CN-122014184-A - Injection process of efficient microemulsion oil displacement agent suitable for low-permeability oil reservoir

CN122014184ACN 122014184 ACN122014184 ACN 122014184ACN-122014184-A

Abstract

The invention relates to the technical field of chemical oil displacement control, in particular to an injection process of a high-efficiency microemulsion oil displacement agent suitable for a low-permeability oil reservoir. The method comprises the steps of monitoring data in a preset injection disturbance mode, performing time domain alignment, obtaining a corrected pressure sequence and a corrected flow sequence after removing a background trend line, further obtaining dynamic fluctuation resistance ratio according to fluctuation difference of the corrected pressure sequence and the corrected flow sequence, judging a fluid state, performing phase space reconstruction on the normalized corrected pressure sequence when judging that the fluid is in a high-resistance response state, calculating a fluctuation regularity index, further comparing the fluctuation regularity index with a preset reference fluctuation regularity, setting a fluid state marker, and finally regulating and controlling injection of the high-efficiency microemulsion oil displacement agent based on the fluid state marker, so that the fluid state is accurately distinguished under a high-pressure working condition, and the oil displacement economic benefit is optimized.

Inventors

YAN JIAN
QIU YINGYING
WANG RUISI
WANG ZHENGYI
YANG XUAN
LI MINGYAO

Assignees

西安石油大学

Dates

Publication Date: 20260512
Application Date: 20260414

Claims (10)

1. An injection process of a high-efficiency microemulsion oil displacement agent suitable for a low-permeability oil reservoir, which is characterized by comprising the following steps of: Monitoring data in a preset injection disturbance mode, performing time domain alignment on flow data and pressure data in a current data buffer zone based on cross-correlation analysis, respectively extracting aligned pressure data and background trend lines of the flow data, and acquiring a corrected pressure sequence and a corrected flow sequence after the background trend lines are removed; Acquiring dynamic fluctuation resistance ratio according to fluctuation difference of the corrected pressure sequence and the corrected flow sequence, and judging the fluid state by combining a preset leakage threshold value; when the fluid is in a high-resistance response state, carrying out phase space reconstruction on the normalized corrected pressure sequence, constructing a recursion diagram matrix and calculating a fluctuation regularity index; setting a fluid state zone bit by comparing the fluctuation rule index with a preset reference fluctuation rule, and setting the fluid state zone bit to be in a preset first state when the fluid is judged not to be in a high resistance response state; And regulating and controlling the injection of the high-efficiency microemulsion oil displacement agent based on the fluid state marker bit.
2. The injection process of the high-efficiency microemulsion displacement agent suitable for low-permeability reservoirs according to claim 1, wherein the method for obtaining the fluctuation regularity index comprises the following steps: Extracting a state vector from the normalized corrected pressure sequence according to a preset embedding dimension and delay time, constructing a recursion diagram matrix based on the state vector, counting the length distribution of line segments parallel to a main diagonal in the recursion diagram matrix, and calculating a deterministic index as a fluctuation regularity index.
3. The injection process of the efficient microemulsion displacement agent suitable for the low-permeability oil reservoir, which is disclosed in claim 1, is characterized in that when the fluctuation regularity index is not less than the preset reference fluctuation regularity, the fluid state flag bit is set to be in a preset second state, and when the fluctuation regularity index is less than the preset reference fluctuation regularity, the fluid state flag bit is set to be in a preset third state.
4. The injection process of the high-efficiency microemulsion oil displacement agent suitable for the low-permeability oil reservoir according to claim 3, wherein the method for regulating the injection of the high-efficiency microemulsion oil displacement agent based on the fluid status flag comprises the following steps: Executing a hierarchical regulation strategy according to the current fluid state, namely increasing injection displacement in a preset probing window according to a preset probing proportion when the fluid state is in the preset first state, and starting a channel plugging agent injection pump to mix a high-viscosity gel slug with preset gradation into an injection pipeline if the ratio of the maximum dynamic fluctuation resistance calculated in the preset probing window is smaller than a preset leakage threshold value and the increasing rate of the maximum dynamic fluctuation resistance relative to the dynamic fluctuation resistance before the preset probing window is smaller than a preset rising threshold value; When the interface activity regulator is in the preset second state, increasing the injection concentration of the interface activity regulator by a preset concentration step length; And when the injection pump is in the preset third state, maintaining the injection pump speed unchanged.
5. The injection process of the high-efficiency microemulsion displacement agent for low-permeability reservoirs according to claim 4, wherein the inhibition phase is completed after the injection of the high-viscosity gel or the increase of the injection concentration of the interfacial activity modifier, and the accumulated injection volume is monitored to reach the volume of the well pipe column.
6. The injection process of the high-efficiency microemulsion displacement agent suitable for a low-permeability oil reservoir according to claim 1, wherein the method for acquiring the background trend line comprises the following steps: And respectively carrying out linear fitting on the pressure data and the flow data after alignment, and taking the fitting straight line as each background trend line.
7. The injection process of the high-efficiency microemulsion displacement agent suitable for a low-permeability oil reservoir according to claim 1, wherein the method for acquiring the dynamic fluctuation resistance ratio comprises the following steps: and obtaining dynamic fluctuation resistance ratio according to the difference between the standard deviation of the corrected pressure sequence and the standard deviation of the corrected flow sequence.
8. The injection process of a high efficiency microemulsion displacement agent suitable for low permeability reservoirs of claim 1, wherein said method of determining fluid status comprises: And when the dynamic fluctuation resistance ratio is greater than or equal to the preset leakage threshold value, judging that the fluid is in a high resistance response state.
9. The injection process of the high-efficiency microemulsion displacement agent suitable for low-permeability reservoirs according to claim 1, wherein the method for acquiring the preset reference fluctuation regularity comprises the following steps: And calculating a fluctuation regularity index according to the flow data and the pressure data in the data buffer zone when the stratum connectivity is known to be good or in the water injection stage just established, and taking the fluctuation regularity index of a preset proportion as a preset reference fluctuation regularity.
10. The injection process of the efficient microemulsion displacement agent suitable for the low-permeability oil reservoir, which is disclosed in claim 1, is characterized in that the preset injection disturbance mode is to superimpose a preset sinusoidal flow disturbance signal on the basis of preset constant current injection.

