Explosive fracturing simulation experiment for low permeability reservoirs and fractal characteristics of cracks produced

摘要

Based on the explosive fracturing simulation experiment for low permeability reservoir, growths of the cracks produced by the explosive fracturing in the samples were analyzed. And associated with fractal geometry theory, the cracks fractal characteristics were studied and the influences of explosive quantity and confining pressure on the cracks fractal dimension were analyzed. Different explosive quantities and confining pressures under which the simulation experiment was carried out were designed. After the experiment, the fractal dimension of the cracks produced by explosive fracturing in different samples was got by the box dimension calculation method. The results show that: With the increase of explosive quantity, the amount, length and width of the cracks on the surface of the sample produced by explosive fracturing simulation experiment under the same confining pressure increase. The amount and length of the cracks produced by explosive fracturing under the same explosive quantity decrease with the increase of confining pressure. Under the same confining pressure, the cracks fractal dimension increases with the increase of explosive quantity, and the relationship between them is approximately linear when the confining pressure is relatively low and approximately nonlinear when the confining pressure is relatively high. Under the same explosive quantity, the cracks fractal dimension decreases with the increase of confining pressure. It is suggested that site operation should match the explosive quantity with the confining pressure, and the charge pattern of axial coupling and radial uncoupling should be applied.