凝胶复合防漏堵漏技术在火焰山腹地表层的应用

Application of a Composite Gel Lost Circulation Material in the Top Section of Wells Drilled in the Central Region of the Mountain of Fire

吐哈盆地鲁克沁油田火焰山腹地表层钻井过程中,恶性井漏频繁发生,堵漏时间占表层钻井周期的60%以上,严重影响了鲁克沁油田的开发上产效果。针对火焰山腹地表层恶性漏失技术难题,在多次常规堵漏、注水泥堵漏、综合堵漏、膨胀堵漏、雷特堵漏和凝胶堵漏等多种堵漏方式效果不佳的情况下,研发了凝胶复合防漏堵漏技术。该技术的主剂是一种水溶性高分子聚合物堵漏凝胶,其分子链呈空间网状凝胶结构,利用结构性流体较强的剪切稀释性,通过引入不同粒径的刚性堵漏材料和可变形颗粒实现紧密堆积和压实,提高地层承压能力,形成具有防漏和堵漏双重功能的堵漏体系。凝胶复合防漏堵漏技术在火焰山腹地玉北10-20、玉北8-17、玉北8-16等5口井表层进行了现场试验。应用结果表明,比同区块平均漏失量降低74.3%,堵漏损失时间节约93.5%,表层钻井周期节约57.8%。该技术对失返性漏失、溶洞型漏失以及返出量较小的裂缝性漏失具有良好的堵漏效果。

Severe mud losses have frequently taken place in drilling the top formation in the Lukeqin oilfeld located in the central region of the Mountain of Fire, Tuha Basin. Time spent in controlling mud losses accounted for more than 60% of the time drilling the top section, badly affected the development of the Lukeqin oilfeld. Lost circulation control with conventional method, cement slurry squeezing, mixed lost circulation materials （LCMs）, expandable LCMs, Neotoy fber LCMs and gel LCMs, has been proved unsuccessful. For the effective control of mud losses in drilling the top section, a composite gel LCM was developed. The gel LCM is a water soluble high molecular weight polymer whose molecular chains exhibit spatial network gel structure. Based on the shear thinning property of structured fuids, some rigid LCMs of different particle sizes and deformable particles are introduced into the gel LCM to obtain close packing and consolidation of the LCM particles, thereby enhancing the pressure bearing capacity of the formation. The gel LCM has the ability to both prevent and control mud losses. The gel LCM has been tried on the well Yubei10-20, the well Yubei8-17 and the well Yubei8-16 located in the central region of the Mountain of Fire. Compared with other wells drilled in that area, the volume of mud lost was reduced by 74.3%, time spent controlling lost circulation was saved by 93.5%, and time spent drilling the top section was saved by 57.8%. The gel LCM has been proved to be an effective LCM in controlling lost return, mud losses into caves, and mud losses into fractures with only small volume of mud return.