Optimization of Fast Drilling Technology for Ultra-Deep Wells in the Shunbei Oilfield

Drilling processes of the Shunbei Oilfield are problematized by complicated conditions and prolonged drilling time due to susceptibility of igneous rocks to lost circulation and collapse,instability of ophiolite intrusive masses and low rates of penetration (ROPs) in Paleozoic Formations.Lab research results showed lost circulation induced by micro-fractures in Permian Formations and difficulties in maintaining stability of sidewalls due to chipping of doleritic rocks were key challenges for optimized and fast drilling operations.Under such circumstances,casing programs and drilling fluid systems with desirable lost-circulation and instability resistance properties were developed for the optimized and fast drilling operations.Borehole stability and fast drilling were key attributes.Field tests were implemented for the innovative technologies in 5 existing wells in the Shunbei Oilfield.Test results showed that lost circulation,sidewall instability and other problems were eliminated effectively for safe drilling of Permian igneous rocks and Sangtamu intrusive masses.The average drilling time for these wells was 173.42 d,which was 14.73% shorter than that required prior to application of the optimized fast drilling technologies.Application of the optimized and fast drilling technologies could effectively accelerate exploration and development of the Shunbei Oilfield.In addition,these technologies might provide reliable technical solutions to achieve million-ton oil productivity of the oilfield.