Study on Fracture Propagation Law of Fractured Reservoir

The fracture is the main reservoir space of fractured reservoirs, the oil and gas content and seepage space are ideal. The natural fractures can be communicated, oil and gas migration channels with high permeability can be formed, and oil and gas production capacity of reservoir can be improved by volume fracturing. It is very important to fully communicate natural fractures to ensure the stimulated effect of fractured reservoir. Therefore, based on the geological conditions of fractured reservoirs, this paper fully considers the influence of geostress, natural fracture density, angle, brittleness index, injection rate, fracturing fluid viscosity. The research results show that the horizontal stress contrast and natural fracture characteristics are the main geological parameters that determine the fracture propagation shape of horizontal well volume fracturing in fractured reservoirs; The horizontal stress contrast is less than 8MPa, the hydraulic fracture is easy to extend along the natural fracture trend, forming a complex fracture network, and the stimulated volume of single stage can reach 30 × 104m3; High injection rate (≥16 m3) is conducive to the simultaneous initiation and expansion of multiple clusters of fractures in horizontal wells and the communication of natural fracture system, reducing fracturing fluid filtration and increasing stimulated reservoir volume (SRV); The use of high viscosity liquid (base fluid) for fracturing in the early stage will help to improve the efficiency of dense perforation cluster and cut down the filtration of fracturing fluid. The injection of low viscosity liquid (slippery water) in the later stage will promote the opening of natural fractures. The optimal proportion of slippery water is 60%–70%. The research results of this paper provide a basis for the fracturing scheme design of fractured reservoirs.