低渗复杂断块整体压裂裂缝参数优化设计

低渗复杂断块油藏在进行整体压裂改造时，由于其地应力场分布复杂且井网形式不规则，常规整体压裂产量预测方法不再适用。为此，将油藏数值模拟中的新型网格结构——PEBI网格应用到整体压裂优化设计中，实现了不规则井网条件下任意方位裂缝的模拟，并证实了PEBI网格模拟水力裂缝相对于传统直角网格的优越性。根据濮城油田卫42断块压裂注采井网的实际特点，抽象出适用于复杂断块油藏的3种典型的注采井位关系，并在此基础上进行了裂缝与井网匹配关系和裂缝参数的优化研究。指出：在复杂断块油藏的整体压裂中，注采井位相对角度存在最优值，应根据具体地应力方向进行优化；远离断层区域地应力方向一致，应造长缝，断层附近区域地应力方向容易发生偏转，应重点优化缝长；就特低渗透复杂断块油田而言，注采相对井位、压裂规模对于开发效果的影响要远远大干裂缝导流能力的影响。图10表2参11

Optimization design of integral fracturing parameters for low-permeability highly faulted reservoirs

For the integral fracturing treatment of low-permeability highly faulted reservoirs, due to the complicated field stress distribution and irregular well patterns, it is difficult for hydraulic fractures and well arrays to be parallel or to be 45 degree. The conventional post-fracturing performance forecast method cannot be used. PEBI grid, a new type of grid in reservoir simulation technology, was applied into the optimization design of integral fracturing, so the simulations of irregular well patterns and arbitrary fracture orientations could be made. The advantages of PEBI grid over the conventional Cartesian grid were proved. Aiming at the characteristics of fractured flooding pattern of Wei 42 fault block in Pucheng Oilfield, three types of injection-production well position were summarized, which are suitable for other highly faulted reservoirs. The match of hydraulic fractures and well patterns were optimized. The angles among injectors and producers have the optimum value, which should be optimized by practical field stress; long fractures should be made in the area far away from the faults, but fracture length should be optimized well in the area near faults because the stress orientation tended to change; the relative injectors and producers position and fracture length have much bigger effects on development than fracture conductivity for ultra-low permeability reservoirs.