Field tests of high-density oil-based drilling fluid application in horizontal segment

The operation experience of horizontal segment well in the southern Sichuan area within hard brittle shale layer Longmaxi formation demonstrates that high-density oil-based drilling fluid (HDOF) induced down-hole working condition, which is typically high-temperature, high-pressure and solid-phase-dominant, will directly impact stability wellbore wall. Focusing on bottom-hole osmotic pressure solid phase content a series density-reduction field tests, we found some helpful countermeasures. In this paper, study discuss high measures, provide details tests indicate maintaining higher at can reduce pore bottom hole, widen density window, maintain By improving HDOF formula, such as using new treatment agents (e.g. polymer modified nano-sealing agent, ultra-micro barite weight additive) optimizing particle size distribution HDOF, effectively address problems. test "pressure-controlled + reduction" operations therefore proved to be capable reducing complexity faults, rate penetration, saving overall cost.