CO₂ mineralization in volcanogenic sandstones: geochemical characterization of the Etchegoin formation, San Joaquin Basin

Abstract

Volcanogenic sandstones are typically rich in volcanic rock fragments that can provide reactive minerals for CO 2 mineralization in a scenario of CO 2 sequestration. To quantitatively evaluate the extent and time scale of CO 2 mineralization in potential reservoir formations, we characterized example high-porosity volcanic sand from the San Joaquin Valley of southern Central California. Samples were collected from the volcanic-rich members of the Etchegoin Formation in the San Joaquin Basin near Coalinga, California. Thin sections made from these samples were examined under petrographic microscope to identify mineral compositions, and then scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) were used to gather quantitative information on mineral abundances, distribution, and reactive surface areas. Porosity and permeability were also measured using core plugs made from outcrop samples. Results show that the Etchegoin volcanic sandstone has a high percentage (10-15%) of reactive minerals (pyroxenes, Fe-Ti spinel and clays), and high reactive surface areas at about 1 m 2 /kg. Reactive transport modeling is conducted and shows that these reactive minerals could mineralize 92% of injected and capillary-trapped CO 2 within 1000 years of injection. Possible effects of heterogeneity on CO 2 injection and mineralization are also studied using the reactive transport code TOUGHREACT. Vertical heterogeneity of mineralogy and hydrology increases both CO 2 injectivity and mineralization. Available volcanogenic sandstones worldwide like the Etchegoin sandstone are summarized from the literature, with formations from the western USA that have CO 2 sequestration potential emphasized.

CO2 capture and mineralization using carbide slag doped fly ash

“…According to the capture process at different stages, there are generally three main methods to capture CO 2 —pre‐combustion, oxy‐fuel combustion, and post‐combustion. Many authors have summarized the inherent advantages and disadvantages of the three pathways . It is believed that pre‐combustion capture is applicable to gasification plants and oxy‐fuel combustion can be applied to new‐build power plants.…”

“…In China, 6000 million tons of fly ash from coal combustion of products is generated every year. Less than one third of this fly ash is recycled for productive purposes . Despite the numerous environmental issues, coal will remain a major source of electric power for years to come, owing to the relative lack of suitable alternatives to coal as an energy source.…”

“…Carbide slag is a kind of industrial waste mainly discharged from the polyvinyl chloride industry. It is estimated that around 56 million tons of carbide slag is produced annually in the world, of which China's production accounts for one third . With the novel mineral carbonation technology developed in this work, the emissions of CO 2 were controlled at a local point‐source with the use of coal combustion fly ash and carbide slag as feedstock.…”

“…Many authors have summarized the inherent advantages and disadvantages of the three pathways. [5][6][7][8] It is believed that pre-combustion capture is applicable to gasification plants and oxy-fuel combustion can be applied to new-build power plants. Chemical absorption is a frequently used post-combustion capture technique with a high CO 2 capture efficiency.…”

“…It is estimated that around 56 million tons of carbide slag is produced annually in the world, of which China's production accounts for one third. 6,7 With the novel mineral carbonation technology developed in this work, the emissions of CO 2 were controlled at a local point-source with the use of coal combustion fly ash and carbide slag as feedstock. This is a very effective way to minimize the CCS cost while saving or reducing the current transfer, treatment and disposal costs of solid waste.…”