Sweep efficiency and frontal movement of water alternate gas in a linear displacement model by streaming potentials
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Date
2022
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Publisher
Universiti Teknologi Malaysia
Abstract
Spontaneous potential (SP) is commonly measured during reservoir characterization. However, SP signals are also generated during hydrocarbon production due to the streaming potential occurrence. Measurement of SP has been proposed as a method to detect and monitor water encroachment. In principle, SP signals could also be monitored during production from a single well, with pressure support provided by a water alternate gas (WAG) process. This study aims to determine the sweep efficiency and frontal movement during WAG injection process using streaming potential. The WAG process was conducted with the ratios (water : gas) 1 : 1, 2 : 1, and 3 : 1. The streaming potential signals were measured using non-polarizing of Ag/AgCl electrodes, installed along a linear model and measurement was recorded continuously using NIDAS and the Labview software. Measurement of streaming potential has been previously proposed to detect the water encroachment towards a production well. The peak of the signal corresponds to the waterfront where there is a change of saturation from ionic water to non-polar hydrocarbon. The frontal movement was detected during slug injection using streaming potential signal. The signals were higher corresponded to the waterfront but lower due to the presence of injected gas. Although the signals were of tiny value a ranging from 0 to 1 mV, they were still measurable. WAG ratio of 3 : 1 was chosen to be the optimum ratio because its yields the highest sweep efficiency which is 62% compared to ratio of 1 : 1 (55%) and 2 : 1 (60%). These results present the finding in monitoring sweep efficiency and frontal movement during WAG process using streaming potentials. This fundamental knowledge can lead to developing a new approach in monitoring WAG process which will result in a more efficient EOR process. A better monitoring will lead to a more efficient displacement with great benefits in terms of economy and environmental conservation.
Description
Thesis (PhD. (Petroleum Engineering))
Keywords
Enhanced oil recovery, Oil reservoir engineering