Study On The Effect Of Filling Material Brittleness On Hydraulic Fracture Propagation

Due to the tightness of the reservoir and the low conductivity of natural fractures,hydraulic fracturing has become one of the important technical measures to increase oil and gas production and injection water injection wells.The simulation of hydraulic fractures in unconventional reservoirs is very different from conventional hydraulic fracture simulations,and it is more difficult.Compared with the conventional hydraulic fracture extension simulation,there are three main difficulties: the uncertainty of the fracture propagation direction,the difficulty of applying fluid pressure and the existence of natural fractures.To study these three problems,observe and analyze the hydraulic fracture propagation from the perspective of the physical model experiment(large size 30 × 30 × 30 cm true triaxial hydraulic fracturing test simulation;mainly the interaction of hydraulic fractures and natural fractures).In the process of fracturing,the existence of natural cracks has a huge impact on it.This article mainly studies the influence of natural crack filler on the extension and expansion of hydraulic cracks.Based on the intersection criterion of natural cracks and hydraulic cracks and rock brittleness evaluation method,combined with a single natural crack and hydraulic crack,the study of different stress ratios and different filling crack The cracks extend and expand.The formation and expansion of hydraulic fracturing fractures are studied by using the permeability,azimuth of the filler fractures and the mineral brittleness of natural cores as variables.Combined with the fact that hydraulic cracks and natural cracks may meet during fracturing,the crack propagation criteria before and after the hydraulic cracks and natural cracks meet are established to determine the direction of hydraulic crack extension and expansion.Designed models of natural crack fillers with different materials(no filling,filled,and isolated filling)to simulate natural cracks with different permeability.Designed different filler interlayer azimuth angles to simulate natural crack angles.Designed different core cement sand mixing ratios to simulate the brittleness of different natural core minerals.Observe the formation of artificial hydraulic fracturing fractures.Verification of the permeability of different natural fractures,different natural fracture azimuths,different stress ratios and different rock brittleness preset fractures.The formation and fracture trend of artificial hydraulic fracturing fractures.