An oil reservoir "pressure-suffocation-production" integrated pressure flooding experimental device and testing method

Abstract

The application discloses an oil reservoir "pressure-suffocation-production" integrated pressure displacement experimental device and a testing method. The experimental device comprises a displacement pump, a first intermediate container, a second intermediate container, a core holder, a waste liquid collecting device and an information acquisition instrument. The displacement pump is connected with the two parallel intermediate containers. The two intermediate containers are connected to the inlet end of the core holder. The core holder is provided with a confining pressure device and a heating device. The held core comprises a prefabricated artificial fracture. The information acquisition instrument is used for collecting experimental test data. The application also provides an oil reservoir "pressure-suffocation-production" integrated pressure displacement experimental testing method. The application simulates the "pressure-suffocation-production" integrated pressure displacement process of a tight oil reservoir through an experimental method, quantitatively evaluates the pressure displacement imbibition efficiency, the displacement oil washing efficiency and the pressure displacement recovery rate, and can provide a reference for a pressure displacement development plan of an oilfield. The principle is reliable, the operability is high, and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of petroleum engineering technology, specifically to an integrated pressure-flooding experimental device and testing method for oil reservoir "pressure-flooding-production". Background Technology

[0002] With the development of oil and gas exploration and development technologies, China's oil and gas exploration and development industry is now moving towards unconventional oil and gas resources with lower abundance and poorer physical properties. Low-permeability tight reservoirs are an important component of unconventional resources. Addressing the challenges of "injection failure and production failure" faced by low-permeability tight reservoirs, oilfields have recently proposed an integrated "pressure-suppression-production" technology. This technology can improve reservoir flow channels, replenish formation energy, expand swept volume, and enhance oil washing efficiency, ultimately achieving the goal of improving reservoir recovery.

[0003] The integrated hydraulic fracturing technology combines single-well fracturing, conventional waterflooding, and oilfield chemical flooding into a continuous and complete development process. The application of hydraulic fracturing technology in oilfields mainly includes three important processes: fracturing, waterflooding, and production. "Fracturing" involves injecting a large amount of clean water and oil displacement agent from the water well end at reservoir micro-fracture pressure. As the reservoir fractures and fractures extend, the oil displacement agent is displaced along the fractures into the formation pores. "Waterflooding" involves simultaneously shutting down both the production well and the injection well after hydraulic fracturing, maintaining a "sealed" formation. Then, the injected water in the formation fractures and the crude oil in the matrix undergo oil-water replacement under the influence of formation permeability forces (capillary force, osmotic pressure), increasing the oil saturation in the fractures. "Production" involves simultaneously opening the production well and the injection well, using water injection in the injection well and oil production in the production well to effectively displace the reservoir and improve oil recovery.

[0004] Pressure-driven hydraulic displacement (PWD) technology is one of the key methods for developing low-permeability tight oil reservoirs in China, and also one of the major technical challenges in oilfield development. Due to its relatively late start, domestic research on PWD technology has only just begun, focusing on its technical mechanisms and experimental methods. While domestic experimental studies have been conducted on core displacement and matrix permeation, there has been no research on a complete, continuous, integrated PWD system encompassing pressure-flooding and production. Consequently, the development of PWD technology lacks both experimental and theoretical support. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing an integrated pressure-drive experimental device and testing method for realistically simulating the "pressure-suppression-production" process in tight oil reservoirs.

[0006] The technical solution adopted in this invention is:

[0007] On the one hand, this invention provides an integrated pressure-flooding experimental device for oil reservoir "pressure-flooding-production", including a displacement pump, a first intermediate container, a second intermediate container, a core holder, a waste liquid collection device, and an information acquisition instrument.

[0008] The displacement pump is connected to the first intermediate container and the second intermediate container, which are connected in parallel and respectively contain simulated oil and pressure-driven injection fluid. The first intermediate container and the second intermediate container are connected to the inlet end of the core holder.

[0009] The waste liquid collection device is provided at the outlet end of the core holder. The core holder is equipped with a confining pressure device and a heating device. The core held in the core holder includes pre-fabricated artificial cracks.

