Abstract: Subsurface Fracture System in North Summit Gas-Storage Field, Appalachian Basin

Guojun Zhou, Robert C. Shumaker

In the Appalachian basin, many of the deeply buried reservoirs have low matrix porosity; therefore, gas production and storage commonly depend on fracture porosity and permeability. The new log tool, Formation MicroScanner (FMS) (Schlumberger), can indicate the orientation of fractures in the well bore, which permits one to map their density and distribution. A detached foreland is studied to determine the relationship of fractures to the structural position and lithology of the storage reservoirs.

The oriented cores taken in the field present an unusual opportunity to compare the results of fracture analysis using the FMS with fractures in the cores. The scanning electric microscope is used to look at microfractures and the cements filling the fractures. Analysis of FMS logs from 14 wells helped determine the three-dimensional distribution of fracture permeability, which forms the basis for estimating the storage capacity of the reservoirs. This estimation is compared with the gas volume taken by the reservoirs. Effective modification is then made to the formula derived to estimate the storage capacity of the reservoirs. Finally, a geologic history is studied to compare the fracture history and the time of fold formation, and a fracture model is made based on fracture origin an distribution (density and orientation) in different lithologies and structure position.

AAPG Search and Discovery Article #90984©1994 AAPG Annual Convention, East Lansing, Michigan, September 18-20, 1994