Wettability Alteration in High-Temperature and High-Salinity Carbonate Reservoirs

Sharma, Gaurav; Mohanty, Kishore K.

doi:10.2118/147306-pa

Cited by 172 publications

(71 citation statements)

References 12 publications

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“…Based on their polar head group, surfactants are most commonly classified in cationic (positive charge), anionic (negative charge) and nonionic (no charge). In previous studies, cationic surfactants have shown improve oil recovery by wettability alteration in oil-wet chalk rocks (Austad et al 1998;Sharma and Mohanty 2013;Zhang and Austad 2005); however, this type of surfactant requires high concentrations and is too expensive to economically be implemented on the field (Adibhatla and Mohanty 2008;Chen et al 2001). In addition, anionic and nonionic surfactants have also been studied in fracture carbonates and chalk reservoirs effectively shifting wettability and reducing IFT, improving oil imbibition (Adibhatla and Mohanty 2008;Austad et al 1998;Babadagli et al 1999;Chen et al 2001;Sharma and Mohanty 2013;Wang et al 2012;Zhang and Austad 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Various experiments have been conducted on the study of wettability and IFT alteration using surfactants based on spontaneous and forced imbibition in carbonate and sandstone reservoirs (Adibhatla and Mohanty 2008;Austad et al 1998;Babadagli et al 1999;Chen et al 2001;Hirasaki and Zhang 2003;Sharma and Mohanty 2013;Shuler et al 2011;Wang et al 2012;Zhang and Austad 2005); however, these experiments have limited application on unconventional reservoirs due to their ultralow permeability and low porosity values. There is limited literature on the study of combined effect of wettability and the corresponding IFT alteration effect on imbibition process on core samples from unconventional plays.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Surfactants for Wettability Alteration in Stimulation Fluids and the Potential for Surfactant EOR in Unconventional Liquid Reservoirs

Alvarez

Neog

Jais

et al. 2014

SPE Unconventional Resources Conference

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Wettability alteration in shale formations can be an important factor in improving the performance of hydraulic fracturing treatments. The use of surfactants in the frac fluid, at proper concentrations, has shown to change wettability in Unconventional Liquid Reservoirs (ULR) favoring the process of imbibition. This study evaluates and compares the efficiency of anionic and nonionic surfactants in recovering hydrocarbons in carbonate and siliceous preserved side-wall core. The techniques developed also open the door for investigation of low concentration surfactants for enhanced oil recovery (EOR) in ULR. Contact angle (CA) experiments were performed, using the captive bubble method, to measure the magnitude of wettability alteration on intermediate to oil-wet ULR core at reservoir temperature (165 °F). Different types of anionic and nonionic surfactants at field concentrations were used. The results showed that all surfactants lower the CA at the concentration tested. However, anionic surfactants showed better results as observed by lower contact angles. IFT measurements were also performed, using the pendant drop and spinning drop methods, at reservoir temperature using reservoir crude oil and anionic and nonionic surfactants at the same concentrations. The IFT reduction was similar for each type of surfactant compared to regular frac fluid without any surfactant, but anionic surfactant showed slightly better capability of reducing IFT than nonionic surfactants. Computed tomography (CT) scan methods were used to gauge the performance of these surfactants in improving oil recovery. The magnitude of penetration or imbibition into artificially-fractured ULR cores was studied for both anionic and nonionic surfactants. Frac fluids containing surfactants were mixed with a dopant salt to trace the movement of these fluids and measure the penetration numerically. Both, anionic and nonionic, surfactants have higher penetration magnitudes compared to slick water without surfactant. However, anionic surfactants displaced a higher observable amount of liquid hydrocarbon from the shale cores. This observation agrees qualitatively with the results observed in the CA experiments where anionic surfactants showed the lowest contact angles. From the results obtained, it can be concluded that anionic surfactants alter wettability in these ULR core, giving lower CA, better spontaneous imbibition and higher oil recovery than nonionic surfactants. These observed wettability changes induced by surfactants mixed in the frac fluids can improve matrix penetration with spontaneous imbibition which opens further discussions for EOR potential in shale formations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of Surfactants for Wettability Alteration in Stimulation Fluids and the Potential for Surfactant EOR in Unconventional Liquid Reservoirs

Alvarez

Neog

Jais

et al. 2014

SPE Unconventional Resources Conference

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“…Similar experimental work is not available for carbonate minerals. The carbonate rock constituent mineral, calcite, is a positively charged surface at neutral pH conditions (Somasundaran and Agar 1967;Anderson 1986). This is because of the dissolution of the surface ions from the crystal structure that leaves behind positive and negative sites that are then hydrolyzed.…”

Section: Introductionmentioning

confidence: 99%

“…It is shown that the recovery by displacement tests using modified brine, with higher sulfate content but no reduction in salinity, is as high as 80% with an incremental recovery of 40% of OOIP. Contact-angle measurements were used as a screening method to narrow down the list of added surfactants that create water-wetting conditions (Sharma and Mohanty 2013). Use of added surfactants led to 70-80% recovery by imbibition, mainly attributed to wettability alteration.…”