[0010] The information acquisition device is connected to the displacement pump, core holder, and heating device, and is used to collect experimental test data.

[0011] Preferably, the displacement pump is a constant speed and constant pressure pump.

[0012] Preferably, the integrated pressure-driven experimental device is equipped with a pressure gauge and a thermometer.

[0013] On the other hand, the present invention provides an integrated pressure-flooding experimental testing method for tight oil reservoirs, comprising the following steps:

[0014] Step 1: Prepare experimental materials based on the characteristic parameters of the target block in the oilfield. The experimental materials include core samples, simulated formation aqueous solution, pressure-driven injection fluid, and simulated oil. Measure the initial crude oil signal quantity V1 in the core sample.

[0015] Step 2: Set the experimental pressure drive displacement according to the on-site pressure drive construction displacement, simulate the pressure drive water injection process, and stop the displacement when the experimental pressure drive water injection is sufficient, and measure the crude oil signal quantity V2 after core pressure drive water injection.

[0016] Step 3: Optimize the well shut-in time, close the inlet and outlet ends of the core holder, conduct a high-temperature and high-pressure well shut-in simulation, and measure the crude oil signal quantity V3 after core well shut-in and seepage absorption;

[0017] Step 4: Set the experimental displacement rate according to the conventional water injection rate on site, simulate the conventional water injection process, and end the displacement when the change in the oil-bearing signal of the core meets the requirements. Measure the crude oil signal V4 after the core displacement.

[0018] Step 5: Based on the experimental test data, evaluate the well penetration efficiency, displacement and washing oil efficiency, or pressure-driven recovery rate during the integrated pressure-drive process.

[0019] Preferably, step 1 further includes: preparing an artificial core based on the mineral composition and physical properties of the reservoir rocks in the target block, and pre-fabricating artificial fractures in the artificial core; and preparing standard formation water using heavy water D2O to simulate formation aqueous solution.

[0020] Preferably, step 1 further includes: placing the dried core into simulated oil, saturating the simulated oil by vacuum pumping, then taking out the core and placing it in a drying box to heat it to simulate an aged core, and measuring the initial crude oil signal quantity of the core using a nuclear magnetic resonance device after drying.

[0021] Preferably, step 1 further includes: the core crude oil signal quantity is the sum of the crude oil signal quantity in the core pores and the crude oil signal quantity in the fractures.

[0022] Preferably, step 2 further includes: based on the principle of linear velocity similarity, converting the on-site pressure drive displacement into a laboratory displacement, wherein the displacement is determined by the following method:

[0023]

[0024] Where: v1 is the displacement velocity, Q c For construction displacement, Q e For the experimental displacement, N p S represents the number of perforations in the pressure-driven section. p S represents the area of ​​a single perforation hole in the pressure drive section. c This represents the injection end area of ​​the experimental core.

[0025] Preferably, step 2 further includes: the method for determining the experimental pressure-driven water injection volume is as follows:

[0026]

[0027] Where: V L To test the water injection rate of pressure drive, V s V represents the water injection volume for on-site construction pressure driving. e The area to be controlled by the water injection well in the oilfield is defined as follows: φ1 represents the porosity of the oilfield reservoir, and r represents the area to be controlled by the well. c L is the radius of the experimental core. c φ2 represents the length of the experimental core and φ2 represents the porosity of the experimental core.

[0028] Preferably, step 3 further includes: well suffocation time t m The method for determining this is as follows:

[0029]

[0030] Where: t e For the experiment of well suffocation time, t m The time for well closure during on-site construction; E is the Young's modulus of the experimental rock sample; μ e For the viscosity of the experimental fluid, r c Q is the radius of the experimental core. e This is the experimental flow rate.

[0031] Preferably, step 4 further includes: determining the experimental displacement rate based on the conventional on-site water injection and drainage rate.

[0032]

[0033] Where: v2 is the displacement velocity, Q c1 For conventional water injection and discharge, v e To determine the displacement rate in the experiment, N p S represents the number of perforations in the pressure-driven section. p S represents the area of ​​a single perforation hole in the pressure drive section. c This represents the injection end area of ​​the experimental core.

