Influence of brine composition and fines migration on crude oil/brine/rock interactions and oil recovery

Tang, Guiqian; Morrow, Norman R.

doi:10.1016/s0920-4105(99)00034-0

Cited by 929 publications

(626 citation statements)

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“…Moreover, the presence of clay minerals is seen to be a key requirement for low-salinity EOR to operate. 4,[6][7][8] This is due to the role that clays play in determining the wettability state of a rock. Clay minerals and quartz grains are widely present in the pores of sandstone reservoirs, where they form surface coatings.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

et al. 2015

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Publisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Journal of physical chemistry C, copyright c 2015 American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/acs.jpcc.5b00555Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractEnhanced oil recovery is becoming commonplace in order to maximise recovery from oilfields. One of these methods, low-salinity enhanced oil recovery (EOR) has shown promise, however the fundamental underlying chemistry requires elucidating. Here, three mechanisms proposed to account for low-salinity enhanced oil recovery in sandstone reservoirs are investigated using molecular dynamic simulations. The mechanisms probed are electric double layer expansion, multicomponent ionic exchange and pH effects arising at clay mineral surfaces. Simulations of smectite basal planes interacting with uncharged non-polar decane, uncharged polar decanoic acid and charged Nadecanoate model compounds are used to this end. Various salt concentrations of NaCl are modelled: 0% , 1% , 5% and 35% to determine the role of salinity upon the three separate mechanisms. Furthermore, the initial oil/water-wetness of the clay surface is modeled. Results show that electric double layer expansion is not able to fully explain the effects of low-salinity enhanced oil recovery. The pH surrounding a clays basal plane, and hence the protonation and charge of acid molecules is determined to be one of the dominant effects driving low-salinity EOR. Further, results present that the presence of calcium cations can drastically alter the oil wettability of a clay ⇤To whom correspondence should be addressed mineral surface. Replacing all divalent cations with monovalent cations through multicomponent cation exchange dramatically increases the water wettability of a clay surface, and will increase EOR.

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

et al. 2015

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“…According to Tang and Morrow (1999), the stripping of the clay particles from the rock surface is related to the expansion the electric double layer, which is related to the decrease in the salinity. This LSF effect is mainly present in sandstone reservoirs, but the expansion of the EDL can occur during LSF in carbonates as well.…”

Section: Fines Migrationmentioning

confidence: 99%

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Ouden¹,

Nasralla²,

Guo³

et al. 2015

Proceedings

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Master of ScienceCalcite dissolution behaviour during low salinity water flooding in carbonate rockby Liselotte den OudenLow salinity water flooding (LSF) has been proved to be a promising enhanced oil recovery method for sandstone reservoirs. The efficiency of LSF in carbonate reservoirs has not been proven completely yet, because there are still uncertainties about the LSF recovery mechanism in carbonate. From experimental studies, it was shown that wettability alteration, due to salinity reduction, is able to mobilize the remaining oil. Some studies attributed the wettability alteration by LSF to Calcite dissolution. Furthermore, Calcite dissolution can influence the salinity and pH of injected brines, and hence the oil recovery.However, there is a lack of experimental data on the Calcite dissolution effect of LSF in carbonate rock.The objective of this experimental study was to get a better understanding of the Calcite dissolution behaviour and how it might affect the oil recovery. Bulk and coreflood experiments have been performed; the experimental data was history matched with the use of PHREEQC. Calcite dissolution decreased with decreasing P CO2 and increased with decreasing pH and increasing NaCl salinity from 500-2000PPM.Increasing the injection rate reduced the interaction time and therefore Calcite dissolution did not reach equilibrium in coreflood at high rates. Calcite dissolution from chalk matched with the Calcite dissolution from pure Calcite, while Calcium concentration in effluent from limestone was higher. The two-phase coreflood experiment confirmed that Calcite dissolution occurs as well if oil is present in the porous media, but showed lower values than in single-phase coreflood experiment. pH increased from 5-6 to 9.5 due to Calcite dissolution, which might have an effect on the rock and oil surface charges, and hence oil recovery improvement. The effluent of the two-phase coreflood showed that an emulsion was formed, which suggested formation of in-situ surfactants. From CT scans, micro-CT scans and material mass balance calculations an increase in porosity around 1% was observed. The increase in the total dissolved species due to Calcite dissolution was not significant, which will not harm LSF effect.

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“…The hypothesis that migration of detached mixed-wet clay particles with absorbed residual oil drops (Tang and Morrow 1999) has no relevance to the standard capillary number. Their hypothesis claims that the increased recovery originates from those oil drops adhering Influence of salinity on injection pressure difference and water permeability.…”

Section: Water Permeability Reduction: the Only Dynamic Variable Whicmentioning

confidence: 99%

“…(Loahardjo et al 2007) Many hypotheses have been proposed to explain the oil recovery mechanism of low salinity water injections. Those included migration of detached mixed-wet clay particles with absorbed residual oil drops (Tang and Morrow 1999), wettability alteration toward increased water-wetness (Tang and Morrow 1999;Ligthelm et al 2009;Austad and Puntervold 2010;Sorbie and Collins 2010), saponification (McGuire et al 2005), and cation exchange (Lager et al 2006;Lebedeva et al 2009;Austad and Puntervold 2010). However, none of these hypotheses has been verified by experiments.…”

Section: Introductionmentioning

confidence: 99%

Oil Recovery by Low Salinity Water Injection into a Reservoir: A New Study of Tertiary Oil Recovery Mechanism

2011

Transp Porous Med

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Low salinity water injections for oil recovery have shown seemingly promising results in the case of clay-bearing sandstones saturated with asphaltic crude oil. Reported data showed that low salinity water injection could provide up to 20% pore volume (PV) of additional oil recovery for core samples and up to 25% PV for reservoirs in near wellbore regions, compared with brine injection at the same Darcy velocity. The question remains as to whether this additional recovery is also attainable in reservoirs. The answer requires a thorough understanding of oil recovery mechanism of low salinity water injections. Numerous hypotheses have been proposed to explain the increased oil recovery using low salinity water, including migration of detached mixed-wet clay particles with absorbed residual oil drops, wettability alteration toward increased water-wetness, and emulsion formation. However, many later reports showed that a higher oil recovery associated with low salinity water injection at the common laboratory flow velocity was neither necessarily accompanied by migration of clay particles, nor necessarily accompanied by emulsion. Moreover, increased water-wetness has been shown to cause the reduction of oil recovery. The present study is based on both experimental and theoretical analyses. Our study reveals that the increased oil recovery is only related to the reduction of water permeability due to physical plugging of the porous network by swelling clay aggregates or migrating clay particles and crystals. At a fixed apparent flow velocity, the value of negative pressure gradient along the flow path increases as the water permeability decreases. Some oil drops and blobs can be mobilized under the increased negative pressure gradient and contribute to the additional oil recovery. Based on the revealed mechanism, we conclude that low salinity water injection cannot be superior to brine injection in any clay-bearing sandstone reservoir at the maximum permitted injection pressure. Through our study of low salinity water injection, the theory of tertiary oil recovery has been notably improved. Keywords

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Influence of brine composition and fines migration on crude oil/brine/rock interactions and oil recovery

Cited by 929 publications

References 13 publications

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

Molecular Dynamic Simulations of Montmorillonite–Organic Interactions under Varying Salinity: An Insight into Enhanced Oil Recovery

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Oil Recovery by Low Salinity Water Injection into a Reservoir: A New Study of Tertiary Oil Recovery Mechanism

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