Rock mechanical properties and fracture propagation characteristics of tight sandstone in Xujiahe Formation of X block
Xujiahe Formation is an important area for the exploration and development of tight sandstone gas in the Sichuan Basin,while the characteristics of rock mechanics,fracture mechanics and fracture propaga-tion are still not fully studied.This article uses thermal solid coupling triaxial compression and fracture toughness evaluation experiments to obtain the rock mechanical properties parameters and fracture toughness of dense sandstone.The elastic mechanical brittleness index and the brittleness index calculated using frac-ture toughness are calculated separately to evaluate the reservoir brittleness.By using the true triaxial high temperature and high pressure physical simulation test system,under the condition of 60℃,the physical simulation test of crack propagation with different horizontal stress difference,fracturing fluid viscosity and injection rate is carried out,and the law of fracture propagation is analyzed.The results show that the brit-tleness index of elastic mechanics of tight sandstone in Xujiahe Formation ranges from 34.1-62.9,with an average of 42.99;the brittleness index of fracture toughness ranges from 7.68-9.39 m-1/2,with an aver-age of 8.54 m-1/2.The greater the viscosity of the fracturing fluid,the greater the fracture deflection angle,and the greater the penetration depth of the cracks in the rock sample.In the process of hydraulic fracturing treatment,the pump injection rate and fracturing fluid viscosity can be appropriately increased according to the conditions,and the possibility of complex fracture network formed by reservoir volume fracturing can be improved.The smaller the perforation cluster spacing,the more serious the interference between fractures.Increasing pump displacement combined with temporary plugging technology can promote the even expansion of multiple fractures.The research results can provide theoretical support for the hydraulic fracturing of tight sandstone in Xujiahe Formation.
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维普
