Fast drilling technology for ultra-deep horizontal Well 101-1H in Yuanba acidic gas reservoir

In line with the problems of low drilling rate in continental high pressure formations, severe fluid loss in marine pay zone and difficulty in geosteering in ultra-deep HTHP wells during drilling of ultra-deep horizontal wells into Yuanba sulfur-containing gas pools, the Yuanba 101-1H Well realized effective increase in drilling rate in hard land formation of tight sandstone, through extending the depth of gas drilling, using torque impactor and composite drilling technology of straight screw combined with PDC drilling bit; the use of equal-wall thickness straight screw together with EM1316 PDC drilling bit effectively increased the drilling rate in straight hole section in marine homogeneous formation of high strength and low abrasiveness. The use of adjustable high temperature screw in horizontal section, in conjunction with under-gauge double-stabilizer angle holding assembly, not only improved composite drilling rate, but aslo ensured the overall dogleg severity of the wellbore, equal to the rotary steering drilling tool in effectiveness. The double-effect wear-proof technique reduced the wear on casing and ensured the sealing performance of the string. The result of field application shows that the total depth of Yuanba 101-1H Well is 7 971 m and its vertical depth is 6 946.44 m, which is a new record in drilling and completion depth in ultra-deep horizontal wells with high sulfur content in Yuanba work area; the drilling cycle was 380 d, 54 d shorter than the designed cycle and 149.92 d shorter than the average drilling period of the previous development and appraisal horizontal wells; the increase in drilling rate was remarkable, providing favorable experiences for drilling of similar wells.