Application of the TDS Technique in Gas Reservoirs

Abstract

Tiab’s Direct Synthesis (TDS) is a direct technique to interpret transit well pressure tests. It is analysis of pressure and pressure derivative without type-curve matching. This method uses log-log Plot of the pressure and pressure derivative versus time to compute reservoir parameters such as permeability, wellbore storage, skin factor, and average reservoir pressure. The main objective of this study is to apply TDS technique for gas reservoirs “long test”, and show the advantage of TDS technique, where this technique is particularly useful when the late-time infinite acting radial flow is not observed, which is called “short test”. Two cases are presented in the study to analyze pressure data using TDS technique, a build -up test is conducted on the well (4U11) from Faregh field and well (5A5) from Gialo field. Based on the results and comparing between the long and short test; the results were converged, which indicates that TDS can be used if some flow regimes are not available. The technique is useful method for analyzing pressure test.