ROP enhancing technologies applied in conventional exploration wells in western South China Sea oilfield

The formation of Western South China Sea Oilfield is characterized by frequently alternating sand and mudstone, large dip angle, high shale content, many faults, easy collapse, high gravel content, strong abrasiveness and many complex drilling conditions, which greatly limits the drilling efficiency of conventional exploratory wells. To solve these problems, after many years of practice and exploration, a series of ROP improvement techniques and supporting measures were developed and applied in complicated situations including making up personalized bits according to formation characteristics, using torsional and flushing tools in hardly drilled strata, flexibly applying unconventional well profile, employing vertical guidance system to prevent deviation in steep strata, and using strong plugging drilling fluid system to reduce collapse and circulation loss. Meanwhile, the technical principles, matching process measures and field application effects were discussed in details. In recent years, the application results of more than 100 conventional exploration wells in Western South China Sea oilfield show that the average penetration rate has increased from 24m/h to 40m/h, the production efficiency has increased from 88% to 98%, and the drilling complexity rate has been significantly reduced, providing a reference for similar oilfield to improve drilling efficiency.