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The Utility of Enhanced Mudlogging Methodologies for Improving Geosteering of Horizontal Wells.

Scott Wright and Tim Dean

The analysis of rock materials cut by drill bits and transported to the surface in the drilling fluid is commonly known as mud logging. Data from such analysis are most valuable to the geologist responsible for operational decisions on the well if the analytical processes utilized to derive the data are scientifically robust and done in a highly standardized and timely manner. In practice, complex methodologies and procedures are difficult to rigorously quality control in the field, petrological descriptions are not standardized between mud logging companies and training of technical personnel is often uneven. The utility of a new type of interactive checklist/instructional software designed to address these problems is investigated in the context of conventional mudlogging operations and in enhanced mudlogging including high resolution, calibrated micro-imaging and precise bulk density measurements. Since such enhanced petrologic data are available in near real time during the drilling process, they have critical value in informing operational drilling decisions based on geologic data. This is especially true in the context of geosteering, where in its conventional methodology, only a single geologic parameter, intrinsic gamma ray radioactivity, is utilized to establish stratigraphic position relative to the target interval. The utility of the additional petrological parameters of color, texture, mineralogy and density available from enhanced mudlogging to provide for a far less ambiguous correlation across faults in a conventionally geosteered horizontal shale gas well targeting the Marcellus formation is evaluated and compared to gamma ray only interpretation results.


AAPG Search and Discovery Article #90152©2012 AAPG Southwest Section Meeting, Fort Worth, Texas, 19-22 May 2012