Bello Abdulwahab Muhammad, Al-Yaseri Ahmed, Amao Abduljamiu O, Al-Ramadan Khalid
Center of Integrative Petroleum Research (CIPR), College of Petroleum Engineering and Geoscience, King Fahd University of Petroleum and Minerals, Dhahran 34463, Saudi Arabia.
College of Petroleum Engineering and Geoscience, King Fahd University of Petroleum and Minerals, Dhahran 34463, Saudi Arabia.
ACS Omega. 2024 Jul 15;9(29):31578-31585. doi: 10.1021/acsomega.4c01256. eCollection 2024 Jul 23.
The success of any carbon capture and storage method largely depends on, among other factors, its safety, reliability, and thorough understanding of the interactions among CO, underground geological formation, and resident brine. Upon injection into the subsurface rock formation, CO interacts with the host geological formation and brine, initiating complex geochemical reactions that are often poorly understood and could potentially affect the overall stability and storage capacity of the geological formation, particularly those in close proximity to an intense heat source. For instance, the impact of intense and prolonged heat due to, say, magmatic intrusion on sandstones' framework, authigenic mineralogies, and CO-storage potentials is still poorly understood. Consequently, in this study, we have investigated the impact of firing on CO-rock-brine reactions in the Bandera Gray (BG) sandstone. Prior to the CO injection using 60 000 ppm brine at 75 °C and 28.7 MPa for 30 days, two samples of the BG sandstone were fired for 6 h in a muffle furnace at 700 and 1100 °C each. The BG samples were then studied for XRD, SEM, and ICP-OES analyses before and after the CO injection, mainly to investigate any changes in mineralogical compositions and fluid chemistry. To determine the impact of the CO-rock-brine interactions on the authigenic and framework mineralogies of the BG sandstones under low pH (∼3) conditions, powdered samples of the pre- and postfired BG sandstones were treated with nitric acid. The findings of the study indicate that there were no observable reactions involving rock-forming minerals and carbonate cement in the unfired and fired (at 700 °C) sandstones after the CO injection. However, pervasive feldspar-dissolution porosity was formed in the postfired BG sandstone (1100 °C) after CO injection. This was mainly because albite was partly to pervasively transformed into anorthite during firing at 1100 °C, making the feldspar highly susceptible to dissolution under CO conditions. This implies that the conversion of albite into chemically unstable anorthite in natural sandstones that underwent intense and prolonged heating could develop significant amounts of secondary dissolution porosity due to CO injection, thereby impacting their storage capacities and overall petrophysical properties. This dissolution was separately corroborated using a nitric acid treatment. The findings of the study will provide a better understanding of the CO-rock-brine reactions involving sandstones that experienced intense heat due to, for instance, magmatic activity over a long geologic time scale, which has largely transformed the chemistry of their feldspars, particularly plagioclase.
任何碳捕获与封存方法的成功，在很大程度上取决于其安全性、可靠性，以及对二氧化碳（CO）、地下地质构造和原生盐水之间相互作用的透彻理解等因素。注入地下岩层后，CO会与宿主地质构造和盐水相互作用，引发复杂的地球化学反应，而这些反应往往鲜为人知，并且可能会影响地质构造的整体稳定性和存储容量，尤其是那些靠近强烈热源的构造。例如，由于岩浆侵入等原因导致的强烈且持续的高温对砂岩骨架、自生矿物学以及CO存储潜力的影响，仍然了解甚少。因此，在本研究中，我们调查了焙烧对班德拉灰（BG）砂岩中CO - 岩石 - 盐水反应的影响。在75°C和28.7MPa条件下使用60000ppm盐水注入CO持续30天之前，取两份BG砂岩样品分别在马弗炉中于700°C和1100°C焙烧6小时。然后在注入CO前后对BG样品进行X射线衍射（XRD）、扫描电子显微镜（SEM）和电感耦合等离子体发射光谱（ICP - OES）分析，主要是为了研究矿物成分和流体化学的任何变化。为了确定在低pH（约为3）条件下CO - 岩石 - 盐水相互作用对BG砂岩自生矿物和骨架矿物学的影响，对焙烧前后的BG砂岩粉末样品进行了硝酸处理。研究结果表明，注入CO后，未焙烧和焙烧（700°C）的砂岩中未观察到涉及造岩矿物和碳酸盐胶结物的反应。然而，注入CO后，焙烧后的BG砂岩（1100°C）中形成了普遍的长石溶解孔隙。这主要是因为钠长石在1100°C焙烧过程中部分至普遍地转变为钙长石，使得长石在CO条件下极易溶解。这意味着在经历了强烈且持续加热的天然砂岩中，钠长石转变为化学性质不稳定的钙长石，可能会由于注入CO而产生大量次生溶解孔隙，从而影响其存储容量和整体岩石物理性质。这种溶解通过硝酸处理得到了单独验证。该研究结果将有助于更好地理解在漫长地质时间尺度上因岩浆活动等经历强烈加热的砂岩所涉及的CO - 岩石 - 盐水反应，这种加热在很大程度上改变了其长石尤其是斜长石的化学性质。
