致密砂岩气藏压裂液体系对储层基质伤害性能评价

Evaluation on the Damage of Fracture Fluid System to the Matrix in Tight Sandstone Gas Reservoir

致密砂岩气藏由于其低孔低渗的储层特性,必须通过压裂增产措施才能实现其经济产能。以延安气田山西组致密砂岩气藏为研究对象,探讨了致密砂岩气藏压裂液评价方法,并进行了压裂液滤液对储层岩石基质渗透率伤害率和压裂液伤害后核磁共振测试试验;研究中基于压裂液与地层流体及工作液的配伍性研究,对压裂液的乳化率和残渣进行了测定,筛选出了3种适用于延安气田致密气高效开发的压裂液体系。基于岩心伤害测试评价和核磁共振测试评价表明,羟丙基胍胶(一级)弱碱性压裂液体系、羟甲基羟丙基胍胶酸性压裂液体系、黏弹性表面活性剂VES体系虽均能满足延安气田压裂液作业要求,但是对比其他2种压裂液体系,羟丙基胍胶(一级)弱碱性压裂液体系具有低伤害、低残渣和高返排的优势,建议采用羟丙基胍胶(一级)弱碱性压裂液体系作为延长致密砂岩气藏储层改造的工作液体系,为该油田储层保护和有效开发提供支持。

Fracturing stimulation technology was an important treatment for an economic producibility in the development of tight gas reservoir because of its low porosity and low permeability.By taking the tight gas reservoir in Shanxi Formation of Yan'an Gas Field as object of study,the methods for fracturing fluid evaluation in tight sandstone gas reservoirs were discussed,NMR experiments were performed on the damage of fracturing fluid on rock matrix permeability and the damage of fracturing fluids.Based on the study of the compatibility between the fracturing fluid,formation fluid and working fluid,the emulsifying rate and residues in the fracturing fluid were detected,3kinds of high efficient fracturing fluid systems suitable for the tight gas development in Yan'an Gas Field were chosen.The core damage evaluation and NMR test show that compared with acid fracturing fluid system and VES,the hydroxypropyl guar gum weak alkaline fracturing fluid system with the advantage of low damage,low residue and high flowback is more suitable for the development of tight gas reservoir in Yan'an Gas Field.The hydroxypropyl guar gum weak alkaline fracturing fluid system is the best choice for the development of the tight gas reservoir,it provides reference for the reservoir protection and development.