长庆油田压裂返排液对储层支撑裂缝损害室内研究

Laboratory Study on the Damage of Reservoir Propped Fractures Caused by Fracturing Flowback Fluid in Changqing Oilfield

为降低压裂返排液对储层支撑裂缝的损害,对长庆油田目前使用的压裂液类型如胍胶体系、生物胶体系、滑溜水体系及滑溜水-胍胶体系开展了压裂返排液对储层支撑裂缝损害的研究。首先在室内测定了4种压裂返排液体系的pH值、密度、固相含量、颗粒粒径;然后对4种压裂返排液进行了预处理,评价了压裂返排液对岩心基质渗透率损害程度;最后探讨了4种压裂返排液中悬浮物粒径、悬浮物浓度与支撑裂缝损害之间的关系。评价结果表明,胍胶和生物胶对支撑裂缝的损害程度较小,滑溜水和滑溜水-胍胶混合液对支撑裂缝的损害程度较大;随着悬浮物颗粒粒径以及质量浓度的减小,压裂返排液对支撑裂缝损害也随之减弱;压裂返排液对地层岩心基质损害率较小,可以实现压裂返排液体系的再利用,具有一定的应用前景。

In order to reduce the damage of fracturing fluid to the reservoir propped fractures,for the type of fracturing fluids in Changqing Oilfield was studied,the damage of the guanidine gum system,biological glue system,slippery water system and guanidine gum mixed with slippery water system of flowback fluid on the reservoir propped fractures was studied.First in laboratory,the pH,density,solid content,particle size of four kinds of fracturing fluid systems were determined.Then the four fracturing fluids were pretreated,the damage level core matrix permeability induced by the fracturing flowback fluid was evaluated.The relationship between the particle size of suspended solid,its concentration and the damage of the propped fracture of the four fracturing fluids was discussed.The evaluation results show that the damage of reservoir propped fractures by the guanidine gum system and biological glue system was smaller,and the damage of reservoir propped fractures by slippery water system and guanidine gum mixed with slippery water system was larger.With the decrease of the particle size and concentration of suspended material,the damage of fracturing fluid flowback to support the fractures is weakened.The damage rate of the fracturing fluid to the formation of the core matrix is less,and it can realize the reuse of fracturing flowback fluid system,and it has a certain application prospect.