[0034] Preferably, step 5 further includes: calculating the well oil-water permeation efficiency E1 based on the change in T2 spectrum signal of crude oil in the matrix and fractures before and after well closure, using the following formula:

[0035]

[0036] In the formula: E1 is the well penetration efficiency, V2 is the crude oil signal after core injection, V3 is the crude oil signal after well penetration, and V... 21 V represents the crude oil signal quantity in the matrix pores after core hydraulic water injection. 22 V represents the crude oil signal quantity in the fracture after core hydraulic water injection. 31 V represents the crude oil signal quantity in the matrix pores after core well immersion and seepage. 32 This refers to the crude oil signal quantity in the fractures after seepage and absorption in a core well.

[0037] Based on the changes in T2 spectral signals of crude oil in the matrix and fractures before and after displacement, the matrix washout efficiency E2, fracture displacement efficiency E3, or hydraulic oil recovery rate E2 are calculated. T The calculation formula is as follows:

[0038]

[0039] Where: E2 is the matrix washing efficiency, E3 is the fracture displacement efficiency, and E T V1 represents the oil recovery rate, V2 represents the crude oil signal after water injection in the core, and V4 represents the crude oil signal after displacement in the core. 21 V represents the crude oil signal quantity in the matrix pores after core hydraulic water injection. 22 V represents the crude oil signal quantity in the fracture after core hydraulic water injection. 41 V represents the crude oil signal quantity in the matrix pores after core displacement. 42 This represents the crude oil signal quantity in the fracture after core displacement.

[0040] Compared with the prior art, the advantages of the present invention are as follows: The present invention proposes an integrated pressure-flooding experimental device and testing method for oil reservoir "pressure-flooding-production". The present invention simulates the integrated pressure-flooding process of oil reservoir through experiments, and quantitatively evaluates the pressure-flooding permeation efficiency, displacement and washing oil efficiency and pressure-flooding recovery rate. It can provide a reference for the pressure-flooding development scheme of oilfields, and the principle is reliable, the operation is strong, and it has broad application prospects. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the integrated pressure-suppression-production experimental device for oil reservoirs according to the present invention.

[0042] In the diagram: 1-Information acquisition device, 2-Flow meter, 3-Displacement pump, 4-Valve, 5-First intermediate container, 6-Second intermediate container, 7-Pressure gauge, 8-Thermometer, 9-Core holder, 10-Containing pressure pump, 11-Heating device, 12-Waste liquid collection device, 13-Connecting pipeline. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1 As shown, the present invention provides an integrated pressure-flooding experimental device for oil reservoir "pressure-flooding-production". The experimental device includes a displacement pump 3, a first intermediate container 5, a second intermediate container 6, a core holder 9, a waste liquid collection device 12, and an information acquisition instrument 1, which are connected sequentially by pipeline 13. The core holder 9 is also connected to a confining pressure pump 10 for applying pressure to the core placed in the core holder 9 and a heating device 11 for heating the core. A pressure gauge 7 is connected between the first intermediate container 5, the second intermediate container 6, and the information acquisition instrument 1. A thermometer 8 is connected between the heating device 11 and the information acquisition instrument 1. A flow meter 2 is connected between the displacement pump 3 and the information acquisition instrument 1. The displacement pump 3 is preferably a constant speed and constant pressure pump.

[0045] On the other hand, the present invention provides an integrated pressure drive experimental device and testing method for oil reservoir "pressure-suppression-production", including the following steps:

[0046] Step 1: Prepare experimental materials based on the characteristic parameters of the target block in the oilfield. The experimental materials include core samples, simulated formation aqueous solution, pressure-driven injection fluid, and simulated oil. Measure the initial crude oil signal quantity V1 in the core sample.