Description

Injection process of efficient microemulsion oil displacement agent suitable for low-permeability oil reservoir Technical Field The invention relates to the technical field of chemical oil displacement control, in particular to an injection process of a high-efficiency microemulsion oil displacement agent suitable for a low-permeability oil reservoir. Background In the development process of low-permeability oil reservoirs, because the pore structure of the reservoir is complex and the heterogeneity is strong, the conventional water flooding is difficult to establish effective driving pressure difference, and a microemulsion oil displacement technology is often adopted to improve the substrate utilization degree. However, in the microemulsion injection process, the reservoir fluid flow state has high uncertainty, and the existing monitoring method mainly relies on ground pressure and flow data to calculate injection impedance, and the linear index can identify the low-resistance fracture leakage state, but cannot distinguish whether the reservoir fluid flow state is invalid or valid pore inlet blocking or valid pore seepage when facing high-pressure working conditions. Both are characterized by high values on macroscopic resistance values, so that on site, whether the plugging removal measures should be taken or normal injection is maintained is difficult to judge, and ineffective consumption of chemical agents or loss of oil well productivity is often caused. Disclosure of Invention In order to solve the technical problems that in the low-permeability oil reservoir microemulsion oil displacement process, the fluid state cannot be effectively and accurately distinguished under the high-pressure injection working condition, and the injection of the high-efficiency microemulsion oil displacement agent is difficult to accurately regulate and control, the invention aims to provide an injection process of the high-efficiency microemulsion oil displacement agent suitable for the low-permeability oil reservoir, and the adopted technical scheme is as follows: Monitoring data in a preset injection disturbance mode, performing time domain alignment on flow data and pressure data in a current data buffer zone based on cross-correlation analysis, respectively extracting aligned pressure data and background trend lines of the flow data, and acquiring a corrected pressure sequence and a corrected flow sequence after the background trend lines are removed; Acquiring dynamic fluctuation resistance ratio according to fluctuation difference of the corrected pressure sequence and the corrected flow sequence, and judging the fluid state by combining a preset leakage threshold value; when the fluid is in a high-resistance response state, carrying out phase space reconstruction on the normalized corrected pressure sequence, constructing a recursion diagram matrix and calculating a fluctuation regularity index; setting a fluid state zone bit by comparing the fluctuation rule index with a preset reference fluctuation rule, and setting the fluid state zone bit to be in a preset first state when the fluid is judged not to be in a high resistance response state; And regulating and controlling the injection of the high-efficiency microemulsion oil displacement agent based on the fluid state marker bit. Further, the method for obtaining the fluctuation regularity index comprises the following steps: Extracting a state vector from the normalized corrected pressure sequence according to a preset embedding dimension and delay time, constructing a recursion diagram matrix based on the state vector, counting the length distribution of line segments parallel to a main diagonal in the recursion diagram matrix, and calculating a deterministic index as a fluctuation regularity index. Further, when the fluctuation regularity index is not less than the preset reference fluctuation regularity, setting the fluid state flag bit to be in a preset second state, and when the fluctuation regularity index is less than the preset reference fluctuation regularity, setting the fluid state flag bit to be in a preset third state. Further, the method for regulating and controlling the injection of the efficient microemulsion oil displacement agent based on the fluid state marker bit comprises the following steps: Executing a hierarchical regulation strategy according to the current fluid state, namely increasing injection displacement in a preset probing window according to a preset probing proportion when the fluid state is in the preset first state, and starting a channel plugging agent injection pump to mix a high-viscosity gel slug with preset gradation into an injection pipeline if the ratio of the maximum dynamic fluctuation resistance calculated in the preset probing window is smaller than a preset leakage threshold value and the increasing rate of the maximum dynamic fluctuation resistance relative to the dynamic fluctuation resistance before the prese