安棚裂缝性储层压裂技术研究与应用

安棚裂缝性储层压裂施工早期砂堵的主要原因是压裂形成的人工裂缝易沿天然裂缝延伸形成张开程度不一的多支缝，从而难以形成具有一定缝宽的主裂缝。针对储层特征对压裂液性能的要求，用大量的室内实验确定了压裂液基本配方，根据压裂温度场模型模拟了计算压裂过程中的温度变化；应用升破胶剂浓度和降交联剂浓度的变浓度压裂液优化设计技术，保证压裂施工需要的压裂液粘度和压裂结束后压裂液的迅速破胶和快速返排性能。文章提出了前置液中加入变砂比的段塞式“砂团”充填技术，依次堵住不同缝宽的多支裂缝，以保证形成具有一定缝宽的主裂缝。同时配套多段加砂压裂技术和裂缝强制闭合技术，现场应用效果显著，成功地解决了压裂过程中低砂比砂堵的难题，保证了低渗透裂缝性油藏的压裂开发。

Study and Application of Fracturing Techniques for Anpeng Fractured Reservoir

The main reasons why sand plug is formed at the early stage of fracturing in Anpeng fractured reservoir are the artificial fractures produced by fracturing easily form many branches with different open degree along the natural fractures, so that it is difficult to form main fractures with enough width. Aiming at the requirements of the reservoir features to the fracturing fluid, with lots of in-house experiments, the basic formula of fracturing fluids is determined. According to the temperature field model of fracturing, the temperature variation in the fracturing process is simulated. With the optimized design technology of variable concentration fracturing fluids by increasing the concentration of gel breaker and decreasing the concentration of cross linking agent, it is guaranteed the viscosity of fracturing fluids required in the fracturing process and the performance of rapid gel breaking and flow-back of fracturing fluids after fracturing. The article first proposes the slug sand-group pack technique by the ahead fluid with variable sand proportion to plug the branch fractures with different width and form the main fractures with enough width. Combining with the multistage pack fracturing technique and the fracture forcing closure technique, good results have been achieved in field application. The problem of low sand proportion and sand plug in fracturing process is solved successfully so that fracturing stimulation can be surely used for low permeable fractured reservoirs.