Correlation study between streaming potential signal and waterfront progression during water alternate gas (WAG) injection

Abstract

Spontaneous Potential (SP) is commonly measured during reservoir characterization. The SP signals are also generated during hydrocarbon production due to the streaming potential occurrence. Measurement of streaming potential has been previously proposed to detect the water encroachment towards a production well. The objectives of this study are to quantify the magnitude of the SP signal during production by WAG injection and to investigate the possibility of using SP measurements to monitor the sweep efficiency. The peak of the signal corresponds to the waterfront, where there is a change of saturation from ionic water to non-polar hydrocarbon. Similar trend is predicted in the case of WAG, where we have several interfaces between the injected water and the injected gas. This project involves numerical modeling and experimental work. Results from the experimental work will be used in the simulation work to correlate the measured SP signals with the distance of the waterfront in the WAG process. These observations suggest that WAG displacement process can be monitored indirectly from the signal acquired. Water or gas override can be detected and controlled if wells were equipped with inflow-control valves. This study is significant because monitoring the progress of water and gas in a WAG process is key in the effectiveness of this enhanced oil recovery method. Measurement of the streaming potential provides another method besides using tracers to monitor the WAG profile. Better monitoring will lead to more efficient displacement and great benefits in term of economy and environment.