Well-Controlled Dynamic Reserves Calculation of Abnormally High-Pressured Gas Reservoirs Developed with Edge and Bottom Aquifers

Abstract

A material balance equation (MBE) is usually employed to estimate well-controlled dynamic reserves, but a more accurate calculation of these reserves is crucial. For abnormally pressured reservoirs with aquifers, the abnormally pressure and aquifer are difficult to determine, which leads to inaccurate calculations of well-controlled dynamic reserves. In this work, the MBE was established. Then, the correction function and abnormally pressure effect were deduced to determine well-controlled dynamic reserves calculations for weak aquifers and strong aquifers, respectively. For a weak aquifer, a pressure correction was determined to exist at a pressure coefficient of 1.2, and then the correction function was established to calculate the dynamic reserves. For a strong aquifer, the MBE derived by Walsh was employed to calculate the dynamic reserves and water influx. The relationship between the abnormally pressure effect and the dimensionless formation pressure was proposed. Classical, abnormally high-pressured gas reservoirs, Anderson L and Amu Darya, were selected to validate the accuracy and applicability of the newly developed methods. The results show that an abnormally high-pressure effect has a great influence on the dynamic reserves calculation in the early stage and the water influx has a stronger influence on the dynamic reserves calculation in the late stage.