Fluid substitution in coalbeds

Diane Lespinasse and Robert J. Ferguson


We present an evaluation of the seismic response due to fluids in the pore space of coalbeds. The objective of this project is to perform a fluid substitution in coalbeds and generate the associated synthetic seismograms by implementing a work flow previously developed to evaluate seismic as a monitoring tool for CO2 sequestration in coals. The Mannville coals are one of the most important coalbed methane resources in the Alberta Province, Western of Canada. In order to study the Mannville Group coals we selected the Corbett Field, located 145Km to the NW of Edmonton, as the area of study. In the Corbett Field the targets are two coal seams of the Mannville Group, the Main Seam with 4m thickness and the Lower Seam, with a thickness of 1.5m. Using well log data from the well 100-03-22-062-06W500 of the Corbett Field, we perform a fluid simulation to make an assessment of its production forecast in a 10 years period and complete a fluid substitution. We use Gassmann equation to substitute 100% brine (initial state) in the pore space of Main Seam and Lower Seam by a combination of brine and methane. We also present synthetic seismograms for coalbeds of 10m and 21m thickness in order to establish seismic resolution limits.

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