Well Test Analysis of Naturally Fractured Reservoirs with Unsteady State Behavior Using Direct Synthesis Technique

摘要

This study proposes a new method for analyzing pressure transient in naturally fractured reservoirs (NFR). Parameter estimation is based on the direct synthesis technique. The direct synthesis technique utilizes the characteristic intersection, maximum and minimum points, slopes, and starting time of various straight lines from a log-log plot of pressure and pressure derivative data. Applicability of the empirical expressions developed as a result of this work is demonstrated by successfully analyzing actual pressure transient data. The main advantage of direct synthesis method is for a case where there is no guarantee on the existence of an early-time unit slope line, and/or the late-time infinite acting radial flow line has not been seen due to inner and outer boundaries, lack of points, and severe noise problems. Application of this technique is presented for well test analysis in infinite-acting naturally fractured reservoirs with an unsteady state flow model. Both the effects of wellbore storage and skin are included in the analysis. Comparison between the results obtained in this work and already published results indicates good agreement.