CN-122014234-A - Fracture-cavity oil reservoir gas-water collaborative displacement flow field visualization experiment device and evaluation method based on fluorescence PIV technology

CN122014234ACN 122014234 ACN122014234 ACN 122014234ACN-122014234-A

Abstract

The invention discloses a fracture-cavity oil reservoir gas-water collaborative displacement flow field visualization experiment device and an evaluation method based on a fluorescence PIV technology, the device comprises a transparent fracture-cavity model, an immersion tank, external matching liquid, an injection fluid pump, a double-pulse laser, a sheet light shaping unit, a high-speed camera, a temperature control assembly, an outlet back pressure and output metering assembly and a data acquisition and processing assembly, and is used for acquiring a liquid phase image sequence and calculating a liquid phase velocity field under the condition of gas-water collaborative displacement. The method comprises the steps of establishing an optical correction visualization experimental platform, carrying out flow state self-adaptive injection parameter calculation, carrying out gas-water collaborative displacement and multidimensional data acquisition, carrying out data processing and flow field calculation, and realizing macro-micro collaborative quantitative evaluation based on an eddy oil displacement efficiency index SEIV.

Inventors

XIAO WENLIAN
PENG PENG
XU YU
ZHANG YUHAO
WANG GUOHUAN
Ling Zhengping
ZHENG LINGLI
TANG YANBING
Cheng Qianrui
CHEN HAOYU
TIAN ZHIYU

Assignees

西南石油大学

Dates

Publication Date: 20260512
Application Date: 20260330

Claims (10)

1. A visual experimental device for a fracture-cavity type oil reservoir gas-water collaborative displacement flow field based on a fluorescence PIV technology is characterized by comprising a transparent fracture cavity model, an immersion tank, an external matching liquid, an injection fluid pump, a double-pulse laser, a sheet light shaping unit, a high-speed camera, a temperature control component, an outlet back pressure and output metering component and a data acquisition and processing component, wherein the transparent fracture cavity model is provided with an inlet and an outlet and is used for representing a fracture-cavity type oil reservoir fracture-solution cavity combined reservoir space structure, the transparent fracture cavity model is integrally immersed in the immersion tank and the external matching liquid, the injection fluid pump is communicated with the inlet of the transparent fracture cavity model and is used for injecting gas-phase fluid and liquid-phase fluid into the transparent fracture cavity model to perform gas-displacement, water-displacement or gas-water collaborative displacement experiments, laser emitted by the double-pulse laser forms laser light through the sheet light shaping unit and irradiates an internal measurement plane of the transparent fracture cavity model, the high-speed camera is used for acquiring an image sequence of the internal liquid phase of the fracture cavity, the liquid-phase fluid pump is not filled into the liquid-phase fluid reservoir fracture cavity, the liquid-phase tracer component is used for controlling the refractive index, the liquid-phase fluid is filled into the liquid-phase fluid reservoir cavity model, the liquid-phase fluid is filled into the liquid-phase fluid reservoir, the liquid-phase fluid is used for controlling the liquid-phase pressure contrast fluid pump is connected with the external fluid, and the external fluid is used for controlling the pressure-phase fluid, the pressure is respectively connected with the fluid, and the external fluid is filled with the fluid-phase pressure control component is used for controlling the pressure-phase, and the pressure-contrast fluid, the pressure control component is used for the pressure-filled fluid, and the pressure is connected with the external fluid, and the pressure sensor is used for the pressure, the high-speed camera, the temperature control assembly and the outlet back pressure are connected with the output metering assembly and used for synchronously collecting image data, pressure data, flow data and output data and calculating a liquid phase speed field based on the image sequence.
2. The experimental apparatus of claim 1, wherein the transparent fracture-cavity modeling material has an index of refraction of The refractive index of the liquid phase fluid is The refractive index of the external matching fluid is And satisfies: ; ; 。
3. The experimental device of claim 1, wherein the transparent fracture-cavity model adopts a modularized structure and comprises an upper cover plate, a middle runner layer and a lower bottom plate, wherein the middle runner layer is a replaceable runner layer and is used for constructing internal runners with different fracture-cavity combination forms, scale parameters and communication relations, and fluorescent tracer particles in the liquid phase fluid are fluorescent microspheres.
4. The experimental set-up of claim 1, wherein the injection fluid pump comprises a gas phase intermediate container for temporary storage or stabilization of gas phase fluid, a liquid phase intermediate container for temporary storage of liquid phase fluid, and an inlet end pressure sensor for monitoring injection end pressure changes.
5. The experimental set-up of claim 1, wherein the outlet back pressure and yield metering assembly comprises a gas-liquid separator for gas-liquid separation of produced fluid, a gas flow meter for measuring produced gas flow, an outlet end pressure sensor for monitoring outlet pressure changes, and a produced fluid pump for delivering produced fluid to a subsequent collection or processing unit.
6. A method for visually evaluating a fracture-cavity oil reservoir gas-water collaborative displacement flow field based on an experimental device according to any one of claims 1 to 5 is characterized by comprising the following steps of S1, establishing an optical correction visual experimental platform, placing a transparent fracture cavity model in an immersion tank and an external matching liquid, carrying out refractive index matching on a transparent fracture cavity model material, liquid phase fluid and the external matching liquid, controlling the experimental environment temperature, S2, extracting characteristic dimensions of the transparent fracture cavity model, carrying out fluid state self-adaptive injection parameter calculation, determining injection parameters according to a main control flow mechanism, S3, injecting gas phase fluid and liquid phase fluid into the transparent fracture cavity model, carrying out gas-water collaborative displacement experiment, collecting PIV image data and output metering data, S4, preprocessing the collected image, generating a gas phase mask, eliminating interference of the gas phase mask, carrying out PIV calculation on the processed image, and obtaining a liquid phase velocity field, a vortex flow meter vortex efficiency index based on the liquid phase velocity field, the vortex flow meter, and carrying out microscopic evaluation by combining water content and quantitative oil displacement.
7. The method according to claim 6, wherein in step S2, the difference in density of the fluid is used Interfacial tension Viscosity of liquid phase Acceleration of gravity Geometric feature dimensions Calculating the bond number The expression is: ; When (when) In the time of capillary number Is the dominant control parameter, wherein: ; When (when) When using Froude number Is the dominant control parameter, wherein: ; When (when) When combined capillary number And Froude number Determining an implantation parameter, wherein, Is the feature injection speed.
8. The method according to claim 6, wherein the image preprocessing in the step S4 comprises background subtraction, image enhancement and abnormal light spot removal, the gas phase mask is generated by identifying a gas phase region in an image, the PIV cross-correlation calculation is performed in a multi-step iterative cross-correlation mode, and the obtained vector field is subjected to pseudo-vector elimination and smoothing processing to obtain a liquid phase velocity field, and the vortex quantity field is calculated by the liquid phase velocity field.
9. The method according to claim 6, wherein the index of the vortex displacement efficiency in step S5 is Calculated as follows: ; Wherein, the In order to observe the area of the object, Is the position At the moment of Is used for the vortex quantity of the air conditioner, In order to achieve a fluid density, Is the position At the moment of Is a fluid velocity vector model of (a), In order to achieve the injection pressure, For injection flow.
10. The evaluation method according to claim 9, wherein the step S5 is performed by Change curve with time and water content Recovery ratio Performing correlation analysis on dynamic change curves of the oil to represent the utilization degree of the residual oil in the gas-water collaborative displacement process, wherein the recovery ratio is as follows Calculated as follows: ; Water content Calculated as follows: ; Wherein, the In order to accumulate the volume of oil produced, Is the volume of the oil phase in the original model, To accumulate the water production volume.

