前置缓速酸加砂压裂中酸岩反应模拟研究  

Simulation of Acid-rock Reaction in Hydraulic Fracturing with Pre-pad Retarded Acid

作　　者：刘飞[1] 赵立强[1] 孟向丽[2] 马旭[3,4] 赵振峰 

机构地区：[1]油气藏地质及开发工程国家重点实验室(西南石油大学),四川成都610500 [2]中海油能源发展股份有限公司工程技术分公司,天津300452 [3]中石油长庆油田分公司油气工艺研究院,陕西西安710021 [4]中石油长庆油田分公司低渗透油气田国家工程实验室,陕西西安710021

出　　处：《石油天然气学报》2014年第1期104-108,8,共5页Journal of Oil and Gas Technology

基　　金：国家科技重大专项(2011ZX05044)

摘　　要：水力压裂是低渗、特低渗砂岩油气藏增产改造的主流技术,但常规水力压裂由于压裂液破胶不彻底等伤害储层而不能使增产效果最大化。室内实验及现场施工表明,前置缓速酸能改善压裂效果。前置酸加砂压裂要求施工结束后返排阶段酸液仍具有一定反应活性,能促使压裂液破胶和清洗支撑裂缝。酸液对滤失区孔隙度和渗透率的改善程度、施工结束后滤失区酸液浓度决定了前置酸对压裂效果的改善程度。基于酸液缓速机理和酸岩反应机理,建立裂缝内和滤失区的酸液浓度分布和矿物浓度分布模型,可用于计算滤失区酸液和矿物浓度分布,以及对孔隙度和渗透率的改善程度,评价前置酸对常规水力压裂效果的改善程度。模拟结果表明氟硼酸和氢氟酸的复合缓速酸液体系能有效改善滤失区孔隙度和渗透率,并保证返排阶段酸液仍具有一定反应活性,可有效促使压裂液破胶和清洗支撑裂缝。Hydraulic fracturing was the mainstream stimulation technique for low and ultra-low permeability reservoirs,by which the effect of conventional fracturing could not be maximized because formation damage would be induced by incompletion of viscosity breaking of fracturing fluid.Laboratory tests and field operation show that hydraulic fracturing with pre-pad acid can improve stimulation effect of conventional hydraulic fracturing.It was required that acid should be reactive during flowback to promote the viscosity break and clean the propped fractures for pre-pad hydraulic fracturing.The improvement of matrix porosity and permeability,acid concentration in the filtration zone after completion of acid operation determined the improvement level of pre-pad acid.On basis of the retarding mechanism and acid-rock reaction mechanism,an acidizing model was established to calculate acid concentration and mineral concentrations in hydraulic fracture and filtration zone,porosity and permeability improvement and evaluate the improvement level of operation effect of pre-pad on conventional hydraulic fracturing.The simulation results show that the HBF4/HF retarded acid can improve porosity and permeability effectively in the filtration zone,maintain relatively higher concentration of hydrofluoric acid to ensure gel breaking and cleaning propped fractures during flowback.

关 键 词：缓速酸 前置酸压裂 酸岩反应 三酸三矿物模型 

分 类 号：TE357.2[石油与天然气工程—油气田开发工程]