[0047] ① Prepare standard artificial rock cores (2.5cm in diameter and 5cm in length) based on the mineral composition and physical properties of the reservoir rocks in the target block, and prefabricate artificial fractures in the rock cores;

[0048] ②According to the industry standard water-based fracturing fluid performance evaluation method (SY / T 5107-2005), standard formation water (2.0% KCl + 5.5% NaCl + 0.45% MgCl2 + 0.55% CaCl2) was prepared using heavy water (D2O) to simulate formation aqueous solution. The purpose is to shield the hydrogen signal of the water phase during the oil-water two-phase flow process by using heavy water. Therefore, the hydrogen signal detected by the nuclear magnetic resonance equipment during the displacement process all comes from the simulated oil.

[0049] ③ Prepare the pressure flooding injection fluid by mixing simulated formation water and oil displacement agent at a certain concentration;

[0050] ④ Prepare simulated oil by mixing kerosene and oil-soluble red solution in a certain proportion;

[0051] ⑤ Place the dried core into simulated oil and saturate it with a vacuum pump for 24 hours. Remove the core and place it in a drying oven to heat (60℃) to simulate core aging. After 24 hours, remove the core and perform T2 spectrum signal acquisition on the core under these conditions using nuclear magnetic resonance equipment to obtain the initial crude oil signal quantity V1 of the core. At the same time, the crude oil signal quantity V in the core pores can also be obtained. 11 Crude oil signal V in the crack 12 Where V1 = V 11 +V 12 .

[0052] Step 2: Set the experimental pressure drive displacement according to the on-site pressure drive construction displacement, simulate the pressure drive water injection process, and stop the displacement when the experimental pressure drive water injection is sufficient, and measure the crude oil signal quantity V2 after core pressure drive water injection.

[0053] ① Load the oil-saturated core into the core holder 9, turn on the confining pressure pump 10 and heating device 11, and set the pressure drive test loading conditions according to the formation stress and formation temperature. The test temperature is determined by the formation temperature, and the test confining pressure σ c Determined by the following formula:

[0054] σ` Z =σ Z -αP P

[0055] σ` H =σ H -αP P

[0056] σ` h =σ h -αP P

[0057] σ c =(σ` Z +σ` H +σ` h ) / 3

[0058] Where: σ z For effective vertical stress, σ H `For the effective maximum horizontal principal stress, σ h ` is the effective minimum horizontal principal stress, σ z For vertical stress, σ H For the maximum horizontal principal stress, σ h For the minimum horizontal principal stress, P p σ is the formation pore pressure, α is the effective stress coefficient, and σ is the formation pore pressure. c The confining pressure is for the experiment.

[0059] ② After the temperature and confining pressure stabilize, displacement begins by injecting the displacement fluid into the core at a constant speed v1 using a constant-speed, constant-pressure pump. Based on the principle of linear velocity similarity, the displacement rate during on-site pressure drive is converted into the laboratory displacement rate, which is determined by the following formula:

[0060]

[0061] Where: v1 is the displacement velocity, Q c For construction displacement, Q e For the experimental displacement, N p S represents the number of perforations in the pressure-driven section. p S represents the area of ​​a single perforation hole in the pressure drive section. c This represents the injection end area of ​​the experimental core.

[0062] ③ Displacement to V L At that time, displacement was stopped, and the inlet and outlet of the core holder 9 were closed. The experimental pressure-driven water injection volume V... L It is obtained by converting the in-situ displacement volume through pore volume, as shown in the following formula:

[0063]

[0064] Where: V L To test the water injection rate of pressure drive, V s V represents the water injection volume for on-site construction pressure driving. e To define the control range of water injection wells in the oilfield. r represents the porosity of the oilfield reservoir. c L is the radius of the experimental core. c For the length of the experimental core, To test the porosity of the core sample.

[0065] ④ By acquiring T2 spectrum signals using nuclear magnetic resonance equipment, the crude oil signal quantity V2 after core injection and water displacement can be obtained, and the crude oil signal quantity V in the core pores can also be obtained. 21 Crude oil signal V in the crack 22 Where V2 = V 21 +V 22 .

