气体介质条件下的固井技术

近年来，四川油气田大力推广应用了气体钻井技术，对于大幅度提高机械钻速和避免井漏等钻井复杂情况起到了十分重要的作用。为了避免气体钻井结束后替入钻井液可能引发的井漏、井眼不稳定等复杂情况，缩短钻井周期、降低钻井成本，进一步提高固井质量，在川渝地区探索实践了气体介质条件下339.7 mm表层套管和244.5 mm技术套管共18井次的干井筒固井作业，基本形成了一套气体钻井后干井筒（井眼内为纯气体时的井筒简称为干井筒）固井工艺技术方案与措施。在干井筒固井施工过程中，主要作业环节的工艺技术包括：气体介质条件下井眼准备及下套管技术、非连续液相注水泥技术等，并介绍了防井漏、防井壁失稳、防环空堵塞等技术。实践表明：干井筒固井施工的固井质量明显高于常规固井的质量；注水泥浆施工工程风险小；可消除气体钻井结束后替入钻井液再固井作业可能带来的井下复杂情况。

A new technology: Cementing in gas medium

Gas drilling technology is widely used in Sichuan oil and fields in recent years. It has played an important role in large ROP improvement, prevention of lost circulations and other drilling problems. To avoid lost circulation or wellbore instability when drilling fluid circulated downhole after gas drilling, or to shorten drilling cycle and reduce drilling costs, it is recognized that the cementing quality needs to be improved further. 18 dry hole (well with pure gas inside) cementing jobs have been tried in 339.7 mm and 244.5 mm holes in Sichuan and Chongqing oil or gas fields and a set of technology for dry hole cementing after gas drilling is developed, including wellbore preparation, casing running, incontinuous liquid slurry injection, etc. And lost circulation prevention, wellbore instability prevention, and annulus plugging prevention are introduced. The application results prove the cementing quality is obviously improved by this new technology. And the cementing risks are low, the downhole accidents possibly caused by drilling fluid circulation after gas drilling can be eliminated.