The low salinity effect observed on sandstone model surfaces

Hassenkam, Tue; Mitchell, A. C.; Pedersen, Christian; Skovbjerg, L.L.; Bovet, N.; Stipp, S. L. S.

doi:10.1016/j.colsurfa.2012.03.058

Cited by 73 publications

(81 citation statements)

References 24 publications

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“…Our results indicate that increased oil release by low salinity waterflooding could take place as suggested by Lager and colleagues but not exclusively so. The low salinity effect on reservoir sand grains is more generally consistent with previous studies on model surfaces (Hassenkam, Mitchell, et al 2012) but the question remains if the general mechanism we observe at nanometre scale is an indicator of what is observed at kilometre scale. Two important independent observations show that it does.…”

Section: Resultssupporting

confidence: 89%

“…We were not able to confirm the mechanism proposed by Lager et al but we could not disprove it either. We have also tested the low salinity effect on various model mineral surfaces both with acidic tips (functionalised with -COO(H) and hydrophobic tips (functionalised with -CH 3 ) (Hassenkam, Mitchell, et al 2012). The conclusion from these studies was that we consistently observe a low salinity response on most of the studied surfaces with both types of tips.…”

Section: Introductionmentioning

confidence: 99%

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A Fast Alternative to Core Plug Tests for Optimising Injection Water Salinity for EOR

et al. 2014

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Core tests have demonstrated that decreasing the salinity of injection water can increase oil recovery. Although recovery is enhanced by simply decreasing salt content, optimising injection water salinty would offer a clear economic advantage for several reasons. Too low salinity risks swelling of the clays which would lead to permanent reservoir damage but evidence of effectiveness at moderate salinity would offer the opportunity to dispose of produced water. The goal is to define boundary conditions so injection water salinity is high enough to prevent reservoir damage and low enough to induce the low salinity effect while keeping costs and operational requirements at a minimum. Traditional core plug testing for optimising conditions has some limitations. Each test requires a fresh sample, core testing requires sophisticated and expensive equipment, and reliable core test data requires several months because cores must be cleaned, restored and aged before the tests can begin. It is also difficult to compare data from one core with results from another because no two cores are identical, making it difficult to distinguish between effects resulting from different conditions and effects resulting from different cores. Gathering statistics is limited by the time required for each test and the fact that core material is in short supply. Thus, our aim was to explore the possibility of a cheaper, faster alternative. We developed a method that uses atomic force microscopy (AFM) to investigate the relationship between the wettability of pore surfaces and water salinity. We functionalise AFM tips with organic molecules and use them to represent tiny oil droplets of nonpolar or polar molecules and we use sand grains removed from core plugs to represent the pore walls in sandstone. We bring our "oil" close to the sand grain surface and measure the work of adhesion between the tip and the surface. Repeated "feeling" the surface with the tip produces data that can be converted to maps of adhesion and contact angle. Adhesion work is proportional to wettability and is directly correlated with the salinity of the fluid in contact with the tip and the particle surface. From our measurements, the threshold values for the onset of the low salinity response is 5,000 to 8,000 ppm, which benchmarks remarkably well with observations from core plug tests. Changing either the type of "oil" on our probe or the character of the grain surface both affect the adhesion response. From a mechanistic perspective, the correlation between salinity and adhesion provides evidence for the role of electrical double layer expansion in the low salinity response; expansion of the double layer decreases oil wettability. Because AFM experiments can be done relatively quickly on very little material, it gives the possibility of testing salinity response on samples from throughout a reservoir and for gathering statistics. Our approach provides a range of data that can be used to screen core plug testing conditions and to provide extra data that would be too...

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

A Fast Alternative to Core Plug Tests for Optimising Injection Water Salinity for EOR

et al. 2014

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“…In this process, the brine chemistry has been recognized as an important parameter critically affecting the efficiency of the process. Different laboratory and field studies have proved the remarkable low salinity effect on the ultimate oil recovery and reported greater oil recovery with decreasing the ionic strength of water (Ashraf et al, 2010;Hassenkam et al, 2012). On the other hand, the brine chemistry drastically affects the interactions of colloidal particles, situated on the pore walls, with the medium surface (Lager et al, 2008;Nasralla et al, 2011).…”

Section: Introductionmentioning

confidence: 96%

Application of nanofluid to control fines migration to improve the performance of low salinity water flooding and alkaline flooding

Assef

Arab

Pourafshary

2014

Journal of Petroleum Science and Engineering

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“…Adventitious organic material is also observed on freshly fractured model surfaces, on polished surfaces, and even on surfaces freshly cleaned using UV-ozone treatment. 11 This adsorbed carbon contamination comes spontaneously from the air or solution in contact with the solid phase and affects the adsorption properties of the pore surfaces. Thus, the history of the sediment has a strong effect on its wetting properties.…”

Section: ■ Introductionmentioning

confidence: 99%

Salinity-Dependent Adhesion Response Properties of Aluminosilicate (K-Feldspar) Surfaces

et al. 2017

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Flooding sandstone oil reservoirs with low salinity water can lead to a significant increase in oil recovery, a phenomenon called "the low salinity effect". Although there are many factors that contribute to this response, the surface tension on the pore walls is an important one. Sandstone is composed predominantly of quartz with some clay, but feldspar grains are often also present. While the wettability of quartz and clay surfaces has been thoroughly investigated, little is known about the adhesion properties of feldspar. We explored the interaction of model oil compounds, molecules that terminate with carboxyl, −COO(H), and alkyl, −CH 3 , with freshly cleaved, museum quality perthitic microcline, K x Na (1−x) AlSi 3 O 8 , a K-feldspar. Microcline is a member of the orthoclase family, a type of feldspar that weathers more slowly than the plagioclase series, and thus is more likely to be preserved in well sorted sandstone. Adhesion forces, measured with the chemical force mapping (CFM) mode of atomic force microscopy (AFM), showed a low salinity effect on the fresh feldspar surfaces. Adhesion force, measured with −COO(H)-functionalized tips, was 60% lower in artificial low salinity seawater (LS, ∼1500 ppm total dissolved solids) than in the high salinity solution, artificial seawater (HS, ASW, ∼35 600 ppm). Adhesion with the −CH 3 tips was as much as 30% lower in LS than in HS. Density functional theory calculations indicated that the low salinity response resulted from expansion of the electric double layer and that contributions from cation bridging are of less importance. Adventitious carbon, that is, organic material that is inherent on all mineral surfaces exposed to air or water, can enhance nonpolar component adhesion by serving as anchor points.

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The low salinity effect observed on sandstone model surfaces

Cited by 73 publications

References 24 publications

A Fast Alternative to Core Plug Tests for Optimising Injection Water Salinity for EOR

A Fast Alternative to Core Plug Tests for Optimising Injection Water Salinity for EOR

Application of nanofluid to control fines migration to improve the performance of low salinity water flooding and alkaline flooding

Salinity-Dependent Adhesion Response Properties of Aluminosilicate (K-Feldspar) Surfaces

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