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Abstract: Sampling Fracture Parameters in Borehole Imaging Logs and Cores: An Integrated Approach Applied to the Dutch Offshore

H. Homann, B. D. M. Gauthier

Borehole Image logging has become an effective tool for determining fracture parameters in the sub-surface. Parameters like orientation, density, nature (open, filled), trace length and aperture are commonly obtained from these tools. However, other crucial parameters like abutting relationships, fracture termination and origin (tension, shear) are more difficult to derive. They can often be obtained from core data only.

The processing and the interpretation of the full Circumference Borehole Imaging Log (CBILSM) data combined with geological expertise allow us to assess all fracture parameters. We can now describe qualitatively and quantitatively fracture systems regardless of the borehole environment. Subsequent statistical analyses such as automatic cluster recognition and normalisation techniques enable us to define the geometry of the various fracture sets better. The structural geological history and the contribution of each set to the production behaviour of the well can then be addressed. Core and CBILSM data can also be better reconciled.

Examples from wells in the sandstone reservoirs of the Rotliegend (early Permian) formation of the Dutch Offshore will be used to illustrate the methodology and its application.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France