川西沙溪庙组不规则井眼高压气井固井技术

High Pressure Gas Well Cementing Technology of Irregular Borehole in Shaximiao Formation in Western Sichuan

川西沙溪庙组是目前中石化勘探开发的重点天然气工区,该工区采用水平井完井,水平段长700~1000 m,由于该工区泥页岩发育,采用钾石灰水基钻井液钻井,导致井壁失稳,掉块严重,井径扩大率可达33%以上,而且沙溪庙组气层活跃,分布广,压稳困难等难题,导致固井质量优良率低,固井后井口带压井占比多。通过对气窜原因进行剖析,研发双膨胀高密度水泥浆体系,优选冲洗液和隔离液,优化尾管送入钻具结构,应用提高顶替效率措施、压稳防气窜等工艺技术,经高庙33-9HF井应用,产层优良率达到了92.7%,提高了固井质量较好的解决了井口带压等难题,满足了川西沙溪庙组地层的开发的需要,能为同类型井固井提供一定的借鉴作用。

At present, the exploration and development of the western Sichuan area is the focus of Sinopec for the natural gas at the Shaximiao formation. The horizontal completion is used in this area with 700 - 1000 m horizontal section. The potash lime water-based drilling fluid is used for the development of shale in this area, resulting in wellbore instability, severe fall-block and borehole diameter enlargement ratio more than 33%, and the difficult problem in the Shaximiao formation, such as the activity and widely distribution of the natural gas and pressure stability, causing lower cementing excellent rate and more well with wellhead pressure after cementing. By developing double expansion high density cement slurry system through analyzing the cause of gas channeling, optimizing the flushing fluid, spacer fluid and drilling tool structure for tail pipe transportation, applying more efficiency displacement technology, pressure stability and anti-channeling technology, the excellent and good rate of producing formation reach up to 92.7% when these measures used in 33-9HF well and the cementing quality improves. The practice solves the problem of wellhead pressure after cementing, meets the need of the Shaximiao formation exploration in western Sichuan and can provide certain reference function for the same type of cementing.