Application of Reaming and Expandable Pipe in the Ultra-Deep Well LH1

In the fourth spud of ultra-deep risk exploration well LH1 in Huabai Oilfield, complex conditions of lost circulation in upper formation, high pressure water and wellbore collapse in lower formation are drilled. To address the drilling complex and enhance well control, After failure of sealing the complex interval with traditional lost circulation materials like bridging agent and cement, reaming and expandable tube were decided to use to seal the complex interval without running additional casing and reduce the wellbore size. Through the analysis of the difficulties during operation, the corresponding countermeasures were established. Through reaming, wellbore tripping, calliper logging, casing scraping, expandable pipe running simulation tripping and rubber plug passing test, wellbore were well prepared to ensure the running, cementing and expanding of expandable pipe. The 838.15 m Φ219 mm expandable pipe was successfully run to 6080 m and expanded, which set a new record for the depth and length of expandable pipe in China. Subsequent cementing logs showed a overall medium cementing quality, and the complex well interval were able to withstand 2.27 g/cm3 drilling fluid without well loss compared to previous well loss ECD of 1.85 g/cm3. The successful application of reaming and expandable pipe technology in ultra-deep well LH1 showed that the combined technology can provide an effective and reliable new solution to solve the engineering problems such as excessive losses and casing program expansion in ultra-deep well.