A physical simulation device and method for determining the location of the CO2 flooding front

Abstract

This application relates to a physical simulation device and method for determining the location of a CO2 flooding front, belonging to the field of physical simulation devices. The device includes a clamp, an imaging device sleeved on the outside of the clamp, an intermediate container filled with CO2 at the inlet end of the clamp, a back pressure assembly at the outlet end of the clamp, a metering assembly between the back pressure assembly and the clamp, and a confining pressure assembly on the clamp. This application has the effect of determining the location of a CO2 flooding front by analyzing changes in oil phase signals in core samples.

Description

Technical Field

[0001] This application relates to the field of physical simulation devices, and in particular to a physical simulation device and method for determining the location of the CO2 flooding front. Background Technology

[0002] Injecting CO2 into oil reservoirs can not only effectively enhance oil recovery and generate significant economic benefits, but also achieve geological CO2 storage, addressing environmental issues related to CO2 emission reduction and mitigating the greenhouse effect. Statistical data shows that CO2-driven oil recovery can increase reservoir recovery by 10%-30%. Therefore, further in-depth research into the related issues of CO2-based enhanced oil recovery technologies is essential.

[0003] Regarding the aforementioned technologies, the inventors believe that conventional experimental methods can only treat the actual formation model as a "black box," and can only analyze the oil displacement situation by monitoring the injection and production flow rates and pressures. This experimental method cannot accurately grasp the occurrence state and migration process of fluids in porous media, and has certain limitations. Summary of the Invention

[0004] In order to analyze the changes in oil phase signals in rock cores and determine the location of the CO2 flooding front, this application provides a physical simulation device and method for determining the location of the CO2 flooding front.

[0005] This application provides a physical simulation device for determining the location of the CO2 oil displacement front, which adopts the following technical solution:

[0006] A physical simulation device for determining the position of the CO2 flooding front includes a clamp, an imaging device sleeved on the outside of the clamp, an intermediate container at the inlet end of the clamp filled with CO2, a back pressure assembly at the outlet end of the clamp, a metering assembly between the back pressure assembly and the clamp, and a confining pressure assembly on the clamp.

[0007] Optionally, the outlet end of the intermediate container is connected to the inlet end of the clamp, and the inlet end of the intermediate container is provided with a drive pump, which pumps the medium inside the intermediate container into the clamp.

[0008] Optionally, a pressure display and a switching valve are provided between the drive pump and the intermediate container, and a switching valve is provided between the intermediate container and the clamp.

[0009] Optionally, the drive pump is an ISCO pump.

[0010] Optionally, the back pressure assembly includes a back pressure pump, which is connected to the outlet end of the clamp, and a temperature detector and a pressure detector are provided between the back pressure pump and the clamp.

[0011] Optionally, the metering component includes the temperature controller and the fluid meter.

[0012] Optionally, the outlet end of the clamp is also connected to a gas-oil separator, the gas-oil separator has an outlet pipe inserted inside, and the other end of the outlet pipe is connected to a gas processing component.

[0013] This application also provides a physical simulation method for determining the location of the CO2 oil displacement front, applied to the aforementioned physical simulation device for determining the location of the CO2 oil displacement front, the method comprising:

[0014] S01: Prepare the core, wash and dry the core, and measure the core length L, diameter d, porosity φ, and permeability K;

[0015] S02: The core was vacuum-pressurized and saturated with formation water. The saturated water core sample was then steadily displaced with heavy water of equal salinity at a rate of 0.01 mL / min. The displacement rate was then gradually increased to continuously displace the sample up to 10 PV to eliminate the signal of the water phase.

[0016] S03: Load the rock sample into the holder;

[0017] S04: Establish bound water saturation. Use crude oil displacement from low pressure difference to high pressure difference to record gas production and oil production at the outlet end and pressure difference at both ends. Aging the rock sample at formation temperature and measuring the quantitative T2 spectrum curve of the rock sample along the process of nuclear magnetic resonance imaging to calculate the bound water saturation of the rock sample.

[0018] S05: Place the core into the nuclear magnetic resonance core holder, set the holder confining pressure, and set the back pressure at the holder outlet to the CO2 pressure in the intermediate container, with an error of less than 0.1 MPa.

