Ali Mujahid, Awan Faisal Ur Rahman, Ali Muhammad, Al-Yaseri Ahmed, Arif Muhammad, Sánchez-Román Mónica, Keshavarz Alireza, Iglauer Stefan
Petroleum Engineering Discipline, School of Engineering, Edith Cowan University, 270 Joondalup Dr, Joondalup 6027, WA, Australia; Department of Petroleum and Gas Engineering, Dawood University of Engineering and Technology, Muslimabad, 74800 Karachi, Sindh, Pakistan.
Petroleum Engineering Discipline, School of Engineering, Edith Cowan University, 270 Joondalup Dr, Joondalup 6027, WA, Australia; Department of Petroleum and Gas Engineering, Dawood University of Engineering and Technology, Muslimabad, 74800 Karachi, Sindh, Pakistan.
J Colloid Interface Sci. 2021 Apr 15;588:315-325. doi: 10.1016/j.jcis.2020.12.058. Epub 2020 Dec 21.
Millions of tons of CO are stored in CO geological storage (CGS) formations (depleted oil reservoirs and deep saline aquifers) every year. These CGS formations naturally contain small concentrations of water-soluble organic components in particular humic acid (HA), which may drastically affect the rock wettability - a significant factor determining storage capacities and containment security. Hence, it is essential to characterise the effect of humic acid concentration on CO-wettability and its associated impact on storage capacity.
To achieve this, we measured advancing and receding contact angles at reservoir conditions using the pendant drop tilted plate method for various humic acid concentrations (1, 10, and 100 mg/L) as a function of pressure (0.1-25 MPa), temperature (303-333 K), and brine salinity (0-0.3 M NaCl). Further, the influence of humic acid adsorption on the mineral's surface was examined by several independent techniques.
Our results demonstrate that humic acid significantly changes rock wettability from water-wet (0-50°) towards CO-wet (90-110°). An increase in pressure, temperature, and salinity had a similar effect. Humic acid adsorption also increased the surface roughness of the substrates. We conclude that even trace amounts of humic acid (i.e. 1 mg/L), which exist in storage aquifers, significantly increase CO-wettability and thus reduce structural and residual trapping capacities. Therefore, it is pertinent to account for these humic acid concentrations to de-risk CGS projects.
每年有数百万吨的一氧化碳被存储在一氧化碳地质储存（CGS）地层（枯竭油藏和深部盐水层）中。这些CGS地层天然含有少量水溶性有机成分，特别是腐殖酸（HA），这可能会极大地影响岩石润湿性——这是决定储存容量和封存安全性的一个重要因素。因此，必须表征腐殖酸浓度对一氧化碳润湿性的影响及其对储存容量的相关影响。
为实现这一目标，我们使用悬滴倾斜板法，在储层条件下，测量了不同腐殖酸浓度（1、10和100毫克/升）下的前进和后退接触角，这些接触角是压力（0.1 - 25兆帕）、温度（303 - 333开尔文）和盐水盐度（0 - 0.3摩尔/升氯化钠）的函数。此外，还通过几种独立技术研究了腐殖酸吸附对矿物表面的影响。
我们的结果表明，腐殖酸显著改变岩石润湿性，使其从水湿（0 - 50°）变为一氧化碳湿（90 - 110°）。压力、温度和盐度的增加也有类似效果。腐殖酸吸附还增加了基底的表面粗糙度。我们得出结论，即使是储层中存在的痕量腐殖酸（即1毫克/升），也会显著增加一氧化碳润湿性，从而降低结构捕集和残余捕集能力。因此，考虑这些腐殖酸浓度对于降低CGS项目风险至关重要。
