多尺度体积压裂支撑剂导流能力实验研究及应用

裂缝有效导流能力是评价压裂施工效果的主要参数，也是影响压裂增产效果的最重要因素之一。设计了多尺度裂缝导流能力实验方法，采用单一粒径和组合粒径的铺置方式，研究了闭合压力、粒径组合方式、铺砂浓度及应力循化加载条等因素对多尺度主裂缝及分支缝内支撑剂的导流能力变化的影响。实验研究结果表明:随着闭合压力增加，大粒径支撑剂与小粒径支撑剂的导流能力差距逐渐变小，主裂缝及分支缝内支撑剂导流能力逐渐降低，而且这种降低趋势存在明显的转折点。组合粒径铺置条件下，主裂缝及分支缝内支撑剂组合均存在最优的组合方式。主裂缝及分支缝内支撑剂铺置砂浓度越高，导流能力也越高；随着闭合压力增大，高浓度铺砂与低浓度铺砂条件下的导流能力差距逐渐变小。应力加载破坏对支撑剂导流能力的影响是不可逆的。现场应用表明，在满足压裂工艺要求前提下，通过支撑剂组合方式及加砂方式的合理优化，可有效提高裂缝导流能力及压后产量。研究结果为体积压裂方案优化及现场施工提供基础数据依据。 

Experimental study and application for the conductivity of proppant in multi-scale volume fracturing

The effective conductivity of fracture is the main parameter for evaluating the effect of fracturing construction, and it is also one of the most important factors affecting the effect of fracturing. We designed a multi-scale fracture conductivity experimental method, and used a method of single particle size and combined particle size placement to studied the effects of factors such as closure pressure, particle size combination, sanding concentration and stress cycling on the proppant conductivity in main fracture and branching fracture.The experimental results show that:As the closing pressure increases, the difference in the conductivity of the large-size proppant and the small-sized proppant gradually decreases, and the conductivity of the proppant in the main fracture and the branch fracture gradually decreases, and this reduction trend has an obvious turning point.Under the combined particle size placement conditions, there is an optimal proppant combination both in the main fracture and the branch fracture.The higher the sediment concentration of the proppant in the main fracture and the branch fracture, the higher the conductivity will be;As the closing pressure increases, the difference of the conductivity between the high-concentration sanding and the low-concentration sanding becomes smaller.The effect of stress cycling on the proppant conductivity is irreversible.The field application shows that under the premise of meeting the fracturing process requirements, it can effectively improve the fracture conductivity and the post-pressing output by usingthe proppant combination method and the reasonable optimization of the sand adding method.This research provide the basis for the optimization of volume fracturing scheme and on-site construction.