Key technologies for optimized fast drilling of deep exploration wells in Qinghai Oilfield

As the oil reservoir exploration field and depth of Qinghai Oilfield in the Qaidam Basin increases continuously, its main exploration fields are characterized by large formation dip angle, developed high-pressure saline aquifer, complex and diverse pressure system, poor stratigraphic correlation, high geothermal gradient and poor drillability of basement target layer. To solve the technical bottleneck problems restricting rate of penetration (ROP) improvement and leading to complex accidents, a series of studies were carried out from the aspects of unconventional casing program optimization technology, deviation control and fast drilling technology, high-pressure saline control technology, high-quality drilling fluid technology, safe drilling technology for formations with high CO2 content, ROP tool optimization and integration technology and ROP technology for deep basement formations, so as to form the key technologies for the optimized fast drilling of deep exploration wells in Qinghai Oilfield. In 2020, four deep exploration wells were drilled successfully with average well depth of 6 017 m, complex accident rate of 3.41% and average bottom hole displacement of 110.88 m, indicating good application effects. The research results provide valuable experience for the construction of subsequent deep exploration wells in Qinghai Oilfield.