MODELING METHOD FOR GAS PRODUCTION OF COALBED METHANE (CBM) RESERVOIR ROCKS

摘要

The present invention relates to a method for modeling gas production in acoalbed methane gas reservoir. The present invention is characterized byincluding(a) dividing the reservoir in a coalbed methane gas (CBM) development areathroughcomputer modeling and thereby forming a three-dimensional grids having apluralityof cell, (b) actually forming at least one drilling hole in the developmentarea andthereby obtaining a sample for each depth in the reservoir, (c) modeling theamountsof ash, water, and gas for the plurality of cells in the three-dimensionalgrids, (d)modeling the pressure change over time in each of the cells in the grid underapremise in which a production well is formed in the grids, and (e) performingaLangmuir experiment for a core sample obtained from step (b), calculating aLangmuir volume correction constant and a pressure correction constant for acase inwhich ash and water are excluded and only coal is present in the core sample,determining a Langmuir function for a maximum amount of gas adsorption withpressure and amounts of ash and water as variables, and applying the Langmuirfunction to each of the cells in the grids to calculate an amount of gasdetected due topressure change in each cell over time.