Preparation method for fracture physical simulation test piece of coal-measure composite reservoir

Abstract

The invention discloses a preparation method for a fracture physical simulation test piece of a coal-measure composite reservoir, which is particularly suitable for the field of coal-measure gas development geology and rock mechanics. The preparation method comprises the following steps: first, acquiring large blocks of fresh coal samples and small blocks of rock samples with different lithologies; performing laser scanning on cross sections of the large blocks of the fresh coal samples and calculating the fractal dimension value of surface topography; carrying out X-diffraction analysis and rock mechanical test on the small blocks of the rock samples; blending and simulating different formulae by utilizing sand, cement and clay according to detection results; determining rock combinationtypes and stratum thickness with different lithologies of the coal-measure composite reservoir; preparing a coal-containing multi-lithology rock combination cubic test piece by using a mould; respectively drilling boreholes in the central parts of a coal sample and self-made rock samples with different lithologies on the same side surface of the cubic test piece; solidifying steel liquid injectionpipes in the boreholes to simulate the boreholes; performing external casting on the coal-containing multi-lithology rock combination cubic by utilizing a sealing material to prepare the fracture physical simulation test piece of the coal-measure composite reservoir with a standard size. The preparation method is simple in steps and convenient to use; the prepared test piece is closer to an actual situation.

Description

technical field [0001] The invention relates to a method for preparing a physical simulation test piece for fracturing of a coal-measure composite reservoir, and is especially suitable for the preparation method of a physical simulation test piece for fracturing of a coal-measure composite reservoir used in the fields of coal-measure gas development geology and rock mechanics. Background technique [0002] In my country's eastern margin of the Ordos Basin, eastern Yunnan-western Guizhou and other multi-coal seam areas, coal rocks, tight sandstones, and mud shales and other lithological reservoirs often overlap vertically, and the rock layers are thin and interbedded frequently, forming coal measures. Composite reservoirs are rich in unconventional natural gas resources and have great potential for development. [0003] Coal-measure composite reservoirs generally have the characteristics of low porosity and low permeability. Combined production of multi-type reservoirs is the ...

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Problems solved by technology

[0009] Although the above-mentioned patents include coal rocks and rocks of different lithologies, there are deficiencies: first, a large rock cutting machine is used in the preparation of the phantom sample, so that the surface of the coal and the rock is smooth, and there is a flat contact between the two, which is different from the The contact interface between the actual coal rock and its irregular roof and floor is different; when the two coal-measure composite reservoirs are developed, combined pressure and co-production are emphasized, and the single-layer fracturing mode in this invention is not enough to guide the actual coal-measure composite reservoir multi-layer composite Extension and expansion of fractures during fracturing

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