Adsorption of EOR Chemicals under Laboratory and Reservoir Conditions, Part 1 - Iron Abundance and Oxidation State

Levitt, David; Weatherl, Robin; Harris, H. Wayne; McNeil, Robert I.; Didier, Mathilde; Loriau, Matthieu; Gaucher, Eric C.; Bourrel, M.

doi:10.3997/2214-4609.201412159

Cited by 20 publications

(18 citation statements)

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“…The confounding role of iron oxidation in surfactant adsorption measurements, first identified by Wang in 1993 [1], is presented in detail in Part I of this investigation [2].…”

Section: Introductionmentioning

confidence: 87%

Adsorption of EOR Chemicals Under Laboratory and Reservoir Conditions, Part II: Bacterial Reduction Methods

Harris

Grimaud

Levitt

2015

Day 1 Tue, August 11, 2015

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We have successfully performed bacterial reduction of an iron-containing outcrop sand sample under static conditions using Shewanella genus bacteria. Adsorption of an anionic (alkyl benzyl sulfonate) surfactant was around 7-times lower on treated outcrop samples. Most of this reduction (~3X) occurs over the first 3-4 days of incubation, contemporaneously with iron dissolution and limited biofilm formation. Continued incubation after this point attends the formation of significant biofilm, as well as a continued decrease in surfactant adsorption. Non-iron-reducing bacteria also formed biofilm on outcrop samples, yielding a significant (though smaller) decrease in surfactant adsorption. Microscopy demonstrates preferential attachment of biofilm to iron minerals in a heterogenous outrop sample. Repeated rinsing results in a removal of biofilm formed by iron-reducing or bacteria and a corresponding increase in surfactant adsorption to about 1/3 to 1/2 of original levels. This proof of concept for a bacterial core restoration method using iron-reducing bacteria is considered successful, with the caveat that care must be taken to minimize and/or remove biofilm in order to avoid biofilm-related artifacts. Implications of these results for the determination of reservoir rock-fluid properties in biologically-active reservoirs are also discussed.

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“…The confounding role of iron oxidation in surfactant adsorption measurements, first identified by Wang in 1993 [1], is presented in detail in Part I of this investigation [2].…”

Section: Introductionmentioning

confidence: 87%

Adsorption of EOR Chemicals Under Laboratory and Reservoir Conditions, Part II: Bacterial Reduction Methods

Harris

Grimaud

Levitt

2015

Day 1 Tue, August 11, 2015

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“…Rinsing with NaHCO 3 reduces P550 adsorption by about half, or that corresponding to a dense monolayer. Levitt et al (2015) propose the hypothesis that high levels of adsorption reported on pyrite in the literature (Bae, 2012) are due to rapid oxidation, yielding either a higher SSA, more positive surface charge, or both. This is suggested as a mechanism by which oxidation increases the adsorption of anionic surfactants over relatively short time spans.…”

Section: Hydrous Ferrous Oxide (Hfo)mentioning

confidence: 99%

“…The origin, abundance, and oxidation state of iron in reservoir and outcrop cores, as well as the effect of these factors on surfactant adsorption and wettability, is discussed in detail by Levitt et al (2015). The literature review below will briefly summarize the framework necessary to discuss adsorption values, present literature values for adsorption on common minerals, and put forward proposed chemical treatment methods for core restoration.…”

Section: Introductionmentioning

confidence: 99%

“…Adsorption Framework: Molecular packing area (MPA) Levitt et al (2015) summarizes the classic 4 stages of surfactant adsorption described in the literature (Somasundaran and Fuerstenau, 1966;Cases et al, 1982;Somasundaran and Zhang, 2006). For the case of the adsorption of an ionic surfactant on an oppositely-charged, highly-energetic surface, this culminates, at surfactant concentration above the CMC, in the formation of a dense-packed monolayer or bilayer, as illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption of EOR Chemicals Under Laboratory and Reservoir Conditions, Part III: Chemical Treatment Methods