[0066] Step 3: Optimize the well shut-in time, close the inlet and outlet ends of the core holder 9, conduct a high-temperature and high-pressure well shut-in simulation, measure the crude oil signal quantity V3 after core well shut-in seepage, and simulate the oil-water seepage and replacement process of the well shut-in.

[0067] ① Close the inlet and outlet of the core holder 9 to maintain the core in a high-temperature, high-pressure sealed state. The method for determining the temperature and pressure is the same as in step 1. The sealed time is t. m We obtain it from the following formula:

[0068]

[0069] Where: t e The time (s) for well suffocation in the experiment, t m The time for well suffocation during on-site construction (s) is given by E, where E is the Young's modulus of the experimental rock sample (Pa), and μ is the value of μ. e r is the viscosity of the experimental fluid (mPa·s). c Q is the radius (m) of the experimental core. e Experimental flow rate (m 3 / s).

[0070] ② After the well is sealed, T2 spectrum signals are acquired using nuclear magnetic resonance equipment to obtain the crude oil signal quantity V3 after core permeation, and the crude oil signal quantity V in the core pores can also be obtained. 31 Crude oil signal V in the crack 32 Where V3 = V 31 +V 32 .

[0071] Step 4: Set the experimental displacement rate according to the conventional water injection rate on site, simulate the conventional water injection process, and end the displacement when the change in the oil-bearing signal of the core meets the requirements. Measure the crude oil signal V4 after the core displacement.

[0072] ① Open the inlet and outlet of the core holder 9, and inject the displacement fluid into the core at a constant speed v2 using a constant speed and constant pressure pump. Based on the principle of linear velocity similarity, the conventional on-site water injection rate is converted into the laboratory displacement rate, and the displacement rate is determined by the following formula:

[0073]

[0074] Where: v1 is the displacement velocity (m / s), Q c1For conventional water injection and discharge (m³) 3 / s), Q e For the experimental displacement (m) 3 / s, N p S represents the number of perforations in the pressure-driven section. p The area of ​​a single perforation hole in the pressure drive section (m²) 2 ), S c The injection end area of ​​the experimental core (m²) 2 ).

[0075] ② Test the T2 NMR spectrum of the oil signal in the core every 30 minutes until the difference in oil signal intensity in the T2 spectrum of the core is less than 5%, at which point the displacement is terminated.

[0076] ③ After displacement, T2 spectrum signals were acquired using nuclear magnetic resonance equipment to obtain the crude oil signal quantity V4 after core displacement, and the crude oil signal quantity V in the core pores could also be obtained. 41 Crude oil signal V in the crack 42 Where V4 = V 41 +V 42 .

[0077] Step 5: Based on the experimental test data, evaluate the well penetration efficiency, displacement and washing oil efficiency, or pressure-driven recovery rate during the integrated pressure-drive process.

[0078] ①Based on the changes in the T2 spectrum signal of crude oil in the matrix and fractures before and after well sealing, the oil-water permeation efficiency E1 of the sealed well is calculated. The calculation formula is as follows:

[0079]

[0080] In the formula: E1 is the well penetration efficiency, V2 is the crude oil signal after core injection, V3 is the crude oil signal after well penetration, and V... 21 V represents the crude oil signal quantity in the matrix pores after core hydraulic water injection. 22 V represents the crude oil signal quantity in the fracture after core hydraulic water injection. 31 V represents the crude oil signal quantity in the matrix pores after core well immersion and seepage. 32 This refers to the crude oil signal quantity in the fractures after seepage and absorption in a core well.

[0081] ②Based on the changes in T2 spectral signals of crude oil in the matrix and fractures before and after displacement, the matrix wash efficiency E2, fracture displacement efficiency E3, and pressure-driven oil recovery rate E are calculated. T The calculation formula is as follows:

[0082]

[0083] Where: E2 is the matrix washing efficiency, E3 is the fracture displacement efficiency, and E TV1 represents the oil recovery rate, V2 represents the crude oil signal after water injection in the core, and V4 represents the crude oil signal after displacement in the core. 21 V represents the crude oil signal quantity in the matrix pores after core hydraulic water injection. 22 V represents the crude oil signal quantity in the fracture after core hydraulic water injection. 41 V represents the crude oil signal quantity in the matrix pores after core displacement. 42 This represents the crude oil signal quantity in the fracture after core displacement.

