非常规油气藏体积改造技术——内涵、优化设计与实现

系统阐述了体积改造技术的基本内涵、优化设计及实现方法。其内涵包括5个方面:①可"打碎"储集层,形成复杂缝网,"创造"人造渗透率;②裂缝起裂不是单一张开型破坏,而是剪切破坏及错断和滑移等;③"突破"传统压裂裂缝渗流理论模式,大幅度缩短流体有效渗流距离;④适用于较高脆性岩层的改造;⑤采用"分段多簇射孔"。分析表明:流体穿过100 m渗透率为0.000 001×10 3μm2的基质向裂缝渗流需要的时间超过100×104a,只有体积改造形成裂缝网络才能使流体从基质向裂缝实现"最短距离"渗流。簇间距优化、非均匀布段(簇)、优化支撑剂铺置模式等是实现体积改造的关键理念;加密分簇技术、多次停泵注入模式及多次端部脱砂压裂技术是低脆性指数地层实现体积改造的技术关键。体积改造技术在致密砂岩(油、气)、火山岩、碳酸盐岩的改造中有良好的应用前景,利用多层多分支井技术对储集层实施"立体式"体积改造是高效开发非常规油气藏的未来发展方向。

Volume fracturing technology of unconventional reservoirs:Connotation, optimization design and implementation

The connotation,optimization design and implementation of the volume Fracturing technique are discussed.The connotation includes five aspects as follows:(1) break up reservoirs to form complex fracture network,and "create" the artificial permeability;(2) fracture initiation is not single open-fracture but shear failure and slip;(3) "breakthrough" the traditional fracturing seepage theory model,greatly shorten the effective fluid seepage distance;(4) more suitable for high brittleness formations;(5) multi-stage and multi-cluster perforation mode.Research shows that: the time required to seep through matrix(0.000 001 × 10 3μm2) to fracture for 100 m distance is about more than 100 × 104years,and only volume fracturing can realize "the most short-distance" seepage.Cluster spacing optimization,non-uniform stage(cluster) interval and proppant transportation are the key to achieve volume fracturing.Small cluster interval technology,multiple stop-injection mode and tip screen-out fracturing technology are the key techniques to realize volume fracturing in low brittleness formations.Volume fracturing technique has a good application prospect in tight oil(gas),volcanic and carbonate,and the further developed "integrated" volume fracturing(based on multi-layer and multi-branch well technology) is the future development direction of unconventional reservoir development.