Monitoring Geomechanical Changes in Naturally Fractured Reservoirs through Rate Correlation Analysis

A newly developed technology analyses the readily available fluid production histories from existing wells to develop statistical correlations in rate fluctuations. Results of the application of this novel technology to naturally fractured fields in the North Sea will be presented. The results reveal surprising characteristics: many of the correlated well pairs are very long-range; they also appear to be stress-related and fault-related. The postulated mechanism is that faults and fractures are reactivated due to the stress perturbations brought about during field development. In one field, comparison with independent data, particularly microseismic recordings, provides very encouraging calibration. Identification of major reservoir pathways is of substantial advantage to efficiency in reservoir management, leading to benefit for practical issues of well placements and configurations, injectivities, productivities, sweep efficiencies, short-term and longer-term forecasting. The means of integrating the technology with other reservoir management processes will be outlined. In particular the techniques can be used in a time-lapse fashion in order to monitor changes in reservoir behaviour and provide real-time updating of reservoir models.