滑溜水在裂缝性碳酸盐岩体积酸压中的研究与应用

Study of Slick Water and Its Application in Spatial Fracturing Fractured Carbonate Formations

滑溜水是页岩气、致密油非常规油气藏体积改造中应用最广泛的压裂液体系,旨在利用低黏滑溜水强的穿透性能激活天然裂缝提高裂缝复杂程度。基于深层裂缝性碳酸盐岩储层基质物性差、非均质性强,裂缝是主要储集空间和渗流通道的储层特征,提高改造体积是实现高产稳产的核心,需采用低黏流体大排量注入来提高天然裂缝激活几率,提出滑溜水、冻胶和转向酸复合的体积酸压技术。评价了新型聚合物类滑溜水性能,利用室内实验(大物模、酸液滤失)和数值模拟相结合的方法研究了滑溜水在体积酸压中的作用机理,研究表明:新型聚合物类滑溜水具有较好的减阻性能,能够降低施工管柱摩阻,实现大排量施工,助力改造效果提升;滑溜水大排量注入形成复杂裂缝,低黏酸液注入形成酸蚀蚓孔提高裂缝连通性,滑溜水与低黏酸交替注入,实现微细裂缝“水力+酸蚀”缝网构建。上述研究成果现场应用显著,AT3x井压后获日产油35m^3、日产气50.3×10^4m^3高产油气流,为国内超高温深层复杂储层高效改造提供新的技术指导。

Slickwater is a fracturing fluid widely used in fracturing unconventional petroleum reservoirs such as shale gas reservoirs and tight oil reservoirs.Slick water has low viscosity and high penetration performance which are helpful in enhancing the complexity of natural fractures.Generally speaking,deep fractured carbonate reservoirs have matrix rocks of poor physical properties and strong inhomogeneity,and fractures are the main spaces and channels for the petroleum to stay and flow through.Therefore,increasing the volume of rocks being fractured is the key to produce more petroleum,and this goal can be achieved by performing spatial fracturing with fracturing fluid composed of low viscosity slick water,gel and converting acid.Low viscosity and high injection flow rate help activate more natural fractures in rocks.In this paper the evaluation of a new slick water containing polymers is discussed.Laboratory study and numerical simulation were combined to ascertain the working mechanisms of slick water in spatial fracturing.It was found that: 1) the new polymer slick water has good drag reducing property,and is able to reduce the fraction and drag acting on the pipe string,thereby realizing high flow arte injection and improving stimulation efficiency.2)Complex fractures are generated with injection of slick water at high flow rates,and the connectivity of the fractures is enhanced by forming acid-etched wormholes by the injection of low-viscosity acids.Alternated injection of slick water (hydraulic fracturing) and low-viscosity acid (acid etching) gives birth to networked fine fractures.By applying these studying results in field operations,the well AT3x has acquired daily oil production rate of 35 m^3 and daily gas production rate of 50.3×10^4 m^3,providing a new technical reference for stimulating complex deep high temperature reservoirs in China.