ABSTRACT: Influence of Structural Evolution on Reservoir Development and Distribution in the Silurian Fusselman: Vermejo-Moore Hooper Field, Loving and Ward Counties, Texas

COLLEARY, WILLIAM M., and CO, JOHN R. HULME, Colorado School of Mines, Golden, CO, and JAMES W. CRAFTON, Colorado School of Mines, Golden, CO, and Gas Research Institute, Chicago, IL

The Vermejo-Moore Hooper field lies in the deep Delaware basin adjacent to the Pecos River in Loving and Ward counties, Texas. Discovered in 1973, the field produces dry gas from the Fusselman and Ellenburger formations. The Fusselman reservoir has produced over 400 bcf of gas from depths between 18,500 and 19,200 ft. The field primarily is a structural trap, but the distribution of reserves in the reservoir suggests a strong stratigraphic component.

The reservoir is composed of fractured dolomites and cherts of the Silurian Fusselman and overlying Wristen formations. Unconformities and their accompanying diagenetic processes play a major role in the reservoir. The occurrence of pervasive dolomitization and nodular cherts are interpreted to indicate diagenesis associated with subaerial exposure and karsting. Thick sections also may be absent due to erosion over paleostructures, and preserved in flanking positions.

Detailed paleostructural interpretation of the Vermejo-Moore Hooper field reveals a history of recurrent movement of the basement and demonstrates the influence of structural growth on the development and distribution of porosity and permeability in the Fusselman reservoir. Early structural growth can influence the distribution of both depositional facies and erosional processes.

Paleostructure maps in the Silurian-Devonian indicate that a series of northwest-southeast-trending, low-relief structures existed during the Silurian. Growth of these structures through the Devonian can be documented and the presence of fault-bounded basement

blocks can be inferred. The influence of this structural growth on the development of the reservoir is also demonstrated.

AAPG Search and Discovery Article #91018©1992 AAPG Southwest Section Meeting, Midland, Texas, April 21-24, 1992 (2009)