A microseismic experiment in Abu Dhabi, United Arab Emirates: implications for carbonate reservoir monitoring

Abstract

A microseismic experiment utilizing a single downhole array of eight 3-component receivers was conducted in an offshore oilfield in the emirate of Abu Dhabi in the United Arab Emirates. The Lower Cretaceous Thamama Group is the major carbonate reservoir in the field producing from six zones. Microseismic data was acquired in conjunction with gas injections that took place in the Thamama IV A and IV B reservoirs during 9 days of acquisition. The aim of the experiment was to monitor the microseismic activity arising in the carbonate reservoirs as a result of gas injection. A total of 103 microseismic events were detected from two of the receivers. For the majority of these events, there were no well-defined P wave arrivals, probably due to the presence of strong background noise and the very weak microseismic signals. The results from this experiment indicate that the detected events are probably related to the microseismic activities caused by the gas injection within the Thamama IV B reservoir. Therefore, downhole microseismic monitoring methods can potentially provide valuable information about the fracture systems within the carbonate reservoirs of Abu Dhabi's oilfields.