[0084] Calculation Example

[0085] To facilitate a thorough understanding of the technical steps and advantages of this invention by those skilled in the art, the invention is further illustrated by the following calculation examples.

[0086] Step 1: Prepare experimental materials based on the characteristic parameters of the target block in the oilfield. The experimental materials include core samples, simulated formation aqueous solution, pressure-driven injection fluid, and simulated oil. Measure the initial crude oil signal quantity V1 in the core sample.

[0087] Standard artificial cores were prepared based on the mineral composition and physical properties of the reservoir rocks in the target block, and artificial fractures were prefabricated in the cores. Standard formation water and pressure-driven injection fluid were prepared using heavy water (D2O). Simulated oil was prepared by mixing kerosene and oil-soluble red solution at a volume ratio of 10:1. The simulated oil was saturated by vacuum pumping for 24 hours, and the core was heated to simulate aging for 24 hours. The core T2 spectrum signal was acquired using nuclear magnetic resonance equipment, and the initial crude oil signal quantity of the core was obtained as 26556. At the same time, the crude oil signal quantity in the core pores was obtained as 24156, and the crude oil signal quantity in the fractures was obtained as 2400.

[0088] Step 2: Set the experimental pressure drive displacement according to the on-site pressure drive construction displacement, simulate the pressure drive water injection process, and stop the displacement when the experimental pressure drive water injection is sufficient, and measure the crude oil signal quantity V2 after core pressure drive water injection.

[0089] The loading conditions for the pressure drive experiment were set according to the formation stress and formation temperature. The formation temperature was used to determine the experimental temperature (85℃). The experimental confining pressure was calculated to be 5MPa using a formula.

[0090] Based on the principle of linear velocity similarity, the displacement (1m³) during on-site pressure drive construction is calculated according to the formula. 3 Converting ( / min) to laboratory displacement (0.5 cm³) 3 ( / min), and after the temperature and confining pressure stabilize, begin displacement using a constant-speed, constant-pressure pump at a constant rate of 0.1 cm / min. 3 Inject displacement fluid into the core at a rate of / min.

[0091]

[0092] The on-site single-well pressure-driven water injection capacity is 20,000 m³.3 Based on the formula, it can be converted into laboratory pressure-driven water injection volume V. L It is 45.5cm 3 Driven to V L At that time, stop the displacement and close the inlet and outlet of the core holder.

[0093]

[0094] T2 spectrum signal acquisition using nuclear magnetic resonance equipment yielded crude oil signal quantity of 22562 after core pressure-driven water injection, crude oil signal quantity of 21537 in core pores, and crude oil signal quantity of 1025 in fractures.

[0095] Step 3: Optimize the well shut-in time, close the inlet and outlet ends of the core holder, conduct a high-temperature and high-pressure well shut-in simulation, and measure the crude oil signal quantity V3 after core well shut-in and seepage absorption.

[0096] The inlet and outlet of the core holder are closed to maintain the core in a high-temperature, high-pressure well-sealing state. The well-sealing time in the oilfield is 30 days, and the well-sealing time in the laboratory is t. m The value is 85.6h, obtained from the following formula.

[0097]

[0098] After the well was sealed, T2 spectrum signals were acquired using nuclear magnetic resonance equipment. The crude oil signal after the core was sealed and absorbed was 22548. At the same time, the crude oil signal in the core pores was 20685, and the crude oil signal in the fractures was 1863.

[0099] Step 4: Set the experimental displacement rate according to the conventional water injection rate on site, simulate the conventional water injection process, and end the displacement when the change in the oil-bearing signal of the core meets the requirements. Measure the crude oil signal V4 after the core displacement.

[0100] Based on the principle of linear velocity similarity, the formula is used to calculate the on-site conventional water injection and discharge volume (30m³). 3 / d) converted to laboratory displacement rate (0.01cm) 3 ( / min), delivered at a constant speed of 0.01cm / min by a constant-speed, constant-pressure pump. 3 Inject displacement fluid into the core at a rate of / min.