Levitt

Bourrel

2016

All Days

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This is the final installment in a series of three papers examining iron mineralogy and its effect on surfactant adsorption in reservoir and outcrop rock samples. The goal of these studies is to establish best practices for obtaining surfactant adsorption values representative of those in a reduced oil reservoir, despite performing experiments in an oxidizing laboratory atmosphere.This article follows two others examining the abundance and form of iron in the reservoir and in core samples (Part I: Levitt et al., 2015), and a proposed core restoration technique utilizing iron-reducing bacteria (Part II: Harris et al., 2015). In this Part III, chemical reduction methods are examined.Surfactant retention is a leading uncertainty in economic forecasting of chemical EOR, in large part due to the order-of-magnitude effects of artifacts such as improper core preservation. The industry standard is to (a) limit atmospheric contact of cores to the extent feasible, and (b) when necessary, reduce oxidized cores using strong reducing agents such as sodium dithionite, along with buffering and chelating agents such as sodium bicarbonate and EDTA or sodium citrate. However few studies have been performed to determine whether such invasive treatments are necessary, or what unintended effects the use of such reactive chemicals may have.The most striking conclusion from these studies is the lack of clear evidence of any advantage of electrochemical reduction versus a simpler treatment with chelators such as sodium citrate or EDTA. Wang (1993) suggests that oxidation of reservoir cores leads to higher surfactant adsorption due to the reduction of clays, which yields a more negative surface charge. Static experiments with montmorillonite clay, as well as an oxidized outcrop containing significant clay and iron content, illustrate that rinsing with non-reducing agents such as sodium bicarbonate, EDTA, or sodium citrate can lower adsorption as much as a strong reducing agent such as sodium dithionite. In the case of montmorillonite, cation exchange appears to be the mechanism by which adsorption is lowered, and so NaCl alone is sufficient to lower adsorption to near-zero values. For the iron-and clay-containing outcrop material, initial measurements indicating ЉadsorptionЉ far in excess of a dense bilayer were due in fact to the precipitation of sulfonate surfactant with calcium, which eluded from the dissolution of small amounts of anhydrite. An alkyl alkoxy sulfonate surfactant showed higher calcium tolerance, and did not yield ЉmultilayerЉ adsorption when equilibrated with the anhydrite-containing core sample.While treatment with a citrate-bicarbonate-dithionite solution does indeed lower adsorption several-fold further, solutions of either sodium bicarbonate or EDTA are at least as effective, and sodium citrate is almost as effective. These non-reductive treatments remove small amounts (~0.1% -~0.2% of rock mass) of Fe and Al, and fines are invariably apparent in treatment fluids, both of which suggest removal of small amounts of t...

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“…Thus, low surfactant retention is the key to low cost CEOR so much attention has been focused on this area of research. Recent studies of surfactant retention have been reported by Zhang and Somasundaran (2006), Solairaj et al (2012), ShamsiJazeyi et al (2014aShamsiJazeyi et al ( , 2014b, Southwick et al (2014), Levitt et al (2015), Tay et al (2015), van den Pol et al (2015) and van der Lee et al (2015). Surfactant retention is caused by both adsorption on the rock surface and trapping of a surfactant-rich phase.…”

Section: Introductionmentioning

confidence: 96%

A Systematic Method for Reducing Surfactant Retention to Extremely Low Levels

et al. 2016

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The chemical cost to recover an incremental barrel of oil is directly proportional to the surfactant retention, so the single most effective way to reduce the cost is to reduce surfactant retention. The main objective of this research was to demonstrate how surfactant retention could be reduced to almost zero by careful optimization of the chemical formulations for different crude oils. Although surfactant retention has been studied for many years over a wide range of reservoir conditions, its dependence on the rheological behavior of the microemulsion that forms in-situ has not been adequately studied. Thus, in this paper we emphasize the importance of microemulsion rheology and demonstrate how to develop and test formulations with properties that give very low surfactant retention. Novel co-solvents (iso-butanol (IBA) alkoxylates and phenol alkoxylates) were tested in some of the formulations with excellent results. Unlike classical co-solvents used to optimize chemical formulations, the new co-solvents cause only a slight increase in the interfacial tension. A series of ASP corefloods were performed in sandstone cores with and without oil to measure surfactant and co-solvent retention and to elucidate the effects of microemulsion viscosity, salinity gradient, clay content, surfactant concentration and other variables. Dynamic adsorption was measured in cores with the same mineralogy and compared with the retention from oil recovery corefloods to determine the component of the retention due to phase trapping.

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Adsorption of EOR Chemicals under Laboratory and Reservoir Conditions, Part 1 - Iron Abundance and Oxidation State

Cited by 20 publications

References 0 publications

Adsorption of EOR Chemicals Under Laboratory and Reservoir Conditions, Part II: Bacterial Reduction Methods

Adsorption of EOR Chemicals Under Laboratory and Reservoir Conditions, Part II: Bacterial Reduction Methods

Adsorption of EOR Chemicals Under Laboratory and Reservoir Conditions, Part III: Chemical Treatment Methods

A Systematic Method for Reducing Surfactant Retention to Extremely Low Levels

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