Section: Introductionmentioning

confidence: 99%

Impact of Brine Composition on Calcite Wettability: A Sensitivity Study

AlShaikh

Mahadevan²

2016

SPE Journal

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Brine composition change has a significant demonstrated impact on the recovery of oil in laboratory corefloods. Although low-salinity waterflood in clastics has been studied extensively, the impact of brine composition on the wettability and recovery in carbonates is relatively less understood and studies are more recent. Wettability measurements by use of contact angles can reflect the surface energy changes caused by adsorption of compounds present in crude oil and the electrostatic, structural components caused by the formation of the double layer.In this study, the impact of ion composition on the contact angles and interfacial tensions (IFTs) between crude oil, brine, and restored/aged calcite-mineral surface is studied by use of a drop-profile-analysis method. A 13-factor experimental design is used to quantify the impact of six salts and seven interactions. This experimental method design, following the Taguchi method (Roy 1990), is used to identify the combination of different salts that leads to the lowest oil-wetness and highest water-wetness as measured through the contact angles. In addition, the impact of the total dissolved solids (TDS) on both the wettability and the IFT is studied for the selected crude oil/brine system.The analysis of variance of the measurements shows that the Alkali/Alkaline Earth metal chloride concentration has a significant impact on the wettability measured with static contact angles. The interactions between sodium chloride and sodium sulfate concentration; between sodium chloride and magnesium chloride salt concentration; and between sodium chloride and calcium chloride concentration are significant. The most-favorable interaction response is obtained at the highest sodium sulfate concentration along with lower sodium chloride, calcium chloride, and magnesium chloride concentrations.Therefore, a combination of higher concentration of sulfate anions with lower cation concentration and reduced salinity can lead to more-water-wet conditions. This composition is found to lead to the lowest contact angle or the most-water-wet condition. It is interesting to note that the lowest contact angle of approximately 29 (highly water-wet) is obtained with a relatively high TDS content of 134.5 g/L. This observation is in line with some of the recent studies reported in the literature on carbonate-rock corefloods and offers a fundamental explanation.

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“…Recent years have witnessed an increasing interest in surfactant mediated wettability alteration and enhanced spontaneous imbibition in oil-wet carbonates. There are a wide range of choices in the selections of surfactants: nonionic surfactants (Vijapurapu and Rao, 2004;Standnes et al, 2002;Xie et al, 2005), cationic surfactants (Austad et al, 1998;Standnes et al, 2002) and anionic surfactants (Seethepalli et al, 2004, Sharma andMohanty, 2011;Chen and Mohanty, 2013).…”

Section: Introductionmentioning

confidence: 99%

Surfactant-Enhanced Oil Recovery from Fractured Oil-wet Carbonates: Effects of Low IFT and Wettability Alteration

Chen

Mohanty

2015

Day 1 Mon, April 13, 2015

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The performance of surfactant-enhanced oil recovery (EOR) in fractured carbonates relies on spontaneous imbibition or low IFT-aided gravity drainage. This work investigated the synergism between wettability effects and IFT reduction mediated by a variety of surfactants through experiments and numerical simulation studies. Experiments have shown that oil can be recovered from oil-wet Silurian dolomite fracture blocks either by capillarity driven imbibition, gravity-driven imbibition or low tension-aided gravity drainage. The mixture of wettability alteration (WA) surfacant with IFT reduction surfactant exhibits the synergistic effect on the imbibition oil recovery from oil-wet carbonate rocks. It was found that divalent ion scavengers help the wettability altertion capability of some sulfonate surfactants in hard brine, which leads to the high oil recovery up to 70% OOIP (IFTϩWA), compared with oil recovery of 30-50% OOIP by sulfonate surfactant only (only IFT reduction). We proposed a mechanism that the presence of a sufficient amount of divalent ion scavengers in the anionic surfactant formulation reduces the free divalent cations in hard brine, which then promotes the release of surfactant monomers from the micelles and enhances wettability alteration by surfactant adsorption. The UTCHEM simulation results confirmed the existence of synergism between IFT reduction and WA in spontaneous imbibition processes. According to the capillary desaturation curve (CDC), that residual oil saturation after gravity drainage is approximately 10% to 20% higher than gravity-driven spontaneous imbibition when two processes have the similar trapping numbers, confirming that the wettability alteration contributes to the ultimate oil recovery.

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Wettability Alteration in High-Temperature and High-Salinity Carbonate Reservoirs

Abstract: DedicationTo my parents Shakuntala and Vasudev Sharma and my sister Neelam Sharma.v

Cited by 172 publications

References 12 publications

Impact of Surfactants for Wettability Alteration in Stimulation Fluids and the Potential for Surfactant EOR in Unconventional Liquid Reservoirs

Impact of Surfactants for Wettability Alteration in Stimulation Fluids and the Potential for Surfactant EOR in Unconventional Liquid Reservoirs

Impact of Brine Composition on Calcite Wettability: A Sensitivity Study

Surfactant-Enhanced Oil Recovery from Fractured Oil-wet Carbonates: Effects of Low IFT and Wettability Alteration

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