Coal sample preparation device for true three-dimensional permeability determination

Abstract

The invention relates to a coal sample preparation device for the true three-dimensional permeability determination. The preparation device comprises a fixed support, the fixed support is provided with a sample loading bench, and the sample loading bench is formed by a loading plane and a sample holder arranged on the loading plane; and a sliding guide rail is arranged over the sample loading bench, the sliding guide rail is slidingly provided with a sliding block, the sliding block is provided with a vertically downward jet nozzle, the jet nozzle is a flat seam nozzle, the flat seam of the flat seam nozzle and the sliding guide rail are arranged in a longitudinal parallel mode. The coal sample preparation device for the true three-dimensional permeability determination adopts the flat seam nozzle, so a jet flow jetted by the flat seam nozzle forms a plane type jet flow, and a stress concentration problem caused by the strong heterogeneity of the internal structure of coal can be maximally reduced, so the coal sample fragmentation risk is reduced, and the coal sample molding rate is improved; coal sample cutting is carried out in a plane type jet mode, so the cutting speed of a water jet flow is improved, thereby cutting surfaces are flattened, and the cutting effect is good.

Description

technical field [0001] The invention relates to a preparation device for testing coal samples, in particular to a coal sample preparation device for true three-dimensional permeability measurement. Background technique [0002] The permeability of coal reservoir is one of the key factors restricting the commercial development of coalbed methane, and the change of permeability directly affects the productivity of coalbed methane wells. At the same time, the permeability of coal seam also has an important impact on gas outburst in coal mines and gas drainage in coal reservoirs. In the process of mine production or coalbed methane drainage, due to the influence of engineering, the balance of original rock stress field and original reservoir pressure is destroyed, resulting in the redistribution of stress around the working space and the change of gas (coalbed methane) flow state. As a result, the seepage characteristics of gas (coalbed methane) in the pores and fissures of coa...

AI Technical Summary

Problems solved by technology

The disadvantage of the first method is that only one direction of stress loading is realized, and the permeability in one direction perpendicular to the bottom surface can only be measured

The second measurement method is superior to the one-dimensional permeability measurement method, that is, the stress state in two directions can be simulated, but the actual ground stress is composed of a vertical stress and two mutually perpendicular horizontal stresses. The measurement method still cannot truly reproduce the actual stress state, and there is a certain deviation between the experimentally measured permeability value and the real value

However, the point-shaped energy-gathering water jet technology commonly used in water jet cutting is difficult to apply to coal and rock with low mechanical strength and brittleness.

Therefore, the current water jet cutting method has not been applied to the cutting of soft and fragile materials such as coal and rock.

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