[0019] S06: Turn on the ISCO pump and inject CO2 from the intermediate container into the rock core in the holder at a constant injection rate of 0.01PV / min. During the experiment, record the gas production and oil production at the outlet end and continuously measure the quantitative curve of the rock sample along the nuclear magnetic resonance imaging process. After the experiment, measure the weight of the rock sample.

[0020] S07: The dynamic distribution of oil phase signals in the core during CO2 flooding was obtained using imaging equipment. CO2 was injected at a rate of 0.01 PV / min using an ISCO pump. The quantitative curve along the imaging path was divided into low signal amplitude segment, medium signal amplitude segment, and high signal amplitude segment.

[0021] S08: Compared with the quantitative curve of rock sample imaging along the path in the bound water state, the signal amplitude of the low signal amplitude segment of the three curves decreased the most. The oil displacement efficiency corresponding to the low signal amplitude segment was calculated. The part with an oil displacement efficiency greater than % was regarded as the location swept by the CO2-miscible zone. The dimensionless position of the core corresponding to the signal amplitude when it started to rise was defined as the location of the CO2 oil displacement front.

[0022] S09: Calculate the oil displacement efficiency E corresponding to the low signal amplitude segment of the quantitative imaging curve along the path for different injected CO2 PV numbers. low .

[0023] Optionally, in S09, the oil displacement efficiency E low The formula is as follows:

[0024]

[0025] In the formula:

[0026] X-ray nuclear magnetic resonance quantitative curve of core dimensionless location;

[0027] X low —Dimensionless location of the core at the end of the low-signal amplitude segment of the quantitative curve along the nuclear magnetic resonance path;

[0028] X o —Dimensionless core position of crude oil under bound water state corresponding to the nuclear magnetic resonance quantitative curve along the path;

[0029] X o,i —Dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under bound water conditions;

[0030] m(X o ) i —Amplitude value corresponding to the dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under bound water conditions;

[0031] X o —Dimensionless core position of crude oil corresponding to the NMR quantitative curve along the path under displacement condition;

[0032] X o,i —The dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under displacement conditions;

[0033] m(X o ) i —The amplitude value corresponding to the dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under displacement state.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. A physical simulation experiment of CO2 miscible flooding was completed based on the nuclear magnetic resonance displacement system, back pressure system, and metering system. During the experiment, the gas production and oil production at the outlet end were recorded, and the quantitative curve of nuclear magnetic resonance imaging along the rock sample was continuously measured. The change of oil phase signal in the rock core was determined by analyzing the quantitative curve of nuclear magnetic resonance imaging along the rock sample to determine the position of the CO2 flooding front. The results are more accurate and have higher applicability. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a physical simulation device for determining the position of the CO2 flooding front in an embodiment of this application.

[0037] Figure 2 This is a schematic diagram of the dynamic distribution of oil phase signals in the core during CO2 flooding, obtained by a nuclear magnetic resonance spectrometer in a physical simulation device for determining the location of the CO2 flooding front in an embodiment of this application.

[0038] Explanation of reference numerals in the attached drawings: 1. Clamp; 2. Imaging device; 3. Intermediate container; 4. Drive assembly; 41. Drive pump; 42. Pressure display; 5. Back pressure assembly; 51. Back pressure pump; 52. Temperature detector; 53. Pressure detector; 6. Metering assembly; 61. Temperature controller; 62. Fluid meter; 7. Confining pressure assembly; 71. Confining pressure pump; 8. Exhaust gas treatment assembly; 81. Gas-oil separator; 811. Inlet pipe; 812. Outlet pipe; 82. Gas treatment assembly. Detailed Implementation

[0039] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0041] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0042] This application discloses a physical simulation device for determining the location of the CO2 flooding front. (Refer to...) Figure 1 , Figure 2A physical simulation device for determining the location of the CO2 flooding front includes a gripper 1, with an imaging device 2 sleeved on the outside of the gripper 1. In some embodiments, the imaging device 2 may be a magnetic resonance imaging device. An intermediate container 3 is located at the inlet end of the gripper 1, and the interior of the intermediate container 3 is filled with CO2 gas. A drive assembly 4 is also located at the inlet end of the intermediate container 3, which pumps the medium inside the intermediate container 3 into the interior of the gripper 1. A backpressure assembly 5 is located at the outlet end of the gripper 1, and a metering assembly 6 is also located between the backpressure assembly 5 and the gripper 1. A confining pressure assembly 7 is located on the outside of the gripper 1, which performs confining pressure operation on the gripper 1. An exhaust gas treatment assembly 8 is also located at the outlet end of the gripper 1.

