Abstract
Low Salinity Water (LSW) and Alkaline-Surfactant-Polymer (ASP) flooding are emerging enhanced oil recovery methods that help recover oil from the reservoir after primary and secondary recovery processes. Experimental studies on LSW and ASP flooding have indicated potential in additional oil recovery. In this paper, numerical simulation was performed to study the combined effects of LSW and ASP flooding. A heterogenous reservoir initially saturated with oil and water was modelled using Eclipse. The wells were completed with an inverse five-spot pattern and the production life of the reservoir was taken to be five years. The results showed that LSW flooding using a salt concentration of 1 000 ppm achieved a higher oil recovery than conventional (high salinity) water flooding with a salt concentration of 35 000 ppm. The oil recovery for conventional water flooding was 59.5% and that of low salinity flooding was 64.1%. The overall oil recovery for LSW combined with alkaline, surfactant and polymer flooding were 64.1%, 70.5% and 62.6%, respectively. The model indicated an increase in overall oil recovery of 91% when alkaline, surfactant and polymer were combined and injected as the same slug as opposed to the injection of the chemicals individually. This was attributed to the synergy of the chemicals. The alkaline and the surfactant reduce the interfacial tension between the oil and water and the polymer improves the mobility ratio thereby increasing sweep efficiency.
Highlights
Oil production traditionally runs through series of stages namely primary, secondary, and tertiary recovery process
Several flooding techniques were used to ascertain the effectiveness of Low Salinity Water (LSW), alkaline, surfactant and polymer flooding
This study investigated the combination of LSW flooding and alkaline, surfactant, polymer flooding for enhanced oil recovery in a reservoir initially saturated with oil and water
Summary
Oil production traditionally runs through series of stages namely primary, secondary, and tertiary recovery process. Alkaline-Surfactant-Polymer (ASP) flooding uses a combination of alkaline, surfactant and polymer as the injection slug for further improvement on oil recovery [6] It has been demonstrated in experimental works as an effective EOR method with recovery factor up to 98% of the OOIP [7]. Experimental works using cores in low salinity and ASP flooding which have been documented in literature [10, 11], have shown improvement in displacement efficiency yielding high oil recovery. This research seeks to move a step further by utilising numerical simulation to study the combined effects of low salinity and ASP flooding It is a fairly new recovery process and has the potential to yield an increase in oil recovery as a result of the synergy of the recovery techniques. This is because, with the injection well situated at the centre of the reservoir, the injected fluid swept the oil all the way to the corners of the reservoir where the production wells were located improving oil recovery
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More From: International Journal of Oil, Gas and Coal Engineering
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