The use of the Measurement While Drilling (MWD) tool in formation evaluation has proved invaluable in terms of operational cost, time and reliability of data. The tool suffers less from invasion effect when compared to conventional wireline tools and so can be deployed in hostile borehole environments. Measurement While Drilling data when properly interpreted provide useful information on the hydrocarbon type saturating the pores of a formation, compaction condition and evaluation of over pressure zones in the field as well as the provision of porosity, density and fracture data of the formation logged. Interpretation of case history on the significance of both MWD and wireline data show that MWD offers better data borehole conditions change rapidly after drilling. However, data from both sources when combined offer a better and complete reservoir evaluation.
Key words: Drilling, invasion, MWD, reservoir, formation evaluation.
(Global Journal of Pure and Applied Sciences: 2002 8(2): 265-270)