A Model for Development, Sensitivity Analysis, and Optimization of Gas Reservoirs with and without Aquifer: Part II-The Sensitivity Analysis

Abstract

ABSTRACT A computational model for development and optimization of the gas reservoirs with or without water inflow was presented in Part I of this series of two papers. In this Part II, a sensitivity analysis will be presented. The most important variables involved in the development of a Gas Reservoir with or without aquifer will be studied. Furthermore, the effect due to neglecting the rock and water compressibility terms for volumetric, steady state, and steady state system on the development of a gas reservoir will be studied. The model used for the sensitivity analysis was written in Fortran 77 and run by using the Multics System. The main purpose of the model is to determine the number of wells to be produced, and reservoir pressure at each period of time that depends upon the production schedule. The conclusions from the sensitivity analysis performed are as follows: Permeability and water viscosity do not have a great effect on finite aquifer but create high affect on infinite aquifer, especially low permeability and high water viscosity; rock and water compressibility affect finite aquifer more than infinite aquifer; each value of porosity will limit the minimum value of reservoir pressure for an infinite aquifer; and the rock and water compressibility term in material balance equation must be considered in the case of problems involving economic decisions.