Gas in the Uinta Basin, Utah - Resources in continuous accumulations

Abstract

Continuous-type gas plays can be envisioned as large areas within which the reservoir rock is everywhere charged with gas. As part of its 1995 National Assessment of oil and gas resources, the US Geological Survey identified four continuous-type gas plays in the Unita Basin. These occur in sandstone reservoirs of the lower Tertiary Wasatch Formation (two plays) and the underlying Upper Cretaceous Mesaverde Group (two plays). Only the play representing the eastern part of the Wasatch Formation continuous accumulation (Natural Buttes area) has been the target of appreciable drilling activity to date. The volume of undiscovered gas estimated to be recoverable from these fur plays using existing technology and development practices ranges between 3.7 trillion cubic feet of gas (TCFG) (95th fractile) and 11.9 TCFG (5th fractile), and averages 7.0 TCFG. However, these are geologically based resource estimates, made without direct reference to economic viability. Economic analysis indicates that only a fraction of this assessed resource could be economically found and produced at prices less than $2.00 per thousand cubic feet of gas (MCFG), based on costs that prevailed at the beginning of 1993. Production characteristics of continuous-type gas plays vary significantly from well to well. Difficulty in identifying locationsmore » with poor production characteristics in advance of drilling contributes to the unfavorable economics of some plays. The need exists for improvements in technology and geologic understanding that increase the changes of selectively drilling the more productive locations within a continuous-type play.« less