METHODS FOR GAS INVENTORY VERIFICATION IN UNDERGROUND RESERVOIRS, WITH AN EMPHASIS ON REDUCING RISK

A problem usually found in the gas industry is the verification of natural gas stored in underground reservoirs. Errors in this process, where a great amount of uncertainty is expected, may lead to extremely high costs.;The concept of the Expected Value of Perfect Information is applied along with the modeling approach in order to calculate the probability of detecting gas migration from the storage facility, and to provide an upper limit on the amount of money that a company should spend on gas inventory monitoring.;This research demonstrates the importance of modeling a reservoir as a means of estimating the expected value of the information provided by well pressure data. The method of solution makes it possible to quantify the economic risk associated with each alternative. Methods for inventory monitoring are recommended for different types of reservoirs.;This dissertation proposes a way of determining the best method for inventory verification. The information provided by various inventory techniques is assessed by simulating reservoir operations on a microcomputer.