James R. Lancaster¹, John H. Dolloff²

(1) Evaluations, Inc, Littleton, CO
(2) Ripley Energy Associates, Golden, CO

ABSTRACT: Log-derived Total Organic Carbon is used to Estimate the Gas Storage Capacity of the Lewis Shales, San Juan Basin, New Mexico and the Sand Wash Basin, Colorado

An application of laboratory core and sample analyses for determining gas storage capacity from total organic carbon is compared with a study using wireline logs to compute total organic carbon. Results of log-based total organic carbon converted to gas storage capacity are comparable to those determined with laboratory procedures. Data are presented for the Late Cretaceous Lewis formation on wells located in the San Juan Basin, New Mexico and the Sand Wash Basin in Colorado. The San Juan Basin example is typical of currently developing gas production from previously unrecognized fractured Lewis Shale intervals.

Using previously published table data, equations were generated to compute the gas storage capacity in standard cubic feet per ton from total organic carbon values. This poster includes: 1.) results of the technique for computing total organic carbon from wireline logs, 2.) examples of laboratory analyses and log-derived total organic carbon for determining adsorbed gas, 3.) verification of these techniques on a San Juan Basin well, 4.) applications of the wireline logs technique on two Sand Wash Basin wells.

Producing gas directly from source rocks in re-completed existing cased well bores, as in the San Juan Basin, may be a viable low-cost means of increasing gas production in the Sand Wash and other basins.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado