Wellbore pressure management is a critical part of the drillingprocess. In normal drilling practices, static and dynamic fluidpressures are used to contain formation pressures and to assurewellbore stability. Excessive fluid pressure while circulatingcan create problems including reduced operating marginsbetween fracture and pore pressures and, in the extreme, lostcirculation. To address these problems, an EquivalentCirculation Density (ECD) Reduction Tool (RT) hasbeen developed.The ECD RT is designed to counter the frictional pressureeffects that exist while circulating. The tool is expected tohave a broad range of drilling applications including; thenarrow pore/fracture pressure margin deepwater environment,wellbores prone to instability, pressure depleted reservoirs,and extended reach wells.The tool has the potential to:? Improve wellbore stability? Extend hole intervals and reduce casing requirements? Improve well control? Reduce lost circulation? Reduce differential sticking? Improve hole cleaning in ERD wells through the useof higher flow ratesThis paper describes a new downhole tool for ECDreduction, which is run as an integral part of the drill string. Aprototype tool has been built to operate inside 10-3/4' to 13-3/8' casing. This tool has undergone laboratory testing andfull-scale technology trials are in progress. The designfeatures of this prototype are discussed along with thelaboratory test results obtained to date.
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