ABSTRACT: Gas Potential and Development of the Central Piceance Basin, Northwest Colorado

Kurt Reinecke

Economic gas production has been established from Upper Cretaceous and Tertiary reservoirs in the central Piceance basin. Upper Cretaceous reservoirs lie above the Rollins Formation and consist of lenticular fluvial Mesaverde sandstones and Cameo coal seams. In developed gas fields the lower two-thirds of the 3000-ft fluvial Mesaverde section is gas saturated with little associated water production, whereas both gas and water production are possible in the upper one-third. The Mesaverde appears to be a basin-centered gas trap; up structural dip and toward the basin perimeter outcrop, Mesaverde sandstones become progressively water saturated from the top downward. Massive hydraulic sand-fracturing techniques are used on the low-permeability, multiple-pay sandstones to impr ve gas deliverability.

Persistent and productive Tertiary reservoirs that have been established in the eastward-thickening Wasatch Formation include a basal Eocene Wasatch sandstone designated the G sand and multiple upper Wasatch/Green River fluvial sandstones designated the A or Douglas Creek sands. The G sand appears to have been deposited by some type of fluvial system, but the basin-wide presence of the G sand seems to contradict this interpretation. Below a certain structural datum, closure is needed for hydrocarbon accumulation, whereas above this datum Wasatch reservoirs are generally gas saturated.

The main obstacles that hindered active development of the central Piceance in the past were (1) topography, which increases both drilling and location costs, (2) major acreage blocks that are held for future oil shale development, (3) low gas prices, and (4) lack of gas markets.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990