Research on key technologies for speeding up drilling of ultra-deep shale gas horizontal wells in Da’an block， western Chongqing

Abstract:

In response to the technical difficulties in ultra-deep shale gas horizontal well drilling in the Da’an block， such as low mechanical drilling speed in difficult drilling formations， high failure rate of rotary steering instruments at high temperatures， and long drilling cycles. In aim of efficient and rapid development of Da’an shale gas， the characteristics of encountered formations and technical difficulties in drilling were analyzed. Through the technical research and application such as optimization of wellbore configuration， selection of efficient drill bits， rapid identification of “Platinum targets”， density reduction and speed increase in the horizontal section， surface cooling of oil-based drilling fluid， high-temperature resistant white oil-based drilling fluid system， and equal wall thickness screw technology， the optimal and fast drilling technology for ultra-deep shale gas horizontal wells in the Da’an block was formed. This technology was tested on-site in the Da’an 104H ultra deep shale gas horizontal well， where the actual drilling depth was 6789m， with a horizontal section length of 2406.13m and an average mechanical drilling speed of 10.60m/h， which is 30.54% higher than the average value of 8.12m/h in the block. It can provide technical support for the efficient development of shale gas in Da’an.

Key words:ultra-deep shale gas;horizontal well;drilling speed increase;bit optimization;drilling fluid cooling;Da’an block