Dynamic wettability alteration for combined low salinity brine injection and surfactant flooding on silica surface

A new generation improved oil recovery methods comes from combining techniques to make the overall process of oil recovery more efficient. One of the most promising methods is combined Low Salinity Surfactant (LSS) flooding. Low salinity brine injection has proven by numerous laboratory core flood experiments to give a moderate increase in oil recovery. Current research shows that this method may be further enhanced by introduction of surfactants optimized for lowsal environment by reducing the interfacial tension. Researchers have suggested different mechanisms in the literature such as pH variation, fines migration, multi-component ionic exchange, interfacial tension reduction and wettability alteration for improved oil recovery during lowsal injection. In this study, surfactant solubility in lowsal brine was examined by bottle test experiments. A series of core displacement experiments was conducted on nine crude oil aged Berea core plugs that were designed to determine the impact of brine composition, wettability alteration, Low Salinity Water (LSW) and LSS flooding on Enhancing Oil Recovery (EOR). Laboratory core flooding experiments were conducted on the samples in a heating cabinet at 60 °C using five different brine compositions with different concentrations of NaCl, CaCl2 and MgCl2. The samples were first reached to initial water saturation, Swi, by injecting connate water (high salinity water). LSW injection followed by LSS flooding performed on the samples to obtain the irreducible oil saturation. The results showed a significant potential of oil recovery with maximum additional recovery of 7% Original Oil in Place (OOIP) by injection of LS water (10% LS brine and 90% distilled water) into water-wet cores compared to high salinity waterflooding. It is also concluded that oil recovery increases as wettability changes from water-wet to neutral-wet regardless of the salinity compositions. A reduction in residual oil saturation, Sor, by 1.1–4.8% occurred for various brine compositions after LSS flooding in tertiary recovery mode. The absence of clay swelling and fine migration has been confirmed by the stable differential pressure recorded for both LSW and LSS flooding. Aging the samples at high temperature prevented the problem of fines production. Combined LSS flooding resulted in an additional oil recovery of 9.2% OOIP when applied after LSW flooding. Surfactants improved the oil recovery by reducing the oil-water interfacial tension. In addition, lowsal environment decreased the surfactant retention, thus led to successful LSS flooding. The results showed that combined LSS flooding may be one of the most promising methods in EOR. This hybrid improved oil recovery method is economically more attractive and feasible compared to separate low salinity waterflooding or surfactant flooding.

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A New Insight into Hybrid Surfactant and Low Salinity/Engineered Water Injections in Carbonates Through Geochemical Modeling

10.4043/31128-ms ◽

2021 ◽

Author(s):

Ahmed S. Adila ◽

Emad W. Al-Shalabi ◽

Waleed Alameri

Keyword(s):

Sensitivity Analysis ◽

Simulation Model ◽

Oil Recovery ◽

Surfactant Concentration ◽

Wettability Alteration ◽

Surfactant Flooding ◽

Exchange Reactions ◽

Concentration Data ◽

Low Salinity ◽

Hybrid Surfactant

Abstract Low salinity/engineered water injections (LSWI/EWI) have gained popularity as effective techniques for enhancing oil recovery. Surfactant flooding is also a well-established and commercially-available technique in the oil and gas industry. In this paper, a numerical 2D simulation model was developed to investigate the effect of hybrid surfactant-LSWI/EWI on oil recovery from carbonate cores under harsh conditions. The developed simulation model was validated by history-matching recently conducted surfactant corefloods in the secondary mode of injection. Oil recovery, pressure drop, and surfactant concentration data were utilized. The surfactant flooding model was then coupled with a geochemical model that captures different reactions during LSWI/EWI. The geochemical reactions considered include aqueous, dissolution/precipitation, and ion-exchange reactions. Different simulation scenarios were considered and compared including waterflooding, surfactant flooding, engineered water injection, hybrid surfactant-EWI, and hybrid surfactant-LSWI. Additionally, sensitivity analysis was performed on the hybrid surfactant-EWI process through capturing changes in surfactant injected concentration and adsorption. For the case of LSWI/EWI, wettability alteration was considered as the main mechanism underlying incremental oil recovery. However, both wettability alteration and interfacial tension reduction mechanisms were considered for surfactant flooding depending on the type of surfactant used. The results showed that the hybrid surfactant-EWI altered the wettability and achieved higher oil recovery than that of surfactant-LSWI and other techniques. This highlights the importance of selecting the right combinations of potential ions for a certain reservoir to maximize oil recovery rather than a simple water dilution. The results also highlight the importance of surfactant adsorption and surfactant concentration for the hybrid surfactant-EWI technique. This work provides insights into the application of hybrid surfactant-LSWI/EWI on oil recovery especially in carbonates. The novelty of this work is further expanded through comparing surfactant-LSWI with surfactant-EWI and understanding the controlling parameters of surfactant-EWI through sensitivity analysis.

