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Exploration Strategies and Play Characteristics of Tight-Gas Sandstone Plays

Shanley, Keith W.1; Cluff, Robert M.1; Cumella, Stephen P.2; Robinson, John W.3
1 The Discovery Group, Denver, CO.
2 Bill Barrett Corp, Denver, CO.
3 North Ranch Resources, Littleton, CO.

Exploration for tight-gas resources is rapidly gaining attention in petroleum provinces throughout the world. These ventures correctly reference analogs in North America where tight-gas exploration and production has been ongoing for over 30 years. Careful study of Rocky Mtn. tight-gas plays suggests that two broad play types can be identified. In basins with favorable petroleum-system elements, plays that involve deep-water, paralic, or high net/gross alluvial reservoirs must have a strong focus on trap identification and evolution. In basins where reservoir targets are in low net/gross alluvial reservoirs, the importance of traps depends first on a careful comparison of the minimum acceptable economic threshold and the resource endowment. In cases where the minimum acceptable threshold is much greater than the resource endowment, the search for traps is of paramount importance. In other low net/gross alluvial reservoir systems where the minimum acceptable economic threshold and resource endowment are similar, traps may enable optimization, however, they may not be required for economic success. Thus early exploration efforts should be on pilot projects designed to validate that the threshold and endowment are indeed similar. For low net/gross alluvial plays where there is considerable disparity between the threshold and the endowment, early exploration efforts must be more traditional and have a strong focus on trap identification.

New venture exploration for tight-gas plays is only likely to occur in mature petroleum provinces where the efficacy of the petroleum system has already been established: it is highly unlikely that new venture exploration for tight-gas resources will initially occur in a frontier basin setting. Because of the petrophysical challenges that accompany many of these plays evaluation of tight-gas plays is often fundamentally different from more traditional plays. The time and tasks required to adequately appraise a tight-gas play may be substantially longer than more traditional plays. Because reservoirs are low-permeability, these plays often require drilling 100’s to 1000’s of wells over a time period often spanning decades requiring an organizational competency not needed in more traditional plays. The manpower and capital required on a BOE basis are often much higher than more traditional plays. We will illustrate these different scenarios with examples taken from various Rocky Mountain tight-gas plays.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009