[0043] The outlet end of the intermediate container 3 is connected to the inlet end of the clamp 1, so that the medium inside the intermediate container 3 can enter the interior of the clamp 1. A switch valve is installed on the pipeline between the intermediate container 3 and the clamp 1. The switch valve is used to control the on / off state of the pipeline. A pressure gauge is also installed between the intermediate container 3 and the clamp 1.

[0044] The drive assembly 4 includes a drive pump 41. In some embodiments, the drive pump 41 may be an ISCO pump. The drive pump 41 is connected to the inlet end of the intermediate container 3. The drive pump 41 is used to precisely control the medium located inside the intermediate container 3 to enter the clamp 1.

[0045] A pressure display 42 is provided between the drive pump 41 and the intermediate container 3. The pressure display 42 can display the current drive pressure of the drive pump 41, thereby precisely controlling the gas inside the intermediate container 3 to enter the clamp 1. A switching valve is also provided between the drive pump 41 and the intermediate container 3. The switching valve is used to control the on / off state between the drive pump 41 and the intermediate container 3.

[0046] The confining pressure assembly 7 includes a confining pressure pump 71, which is connected to the outlet end of the clamp 1. The confining pressure pump 71 provides confining pressure to the clamp 1. A pressure gauge is installed between the confining pressure pump 71 and the clamp 1 to display the confining pressure of the confining pressure pump 71. A switching valve is also installed between the clamp 1 and the confining pressure pump 71 to control the on / off connection between the confining pressure pump 71 and the clamp 1.

[0047] The back pressure assembly 5 includes a back pressure pump 51, which is connected to the outlet end of the clamp 1. A temperature detector 52 and a pressure detector 53 are also connected to the outlet end of the clamp 1.

[0048] The metering component 6 includes a temperature controller 61 located between the back pressure pump 51 and the outlet end of the clamp 1. The temperature controller 61 is used to control the temperature inside the system. A fluid meter 62 is also located between the back pressure pump 51 and the outlet end of the clamp 1. The fluid meter 62 is used to detect the flow rate of the fluid.

[0049] The exhaust gas treatment assembly 8 includes a gas-oil separator 81 located at the outlet end of the clamp 1. The gas-oil separator 81 is connected to the clamp 1 via an inlet pipe 811. One end of the inlet pipe 811 extends into the lower middle part of the gas-oil separator 81, so that the outlet end of the inlet pipe 811 is located inside the medium of the gas-oil separator 81.

[0050] An outlet pipe 812 is connected to the top of the gas-oil separator 81. The end of the outlet pipe 812 is located in the upper part of the gas-oil separator 81, and the gas is discharged through the outlet pipe 812. A gas treatment component 82 is also provided at the other end of the outlet pipe 812. The gas treatment component 82 includes a container filled with water, and the end of the outlet pipe 812 extends into the water to treat the gas.

[0051] This application also provides a physical simulation method for determining the location of the CO2 oil displacement front, applied to the aforementioned physical simulation device for determining the location of the CO2 oil displacement front, the method comprising:

[0052] S01: Select a core sample with a length greater than 8cm, wash and dry the core sample according to the national standard GB / T29172-2012 Core Analysis Method, and measure the core sample length L as 8.33cm, diameter d as 2.53cm, porosity as 13.56%, and permeability K as 17.53mD;

[0053] S02: The core was placed in an intermediate container 3 that could withstand a pressure greater than 30 MPa. The intermediate container 3 was evacuated and pressurized to 25 MPa to saturate the formation water for 48 hours. After saturation, the saturated water core sample was stably displaced with heavy water of equal salinity at a rate of 0.01 mL / min. The displacement rate was then gradually increased to continuously displace the sample up to 10 PV to eliminate the signal of the water phase.

[0054] S03: Load the rock sample into the holder 1;

[0055] S04: Establish bound water saturation by displacing crude oil from low pressure differential to high pressure differential, ending when no water is produced at the outlet. Record the gas and oil production at the outlet and the pressure difference between the two ends. Then, age the rock sample at 120℃ for 48 hours. After aging, measure the nuclear magnetic resonance imaging quantitative curve of the rock sample under bound water condition and calculate the bound water saturation of the rock sample.

