A Method to Diagnose Depletion, Skin,<i>kh</i>, and Drive Mechanism Effects Using Reservoir Monitoring Data

Abstract

Abstract The use of permanent sensors provides a continuous source of downhole pressure measurement throughout the life of the well. Moreover, multiphase flowmeters provide simultaneous flow rate measurements. The significant amount of data produced by these sensors has added a new dimension to traditional well test data interpretation techniques. This new dimension is life-of-well time. During the life of the well, permanent-gauge data and flow rate measurements are affected by several dynamic factors including changes in reservoir pressure, skin, permeability-thickness (kh), and reservoir drive mechanism. A major challenge facing the industry today is how to diagnose and respond to the effect of each of these factors. In other words, it is important to know whether a change in measured downhole pressure or flow rate is caused by depletion, changes in skin, kh, or drive mechanism. This study investigates the effects of the above-mentioned factors in two fields in the Gulf of Mexico area. In addition, experience and lessons learned from numerous wells and fields equipped with permanent sensors have been used to develop a diagnostic method. This method uses key reservoir and well performance indicators to derive techniques to distinguish between the effects of depletion, skin, kh and drive mechanism. Best practices in the collection of flow rate and pressure data with suggestions for near-future improvements are included.