Reactive and Weak Zone Drilling Solution: Non-retrievable Casing Drilling

Abstract Non-retrievable casing drilling technology has gained wide recognition from operators for drilling top hole sections in offshore Peninsular Malaysia waters in recent years. The high value realized in reduction of well construction costs and problem resolution in reactive formations has contributed to the high popularity of this innovative drilling technique in this region. Reactive shale zones are the trouble zones commonly seen in the top hole section offshore Peninsular Malaysia. These zones are mainly comprised of soft sandstone and claystone which have caused losses of millions of dollars to operators using conventional drilling techniques. Extra wiper trips are frequently necessary across these trouble zones, and stuck casing can still be a problem. A non-retrievable casing drilling bit, the Defyer, has been successful in avoiding lost time in penetrating these trouble zones, and previously set a casing drilling record of a 13-3/8" application in this area. This success for footage drilled achieved by the casing drilling bit provided encouragement for an attempt that would push the ultimate capability of this system in drilling a long interval through the reactive zones. This paper briefly discusses the planning, implementation process of this long interval 13-3/8" casing drilling through reactive zone and subsequent savings for the operator in this project.