Abdulelah Hesham, Negash Berihun Mamo, Yekeen Nurudeen, Al-Hajri Sameer, Padmanabhan Eswaran, Al-Yaseri Ahmed
Shale Gas Research Group (SGRG), Institute of Hydrocarbon Recovery, Petroleum Engineering Department, Universiti Teknologi PETRONAS, Seri Iskandar 32610, Perak, Malaysia.
School of Engineering, Edith Cowan University, Joondalup, WA 6027, Australia.
ACS Omega. 2020 Aug 5;5(32):20107-20121. doi: 10.1021/acsomega.0c01738. eCollection 2020 Aug 18.
The influence of an anionic surfactant, a cationic surfactant, and salinity on adsorbed methane (CH) 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. CH 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 CH as a function of SDS/CTAB concentration, salinity, and pressure. In case 1, the highest amount of adsorbed CH 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 CH 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.
在一系列系统设计的实验中，评估并模拟了阴离子表面活性剂、阳离子表面活性剂和盐度对页岩中吸附甲烷（CH）的影响。研究了两种情况。在情况1中，将粉碎的马塞勒斯页岩样品与阴离子十二烷基硫酸钠（SDS）和盐水反应。在情况2中，另一组粉碎的马塞勒斯页岩样品用十六烷基三甲基溴化铵（CTAB）和盐水处理。按照Box-Behnken实验设计改变表面活性剂浓度和盐水盐度。然后使用压力平衡池在不同压力（1-50巴）和30°C恒温下对处理后的页岩中的CH吸附进行体积评估。对实验数据的数学分析得出了两个独立的模型，这些模型将吸附的CH量表示为SDS/CTAB浓度、盐度和压力的函数。在情况1中，吸附的CH的最高量约为1 mmol/g。在50巴下，只要SDS浓度保持接近其临界胶束浓度（CMC），即0.2 wt%，且盐度在0.1-20 ppt范围内，就能达到这一量。然而，在情况2中，吸附的CH的最大量仅为0.3 mmol/g。当CTAB浓度高于CMC（>0.029 wt%）时，在50巴和高盐度（约75 ppt）下可获得该值。这些发现为研究人员提供了有助于优化页岩气压裂液中盐度和表面活性剂浓度比例的见解。
