脉冲柱塞加砂压裂新工艺及其在川西地区的先导试验

加砂压裂一直在追求支撑剂的更好铺置,从而形成更长的有效裂缝和更高的导流能力,但是常规工艺总是难以令人满意。在理论分析、PT软件模拟、基础实验及创新性物模实验研究的基础上,通过特殊的泵注程序及纤维、液体等辅助工程手段,研发了一种脉冲柱塞加砂新工艺。该新工艺形成的开放性渗流通道铺砂剖面较之常规工艺在有效缝长和导流能力上具有明显优势,开放性渗流通道有助于改善裂缝清洁度、降低人工裂缝的压降,从而达到延长单井采油气寿命、提高产能效益的目的。在完成原理研究及新工艺优化设计的基础上,进行了现场先导应用与详细的压后评估。结果表明:该工艺可操作性强、实施可行,与地质条件相当的邻井相比,支撑剂成本降低44%~47%、有效缝长与支撑缝长的比值提高约16%,测试18 h返排率高达63%、归一化产量是邻井的1.9~2.3倍,降本增效、提高产量效果明显。该技术在四川盆地川西地区浅中层砂岩气藏及页岩气藏的开发中具有推广价值。

A new technology in impulse-stage sand fracturing and its pilot application in western Sichuan Basin

A better laying of proppants has been always pursued for sand fracturing to form longer effective fractures and higher flow conductivity. However it is always difficult to achieve satisfactory effects by the conventional process. On the basis of theoretical analysis and the simulation by PT software, basic experiments, and innovative physical model experiments, a new impulse-stage fracturing technology was invented through a special pumping process as well as fiber, liquid and other auxiliary engineering means. Compared with conventional fracturing, the open seepage channel created by the new fracturing technology has more advantages with an eye to effective fracture length and flow conductivity. Moreover, the open seepage channel can also improve fracture cleanliness and reduce the pressure loss within artificial fractures in order to prolong the single-well production time and maximize productivity benefits. Upon the completion of the research on principles and the optimal design of this new technology, on-site pilot application and detailed post-fracturing evaluation were conducted. The results indicated that （1） the new technology is highly applicable and feasible, （2） compared with the adjacent wells with similar geological conditions, the proppant cost is reduced by 44% to 47%, the ratio of effective fracture length to propped fracture length is increased by about 16%, the fracturing fluid recovery rate is up to 63% after 18 h in the test, and the normalized yield is improved by 1.9 to 2.3 times, and （3） the new technology significantly lowers the cost and enhances efficiency and yield. The technology has preferable prospect of application in shallow-middle sand gas and shale gas reservoirs in western Sichuan Basin.