Arnold, Bill W.1, J. Matthew Herrin2, Paul M. Basinski3
(1) Sandia National Laboratories, Albuquerque, NM
(2) New Mexico Institute of Mining and Technology, Socorro, NM
(3) El Paso Production Company, Houston, TX
ABSTRACT: Statistical and Geostatistical Analyses of Coal-Bed Methane Production in the Raton Basin, New Mexico and Colorado
Coal-bed methane production may be influenced by multiple factors, including fracture
network characteristics, local geologic structure, regional stress, coal thickness, depth,
hydrology, and pressure history. Understanding the relative importance of these factors
potentially contributes to the optimization of production development.
Average daily gas and water production from 284 CBM wells in four El Paso Production
development pods in the Raton Basin were analyzed. Stepwise linear regression was used to
estimate the relative importance of independent variables, including the first and second
derivatives of upper surface of the Trinidad Sandstone, total coal thickness, groundwater
total dissolved solids, and duration of production, to the gas and water production.
Variogram analysis was used to assess the spatial continuity in production.
The correlation analysis using stepwise linear regression indicates that the total coal
thickness in the Vermejo and Raton Formations accounts for about 14% of the variability in
average daily gas production. The slope of the Trinidad Sandstone parallel to maximum
principal horizontal stress (N 5 E) accounts for about 5% of the variability in average
daily gas production. Significantly better correlation exists between the independent
variables and the ratio of gas to water production, with 44% of the variability in the
gas/water ratio accounted for by the slopes of the Trinidad Sandstone parallel and
perpendicular to maximum principal horizontal stress. Geostatistical analysis with
variography indicates that the spatial correlation in gas and water production among wells
extends about 3 to 6 kilometers.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004