Print this pageMarcellus Shale Log Calibration and Mapping with Legacy Logs
Historically evaluation of borehole logs in conventional reservoirs relied on cores for calibration purposes. Commonly, calibration of the log and core porosity is a key step in conventional reservoir analysis. During the early period of development of shale exploration in the Marcellus Shale, PetroEdge Energy LLC. utilized legacy borehole logs to map the distribution of the Marcellus rock properties. To accurately map the shale it was necessary to perform a calibration for geochemical properties, either TOC or kerogen volume.
The PetroEdge calibration method for shale logs is a modification of the GRI method for organic component calculation using a standard open hole logging suite in an air filled borehole. Public data in New York coupled with a significant gradient in thermal maturity provided a natural laboratory to test the method. Once the technique was tested in New York it was applied to other wells to make regional estimates across the Appalachian Basin.
While rock property mapping is important, drilling results suggest that some of the controls on production may not directly observed on logs. Within a single county area in WV where rock thickness and quality are nearly invariant PetroEdge observed a log normal population of EUR data.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009