Surfactant Flooding 2: The Effect of Alkaline Additives on Permeability and Sweep Efficiency

Krumrine, P.H.; Falcone, James S.; Campbell, Thomas C.

doi:10.2118/9811-pa

Cited by 39 publications

(11 citation statements)

References 13 publications

(3 reference statements)

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“…The surfactant treatment of fractured reservoirs is very different from the traditional surfactant or alkaline-surfactant-polymer flooding of nonfractured reservoirs (Bragg et al 1982;Kalpakci et al 1990;Krumrine et al 1982aKrumrine et al , 1982bFalls et al 1994). For surfactant flooding, the initial oil saturation is the waterflood residual (approximately 35%), and the expected recovery is approximately 20% of OOIP.…”

Section: Introductionmentioning

confidence: 99%

Oil Recovery From Fractured Carbonates by Surfactant-Aided Gravity Drainage: Laboratory Experiments and Mechanistic Simulations

Adibhatla

Mohanty

2008

SPE Reservoir Evaluation &Amp; Engineering

121

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Waterflooding recovers little oil from naturally fractured carbonate reservoirs if the matrix is oil-wet and fracture intensity is high. Laboratory experiments and mechanistic simulations have been conducted to understand the injection of dilute anionic surfactant solutions into oil-wet, fractured reservoirs. In this process, surfactant diffuses into the matrix, lowering the interfacial tension (IFT) and contact angle, which decreases the capillary pressure and increases oil relative permeability, enabling gravity to drain up the oil. The rate of oil recovery increases with an increase in matrix permeability, a decrease in initial gas saturation, a decrease of fracture height or spacing, and an increase in the wettabilityaltering capabilities of the surfactant. Increasing the surfactant concentration does not necessarily enhance the oil recovery rate, because IFT and wettability alterations are not linearly related to surfactant concentration. Adsorption of anionic surfactants on calcite can be suppressed with an increase in pH and a decrease in salinity.

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Section: Introductionmentioning

confidence: 99%

Oil Recovery From Fractured Carbonates by Surfactant-Aided Gravity Drainage: Laboratory Experiments and Mechanistic Simulations

Adibhatla

Mohanty

2008

SPE Reservoir Evaluation &Amp; Engineering

121

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“…Surfactant-polymer flooding, 8 low-tension polymer flooding, 9 and alkaline-surfactant-polymer flooding [10][11][12] were developed from the 1960s through the 1980s. They were technical successes, but they have not been implemented in many fields because of low oil prices during the last 15 years.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical Interactions During Surfactant Flooding of Fractured Carbonate Reservoirs

2004

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Recovery from fractured, oil-wet/mixed-wet, carbonate reservoirs by waterflooding is poor. Dilute surfactant methods are being developed to improve oil recovery from fractured carbonates. This paper investigates the interactions of dilute alkaline anionic surfactant solutions with crude oil on carbonate mineral surfaces. Wettability, phase behavior, interfacial tension, and adsorption experiments have been conducted. Anionic surfactants have been identified that can change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant dodecyl trimethyl ammonium bromide (DTAB) with a west Texas crude oil. All the carbonate surfaces (lithographic limestone, marble, dolomite, and calcite) show similar behavior with respect to wettability alteration with an anionic surfactant. Anionic surfactants, which lower the interfacial tension with the crude oil to very low values (<10 -2 mN/m), have also been identified. The adsorption of the sulphonate surfactants can be suppressed significantly by the addition of Na 2 CO 3 , because the addition of carbonate can change the zeta potential of calcite to a negative value. Greater than 50% OOIP can be recovered from oil-wet carbonate cores by spontaneous imbibition of 0.05 wt% anionic surfactant solutions in the laboratory scale.

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“…Water does not imbibe into the oil-wet matrix because of negative capillary pressure, resulting in very low oil recovery. Thus there is a need of tertiary or enhanced oil recovery techniques like surfactant flooding (Bragg et al 1982;Kalpakci et al 1990;Krumrine et al 1982a;Krumrine et al 1982b;Falls et al 1992) to maximize production from such reservoirs. These techniques were developed in 1960s through 1980s for sandstone reservoirs, but were not widely applied because of low oil prices.…”

