焦石坝龙马溪页岩上部气层压裂工艺优化与现场试验

Optimization and Field Trail of the Fracturing Process of Jiaoshiba Upper Shale Gas Layers

涪陵页岩气田焦石坝区块储层纵向上非均质性较强、各小层地质特征差异明显,尤其是(3)小层以上气层(上部气层)脆性指数降低、高导缝发育。在对比上下部气层地质条件的基础上,分析了上部气层压裂改造的技术难点并提出技术对策,通过应力干扰模拟、缝内净压力计算以及室内压裂模拟对施工参数进行优化,形成了一套以"前置胶液增破裂、低黏减阻水促复杂、优化排量规模控缝高"为主体思路的压裂工艺技术,以充分动用上部气层并减小对下部气层的重复改造。上部气层井JYC-1HF使用该工艺技术,压后采用8 mm油嘴放喷排液,产气量最高达到16.34×104m3/d,井口套管压力17.58 MPa,且该井下部气井流压稳定,为后期涪陵页岩气田上部气层的压裂工艺优化提供了技术借鉴。

There are obvious differences between different layers of geological characteristics on the longitudinal in Jiaoshiba block of Fuling shale gas field,especially the upper layers(above the①-③layers),which have low brittleness index and well developed high conductive fractures.On the basis of the comparison of the geological conditions of the upper and lower shale gas layers,the technical difficulties of fracturing in the upper shale gas layers are analyzed and the technical countermeasures are put forward.By carried out stress interference simulation,internal net pressure calculation and indoor fracturing simulation,a fracturing optimization method was proposed,which use pre-gel to increase the rupture,low viscosity slick water to make complex fractures and optimized displacement to control the height of fractures.This method can fully utilize the upper gas layer and reduce the redevelopment of the lower gas layer.With this fracturing technology,the upper shale gas well JYC-1HF used 8 mm nozzle to flare and flow,the maximum gas production reached 163,400 cubic meters and the wellhead casing pressure was 17.58 MPa.Before and after fracturing,the lower gas well’s gas production volume and pressure of JYC-1HF were stable.It provides technical reference for fracturing process optimization of upper gas layer in Fuling shale gas field.