent, water-soluble viscosity reducer, and tracer into the injection well of the three-dimensional large-scale sand-filled model. The second constant-pressure constant-flow pump is connected to the oil-soluble viscosity reducer intermediate container and the water-soluble viscosity reducer intermediate container, so as to inject oil-soluble viscosity reducer and water-soluble viscosity reducer into the production well of the three-dimensional large-scale sand-filled model.

3. The apparatus for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 2, characterized in that, The injection system also includes a six-way valve, a gas cylinder, a booster pump, and an air compressor. The crude oil intermediate container, the formation water intermediate container, the plugging agent intermediate container, the tracer intermediate container, the water-soluble viscosity reducer intermediate container, and the booster pump are connected to the injection well of the three-dimensional large-scale sand-filled model through the six-way valve. The gas cylinder and the air compressor are respectively connected to the booster pump. The booster pump pressurizes the gas in the gas cylinder and provides a gas source for the experiment as needed.

4. The apparatus for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 2, characterized in that, The device for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery also includes an oven, in which the formation water intermediate container, the crude oil intermediate container, the plugging agent intermediate container, the water-soluble viscosity reducer intermediate container, the oil-soluble viscosity reducer intermediate container, the tracer intermediate container, and the three-dimensional large-scale sand-filled model are all located.

5. The apparatus for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 1, characterized in that, The large-scale three-dimensional sand-filled model includes a three-dimensional model body, a pressure inspection and acquisition module, a resistivity measurement and acquisition module, and a well network module. The three-dimensional model body is used to fill the homogeneous model, interlayer heterogeneous model, and planar interlayer heterogeneous model required for the experiment. The sides and bottom of the three-dimensional model body are provided with holes that connect to the pressure inspection and acquisition module, the resistivity measurement and acquisition module, and the well network module. The pressure inspection and acquisition module collects the pressure data of the three-dimensional model body, the resistivity measurement and acquisition module collects the resistivity data of the three-dimensional model body, and the well network module simulates the well network pattern of the actual well group in the reservoir.

6. The device for simulating inefficient water-driven heavy oil viscosity reduction composite flooding to improve oil recovery according to claim 5, wherein the pressure inspection and acquisition module includes a pressure sensor and a pressure acquisition module, the pressure sensor is connected to the three-dimensional model body, the pressure sensor is connected to the pressure acquisition module, the pressure acquisition module is connected to a computer, and the pressure data of the three-dimensional model body acquired by the pressure sensor is transmitted to the computer through the pressure acquisition module. The resistivity measurement and acquisition module includes a resistivity probe and a resistivity acquisition device. The resistivity probe is connected to the three-dimensional model body, the resistivity probe is connected to the resistivity acquisition device, and the resistivity acquisition device is connected to a computer. The resistivity data of the three-dimensional model body acquired by the resistivity probe is transmitted, converted, and displayed on the computer through the resistivity acquisition device.

7. The apparatus for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 1, characterized in that, The multi-well backpressure monitoring and control system includes a backpressure valve, a constant pressure pump, and a multi-well backpressure monitoring and control system. The backpressure valve is connected to the production well of the three-dimensional large-scale sand-filled model through a pipeline. The constant pressure pump is connected to the backpressure valve. The pump's inlet or outlet action on the backpressure valve increases or decreases the formation pressure. The multi-well backpressure monitoring and control system is connected to a computer to control the production pressure differential.

8. The apparatus for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 7, characterized in that, The multi-well flow metering system includes an electronic balance and a gas flow meter. The electronic balance and the gas flow meter are connected to a computer. The data collection container of the electronic balance is connected to the outlet of the back pressure valve. The electronic balance is used to measure the amount of produced fluid, and the gas flow meter is used to measure the gas flow rate.

