4D Seismic Feasibility in Complex Upper Cretaceous Carbonate Reservoir, Abu Dhabi, UAE

4D seismic reservoir surveillance technique has been always challenging in carbonate reservoirs due to weak signal but favorable for the oil-producing complex and fractured Upper carbonate reservoir in a mature oil field in Abu Dhabi whose development is becoming a challenge because of higher-pressure depletion and increasing water cut. 4D seismic feasibility study, carried out with the objective of identifying pressure depletion and the bypass oil zones, resulted into feasibility of the reservoir monitoring technique subjected to the duration of production interval. 4D seismic amplitude attribute, “Envelope(monitor)-Envelope(base)” and “time-shift” are found above the repeatability noise (∼10%) and detectability limit of 0.149ms respectively over a period of 14 years of production and 9 years of production/water injection period. While technique is not feasible over 2 years of Pilot Water Injection period because of poor 4D signal to be detectable. Since 4D signals are dominantly controlled by accelerability law taken from the worldwide analogue hence a pilot 4D monitor survey is recommended for the calibration of pressure law and hence to consolidate the concept before implementing it on full field scale for optimizing the infill producers as well as water injectors.