Experimental investigation on fracturing effects in hydraulic sand fracturing with acoustic emission and 3d laser scanning.

Due to the extremely low permeability of shale reservoirs, large-scale reservoir fracturing is required. Hydraulic fracturing is one of the most important technologies in shale gas exploration and development. In this paper, the acoustic emission energy and the number of location and fracture surface morphology of specimens before and after fracture are studied through hydraulic sand fracturing test. The test results show that: (1) the energy ratio obtained during hydraulic fracturing without proppant is the smallest, and increasing the confining pressure, as well as reducing the displacement and viscosity of the fracturing fluid will cause the energy ratio to decrease. From the perspective of acoustic emission energy, the proppant play an important role in the generation of fractures during hydraulic sand fracturing; (2) when the confining pressure increases, the number of shale specimens before and after rupture is the largest, but the total number of locating events is smaller than the sanding ratio increased; there is no proppant hydraulic fracturing, the number of specimens before and after the rupture is the largest. And the total number reached the minimum, indicating that the proppant can play an important role in the hydraulic sand fracturing test; (3) the sand is relatively large, the specific surface and standard deviation both reach the maximum, indicating that the fracture surface roughness is the largest under the test condition, and the fracturing effect is the best, but the specific surface and standard deviation are the minimum when fracturing without proppant, so indicating that the fracture surface fracturing effect is the worst at this time.