Optimization of spacing between temporary plugging fracturing clusters in tight conglomerate reservoirs

<br>Tight conglomerate reservoirs need hydraulic fracturing to improve the efficiency of fracture network reconstruction. In this paper, the finite element (FEM) and discrete element (DEM) coupling method is used to simulate the solid calculation problem of hydraulic fracturing, and the flow field in the fracture is solved by the central finite volume method (FVM). The stress interference and cluster spacing optimization of the temporary plugging in the fracture are studied by using this FE-DE-FV coupling method. The results show that the stress interference generated by simultaneous fracturing of multiple fractures is beneficial to the formation of complex fractures, and reasonable cluster spacing can enable the intersection of stress reversal zones. Under the temporary plugging condition, it is difficult to form complex fracture network because the cluster spacing is too small, the fracture extension length is short, the cluster spacing is too large, and the stress interference between the fractures is small. The optimization of cluster spacing is also closely related to the in-situ stress difference. The larger the stress difference is, the smaller the cluster spacing should be used to enhance the stress interference.<br>

致密砾岩储层需借助水力压裂以提升裂缝网络重构效率。本文采用有限元法（FEM）与离散元法（DEM）耦合方法，模拟水力压裂的固体计算问题，并通过中心有限体积法（FVM）求解裂缝内流场。依托该FE-DE-FV耦合方法，本文研究了裂缝内暂堵体的应力干扰效应与簇间距优化问题。研究结果表明：多裂缝同步压裂产生的应力干扰有利于复杂裂缝的形成，合理的簇间距可实现应力反转区的交汇。在暂堵工况下，若簇间距过小则难以形成复杂裂缝网络，且裂缝延伸长度偏短；若簇间距过大，则裂缝间应力干扰程度偏弱。此外，簇间距优化还与地应力差密切相关：地应力差越大，需采用更小的簇间距以强化应力干扰效应。