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.