Detection and Reuse of the Produced Chemicals in Alkaline-Surfactant-Polymer Floods

Detection and Reuse of the Produced Chemicals in Alkaline-Surfactant-Polymer Floods Wei Wang; Wei Wang University of Regina Search for other works by this author on: This Site Google Scholar Yongan Gu Yongan Gu University of Regina Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, Denver, Colorado, October 2003. Paper Number: SPE-84075-MS https://doi.org/10.2118/84075-MS Published: October 05 2003 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Wang, Wei, and Yongan Gu. "Detection and Reuse of the Produced Chemicals in Alkaline-Surfactant-Polymer Floods." Paper presented at the SPE Annual Technical Conference and Exhibition, Denver, Colorado, October 2003. doi: https://doi.org/10.2118/84075-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractAlkaline-Surfactant-Polymer (ASP) flood processes have been increasingly applied in the oil fields due to their high ultimate oil recovery. However, a major technical challenge is how to significantly reduce the amount and the cost of chemicals used such that ASP floods can become cost-effective as well. On the other hand, field applications show that the concentrations of alkali, surfactant and polymer remain relatively high in the produced fluids of ASP floods. Thus, successful detection and reuse of these chemicals can substantially reduce the capital cost and the environmental impact. In this paper, several methods are applied to detect each chemical and quantify its concentration in the produced fluids. Also re-injection of the produced chemicals is conducted for further enhancing oil recovery. More specifically, first, the total interactions of each chemical with the oil-brine-rock system are studied. With the developed detection techniques for each individual chemical used in ASP floods, the total loss of each chemical is measured. The chemical loss is caused by its chemical reactions with the crude oil and the reservoir brine, as well as its adsorption onto the rock surface. Secondly, coreflood tests are performed for alkaline floods, surfactant floods, alkaline-surfactant (AS) floods, and ASP floods to determine their respective tertiary oil recovery. Hence, a better understanding of how each chemical contributes to enhanced oil recovery (EOR) is achieved. Thirdly, typical chemical concentrations in the produced fluids are measured and compared with those in the injected slugs so as to determine the potential of reusing these chemicals in practice. The follow-up coreflood tests of reusing these produced chemicals are carried out by directly re-injecting the produced fluids. The test results show that the produced chemicals can still effectively enhance oil recovery by up to 19.7%. It is anticipated that the detection and reuse techniques studied in this work should facilitate the design, optimization and implementation of ASP flood projects.IntroductionChemical EOR operations are increasingly applied in the oil fields as tertiary oil recovery methods. In the literature, there are some comprehensive studies on chemical flooding. A variety of chemical floods are conducted, such as alkaline flood, surfactant flood, polymer flood, AS, alkaline-polymer (AP) flood and ASP flood. In particular, as one of the most effective EOR techniques, ASP flood has been applied to recover the residual oil in the sandstone and the carbonate reservoirs since 1980. It has been reported that the successful applications of ASP floods in the oil fields can enhance oil recovery up to 20% 1–9.Generally speaking, an ASP flood is a modified alkaline flood. Field applications of alkaline floods alone usually result in poor oil recovery due to the alkaline loss caused by the chemical reactions with the reservoir rocks, low acid number of the crude oil, and adverse mobility ratio10. The major EOR mechanisms of an ASP flood are briefly described as follows. In conjunction with the added surfactant, the surfactants generated in situ by the chemical reactions between the injected alkali and the natural organic acids in the crude oil can result in ultra-low interfacial tension (IFT). The ultra-low IFT at the oil-brine interface helps to emulsify and mobilize the residual oil in a reservoir. In addition, the reservoir rock surface becomes more negatively charged at higher hydroxyl ion concentrations11. These negatively charged ions not only prevent the adsorption of anionic chemicals, such as anionic surfactants and polymers, but also change the wettability of the rock surface12–14. Also, the added surfactant can enhance the salinity tolerance of the alkali15. To achieve the same displacement efficiency as that of micellar-polymer flood, the surfactant concentration required in the ASP flood can be reduced by one order16. On the other hand, the injected polymer can significantly improve the mobility ratio. The adsorption of polymer onto the reservoir rock can reduce the effective water permeability. Hence, polymer flood enhances both the areal and the vertical sweep efficiencies17. Keywords: crude oil, chemical flooding methods, oil recovery, concentration, adsorption, ift, surfactant solution, enhanced recovery, surfactant loss, variation Subjects: Improved and Enhanced Recovery, Chemical flooding methods This content is only available via PDF. 2003. Society of Petroleum Engineers You can access this article if you purchase or spend a download.

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