Recent Experience with Wireline Fracture Detection Logs

In the last year Shell has extensively cored the fractured Mississippian Madison Limestone formation in the Mondak field, extending from Richland County, Montana to McKenzie County, North Dakota. In three wells the authors have recovered over 1500 feet of core which have been analyzed for fractures. In an effort to delineate fractures using wireline logs. The Schlumberger Circumferential Microsonic Tool, the US Geological Survey (USGS) Borehole Acoustic Televiewer, and the Schlumberger Fracture Identification Log were run. The paper discusses the mechanism of fracture detection and interpretation for each of the logging tools and compares their response to the core described fractures. It is concluded that the currently available fracture detection tools do not adequately identify the fractures observed in the Mondak cores. 3 refs.