Drilling technology for Well Fenghuang-X1

Well Fenghuang-X1 is a risk exploratory well in Fuyang exploratory area. In the drilling process, some problems were met, such as stratum uncertainty, poor drillability and grindability of Middle Paleozoic strata, uncontrollable trajectory of big size wellbore with diameter of 311.1 mm, coal mudstone collapse, mass leaking layers, etc. Based on the analyses on the strata characteristics and drillability, the efficient PDC bit and roller bit were selected. For the reasons of uncertainty of deflecting capacity and uncontrollable well track using normal BHA in big size wellbore and hard strata, the new single bending bistable BHA which increased the distance between two centralizers was taken into usage. The methods of plugging while drilling, pressure sealing and novel explosive plugging were taken as plugging methods. The treatments above were taken to raise mud density, and to enhance mud inhibition capacity and anti-collapsing and sealing capacity. The application of the drilling technique on Well Fenghuang-X1 was successful, and offered some experience for drilling similar type of wells.