--> ABSTRACT: Assessment of Gas Resources in Low-Permeability Sandstones of Upper Cretaceous Mesaverde Group, Piceance Basin, Colorado, by Ronald C. Johnson, Robert A. Crovelli, Charles W. Spencer, and Richard F. Mast; #91030 (2010)

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Assessment of Gas Resources in Low-Permeability Sandstones of Upper Cretaceous Mesaverde Group, Piceance Basin, Colorado

Ronald C. Johnson, Robert A. Crovelli, Charles W. Spencer, Richard F. Mast

A modified volumetric approach is used to estimate gas resources in the low-permeability sandstones of the Upper Cretaceous Mesaverde Group in the Piceance basin of western Colorado. The Mesaverde Group was divided into three plays based on stratigraphy--the Williams Fork Formation, the Iles Formation, and the Rollins Sandstone Member (Mesaverde Formation) or Trout Creek Sandstone Member (Iles Formation). Each of these plays was subdivided into a deep-gas play and a shallower gas-water transition play. Variations in thermal maturity were used to define the boundaries of the plays. The aggregated mean in-place gas for all six plays is 419.55 tcf.

The mean in-place resource numbers were run through probability programs, which assign estimates of the gas potential at the 95%, 75%, 50%, 25%, and 5% probability levels both for individual plays and for the aggregate of all six plays. Assuming a 75% degree of dependency between the plays, there is a 95% chance of at least 274.45 tcf of total in-place gas, a 50% chance of 407.60 tcf, and a 5% chance of 605.33 tcf. Next, six different recovery factors were used. The first three assume current technology and a gas price of $5/mcf, and the second three assume future advanced technology without a gas price specified. The most likely estimated recoverable gas figures for the six plays at the 95%, 50%, and 5% probability levels using current technology are 8.75, 13.03, and 19.41 tcf, and u ing future advanced technology are 44.23, 65.97, and 98.39 tcf.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.