Drilling technology of ultra-deep horizontal well Yuanba 103H

Yuanba gas field is rich in natural gas while the main formation is buried deeper than 7000m. In order to enlarge the reserve control area and improve production rate of single well, Well YB103H was drilled in Yuanba area of northeast Sichuan. By applying underbalanced drilling technology in Shaximiao to Xujiahe zones, rotary steerable drilling, temperature resistant drilling fluid system, double friction reduction technology, etc., the major technical challenges were overcomed, such as hard formations, low rate of penetration, high temperature, difficult hole cleaning in horizontal section, high tripping friction, and adding weight on bit. The total depth is 7 729.8 m in Permian Period Changxing Section, with lateral section length of 682.8 m, and vertical depth of 6 761.52 m, which makes it the deepest well in China. The success of Well Yuanba103H accumulates valuable experiences for ultra-deep horizontal drilling.The key drilling technologies are illustrated in detail.which provides important references to wells of the same type.