Key Technologies for Safe and Efficient Drilling of Marine Carbonate Ultra-Deep Oil and Gas Wells

The marine carbonate oil and gas resources in the Tarim Basin and the Sichuan basin have a burial depth of more than 7 000.00 m, with multiple producing formations which exhibit strong heterogeneity, high temperature and high pressure, difficulty in drilling and high risks, all of which result in engineering problems, such as low ROP in drilling/completion, high risk of wellbore integrity failure, etc. To this end, a series of tools and products have been developed, including new drilling speed-up tools, high temperature resistant measuring instruments and cementing tools. Additionally, the following were developet: a high-density drilling fluid system with high temperature resistance; an environmentally-friendly low-friction, high performance plugging system; and an anti-gas channeling cement slurry system. Meanwhile, the rapid drilling technology for penetrating hard formations in a synergistic way. The goal of " precaution-monitoring-control-pressure” closed-loop safety control drilling matching technology for fractured-cave high pressure oil/gas wells was achieved, and key borehole trajectory measurement and control technology for ultra-deep slim hole horizontal wells wee developed. The application of those technologies in drilling many ultra-deep wells with the depth of over 8 000.00 m has set several engineering records, and strongly supported the exploration & development of ultra-deep marine oil/gas wells in Shunbei, Xinjiang and Western Sichuan.