[0101]

[0102] The T2 NMR spectrum of the oil signal in the core was tested every 30 minutes until the difference in oil signal intensity in the core T2 spectrum was less than 5%, at which point the displacement was considered complete. Then, T2 spectrum signals were acquired using NMR equipment, yielding an oil signal intensity of 12959 after core displacement, as well as an oil signal intensity of 12734 in the core pores and 225 in the fractures.

[0103] Step 5: Based on the experimental test data, evaluate the well penetration efficiency, displacement and washing oil efficiency, or pressure-driven recovery rate during the integrated pressure-drive process.

[0104] Based on the changes in the T2 spectrum signal of crude oil in the matrix and fractures before and after well sealing, the oil-water permeation efficiency E1 of the sealed well was calculated to be 3.7%.

[0105]

[0106] Based on the changes in T2 spectral signals of crude oil in the matrix and fractures before and after displacement, the matrix washing efficiency E2 was calculated to be 47.3%, the fracture displacement efficiency E3 to be 78.0%, and the oil recovery rate E... T It is 42.6%.

[0107]

[0108] This invention first prepares experimental materials based on the characteristic parameters of the target block in the oilfield; optimizes the experimental pressure-driven displacement based on the principle of linear velocity similarity to simulate the pressure-driven water injection process; optimizes the well-closing time according to the formula to simulate the oil-water permeation and replacement process in the well-closing; then optimizes the laboratory displacement rate to simulate the conventional water injection production process; finally, evaluates the well-closing permeation efficiency, displacement and washing efficiency, and pressure-driven recovery rate in the integrated pressure-driven process based on the experimental results. This invention simulates the integrated pressure-driven process in tight oil reservoirs of the oilfield through experiments and quantitatively evaluates the pressure-driven permeation efficiency, displacement and washing efficiency, and pressure-driven recovery rate. It provides a reference for the next stage of pressure-driven development in the oilfield, with reliable principles, strong operability, and broad application prospects.

[0109] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for integrated pressure-flooding experimental testing of oil reservoirs, characterized in that, Includes the following steps: The experimental apparatus used in the test method includes a displacement pump, a first intermediate container, a second intermediate container, a core holder, a waste liquid collection device, and an information acquisition instrument. The displacement pump is connected to the first intermediate container and the second intermediate container, which are connected in parallel and respectively contain simulated oil and pressure-driven injection fluid. The first intermediate container and the second intermediate container are connected to the inlet end of the core holder. The waste liquid collection device is provided at the outlet end of the core holder. The core holder is equipped with a confining pressure device and a heating device. The core held in the core holder includes pre-fabricated artificial cracks. The information acquisition device is connected to the displacement pump, the core holder and the heating device, and is used to collect experimental test data. Step 1: Prepare experimental materials based on the characteristic parameters of the target block in the oilfield. The experimental materials include core samples, simulated formation aqueous solution, hydraulic injection fluid, and simulated oil. Measure the initial crude oil signal quantity V1 in the core sample. The crude oil signal quantity includes the crude oil signal quantity in the matrix pores and the crude oil signal quantity in the fractures. Step 2: Set the experimental pressure drive displacement according to the on-site pressure drive construction displacement, simulate the pressure drive water injection process, and stop the displacement when the experimental pressure drive water injection is sufficient, and measure the crude oil signal quantity V2 after core pressure drive water injection. Step 3: Optimize the well shut-in time, close the inlet and outlet ends of the core holder, conduct a high-temperature and high-pressure well shut-in simulation, and measure the crude oil signal quantity V3 after core well shut-in and seepage absorption; Step 4: Set the experimental displacement rate according to the conventional water injection rate on site, simulate the conventional water injection process, and end the displacement when the oil content signal of the core changes little, and measure the crude oil signal V4 after the core displacement. Step 5: Based on the experimental test data, evaluate the well penetration efficiency, displacement and washing oil efficiency, or pressure drive recovery rate during the integrated pressure drive process of "pressure-suppression-production". Based on the changes in the T2 spectrum signal of crude oil in the matrix and fractures before and after well sealing, the oil-water permeation efficiency E1 of the sealed well is calculated using the following formula: In the formula: E1 is the well penetration efficiency, V2 is the crude oil signal after core injection, V3 is the crude oil signal after well penetration, and V... 21 V represents the crude oil signal quantity in the matrix pores after core hydraulic water injection. 22 V represents the crude oil signal quantity in the fracture after core hydraulic water injection. 31 V represents the crude oil signal quantity in the matrix pores after core well immersion and seepage. 32 The signal quantity of crude oil in fractures after core well stagnation and seepage is used; based on the changes in the T2 spectrum signal of crude oil in the matrix and fractures before and after displacement, the matrix wash efficiency E2, fracture displacement efficiency E3, or pressure-driven recovery rate E are calculated. T The calculation formula is as follows: Where: E2 is the matrix washing efficiency, E3 is the fracture displacement efficiency, and E T V1 represents the oil recovery rate, V2 represents the crude oil signal after water injection in the core, and V4 represents the crude oil signal after displacement in the core. 21 V represents the crude oil signal quantity in the matrix pores after core hydraulic water injection. 22 V represents the crude oil signal quantity in the fracture after core hydraulic water injection. 41 V represents the crude oil signal quantity in the matrix pores after core displacement. 42 This represents the crude oil signal quantity in the fracture after core displacement.

2. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 1, characterized in that, Step 1 further includes: preparing artificial rock cores based on the mineral composition and physical property parameters of the reservoir rocks in the target block, and pre-fabricating artificial fractures in the artificial rock cores; and preparing standard formation water using heavy water D2O to simulate formation aqueous solutions.

3. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 1, characterized in that, The dried core was placed in simulated oil, and the simulated oil was saturated by vacuum pumping. Then the core was removed and placed in a drying chamber for heating to simulate aging. After drying, the initial crude oil signal of the core was measured by nuclear magnetic resonance equipment.

4. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 3, characterized in that, The crude oil signal in the core is the sum of the crude oil signal in the core pores and the crude oil signal in the fractures.

5. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 1, characterized in that, Step 2 further includes: based on the principle of linear velocity similarity, converting the on-site pressure drive displacement into a laboratory displacement displacement, and the displacement displacement is determined by the following method: Where: v1 is the displacement velocity, Q c For construction displacement, Q e For the experimental displacement, N p S represents the number of perforations in the pressure-driven section. p S represents the area of ​​a single perforation hole in the pressure drive section. c This represents the injection end area of ​​the experimental core.

6. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 1, characterized in that, Step 2 also includes: the method for determining the experimental pressure-driven water injection volume is as follows: Where: V L To test the water injection rate of pressure drive, V s V represents the water injection volume for on-site construction pressure driving. e The area to be controlled by the water injection well in the oilfield is defined as follows: φ1 represents the porosity of the oilfield reservoir, and r represents the area to be controlled by the well. c L is the radius of the experimental core. c φ2 represents the length of the experimental core and φ2 represents the porosity of the experimental core.

7. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 1, characterized in that, Step 3 also includes: well suffocation time t m The method for determining this is as follows: Where: t e For the experiment of well suffocation time, t m The time for well closure during on-site construction; E is the Young's modulus of the experimental rock sample; μ e For the viscosity of the experimental fluid, r c Q is the radius of the experimental core. e For experimental displacement.

8. The integrated pressure-flooding experimental testing method for oil reservoir "pressure-suppression-production" as described in claim 1, characterized in that, Step 4 also includes: determining the experimental displacement rate based on the conventional on-site water injection and drainage rate. Where: v2 is the displacement velocity, Q c1 For conventional water injection and discharge, Q e For the experimental displacement, N p S represents the number of perforations in the pressure-driven section. p S represents the area of ​​a single perforation hole in the pressure drive section. c This represents the injection end area of ​​the experimental core.

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