Abstract: The Use of High-Resolution Aeromagnetic Surveys to Delineate Basement Controls on Thin-Skinned, Fractured, Tight Gas Reservoirs: Examples from the Piceance Basin

Thomas E. Hoak, Alan L. Klawitter

An analysis of recently-acquired, high-resolution aeromagnetic data, integrated with structural, production history, and seismic analyses of the Piceance Basin identified a strong correlation between basement structures and fractured tight gas reservoir production trends located in thin-skinned structures.

Detailed reservoir characterization of fields associated with Piceance Basin thin-skinned structural traps reveals the importance of fracture-controlled production in these fields. Most importantly, many fields thought to lack fractures, demonstrate insufficient permeability for economic production unless fractures are present.

Seismic data were used to establish the relationship between basement structures recognized on aeromagnetic data and thin-skinned, small-amplitude, anticlinal fractured reservoirs. Seismic interpretation indicates that many thin-skinned structures in the Piceance Basin are related to deeper-level basement features.

The trends and locations of NURE aeromagnetic residuals lie parallel to trends of well-documented surface and subsurface thin-skinned anticlinal structures. To define localized features, a high-resolution aeromagnetic survey was flow in the south-central section of the basin. This new survey reveals that the southeastern Piceance basin is dominated by northwest structural trends typified by the orientations of the Rulison, Divide Creek, and Wolf Creek anticlines. The southwestern basin, in marked contrast, contains E/W-oriented folds such as the Debeque, Bull Creek (new), and Garmesa anticlines. Similar E/W trends are exemplified in the northwest and north-central basin by the Rangely and White River Dome anticlines, respectively.

Aeromagnetic surveys, integrated with critical information about regional structure and fractured reservoir production trends, represent a relatively inexpensive method to document potential fractured tight gas reservoirs. In basins where fractured reservoirs are related to small-scale, thin-skinned structures controlled by basement deformation, aeromagnetic surveys permit a rapid first-order screening for potential exploration targets. ln mature basins, aeromagnetic surveys may reveal previously-overlooked, small-scale structures containing fracture-controlled production, or overlie deeper reservoir plays not previously tested.

AAPG Search and Discovery Article #90959©1995 AAPG Rocky Mountain Section Meeting, Reno, Nevada