Synergetic effect of surfactant concentration, salinity, and pressure on adsorbed methane in shale at low pressure: An experimental and modeling study

Document Type

Journal Article

Publication Title

ACS Omega

Volume

5

Issue

32

First Page

20107

Last Page

20121

PubMed ID

10.1021/acsomega.0c01738

Publisher

American Chemical Society Publications

School

School of Engineering

RAS ID

32295

Funders

Institute of Hydrocarbon Recovery, Universiti Teknologi PETRONAS

Comments

Abdulelah, H., Negash, B. M., Yekeen, N., Al-Hajri, S., Padmanabhan, E., & Al-Yaseri, A. (2020). Synergetic effect of surfactant concentration, salinity, and pressure on adsorbed methane in shale at low pressure: An experimental and modeling study. ACS Omega, 5(32), 20107-20121. https://doi.org/10.1021/acsomega.0c01738

Abstract

© 2020 American Chemical Society. The influence of an anionic surfactant, a cationic surfactant, and salinity on adsorbed methane (CH4) in shale was assessed and modeled in a series of systematically designed experiments. Two cases were investigated. In case 1, the crushed Marcellus shale samples were allowed to react with anionic sodium dodecyl sulfate (SDS) and brine. In case 2, another set of crushed Marcellus shale samples were treated with cetyltrimethylammonium bromide (CTAB) and brine. The surfactant concentration and salinity of brine were varied following the Box-Behnken experimental design. CH4 adsorption was then assessed volumetrically in the treated shale at varying pressures (1-50 bar) and a constant temperature of 30 °C using a pressure equilibrium cell. Mathematical analysis of the experimental data yielded two separate models, which expressed the amount of adsorbed CH4 as a function of SDS/CTAB concentration, salinity, and pressure. In case 1, the highest amount of adsorbed CH4 was about 1 mmol/g. Such an amount was achieved at 50 bar, provided that the SDS concentration is kept close to its critical micelle concentration (CMC), which is 0.2 wt %, and salinity is in the range of 0.1-20 ppt. However, in case 2, the maximum amount of adsorbed CH4 was just 0.3 mmol/g. This value was obtained at 50 bar and high salinity (∼75 ppt) when the CTAB concentration was above the CMC ( > 0.029 wt %). The findings provide researchers with insights that can help in optimizing the ratio of salinity and surfactant concentration used in shale gas fracturing fluid.

DOI

10.1021/acsomega.0c01738

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