Abstract
This paper describes a simplified three-dimensional numerical model for production behavior of the Mobara-type water-dissolved natural gas reservoir composed of alternating beds of sandstones and mudstones. It is assumed that water and gas flow horizontally through the sand-stones and vertically (in one dimension only) through the mudstones. Finite difference approximation method is used to solve the differential flow equations.
Application of the model to a practical Mobara-type field in Chiba Prefecture shows very good coincidence between the calculated and the measured values for the average gas-water-ratio of all the production wells.
Calculation results show that the production behavior remains ordinary-type if gas does not migrate from the mudstones to the sandtones even though pressure is maintained at a constant and a large amount of free gas is supplied at the boundaries, provided that the reservoir be isotropic and homogeneous.
