致密碳酸盐岩水平井分段酸压工艺技术

HORIZONTAL-WELL STAGED ACID FRACTURING TECHNOLOGY FOR TIGHT CARBONATE ROCK

针对大牛地气田下古生界低渗致密碳酸盐岩气藏储层非均质性强、微裂缝发育、酸液滤失严重和直井酸压改造难以有效建产等问题,采用水平井裸眼完井、管外封隔分段压裂工具实施分段,并对孔隙型和裂缝-孔隙型储层分别优选低滤失的胶凝酸和黏弹性清洁转向酸或交联酸酸液体系进行分段酸压改造,从而降低了酸压施工风险,取得了显著的酸压增产效果,实现了该气田致密低渗碳酸盐岩气藏的经济有效开发,也为其它致密碳酸盐岩储层水平井的勘探开发提供了借鉴,值得推广应用。但鉴于水平井裸眼井段长、裂缝发育、酸液滤失量大、酸蚀裂缝短等问题,建议结合碳酸盐岩储层特征尝试采用套管固井来实施水平井的多级分段酸压改造。

With developed microfractures,the lower Paleozoic tight carbonate- rock gas reservoir,Daniudi gasfield,is featured by strong heterogeneity,resulting in not only serious filtration of acidizing fluid but also difficultly and effectively production- constructed by vertical-well acid fracturing.So,some measures were made,such as(1) horizontal-well openhole completion,and(2)fulfilling staged fracturing by external casing packer and staged fracturing facilities,optimizing low-filtration gelling acid,elastic and clean steering acid or crosslinking acid system for porous and porous- fractured reservoirs to carry out staged acid fracturing.These measures can reduce the risk during acid fracturing and an obvious stimulation effect may be obtained.However,due to some existing problems,including long openhole interval of horizontal well,developed fracture,large filtration amount of acidizing fluid,and short etched fracture,a suggestion that casing cementing may be used to implement a multiple and staged acid fracturing,is provided for carbonate rock reservoir.