Test device and method for observing rock hydrofracture crack initiation evolution

Abstract

The invention provides a test device for observing rock hydrofracture crack initiation evolution, which comprises a hydrofracture test machine, a liquid injection assembly, an endoscope assembly and adouble-layer transparent tube, wherein the hydrofracture test machine is used for fixing a cylinder rock sample and applying an axial load and a confining pressure load; the double-layer transparenttube is inserted into the cylinder rock sample, and the outer layer is communicated with the interior of the cylinder rock sample; the liquid injection assembly is communicated with the outer layer ofthe double-layer transparent tube, high-pressure liquid injection is conducted on the outer layer of the double-layer transparent tube; a high-precision camera of the endoscope assembly is inserted into the inner layer of the double-layer transparent tube, and imaging observation and description of the hydrofracture crack initiation evolution process are achieved. A traditional single-layer flowguide tube is replaced with the double-layer transparent tube, dynamic monitoring and imaging description of hydrofracture crack initiation are achieved through the high-precision camera arranged on the inner layer, the transparent window can bear the high-pressure environment in a prefabricated hole, and observation of the high-precision camera is guaranteed.

Description

technical field [0001] The invention relates to the technical field of rock mechanics tests, in particular to a test device and method for observing the initiation and evolution of rock hydraulic fracturing cracks. Background technique [0002] With the large-scale exploitation of shale gas, hydraulic fracturing technology, as an important and effective means to improve the permeability of low-permeability reservoirs, has been paid more and more attention. The formation of hydraulic fractures is mainly divided into three stages: initiation, expansion, and closure. Each stage has an important impact on the final formation of fractures. Therefore, it is very important to observe the development and evolution of fractures. However, due to the concealment and randomness of the formation process of hydraulic fractures, how to monitor and describe the morphology of hydraulic fracture initiation under loading conditions is still a problem to be solved in hydraulic fracturing labora...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a test scheme that can observe the crack initiation evolution of rock hydraulic fracturing, so as to solve the difficult problem that the crack initiation cannot be visually observed and described in the hydraulic fracturing test

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