Experimental system and method for testing crack height expansion under loading stress

Abstract

The invention discloses experimental system and method for loading height extension of cracks in stress test. The experimental system includes: a loading framework which is used for loading a test sample, a loading chamber which is formed in interior of the loading framework and is square in shape, and a true-triaxial ground stress loading unit which loads a pressure to the test sample and includes: an expandable loading plate which has a hollow structure, and a pressure pump, which is communicated with the expandable loading plate and supplies pressure thereto. The expandable loading plate includes: first loading plates between the loading chamber and the test sample and a second loading plate located on one end of the test sample, wherein the first loading plates include at least two groups in the depth direction of the loading chamber; a pressure sensor which is connected to the pressure pump; and a controller electrically connected to the pressure pump and the pressure sensor. Thesystem can achieve independent application of a load of multi-layer horizontal stress field in the vertical direction of the test sample and supplies beneficial technical support to optimization design on height growth controlled fracture technology.

Description

technical field [0001] The invention relates to the technical field of hydraulic fracturing physical simulation experiments in the development of oil and gas fields, in particular to an experimental system and method for testing the expansion of fracture heights by loading stress. Background technique [0002] As one of the main measures for oil and gas stimulation, hydraulic fracturing has been widely used in the modern petroleum industry. With the massive development of low-permeability and complex oil and gas reservoirs (such as natural fracture reservoirs), hydraulic fracturing technology faces new challenges. Reservoir stimulation is faced with more and more complex objects, among which factors including abnormal structural stress, natural fractures, horizontal bedding development, deep large-scale horizontal well type and other factors restrict the understanding of the mechanism of hydraulic fracture initiation and extension. [0003] In order to correctly understand ...

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Problems solved by technology

[0005] However, the common problem in the prior art is that when loading stress at present, the jack is usually used for rigid loading. Due to the restriction of the above-mentioned experimental loading method, only three in-situ stresses, namely vertical and single-layer two-direction horizontal principal stress, can be carried out. value, it is impossible to simulate the difference of horizontal stress in the vertical direction, so it is impossible to carry out the fracture height extension experiment under the condition of interlayer stress difference

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