Well Test Interpretation with TDS Technique: Detection and Absence of Infinite Acting Radial Flow, Case Study

Tiab’s Direct Synthesis (TDS) technique is one of the transit pressure analysis techniques. It provides a direct approach to interpret transit well pressure tests without a type curve. The technique uses pressure derivatives to analyze data and compute reservoir parameters. One of the keys of analysis is identifying whether infinite acting radial flow (IARF) is observed. When IARF is clearly observed, the TDS and conventional methods allow estimation of reservoir parameters. But in real cases, IARF may not be observed or very short due to the short time of test or influence of outer boundary, which makes the conventional methods face limitations and the analysis becomes difficult or sometimes impossible. Thus, the present study applies the TDS technique on the Libyan oil field in both observed and unobserved IARF. Two wells are presented to illustrate the TDS technique. Based on the results, the TDS technique was a very useful and direct technique for analyzing transient pressure tests, especially when infinite acting radial flow is absent, as demonstrated in the analysis of wells.