页岩气储层水力压裂复杂裂缝导流能力实验研究

Experimental Research on Seepage Capacity of Complex Fracture in Shale Gas Reservoir after Hydraulic Fracturing

为研究页岩气储层水力压裂后复杂裂缝导流能力,运用FCES-100裂缝导流仪,选取页岩地面露头岩心,加工成符合实验要求尺寸岩心板,将页岩复杂裂缝简化为转向裂缝和分支裂缝两种形式,用陶粒和覆膜砂两种类型支撑剂进行导流能力实验测试。实验结果表明:裂缝形态对导流能力影响较大,裂缝转向后导流能力明显低于单一裂缝,低闭合压力条件下转向裂缝与单一裂缝导流能力相差35%~40%,随闭合应力增大,差距逐渐增大;低闭合压力下陶粒导流能力高于覆膜砂,而当闭合压力增大后覆膜砂的导流能力反超陶粒,低铺砂浓度下反超趋势更加明显;分支裂缝存在时,等量支撑剂多条分支裂缝的等效导流能力小于单一裂缝,高闭合压力下分支裂缝中不同分支铺砂浓度的差异越大,导流能力与单一裂缝越接近。

In order to study the seepage capacity of complex fracture after fracturing of shale gas well, the outcrop shale being processed into the core plates whose size meets the requirements of the experiments, the complex fractures in the shale being simplified to two types：turning fractures and branching fractures, and ceramsite and coated sand being used as proppant, the seepage capacity of 2 kinds of complex fractures was tested by FCES-100 fracture flow deflector. The experimental results show that ： the fracture morphology has a great influence on its seepage capacity,the seepage capacity of turning fracture is lower 35% -40% than that of single fracture under low closing pressure,and the difference between both increases gradually with the increase of closing pressure;under low closure pres- sure,the seepage capacity of the ceramic proppant fracture is higher than that of the coated proppant fracture, but with the increase of the closure pressure, the seepage capacity of the coated proppant fracture increases gradually and exceeds that of the ceramic proppant fracture, and the exceeding trend becomes more obvious under low sand concentration ; the equivalent seepage capacity of branching frac- ture is lower than that of single fracture under the same amount of proppant,the difference between both dwindles with the increase of the difference in the sand concentration of different branch cracks under high closure pressure.