Section: Introductionmentioning

confidence: 99%

Atomic Force Microscopy Study of Wettability Alteration by Surfactants

2008

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Summary Waterflooding recovers little oil from fractured carbonate reservoirs, if they are oil-wet or mixed-wet. Surfactant-aided gravity drainage has the potential to achieve significant oil recovery by wettability alteration and interfacial tension (IFT) reduction. The goal of this work is to investigate the mechanisms of wettability alteration by crude oil components and surfactants. Contact angles are measured on mineral plates treated with crude oils, crude oil components, and surfactants. Mineral surfaces are also studied by atomic force microscopy (AFM). Surfactant solution imbibition into parallel plates filled with a crude oil is investigated. Wettability of the plates is studied before and after imbibition. Results show that wettability is controlled by the adsorption of asphaltenes. Anionic surfactants can remove these adsorbed components from the mineral surface and induce preferential water wettability. Anionic surfactants studied can imbibe water into initially oil-wet parallel-plate assemblies faster than the cationic surfactant studied. Introduction Waterflooding is an effective method to improve oil recovery from reservoirs. For fractured reservoirs, waterflooding is effective only when water imbibes into the matrix spontaneously. If the matrix is oil-wet, the injected water displaces the oil only from the fractures. Water does not imbibe into the oil-wet matrix because of negative capillary pressure, resulting in very low oil recovery. Thus there is a need of tertiary or enhanced oil recovery techniques like surfactant flooding (Bragg et al. 1982; Kalpakci et al. 1990; Krumrine et al. 1982a; Krumrine et al. 1982b; Falls et al. 1992) to maximize production from such reservoirs. These techniques were developed in 1960s through 1980s for sandstone reservoirs, but were not widely applied because of low oil prices. Austad et al. (Austad and Milter 1997; Standnes and Austad 2000a; Standnes and Austad 2000b; Standnes and Austad 2003c) have recently demonstrated that surfactant flooding in chalk cores can change the wettability from oil-wet to water-wet conditions, thus leading to higher oil recovery (~70 % as compared to 5% when using pure brine). In 2003 (Standnes and Austad 2003a; Standnes and Austad 2003b; Strand et al. 2003), they identified cheap commercial cationic surfactants, C10NH2 and bioderivatives from the coconut palm termed Arquad and Dodigen (priced at US$ 3 per kg). These surfactants could recover 50 to 90% of oil in laboratory experiments. However, the cost involved is still high because of the required high concentration (~1 wt%) and thus there is a need to evaluate other surfactants. The advantage of using cationic surfactants for carbonates is that they have the same charge as the carbonate surfaces and thus have low adsorption. Nonionic surfactants and anionic surfactants have been tested by Chen et al. (2001) in both laboratory experiments and field pilots. Computed tomography scans revealed that surfactant imbibition was caused by countercurrent flow in the beginning and gravity-driven flow during the later stages. The basic idea behind these techniques is to alter wettability (from oil-wet to water-wet) and lower interfacial tension. Hirasaki and Zhang (2004) have studied different ethoxy and propoxy sulfates to achieve very low interfacial tension and alter wettability from oil-wet to intermediate-wet in laboratory experiments. The presence of Na2CO3 reduces the adsorption of anionic surfactant by lowering the zeta potential of calcite surfaces, and thus dilute anionic surfactant/alkali solution flooding seems to be very promising in recovering oil from oil-wet fractured carbonate reservoirs. It is very important to understand the mechanism of wettability alteration to design effective surfactant treatments and identify the components of oil responsible for making a surface oil-wet. It is postulated that oil is often produced in source rocks and then migrates into originally water-wet reservoirs. Some of the ionic/polar components of crude oil, mostly asphaltenes and resins, collect at the water/oil interface (Freer et al. 2003) and adsorb onto the mineral surface, thus rendering the surface oil-wet. In this work, we try to understand the nature of the adsorbed components by AFM. Recently, AFM has been used extensively to get the force-distance measurements between a tip and a surface. These force measurements can be used to calculate the surface energies using the Johnson-Kendall-Roberts (JKR), the Derjaguin-Muller-Toporov (DMT), and like theories (van der Vegte and Hadziioannou 1997; Schneider et al. 2003). AFM is also used extensively for imaging surfaces. It can be used in the contact mode for hard surfaces and in the tapping mode for soft surfaces. It can be used to image dry surfaces or wet surfaces; tapping mode in water is a relatively new technique. AFM images have been used to confirm the deposition of oil components on mineral surfaces (Buckley and Lord 2003; Toulhoat et al. 1994). In this work, crude-oil-treated mica surface is probed using atomic force microscopy before and after surfactant treatment to study the effects of surfactant. AFM measurements are correlated with contact-angle measurements. We also study surfactant solution imbibition into an initially oil-wet parallel plate assembly to relate wettability to oil recovery. Our experimental methodology is described in the next section, the results are discussed in the following section, and the conclusions are summarized in the last section.

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Surfactant Flooding 2: The Effect of Alkaline Additives on Permeability and Sweep Efficiency

Cited by 39 publications

References 13 publications

Oil Recovery From Fractured Carbonates by Surfactant-Aided Gravity Drainage: Laboratory Experiments and Mechanistic Simulations

Oil Recovery From Fractured Carbonates by Surfactant-Aided Gravity Drainage: Laboratory Experiments and Mechanistic Simulations

Physicochemical Interactions During Surfactant Flooding of Fractured Carbonate Reservoirs

Atomic Force Microscopy Study of Wettability Alteration by Surfactants

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