Development of Coal-Gas Production Simulators and Mathematical Models for Well Test Strategies (Computer Models for Single- or Two-Phase Flow of Methane and Water in Heterogeneous Coal Seams to a Single, Vertical Production Well Connected to a Finite Conductivity Vertical Fracture)

摘要

A series of unique, computer-based, finite-difference models for the production of methane from coal seams by vertical wells are presented along with FORTRAN source codes. Included in this series are single-phase (gas), one-dimensional; two-phase (gas-water), one-dimensional; and two-phase (gas-water), two-dimensional models for a single vertical production well. The two-phase, two-dimensional model allows for a single, infinite- or finite-conductivity, vertical fracture extending radially from the wellbore. The natural fracture network (butt and face cleat) of the coal seam has been identified with a porous network and assigned an effective porosity and absolute permeability. A time-dependent source term, based on a first order kinetic model and a Langmuir equilibrium sorption isotherm is used to describe gas desorbing from the coal matrix into the porous network.