Co-Development of Oil Rim and Gas Cap for Offshore Reservoir in Cost Effective Manner Through Integration of Multi-Disciplinary Data

Abstract Field presented here is giant heterogeneous carbonate field consist of multi-stacked reservoirs, located in offshore Abu Dhabi. This paper presents development plan for one of reservoir. It consists of a very large rich gas cap with oil rim. Current development plan is oil production from oil rim with peripheral water injection with no gas injection and production. Significant amount of data (Core, Seismic, Logs, DST, production test & PTA) during the early production period have been collected. All the data have been integrated to prepare robust Co-development of oil-rim and gas cap to maximize oil and condensate value from the reservoir. Reservoir consists of three main porous units: Upper, Middle and Lower Units inter-bedded with dense intervals. Generally the best porosity development is seen in the norther part of the field. Sedimentology study was mainly focused in the upper section of the reservoir. Five facies associations were made based on a low inclination ramp depositional model and diagenetic impact honoring the paragenetic sequence. Facies controlled diagenesis was noticed where abundance of echinoderms controlled the different degree of cementation degrading the reservoir quality. Identifying these dominant echinoderm facies zones allows us better well placement by avoiding them. The output of this study was four facies maps with five facies association distribution representing the four cycles seen in the upper part of the reservoir which is the best reservoir section. These facies maps were incorporated for property distribution in the static model. The reservoir model is constructed using latest acquired seismic and more than 100s of well control for the top of the Reservoir, used as reference structure. Proportional layering was used for different reservoir layers which have been mapped using Isochore. The facies association was distributed using trend map and Vertical proportion curve observed on the Well. Reservoir properties like Porosity and Permeability were distributed using constrained of facies distribution. A newly drilled well also used as for blind test showing the predictability of the model. Dynamic data such PTA and time-lapse MDT has been integrated in the updated model to guide areal and vertical connectivity. Good history matching has been obtained with minimal changes in the static model. With the updated model different sensitivities of gas cap and oil rim development has carried out in terms of co-development timing, lean gas recycling volume, and inner ring water injection in order to maximize oil and condensate value from the reservoir and avoid oil migration in the gas cap.