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Oil Recovery by Low-Salinity Brine Injection: Laboratory Results on Outcrop and Reservoir Cores

10.2118/124277-ms ◽

2009 ◽

Cited By ~ 27

Author(s):

Boussour Soraya ◽

Cissokho Malick ◽

Cordier Philippe ◽

Henri Jacques Bertin ◽

Gerald Hamon

Keyword(s):

Oil Recovery ◽

Low Salinity ◽

Laboratory Results ◽

Brine Injection

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A mechanistic investigation of low salinity water flooding coupled with ion tuning for enhanced oil recovery

RSC Advances ◽

10.1039/d0ra08301a ◽

2020 ◽

Vol 10 (69) ◽

pp. 42570-42583

Author(s):

Rohit Kumar Saw ◽

Ajay Mandal

Keyword(s):

Enhanced Oil Recovery ◽

Oil Recovery ◽

Water Flooding ◽

Wettability Alteration ◽

Rock Surface ◽

Calcite Dissolution ◽

Low Salinity ◽

Low Salinity Water ◽

Mechanistic Investigation ◽

Salinity Water

The combined effects of dilution and ion tuning of seawater for enhanced oil recovery from carbonate reservoirs. Dominating mechanisms are calcite dissolution and the interplay of potential determining ions that lead to wettability alteration of rock surface.

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Phase Behavior, Wettability Alteration, and Oil Recovery of Low-Salinity Surfactant Solutions in Carbonate Reservoirs

SPE Journal ◽

10.2118/200483-pa ◽

2020 ◽

Vol 25 (04) ◽

pp. 1784-1802 ◽

Cited By ~ 1

Author(s):

Sepideh Veiskarami ◽

Arezou Jafari ◽

Aboozar Soleymanzadeh

Keyword(s):

Phase Behavior ◽

Oil Recovery ◽

Wettability Alteration ◽

Study Phase ◽

Low Salinity ◽

Angle Measurements ◽

Contact Angle Measurements ◽

Favorable State ◽

Phase Behaviors ◽

The Impact

Summary Recent investigations have shown that treatment with injected brine composition can improve oil production. Various mechanisms have been suggested to go through the phenomenon; nevertheless, wettability alteration is one of the most commonly proposed mechanisms in the literature. Wettability alteration of the porous media toward a more favorable state reduces the capillary pressure, consequently contributing to the oil detachment from pore walls. In this study, phase behavior, oil recovery, and wettability alteration toward a more favorable state were investigated using a combination of formulations of surfactant and modified low-salinity (LS) brine. Phase behaviors of these various formulations were examined experimentally through observations on relative phase volumes. Experiments were performed in various water/oil ratios (WORs) in the presence of two different oil samples, namely C1 and C2. These experiments were conducted to clarify the impact of each affecting parameter; in particular, the impact of resin and asphaltene of crude oil on the performance of LS surfactant (LSS) flooding. Hereafter, the optimal formulation was flooded into the oil-wet micromodel. Optimum formulations increased the capillary number more than four orders of magnitude higher than that under formation brine (FB) flooding, thus causing oil recovery rates of 61 and 67% for oil samples C1 and C2, respectively. Likewise, the wettability alteration potential of optimized formulations was studied through contact angle measurements. Results showed that LS and LSS solutions could act as possible wettability alternating methods for oil-wet carbonate rocks. Using the optimum formulation resulted in a wettability alteration index (WAI) of 0.66 for sample C1 and 0.49 for sample C2, while using LS brine itself ended in 0.51 and 0.29 for oil samples C1 and C2, respectively.

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