An Analytical Approach for the Estimation of Saturation and Pressure Behavior in Water-drive Gas Reservoirs

Open Access
Paslay, Paul Michael
Graduate Program:
Petroleum and Natural Gas Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 09, 2012
Committee Members:
  • Turgay Ertekin, Thesis Advisor
  • Petroleum Engineering Water-Drive Gas Reservoirs Analytical Comp
This thesis presents a new analytical approach for predicting pressure behavior following production from a water-drive natural gas reservoir. It is difficult to predict the rate of water influx into a gas reservoir because information about the aquifer is often unknown and saturations at points far from the wellbore cannot be directly measured. The analytical model proposed by this research utilizes an idealized composite reservoir model to approximate conditions after water influx into the reservoir. The model has the potential to eliminate the need for numerical simulation to analyze these types of reservoirs, which would be beneficial to small companies that may not have access to expensive numerical simulators. Given the saturation profiles, the model’s forward solution is able to predict pressure build-up behavior for any time during the well’s shut-in period. The results contained in this report show that the analytical composite model can accurately predict pressure build-up behavior in systems with low permeability, and can predict pressure build-up in high permeability systems with slightly less accuracy. Future work involves reversing the analytical solution to predict saturation profiles using only pressure build-up data.