AAPG Bulletin, V. 83 (1999), No. 9, P. 1392-1407.

The Study of a Naturally Fractured Gas Reservoir Using Seismic Techniques¹

C. R. Bates,² H. B. Lynn,³ and M. Simon³

©Copyright 1999.  The American Association of Petroleum Geologists.  All Rights Reserved

¹Manuscript received March 23, 1998; revised manuscript received January 18, 1999; final acceptance January 29, 1999.
²Sedimentary Systems Research Group, University of St. Andrews, Fife, Scotland; e-mail: [email protected]
³Lynn Inc., Houston, Texas.
This work was conducted under Blackhawk Geosciences contract for the U.S. Department of Energy (DOE) Contract #DE-AC21-92MC28135. Pennzoil E and P is thanked for support and commitment to the project. Dave Phillips, Stewart Squires, Mike Jones, and Wallace Beckham are all thanked for their help during the project and for many invaluable discussions. 

ABSTRACT

The upper Green River Formation at the Bluebell-Altamont field, Utah (Figure 1) is a tight gas sand reservoir where economic production can be sustained only in regions of high natural fracturing. In 1994, a demonstration seismic project was conducted at the field to show how exploration for, and the characterization of, naturally fractured gas reservoirs can be more effective through the integrated use of seismic techniques. Study of field exposures, well logs, and regional stress indicators prior to the seismic survey indicated a high degree of preferential orientation to the dominant fracture trend at the field. The seismic survey consisted of two crossing, nine-component surface seismic lines and a nine-component vertical seismic profile. The compression, and shear-wave surface seismic both recorded anisotropies that were related to the presence and azimuth of the natural fracturing. The surface seismic results were supported by results from the nine-component vertical seismic profile. This program demonstrates the potential offered by the use of integrated seismic and geological techniques for the analysis of both land and marine naturally fractured reservoirs; furthermore, it demonstrates the possibilities of reviewing existing databases containing compression-wave surface seismic data for fracture information.