True tri-axial hydraulic fracture test machine and test method

Abstract

The invention relates to a true tri-axial hydraulic fracture test machine which comprises a confining pressure system, an injection system and a true tri-axial test stand, wherein the injection system comprises a fracturing solution container I, a fracturing solution container II and a piston container, and a stirring mechanism is mounted in the fracturing solution container II. A test method comprises the following steps: injecting clear water and an additive into the fracturing solution container II according to a certain proportion, and starting the stirring mechanism to stir; injecting a fracturing solution into a cavity body above a piston plate in the piston container by utilizing pressure; respectively applying confining pressures onto three axial directions of a downhole rock core simultaneously through three high-pressure advection pumps; draining into a cavity body under the piston plate in the piston container through a constant-pressure constant-speed plunger pump I and / or a constant-pressure constant-speed plunger pump II; injecting the fracturing solution into the rock core to start to fracture and taking out the downhole rock core after the end of fracturing to observe fracture expansion condition. The true tri-axial hydraulic fracture test machine provided by the invention has the benefits that the technical scheme is simple and easy to understand, the operation is convenient and fast, the unified control of the confining pressure system and the injection system can be realized, and the fracturing solution is convenient to replace.

Description

technical field [0001] The invention belongs to the technical field of oil and gas reservoir development, and in particular relates to a true triaxial hydraulic fracturing test machine and a test method thereof. Background technique [0002] During the development of oil and gas reservoirs, due to the low-permeability geological characteristics of the reservoirs, the migration of oil and gas is hindered. At this time, hydraulic fracturing has become an important means for the efficient development of such reservoirs. Through hydraulic fracturing, a complex large-scale fracture network with high conductivity can be formed, thereby increasing the drainage area of ​​oil and gas and reducing the flow resistance of oil and gas in the reservoir. Therefore, indoor physical simulation experiments are carried out to study the crack initiation and expansion behavior of fractures. is of great significance. The true three-axis experimental device in the prior art is mainly composed of ...

AI Technical Summary

Problems solved by technology

On the one hand, the triaxial confining pressure device for simulating the stress state of the formation rock and the injection device for simulating the fracturing process are controlled by two independent systems, which cannot be coordinated and controlled on the same platform. , the lack of unified monitoring measures, which not only increases the operating procedures, affects the efficiency of the experiment, but also brings certain safety hazards; on the other hand, the hydraulic pressure source with triaxial confining pressure is pressurized in the form of a plunger pump During the operation, the pressurization rate cannot be effectively controlled, resulting in excessive triaxial pressure difference of the rock mass, causing crushing and deformation, and affecting the experimental results; in addition, the disassembly and assembly of the oil-water separator is not easy to operate, and there are certain difficulties in replacing the fracturing fluid

[0003] With the deepening of the research scope of oil and gas reservoirs, the existing equipment can no longer meet the requirements of the experimental parameters, and there are many control lines and high-pressure pipelines connected between the equipment, which bring certain safety hazards and are not easy to maintain

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