Formation evaluation: benefits of downhole logging while drilling

The development of new downhole measurement systems, coupled with mud-pulse telemetry techniques, allows real time surface evaluation of downhole parameters while drilling. Currently available systems, such as Exploration Logging's DLWD tool, combine formation resistivity and natural gamma ray sensors with directional survey and other measurements. These parameters aid formation evaluation, pressure evaluation, well-bore positioning, and drilling efficiency. For real time applications, such as correlation and bed identification, a DLWD log can be treated as a conventional wireline log. For further evaluation, the interpretation of DLWD data requires an understanding of the differences in the design of MWD tools compared to conventional wireline tools, as well as include physical size, logging speed, borehole effects, invasion, etc. The benefits of real time subsurface data enhance other geologic and engineering data acquisition systems in formation evaluation, pressure evaluation, and well planning.