摘要
须家河组是四川盆地致密砂岩气勘探开发的重要领域,储层岩石力学、断裂力学特性以及裂缝扩展特征尚缺乏研究。本文采用热-固耦合三轴压缩实验和断裂韧性评价实验,获取致密砂岩的岩石力学性质参数和断裂韧性,分别计算储层岩石的弹性力学脆性指数和利用断裂韧性计算的脆性指数,对储层脆性进行评价;采用真三轴高温高压物理模拟实验系统,在60℃条件下,开展不同水平应力差、压裂液黏度、注入排量的裂缝扩展物理模拟实验,分析裂缝扩展规律。结果表明,须家河组致密砂岩储层岩石的弹性力学脆性指数为34.1~62.9,平均值42.99,断裂韧性计算脆性指数为7.68~9.39 m^(-1/2),平均值为8.54 m^(-1/2),为脆性储层;压裂液黏度越大,裂缝偏转角越大,岩样内裂缝贯穿深度越大;在压裂施工过程中,可根据条件适当提高泵注排量和压裂液黏度,来提高储层体积压裂形成复杂缝网的可能性;多簇压裂裂缝存在竞争扩展现象,射孔簇间距越小,缝间干扰越严重;增大泵注排量并结合暂堵技术,可促进多裂缝均衡扩展。研究成果可为须家河组致密砂岩压裂改造提供一定的理论支撑。
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 propagation 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 fracture 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 brittleness 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 average 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.
作者
刘登元
LIU Dengyuan(Oil Production Engineering Research Institute of Daqing Oilfield Co.,Ltd.,PetroChina,Daqing 163453,Heilongjiang,China;Heilongjiang Provincial Key Laboratory of Oil and Gas Reservoir Stimulation,Daqing 163453,Heilongjiang,China)
出处
《石油地质与工程》
CAS
2024年第1期20-27,共8页
Petroleum Geology and Engineering
关键词
须家河组
岩石力学特性
脆性评价
裂缝扩展特征
水力压裂物理模拟
Xujiahe Formation
rock mechanical properties
brittleness evaluation
fracture propagation characteristics
hydraulic fracturing physical simulation
