Visualization system and method for multiphase fluids displacement experiment with large viscosity difference in complex pore structure

A visualization system for a multiphase fluids displacement experiment with large viscosity difference in a complex pore structure, wherein the visualization system comprises:

• an injection pump assembly, a visualization complex pore model, a vacuum pressure device and an image acquisition device;
• the visualization complex pore model comprises an inlet and an outlet, and an interior comprises at least two parts of a complex pore structure, and the permeability of each part of the complex pore structure is different
• the injection pump assembly comprises at least two injection pumps, outlets of the injection pumps are configured to be communicated with the inlet of the visualization complex pore model;
• the at least two injection pumps are configured to inject fluid mediums of different viscosities;
• the vacuum pressure device is configured to provide a vacuum environment which allows a displaced fluid medium to be injected into the complex pore structure of the visualization complex pore model;
• and
• the image acquisition device is configured to capture an experimental image inside the visualization complex pore model in a process in real time, wherein the visualization complex pore model is formed by the following method:
• scanning experimental samples with different permeability through a laboratory micro CT scanning system to obtain CT scanning images of the complex pore structure with different permeability;
• capturing the CT scanning images respectively corresponding to different permeability in accordance with a predetermined ratio to form a grayscale image of the overall structure model by splicing;
• performing image binarization processing on the grayscale image of the overall structure model formed by splicing to obtain a binary image constituting the complex pore structure;
• and
• performing three-dimensional reconstruction of the binary image by a three-dimensional modeling software to obtain a digital model of the complex pore structure, and printing and forming the visualization complex pore model [[(1)]] by using transparent materials in accordance with the digital model of the complex pore structure.

A method for a multiphase fluids displacement experiment with large viscosity difference in a complex pore structure, the method specifically comprising:

• using a 3D printing device to print a visualization complex pore model, wherein the visualization complex pore model comprises an inlet and an outlet, and an interior of the visualization complex pore model comprises at least two parts of a complex pore structure, and the permeability of each part of the complex pore structure is different
• putting the entire printed visualization complex pore model into an ultrasonic cleaning machine for vibration cleaning;
• injecting cleaning liquid into the visualization complex pore model at a predetermined pressure after vibration cleaning, and repeating it several times until support material in the visualization complex pore model is completely removed;
• connecting outlets of a first injection pump, a second injection pump and a third injection pump to the inlet of the visualization complex pore model through independent pipes;
• injecting a displaced fluid medium into the visualization complex pore model through the first injection pump, and stopping injection of the visualization complex pore model until the displaced fluid medium reaches the outlet of the visualization complex pore model, and moving the entire system comprising the visualization complex pore model and the injection pump to an interior of a vacuum pressure device for vacuuming, and stopping vacuuming until bubbles inside the visualization complex pore model move outside the complex pore structure during a vacuuming process;
• taking the entire system out of the vacuum pressure device, turning on the first injection pump to continue injecting the visualization complex pore model with the displaced fluid medium, using gravity and density difference between the displaced fluid medium and the air to control a placement direction of the visualization complex pore model to allow the bubbles to be discharged from the outlet injecting a first driving fluid into the visualization complex pore model through the second injection pump, until the first driving fluid flows out of the outlet of the visualization complex pore model;
• wherein the viscosity of the first driving fluid is lower than the viscosity of the displaced fluid medium;
• injecting a second driving fluid into the visualization complex pore model through the third injection pump, until the second driving fluid flows out of the outlet of the visualization complex pore model;
• wherein the viscosity of the second driving fluid is higher than the viscosity of the displaced fluid medium;
• and
• when the first injection pump, the second injection pump, and the third injection pump are injected into the visualization complex pore model with liquids, capturing an experimental image inside the visualization complex pore model in a real time in a process for experimental analysis.
• wherein the visualization complex pore model is formed by the following method:
• scanning experimental samples with different permeability through a laboratory micro CT scanning system to obtain CT scanning images of the complex pore structure with different permeability;
• capturing the CT scanning images respectively corresponding to different permeability according to a predetermined ratio to form a grayscale image of the overall structure model by splicing;
• performing image binarization processing on the grayscale image of the overall structure model formed by splicing to obtain a binary image constituting the complex pore structure;
• and
• performing three-dimensional reconstruction of the binary image by a three-dimensional modeling software to obtain a digital model of the complex pore structure, and printing and forming the visualization complex pore model [[(1)]] by using transparent materials in accordance with the digital model of the complex pore structure.