Three-dimensional Simulation Analysis Of Effect Of Process Parameters On Fracturing Effect

Based on the characteristics of hydraulic fracturing in shale reservoirs,this paper uses RFPA3 D software to establish a variety of reservoir core numerical models to explore the effect of fracturing fluid displacement and viscosity on hydraulic fracturing in shale reservoirs with different geological conditions.Firstly,a numerical model of unstratified and non-fractured reservoir cores was established to simulate the hydraulic fracturing process of the reservoir.The differences in hydraulic fractures under different displacements and different viscosity were compared and analyzed by comparing the extension pressure and the minimum master.The results showed that as the displacement increases,the crack initiation pressure increases and the fracturing speed becomes faster.When the total amount of fracturing fluid is constant,the larger the displacement,the shorter the total crack length,the shorter the total crack height,and the greater the average crack width.When the fracturing time is fixed,the larger the displacement,the greater the number of cracks,the greater the length of the crack,the greater the total crack height and the greater the average width of the crack.Viscosity has little effect on crack initiation pressure.During the fracturing process,the viscosity has a certain range of influence on the hydraulic fracture,and the viscosity increases appropriately,which can promote the expansion of the hydraulic fracture.However,when the viscosity is too large,the crack propagation is limited.A numerical model of cores containing bedding was established to simulate the hydraulic fracturing process of the reservoir and discuss the effects of displacement and viscosity on hydraulic fracturing.The research shows that in a stratum-bearing reservoir,under small displacement conditions,the cracks pass through the bedding plane and extend perpendicular to the minimum principal stress.When the displacement increases,the bedding plane is gradually opened,and the cracks extend along the bedding plane.The larger the displacement,the faster the bedding plane can be opened.At low viscosity,the cracks pass through the bedding plane.As the viscosity increases,the crack propagation speed decreases,the crack extension pressure increases,the bedding plane is gradually opened,and hydraulic cracks open up the bedding plane of the bedding plane.Finally,a numerical model of cores with natural fractured reservoirs was established to simulate the hydraulic fracturing process of the reservoir and discuss the effects of displacement and viscosity on hydraulic fracturing.The research shows that in natural fractured reservoirs,under the condition of small displacement,the crack propagation is mainly in vertical direction before contact with the natural fissure.After contact with the natural fissures,the crack expands along the natural fissures.The number of natural fissures opened is small.The overall shape of the crack is 70°.As the displacement increases,the number of natural cracks communicated during crack propagation increases.The number of branch cracks increases after cracks extend along natural cracks.The overall shape of the crack is 45°.Appropriately increasing the viscosity can promote the expansion of the cracks,but when the viscosity is too high,the resistance of the fracturing fluid in the cracks is too large,which limits the expansion of the cracks.Ultimately results in the cracks forming complex seam nets only within a limited range around the perforations.