Description

Fracture-cavity oil reservoir gas-water collaborative displacement flow field visualization experiment device and evaluation method based on fluorescence PIV technology Technical Field The invention belongs to the technical field of oil and gas field development experiment technology and multiphase flow field visual test, and particularly relates to a fracture-cavity oil reservoir gas-water collaborative displacement flow field visual experiment device and an evaluation method based on a fluorescence PIV technology. Background Fracture-cavity type carbonate reservoirs commonly develop cracks, karst cavities and combination communication structures thereof, the reservoir space is various in types, large in scale span and strong in heterogeneity, and the migration process of fluid in the reservoir space is simultaneously influenced by gravity, viscous force, interfacial tension and complex boundary conditions. In the water injection, gas injection and gas-water collaborative displacement process, complex flow phenomena such as interface migration, gas-liquid separation, detouring, channeling, local vortex and the like often occur, and the flow phenomena directly influence swept volume, residual oil distribution and final recovery ratio. Therefore, an experimental characterization method capable of truly characterizing the gas-water two-phase flow characteristics in the fracture-cavity oil reservoir is established, and the method has important significance in revealing a gas-water collaborative displacement mechanism and optimizing development parameters. The existing researches on fracture-cavity oil reservoir displacement mechanisms are usually carried out in a visual physical simulation mode, a conventional production parameter monitoring mode or a numerical simulation analysis mode and the like. The visual experiment based on the transparent model can reflect the migration process of the fluid in the fracture-cavity structure to a certain extent, the analysis method based on macroscopic parameters such as pressure, flow, liquid production, water content and recovery ratio can reflect the displacement result, and the numerical simulation method can be used for analyzing the flow field distribution characteristics under specific working conditions. However, most of the methods focus on macroscopic phenomenon observation, yield response analysis or model calculation result characterization, direct acquisition of local flow field structures, liquid phase true speed distribution and vortex driving effects in a fracture-cavity medium is still insufficient, and accurate knowledge of microscopic flow behaviors in a gas-water collaborative displacement process is difficult to realize. Particle image velocimetry (PIV technology), a non-contact flow field measurement method, capable of inverting a fluid velocity field by tracing particle image displacement, has been used in part of visual flow experimental research. However, in the fracture-cavity type oil reservoir transparent model, because the fracture-cavity boundary is complex in shape, curved surfaces, sharp corners, thickness changes and refractive interfaces are locally present, and refractive offset and imaging distortion are easily generated in the laser propagation process, so that a velocity measurement result close to a boundary area is distorted. Meanwhile, in the gas-liquid two-phase displacement process, a gas-liquid interface can generate stronger reflection, scattering and highlighting interference, and an image acquired in a traditional imaging mode often contains interface optical noise and trace particle signals at the same time, so that the pseudo-vector increase, the local velocity field identification failure and the liquid-phase flow field information distortion in the cross-correlation calculation are easily caused, and the application effect of the PIV in the gas-water two-phase flow test of a fracture-cavity oil reservoir is affected. In addition, in the aspect of injection parameter determination, the conventional experimental design is generally processed by adopting a fixed injection speed, an empirical setting or a single similarity criterion, and it is difficult to simultaneously consider the difference of a crack area and a karst cave area on a dominant stress mechanism. For fracture-cavity oil reservoirs, the fracture scale is smaller, the influence of interfacial force is remarkable, the karst cavity scale is larger, the gravity differentiation effect is more remarkable, and the flow control mechanisms in different areas are not consistent. If the experimental parameter design method aiming at the slit hole scale difference and the multi-factor coupling effect is not available, deviation between the experimental working condition and the actual flow characteristic is easy to occur, and the representativeness and comparability of the experimental result are affected. On the other hand, the existing displacement effect evaluation mod