The Use of the Exponential Integral Solution to Predict Maximum Production Rates from Geopressured Aquifers

Abstract

A method was developed to predict production history of a geopressured aquifer with the surface pressure maintained at a constant, minimal value. Production of a geopressured aquifer in this manner would accelerate the recovery of the energy and thereby maximize its present value. The developed technique is centered around the exponential integral solution to the diffusity equation. The constantly changing flow rate is approximated in a stair step fashion using the principle of superposition. The effects of the aquifer boundaries are included by the additional of image wells to create a rectangular shaped aquifer with the well located at any position within the aquifer. Application to south Louisiana geopressured aquifers indicates that production rates are most sensitive to tubing size, formation damage and those parameters that dictate ultimate possible water recovery such as pore volume and initial pressure.