[0056] S05: The mixing pressure of crude oil and CO2 at 120℃ is 27.8MPa. The core is placed in the nuclear magnetic resonance core holder 1, the confining pressure of holder 1 is set to 32MPa, and the back pressure at the outlet of holder 1 is set to 28MPa, which is consistent with the CO2 pressure in intermediate container 3.

[0057] S06: Turn on the ISCO pump and inject CO2 from the intermediate container 3 into the rock core in the holder 1 at a constant injection rate of 0.01PV / min. During the experiment, record the gas production and oil production at the outlet end and continuously measure the quantitative curve of the rock sample along the nuclear magnetic resonance imaging process. After the experiment, measure the weight of the rock sample.

[0058] S07: The dynamic distribution of oil phase signals in the core during CO2 flooding is obtained using imaging equipment. As the injected CO2 PV increases, the amplitude of the oil phase signal at various locations in the core changes continuously. The ISCO pump injects CO2 at a rate of 0.01 PV / min. The quantitative curve along the imaging path is divided into the low signal amplitude segment: the segment with the lower signal amplitude in the curve, located at the bottom of the entire vertical axis; the medium signal amplitude segment: this segment is where the signal amplitude of the low signal amplitude segment begins to increase, and the signal amplitude continues to increase; and the high signal amplitude segment: the segment with the higher signal amplitude in the curve, located at the top of the entire vertical axis.

[0059] S08: Compare the quantitative curves of nuclear magnetic resonance imaging along the path with the bound water state curves for different injected CO2 PV numbers. The signal amplitude of the low signal amplitude segment of the three curves decreases the most. Calculate the oil displacement efficiency corresponding to the low signal amplitude segment. The part with an oil displacement efficiency greater than 90% is regarded as the location swept by the CO2-miscible zone. The dimensionless core position corresponding to when the signal amplitude begins to rise (i.e., when the low signal amplitude segment ends) is defined as the location of the CO2 oil displacement front.

[0060] S09: Calculate the oil displacement efficiency Elow corresponding to the low signal amplitude segment of the quantitative imaging curve along the path for different injected CO2 PV numbers.

[0061] The formula is as follows:

[0062]

[0063] In the formula:

[0064] X-ray nuclear magnetic resonance quantitative curve of core dimensionless location;

[0065] X low —Dimensionless location of the core at the end of the low-signal amplitude segment of the quantitative curve along the nuclear magnetic resonance path;

[0066] X 2o1 —Dimensionless core position of crude oil under bound water state corresponding to the nuclear magnetic resonance quantitative curve along the path;

[0067] X 2o1,i —Dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under bound water conditions;

[0068] m(X 2o1 ) i —Amplitude value corresponding to the dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under bound water conditions;

[0069] X 2o —Dimensionless core position of crude oil corresponding to the NMR quantitative curve along the path under displacement condition;

[0070] X 2o,i —The dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under displacement conditions;

[0071] m(X 2o ) i —The amplitude value corresponding to the dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under displacement state.

[0072] The oil displacement efficiency E corresponding to the low signal amplitude segment of the imaging quantitative curve at 0.3PV, 0.6PV, 0.9PV, and 1.2PV was calculated using equation (1). low Furthermore, the dimensionless position of the core was clearly identified when the signal amplitude began to rise (i.e., at the end of the low signal amplitude segment), and the results are shown in the table below:

[0073]

[0074] In this invention, the term "multiple" refers to at least two or more, unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A physical simulation device for determining the location of the CO2 flooding front, characterized in that: It includes a clamp (1), an imaging device is sleeved on the outside of the clamp (1), an intermediate container (3) is provided at the inlet end of the clamp (1), the interior of the intermediate container (3) is filled with CO2, a back pressure assembly (5) is provided at the outlet end of the clamp (1), a metering assembly (6) is provided between the back pressure assembly (5) and the clamp (1), and a confining pressure assembly (7) is provided on the clamp (1).

2. The physical simulation device for determining the location of the CO2 flooding front according to claim 1, characterized in that: The outlet end of the intermediate container (3) is connected to the inlet end of the clamp (1). The inlet end of the intermediate container (3) is provided with a drive pump (41), which pumps the medium inside the intermediate container (3) into the clamp (1).

3. The physical simulation device for determining the location of the CO2 flooding front according to claim 2, characterized in that: A pressure display (42) and a switching valve are provided between the drive pump (41) and the intermediate container (3), and a switching valve is provided between the intermediate container (3) and the clamp (1).

