An Introduction to Real-time MWD/LWD Technologies for Geo-steering Driling:Based Mainly on Schlumberger’s Tools

Measurement while drilling (MWD) and logging while drilling (LWD), the techniques of informing drilling situation in real-time, have made progress in effective and accurate drilling. Geo-steering drilling techniques have been further developed to maximize the production of not only unconventional but also conventional hydrocarbon reservoir. With the advance in techniques, telemetry systems in particular, classification between MWD and LWD becomes more ambiguous. This paper discusses the historical trends of technical developments of LWD after explaining the concept and important factor techniques of MWD. For description of current technology of LWD, we summarized not only LWD services of Schlumberger, a world leasing company in MWD/LWD serivces but also their case studies. Further, we introduce measurements at the bit, which have been developed to minimize the problem caused by time lag or distance between the drill bit and MWD/LWD sensors.