9. A method for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery, characterized in that, The method for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery uses the apparatus for simulating inefficient water-driven heavy oil viscosity reduction combined flooding to enhance oil recovery as described in claim 1, comprising: Step 1: Determine the reservoir physical properties and derive the similarity criteria; Step 2: Prepare a three-dimensional large-scale sand-filled model; Step 3: Using the prepared three-dimensional large-scale sand-filled model, conduct a simulation experiment of inefficient water-driven heavy oil viscosity reduction composite flooding. Step 4: Collect pressure, resistivity, and temperature data of the large-scale three-dimensional sand-filled model during the experiment; Step 5: After the experiment, test the oil saturation of the samples at different locations to correct the collected saturation. Step 6: Construct a three-dimensional numerical model of viscosity-reducing composite drive based on the three-dimensional large-scale sand-filling model, and use numerical methods to invert the flow field evolution characteristics during the development process.

10. The method for improving oil recovery by simulating inefficient water-driven heavy oil viscosity reduction combined flooding according to claim 9, characterized in that, In step 1, the target block and target well group are selected, and the reservoir characteristics and production dynamics of the well group are analyzed. Parameters such as well pattern, well spacing, layer thickness, crude oil viscosity, permeability, porosity, saturation, and temperature are determined. The similarity criteria for water drive and viscosity-reducing composite drive are derived using the integral analogy method, the main similarity criteria number for viscosity-reducing composite drive is determined, and the parameters of the three-dimensional physical simulation between the reservoir well group prototype and the scale model are converted.

11. The method for simulating inefficient water-driven heavy oil viscosity reduction and combined flooding to enhance oil recovery according to claim 9, characterized in that, In step 2, based on the physical property parameters, sedimentary rhythm and interlayer characteristics determined by the similarity criterion, and combined with the core grain size analysis results, homogeneous models, interlayer heterogeneous models and planar interlayer heterogeneous models required for the experiment are prepared; at the same time, resistivity acquisition devices are evenly arranged according to the actual well pattern during the model making process.

12. The method for improving oil recovery by simulating inefficient water-driven heavy oil viscosity reduction combined flooding according to claim 9, characterized in that, Step 3 includes: Step 31: Perform an airtightness test. Connect the experimental device according to the procedure. Use a gas testing device to check the airtightness. Inject gas into the three-dimensional model body. If the pressure remains stable, the model has good airtightness. Step 32: Saturate the sand-filled model. Use a vacuum pump to evacuate the model. Inject produced formation water into the model at multiple points and at low speed to saturate the formation water. Inject formation crude oil into the model at multiple points and at low speed to saturate the formation crude oil. Check the pressure sensor and resistivity acquisition device to ensure that they are in normal operating condition. Aging is carried out for a set time under reservoir temperature and pressure conditions. Step 33, water drive: According to the injection parameters determined by the similarity criteria, open the formation water intermediate container to inject water from the central well, start production, and drive water drive until the actual reservoir water cut is reached. Step 34: Inject plugging agent. According to the designed injection volume, open the intermediate container of plugging agent and inject the plugging agent with the set PV number from the central well to seal the high-permeability channel between the injection wells. Step 35: Inject viscosity reducer, close the plugging agent valve, open the intermediate viscosity reducer container valve, and inject the water-soluble viscosity reducer with the set PV number; Step 36, proceed with subsequent water drive; close the viscosity reducer injection valve, open the water drive valve and continue water drive; Step 37: Perform production well inflow and outflow to induce production effect; based on experimental requirements, for inefficient production wells, use an injection pump to inject a set amount of oil-soluble viscosity reducer into the production well, and inject a set amount of water-soluble viscosity reducer to further expand the effect. After the well is shut down for a period of time, start production. Step 38: Adjust the flow field; based on the characteristics of the well network, implement measures such as converting production wells into injection wells, densifying the well network, and adjusting the fluid volume of injection and production wells to change the flow lines of the well group and further improve the recovery rate of the well group; Step 39, tracer drive: Close the water drive valve, open the tracer injection valve, and inject water-soluble tracer into the model.

13. The method for improving oil recovery by simulating inefficient water-driven heavy oil viscosity reduction combined flooding according to claim 9, characterized in that, In step 5, the produced liquid is processed and separated, the instantaneous production of oil and water is calculated, and samples are taken and photographed in different areas. The oil saturation of samples at different locations is tested to correct the collected saturation.

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