Micro CT and Experimental Study of Carbonate Precipitation from CO2 and Produced Water Co-Injection into Sandstone

Synergistic sustainability: Future potential of integrating produced water and CO2 for enhanced carbon capture, utilization, and storage (CCUS)

Produced water (PW) and carbon dioxide (CO2) are traditionally considered waste streams the oil and gas industry and other sectors generate. However, these waste products are examples of "waste to wealth" products with a dual nature of being valuable products or disposable byproducts. PW contains various elements and compounds that can be extracted and used in the manufacturing or chemical processing industry. Concentrated brine is generated from PW and can be used as feedstock in chemical processes. On the other hand, excess CO2 produced in various industrial processes needs to be sequestered either through non-conversion processes, such as enhanced oil recovery and storage in geological formations, or through CO2 conversion processes into fuels, polymers, and chemicals. While there is growing interest in reusing these products individually, no studies have explored the opportunities for producing additional chemicals or valuable products by combining CO2 and PW waste streams (CO2-PW). This study identifies the potential resources that can be generated by combining the beneficial reuse of PW and CO2 conversion processes. CO2-PW chemical conversion presents an opportunity to expand the carbon capture, utilization, and storage (CCUS) mix while reducing the environmental impact of disposing of these byproducts. The advantages of utilizing these waste streams for diverse applications are linked with the sustainable management of PW and decarbonization, contributing positively to a more responsible approach to resource management and climate change mitigation.

A review of carbon mineralization mechanism during geological CO2 storage

The CO2 trap mechanisms during carbon capture and storage (CCS) are classified into structural, residual, solution, and mineral traps. The latter is considered as the most permanent and stable storage mechanism as the injected CO2 is stored in solid form by the carbon mineralization. In this study, the carbon mineralization process in geological CO2 storage in basalt, sandstone, carbonate, and shale are reviewed. In addition, relevant studies related to the carbon mineralization mechanisms, and suggestions for future research directions are proposed. The carbon mineralization is defined as the conversion of CO2 into stable carbon minerals by reacting with divalent cations such as Ca2+, Mg2+, or Fe2+. The process is mainly affected by rock types, temperature, fluid composition, injected CO2 phase, competing reaction, and nucleation. Rock properties such as permeability, porosity, and rock strength can be altered by the carbon mineralization. Since changes of the properties are directly related to injectivity, storage capacity, and stability during the geological CO2 storage, the carbon mineralization mechanism should be considered for an optimal CCS design.

Effects of water chemistry on microfabric and micromechanical properties evolution of coastal sediment: A centrifugal model study

Water chemistry alteration induced strength weakening of natural sediment, which leads to the differential settlement of infrastructures in coastal areas, has caused numerous disasters and engineering failures. To thoroughly understand the underlying mechanisms of how water chemistry influences the microfabric and mechanical properties evolution of coastal sediments, herein, the authors adopted centrifuge test, X-ray diffraction (XRD), and atomic force microscope (AFM) to quantitatively study the structure anisotropy index (i.e., orientation index (OI)), micromorphological property (i.e., root mean square height (S_q)), and micromechanics (i.e., microscale apparent modulus) of clay sediments in different water chemistry conditions and gravity gradients. The results show that the change rule of OI is: OI_saline > OI_alkaline > OI_water > OI_acid, along the vertical sedimentary depth. Randomly distributed clay flocs and loose flocculated soil skeleton (mainly consisted by edge-to-face (EF) and edge-to-edge (EE) contact of the kaolinite platelets) are associated with the acidic water chemical conditions. The action of supergravity and face-to-face (FF) repulsive contact mode lead to high degree of anisotropy of kaolinite sediments in alkaline environment. Clay platelets are compacted closely under the synergetic effect of centrifugal pressure and prevailing van der Waals attraction (reduction of electric double layer repulsion) in saline environment. The change of 1/S_q is highly consistent with the change of OI at different depths in different water chemical environments. Along the sedimentary depth (i.e., transition from the normal gravity (1 g) to supergravity (8000 g)), the microscale apparent modulus of kaolinite sediment was found to be the highest in alkaline environment. As the water chemistry changes from alkaline to acidic, however, the microscale apparent modulus of kaolinite aggregate decreased, and it showed the smallest in the saline environment.