深层页岩气地质工程一体化体积压裂关键技术及应用

Key Technologies in Geology-Engineering Integration Volumetric Fracturing for Deep Shale Gas Wells

针对深层页岩气埋深大、两向水平应力差大、垂向应力差小、岩石塑性特征强等地质特征,以地质工程一体化为设计理念,建立了包括测井曲线、页岩总有机碳含量、孔隙度、全烃、关键录井元素、矿物组分、过量硅、矿物脆性、岩石力学参数等评价方法,开展沿水平井段的地质工程双甜点研究,实现地质与工程一体化优选甜点段和最优甜点段准确识别,为深层页岩气水平井压裂改造提供依据.然后,基于高导流的立体缝网为体积压裂的目标函数,开展深层页岩气窄压力窗口下的体积压裂注入模式及工艺参数优化研究,包括迂回双暂堵工艺优化,支撑剂在复杂缝网下的动态运移规律与导流能力研究,以及一体化变黏度高降阻滑溜水研发等.研究成果在现场的应用结果表明,上述基于地质工程一体化的体积压裂技术,压后测试产量较邻井能提高30%~50%以上,可大幅度提高深层页岩气的经济开发效果,对今后垂深超过4500 m的超深层页岩气的经济有效勘探与开发,也同样具有重要的指导和借鉴意义.

According to the geological characteristics of deep shale gas,such as large horizontal stress difference,small vertical stress difference and strong rock plastic characteristics,evaluation methods were established for the logging curve,total organic carbon,porosity,all gas hydrocarbon,key logging elements,silicon,mineral brittleness,rock mechanics parameters,etc..And the geology-engineering double sweet spot study along the horizontal wellbore was carried out based on the design concept of geology-engineering integration,so as to accurately identify optimal geological&engineering sweet spot,providing guidance for horizontal well fracturing in deep shale gas play.Then,based on three-dimensional fracture network with high fracture conductivity as the objective function,the volume fracturing pump mode and key parameter optimizations were studied for deep shale gas well under narrow pressure window,i.e.,circuitous temporary plugging fracturing technology optimization,the dynamic movement of proppant in complex fracture network and test of fracture conductivity,and research and development for integrated variable viscosity slick water,etc..Field applications demonstrate that the geology-engineering integration volumetric fracturing technology could improve post-frac gas production by more than 30%-50%compared with adjacent wells.The technology can greatly improve the economic development of deep shale gas wells,and it also has important guiding significance for shale gas wells with vertical depth more than 4500 m as well.