Publications

Open hole petrophysical evaluation has been traditionally used for predicting and estimating the in-situ reservoir properties. Reservoir performance is frequently monitored by evaluating the periodic changes of the oil saturation and pressure over a period of time. Reservoir management is trivial if the well traverses thick homogeneous and isotropic reservoirs without any co-mingled production. However, if the well is producing co-mingled from numerous sands, it is difficult, if not impossible, to detect which zones have watered out or which zones have been producing. Although the production tools help in identifying zones which are producing water it does not provide a quantitative saturation estimate of the formation producing water Monitoring the reservoir pressure is also critical in understanding the reservoir performance. Routinely this is done in open hole wells. Pressure monitoring is a requirement in a cased hole for understanding the reservoir performance. Combined interpretation of the hydrocarbon saturations, porosity and reservoir pressure are vital inputs for reservoir management. A cased hole evaluation consisting of cased hole resistivity and carbon oxygen logs were acquired in a field producing co-mingled from 35 sands. Cased hole reservoir pressure measurements combined with fluid scanning techniques were carried out to understand the different pressure regime and fluid properties of the different sans. This technique helped in understanding the production behavior of some of these sands. The cased hole logs helped in the evaluation of the different reservoir units. It also highlighted zones of depletion and identified some bypassed zones. The cased hole pressure and fluid scanning technique helped predicting the production from these sands. Under certain conditions the cased hole pressure and fluid scanning technique complemented the results obtained from the cased hole logs. Production water distribution map was generated for the first time in the development stage of this field by integrating saturation values from cased hole and producing water-cut by well. Workover candidates have been re-evaluated based on the water distribution map. Infill drilling locations have also been modified based on the study. These are some critical modifications to the field development program which have been based on the present study. Finally the surveys have provided important insights to complex reservoir settings of the field.