An assessment of the structural and stratigraphic style across the evaluation area shows that several hydrocarbon trap types are possible. The probability of trap preservation is mainly controlled by multiple Tertiary structural, thermal and erosional events. These events have uplifted, tilted, structurally eliminated, thermally altered, and eroded the older stratigraphic section. All of the pre-Tertiary hydrocarbon accumulations within the area have been subjected to these extension-related events, and most have been segmented or breached.

Certain trap types are more readily outlined by current geological and geophysical methods. Conventional seismic imaging of the Paleozoic section is very poor as a result of near-surface noise problems and the inability to transmit and record signal through energy absorbing and highly reflective horizons in the Cenozoic section. This is further complicated by extensional structures which create complex ray paths. The bouguer gravity data can provide a cost-effective first order picture of subsurface basin geometry.

Five potential hydrocarbon trap models are discussed below. These include the Block and Arch Model, Low-Angle Truncation Model, Large-Scale Fold Model, Stratigraphic Model, and the Antler Thrust Model. Western Cordillera has used the Block and Arch trap model as the basis for closure in its Great Basin Exploration Model. We feel this model offers the most promising and predictable trap type within the evaluation area.