Numerical Simulation Study Of Proppant Transport In Schist Reservoir Fractures

Hydraulic fracturing is an important reservoir stimulation technology, whose aim is to form dune-building in a high conductivity in the formation, the morphology of dune-building have great influence on the effect of stimulation. Micro-seismic monitoring data found that the fracturing of shale reservoir forms a complex fracture network, which is different from the conventional sandstone reservoirs that forms wings seam fractures. So the understanding of proppant transport and setting in the conventional sandstone reservoirs does not apply to the shale reservoirs. It is quite necessary to make an in-depth study on the proppant transport and setting in the shale reservoirs. We study the law of proppant transport and setting in the shale reservoirs by using numerical simulation.Based on micro-seismic monitoring data and computational fluid dynamics is used, two-phase flow numerical simulation model is built. Euler-Euler method is used to establish a numerical model in a complex fracture proppant transport, and the model consider alternate drag, the lateral lift, virtual mass force, the volume fraction of the dispersed phase and the dispersed phase the continuous phase density difference of between the two phases of proppant and fracturing fluid. Equations discrete finite volume method, SIMPLE algorithm coupled solver, and the two-phase flow equations using finite volume method to discrete, and coupled SIMPLE algorithm. And a single vertical slit experiments is used to verify the correctness of the numerical model. And conclusions are as follows:(1) Based on micro seismic monitoring and the morphology of complex shale reservoir is analysised. complex fracture geometry is created with different shapes by simplify the morphology of complex fracture.(2) The use of experimental models to verify the feasibility of tablet and method of the numerical model.(3)The proppant transporting and setting in the compelx fractures si similar to the single vertica fracture, and the proppant transporting into the second fracture is divided into two processes:the proppant roll into the second fracture due to the gravity;the proppant is transported into the second fracture.(4)The type of proppant?sand ratio and the inlet velocity have a great influence on the form of proppant sand bank. The equilibrium height of dune-building reduce with the reducing of proppant density and with the increase of inlet velocity. The equilibrium height of proppant sand bank increase with the increase of sand ratio. The dune-building of second fracture is mainly affected by the main fracture.(5)The proppant flow into the second fracture where is closer to entrance of the main fracture, and the dune-building is more higher in this second fracture which is vertical. And the proppant setted in the horizontal fracture in average.In this paper, the mechanism of proppant transport in complex fracture were studied, system research for shale reservoir fracturing optimization design has a certain significance.