Laboratory Investigation of the Impact of Injection-Water Salinity and Ionic Content on Oil Recovery From Carbonate Reservoirs
01 Oct 2011-Spe Reservoir Evaluation & Engineering (Society of Petroleum Engineers)-Vol. 14, Iss: 05, pp 578-593
About: This article is published in Spe Reservoir Evaluation & Engineering.The article was published on 2011-10-01. It has received 535 citations till now. The article focuses on the topics: Enhanced oil recovery & Carbonate.
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TL;DR: In this article, the authors provide a critical review of the results and summarize the achievements of the industry's effort to discover the effect of low-salinity waterflooding.
460 citations
TL;DR: In this paper, the authors explored the mechanism leading to improved oil recovery in carbonate rock and showed that brine composition and (somewhat reduced) salinity can have a positive impact on oil recovery.
Abstract: The low-salinity effect (LSE) in carbonate rock has been less explored in comparison to sandstone rock. Laboratory experiments have shown that brine composition and (somewhat reduced) salinity can have a positive impact on oil recovery in carbonates. However, the mechanism leading to improved oil recovery in carbonate rock is not well understood. Several studies showed that a positive low-salinity flooding (LSF) effect might be associated with dissolution of rock; however, because of equilibration, dissolution may not contribute at reservoir scale, which would make LSF for carbonate rock less attractive for field applications. This raises now the question whether calcite dissolution is the primary mechanism of the LSF effect. In this paper, we aim to first demonstrate the positive response of carbonate rock to low salinity and then to gain insight into the underlying mechanism(s) specific to carbonate rock. We followed a similar methodology as in sandstone rock [Mahani, H.; Berg, S.; Ilic, D.; Bartels, W....
374 citations
TL;DR: In this article, the authors present a comprehensive state-of-the-art review on low salinity/engineered water injection for both sandstones and carbonates, including descriptions of underlying mechanisms, spontaneous imbibition and coreflood laboratory work, field-scale pilots, numerical and modeling work, implementation, comparison between sandstones, other LSWI/EWI applications, and desalination methods.
256 citations
TL;DR: In this paper, a review of recent studies on wettability alteration mechanisms that affect the interactions between the brine and oil and brine/rock interfaces of thin brine films that wet the surface of reservoir rocks is presented.
Abstract: Low-salinity waterflooding is a relatively new method for improved oil recovery that has generated much interest. It is generally believed that low-salinity brine alters the wettability of oil reservoir rocks towards a wetting state that is optimal for recovery. The mechanism(s) by which the wettability alteration occurs is currently an unsettled issue. This paper reviews recent studies on wettability alteration mechanisms that affect the interactions between the brine/oil and brine/rock interfaces of thin brine films that wet the surface of reservoir rocks. Of these mechanisms, we pay particular attention to double-layer expansion, which is closely tied to an increase in the thickness and stability of the thin brine films. Our review examines studies on both sandstones and carbonate rocks. We conclude that the thin-brine-film mechanisms provide a good qualitative, though incomplete, picture of this very complicated problem. We give suggestions for future studies that may help provide a more quantitative and complete understanding of low-salinity waterflooding.
250 citations
Cites background from "Laboratory Investigation of the Imp..."
...[10,11] is more strongly correlated with a change in surface charge from the pH increase as opposed to anhydrite dissolution [41]....
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...mechanism, or to a change in the surface charge of the carbonate, which is consistent with double-layer expansion [10,11]....
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...Anhydrite dissolution may improve oil recovery by increasing the connectivity of the pores so that the reservoir becomesmore permeable to flow [10,11]....
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..., LSE was not even observed in carbonates [10,11]....
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References
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Book•
01 Jan 1991
TL;DR: In this paper, the authors introduce the principles of imaging for nuclear magnetic resonance and describe the influence of magnetic field gradients on the magnetic field. But they do not discuss the application of magnetic resonance in biology and minerals science.
Abstract: Principles of imaging Introductory nuclear magnetic resonance The influence of magnetic field gradients High resolution k-space imaging k-space microscopy in biology and minerals science The measurement of motion using spin echoes Structural imaging using q-space Spatially heterogeneous motion and dynamic NMR microscopy Elements of the NMR microscope.
2,898 citations
TL;DR: In this paper, a single reservoir sandstone core was tested with repeated waterfloods and it was shown that potentially mobile fine particles play a key role in the sensitivity of oil recovery to salinity.
966 citations
TL;DR: The most accurate results are obtained when native-state, cleaned, and restored-state cores are run with native crude oil and brine at reservoir temperature and pressure as discussed by the authors, and they provide cores that have the same wettability as the reservoir.
Abstract: Wettability is a major factor controlling the location, flow and distribution of fluids in a reservoir. The wettability of a core will affect almost all types of core analyses, including capillary pressure, relative permeability, waterflood behavior, electrical properties, and simulated tertiary recovery. The most accurate results are obtained when native- or restored-state cores are run with native crude oil and brine at reservoir temperature and pressure. Such conditions provide cores that have the same wettability as the reservoir. The wettability of originally water-wet reservoir rock can be altered by the adsorption of polar compounds and/or the deposition of organic material that was originally in the crude oil. The degree of alteration is determined by the interaction of the oil constituents, the mineral surface, and the brine chemistry. The procedures for obtaining native-state, cleaned, and restored-state cores are discussed, as well as the effects of coring, preservation, and experimental conditional conditions on wettability. Also reviewed are methods for artificially controlling the wettability during laboratory experiments.
920 citations
Journal Article•
TL;DR: In this paper, the authors describe an experimental investigation into some of the factors controlling the increased oil recovery observed when low salinity brine is injected into oil saturated reservoir core samples.
Abstract: The idea of injecting low salinity water into a petroleum reservoir is not novel and was often used in the 70s prior to the injection of surfactant. Recently it was shown that simply injecting sufficiently low salinity water improves oil recovery. Many possible mechanisms concerning low-salinity waterflood have been proposed in the literature. This paper describes an experimental investigation into some of the factors controlling the increased oil recovery observed when low salinity brine is injected into oil saturated reservoir core samples. Extensive chemical analyses were performed on the effluent showing the extent of interaction between the injected brine, the oil and the rock matrix.
752 citations
TL;DR: In this paper, the effect of wettability on oil recovery from the Berea sandstone was investigated using more than 50 slow-rate laboratory waterfloods, and the results showed that the maximum oil recovery was obtained at very weakly water-wet conditions from shortly after breakthrough up to discontinuation of the test at 20 PV of water injected.
Abstract: This paper presents a definitive account of the effect of wettability on oil recovery from Berea sandstone based on the results of more than 50 slow-rate laboratory waterfloods. Closely reproducible wettability conditions and waterflood recoveries were obtained with wettability, depending on the crude oil, brine composition, aging temperature, and initial water saturation. Maximum oil recovery by waterflooding was obtained at very weakly water-wet conditions from shortly after breakthrough up to discontinuation of the test at 20 PV of water injected. In most of the tests, coproduction of oil and water continued long after breakthrough.
724 citations