Physics based HLD–NAC phase behavior model for surfactant/crude oil/brine systems

The HLD‐NAC model was recently modified to match and predict microemulsion phase behavior experimental data for Winsor type III regions. Until now, the HLD‐NAC model could not generate realistic phase behavior for type II− and type II+ two‐phase regions, leading to significant saturation and composition discontinuities when catastrophe theory is applied. These discontinuities lead to significant failures in modeling surfactant applications. We modify the HLD‐NAC equations to ensure consistency over the entire composition space including type II− and II+ regions. A robust and efficient algorithm is developed that always converges and provides continuous estimates with any formation variable of tie lines and triangles for all Winsor types. Discontinuities are eliminated and limiting tie lines near critical points are determined analytically. The tuning procedure is demonstrated using several sets of experimental data. Excellent predictability of tie lines and tie triangles, and solubilization ratios are shown.

Section: Introductionmentioning

confidence: 99%

Robust Flash Calculation Algorithm for Microemulsion Phase Behavior

Khorsandi

Johns

2016

“…, and the resulting hydrophobicity increases slightly. However, due to the similar structure between the fluoropolymer and hexadecane, an excess adsorption of the fluoropolymer on the core surface decreases the oleophobicity of the gaswetting core [24,25].…”

Section: The Surface Free Energy Of Cores Before and After Treatmentmentioning

confidence: 99%

The Effect of Fluoropolymer on Wettability Alteration of Sandstone at Elevated Temperatures

Jin

Wang

Ren

et al. 2016

Gas condensate reservoirs are generally recovered using a pressure depletion drive. Gas can condensate into the liquid phase near the wellbore region when the reservoir pressure falls below the dew point pressure, which can kill gas deliverability. Wettability alteration is an effective means of overcoming this problem; core wettability can be altered from liquid‐wet to gas‐wet to alleviate the effect of condensate accumulation near the wellbore region. To establish the effect of fluoropolymer on wettability alteration in a gas‐condensate reservoir, a gas‐wetting alteration agent was synthesized by emulsion polymerization using different molar ratios of fluorine‐containing monomers and acrylic monomers. FTIR and SEM were performed to analyze the structure of the gas‐wetting agent. Contact angle measurements were used to assess surface alteration by the Owens two‐liquid method. The effects of alteration agent concentration, salt concentration, pH and temperature on gas‐wetting alteration were also evaluated. Results showed that the best molar ratio of fluoropolymer monomer to acrylic monomers was 1:2. The egg‐like structure of the fluoropolymer latex on the core surface mainly contributes to gas‐wetting alteration. The contact angles of brine and oil can be altered from 23° and 0° to 137° and 67° by 1 wt% FP‐2 treatment, respectively. The surface free energy of the core was reduced from 67.52 to 1.66 mN/m. Moreover, the treated cores remain gas‐wetting up to 100 g L−1 of salt solution, 120 °C and within the pH range of 5–7. This novel gas‐wetting alteration agent can be used to solve the problem of liquid blocking effects in gas condensate reservoirs and improve gas recovery significantly.

“…To date, many studies have employed the HLD equations for several applications such as microemulsion prediction, determination of a hydrophilic-lipophilic characteristic of the surfactant system, and EACN prediction for oil recovery (Acosta et al, 2012;Arpornpong et al, 2018;Budhathoki et al, 2016;Ghosh and Johns, 2014;Jin et al, 2015;Kiran et al, 2009;Nguyen and Sabatini, 2011;Witthayapanyanon et al, 2008). Witthayapanyanon et al (2008) (Budhathoki et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Effect of Ethylene Oxide Group in the Anionic–Nonionic Mixed Surfactant System on Microemulsion Phase Behavior

Kittithammavong

Charoensaeng

Khaodhiar

2020

The phase behavior of microemulsions stabilized by a binary anionic-nonionic surfactant mixture of sodium dihexyl sulfosuccinate (SDHS) and C12-14 alcohol ethoxylate (C 12 − 14 E j ) that contains an ethylene oxide (E j ) group number, j, of either 1, 5, or 9 was investigated for oil remediation. The oil-water interfacial tension (IFT) and optimal salinity of the microemulsion systems with different equivalent alkane carbon numbers (EACN) were examined. The anionic-nonionic surfactant ratio was found to play a pivotal role in the phase transition, IFT, and optimal salinity. The minimum IFT of mixed SDHS − C 12 − 14 E j systems were about three times lower than those of neat SDHS systems. A hydrophilic-lipophilic deviation (HLD) empirical model for the mixed anionic-nonionic surfactant system with the characteristic parameter was proposed, as represented in the excess free energy term G EX RT À Á. The results suggested that the mixed system of SDHS − C 12 − 14 E 1 was more lipophilic, while SDHS − C 12 − 14 E 9 was more hydrophilic than the ideal mixture (no excess free energy during the microemulsion formation), and the SDHS − C 12 − 14 E 5 system was close to the ideal mixture. The findings from this work provide an understanding of how to formulate mixed anionic-nonionic microemulsion systems using the HLD model for oils that possess a wide range of EACN.