薄差层油藏控缝高技术研究及压裂参数优选

Research on fracture height control technology and optimization of fracturing parameters in poor thin layer reservoir

针对薄差层油藏具有层多层薄、非均质性严重等特点,在其压裂过程中经常出现缝高难以控制、铺砂困难、施工压力高的情况,提出了改进的人工隔层控缝高技术。通过增加对主裂缝处理前的小裂缝处理,打开油气通道,采用多次加砂与多级注入相结合的方式,将上浮剂与下沉剂两种转向剂依次泵入裂缝,形成一道人工应力屏障,有效控制裂缝在垂向上的延伸。采用硼酸交联的聚乙烯醇溶液作为压裂液,进一步提高支撑剂的泵入效率。对压裂参数进行优化,并结合累产比随缝数、缝长及导流能力的变化,优选出最佳的参数组合。

Poor thin layer reservoir has the characteristics of thin multiple layers and significant heterogeneity.During the fracturing process,it is often difficult to control fracture height,sand laying and high construction pressure.In this paper,an improved technique of controlling fracture height by artificial barrier was proposed.The oil and gas passage was opened by increasing the treatment of small cracks before the treatment of main cracks.By means of multiple sand adding and multi-stage injection,two kinds of steering agents(floating agent and sinking agent)were pumped into the cracks in turn to form an artificial stress barrier,which is for the effective control of vertical extension of cracks.Boric acid crosslinked polyvinyl alcohol solution was used as fracturing fluid to further improve the pumping efficiency of proppant.Fracturing parameters were optimized,and the best combination of parameters was selected according to the change of cumulative production ratio with fracture number,fracture length and conductivity.