4. The physical simulation device for determining the location of the CO2 flooding front according to claim 2, characterized in that: The drive pump (41) is an ISCO pump.

5. The physical simulation device for determining the location of the CO2 flooding front according to claim 1, characterized in that: The back pressure assembly (5) includes a back pressure pump (51), which is connected to the outlet end of the clamp (1). A temperature detector (52) and a pressure detector (53) are provided between the back pressure pump (51) and the clamp (1).

6. The physical simulation device for determining the location of the CO2 flooding front according to claim 1, characterized in that: The metering component (6) includes the temperature controller (61) and the fluid meter (62).

7. The physical simulation device for determining the location of the CO2 flooding front according to claim 1, characterized in that: The outlet end of the clamp (1) is also connected to a gas-oil separator (81), and an outlet pipe (812) is inserted inside the gas-oil separator (81). The other end of the outlet pipe (812) is connected to a gas processing assembly (82).

8. A physical simulation method for determining the location of the CO2 flooding front, characterized in that, The method, applied to the physical simulation apparatus for determining the location of the CO2 flooding front as described in any one of claims 1-7, comprises: S01: Prepare the core, wash and dry the core, and measure the core length L, diameter d, porosity φ, and permeability K; S02: The core was vacuum-pressurized and saturated with formation water. The saturated water core sample was then steadily displaced with heavy water of equal salinity at a rate of 0.01 mL / min. The displacement rate was then gradually increased to continuously displace the sample up to 10 PV to eliminate the signal of the water phase. S03: Load the rock sample into the holder; S04: Establish bound water saturation. Use crude oil displacement from low pressure difference to high pressure difference to record gas production and oil production at the outlet end and pressure difference at both ends. Aging the rock sample at formation temperature and measuring the quantitative T2 spectrum curve of the rock sample along the process of nuclear magnetic resonance imaging to calculate the bound water saturation of the rock sample. S05: Place the core into the nuclear magnetic resonance core holder, set the holder confining pressure, and set the back pressure at the holder outlet to the CO2 pressure in the intermediate container, with an error of less than 0.1 MPa. S06: Turn on the ISCO pump and inject CO2 from the intermediate container into the rock core in the holder at a constant injection rate of 0.01PV / min. During the experiment, record the gas production and oil production at the outlet end and continuously measure the quantitative curve of the rock sample along the nuclear magnetic resonance imaging process. After the experiment, measure the weight of the rock sample. S07: The dynamic distribution of oil phase signals in the core during CO2 flooding was obtained using imaging equipment. CO2 was injected at a rate of 0.01 PV / min using an ISCO pump. The quantitative curve along the imaging path was divided into low signal amplitude segment, medium signal amplitude segment, and high signal amplitude segment. S08: Compared with the quantitative curve of the rock sample imaging along the way in the bound water state, the signal amplitude of the low signal amplitude segment of the three curves decreased the most. The oil displacement efficiency corresponding to the low signal amplitude segment was calculated. The part with an oil displacement efficiency greater than 90% was regarded as the location swept by the CO2-miscible zone. The dimensionless position of the core corresponding to the start of the signal amplitude increase was defined as the location of the CO2 oil displacement front. S09: Calculate the oil displacement efficiency E corresponding to the low signal amplitude segment of the quantitative imaging curve along the path for different injected CO2 PV numbers. low .

9. The physical simulation method for determining the location of the CO2 flooding front according to claim 8, characterized in that: In S09, the oil displacement efficiency E low The formula is as follows: In the formula: X-ray nuclear magnetic resonance quantitative curve of core dimensionless location; X low —Dimensionless location of the core at the end of the low-signal amplitude segment of the quantitative curve along the nuclear magnetic resonance path; X 2o1 —Dimensionless core position of crude oil under bound water state corresponding to the nuclear magnetic resonance quantitative curve along the path; X 2o1,i —Dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under bound water conditions; m(X 2o1 ) i —Amplitude value corresponding to the dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under bound water conditions; X 2o —Dimensionless core position of crude oil corresponding to the NMR quantitative curve along the path under displacement condition; X 2o,i —The dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under displacement conditions; m(X 2o ) i —The amplitude value corresponding to the dimensionless position of the i-th core in the nuclear magnetic resonance quantitative curve of crude oil under displacement state.

Images