The Potential for Underground CO2 Disposal Near Riyadh

Abstract

Carbon Capture Storage (CCS) and Carbon Capture Utilization and Storage (CCUS) have recently gained global attention as promising techniques to mitigate net CO2 emissions. Within this framework, the Saudi Arabian 2030 vision targets the large-scale deployment of CCS and CCUS projects to promote its circular carbon economy. This study evaluates the potential for underground sequestration of CO2 emitted from industrial sources near Riyadh, Saudi Arabia, which emit 46 Mton/year. A deterministic geologic model corresponding to the Unayzah Formation was constructed using published data incorporating sedimentary facies distribution, porosity, permeability, and connectivity. Compositional simulations were performed to assess the CO2 plume flow in the presence of conduits, barriers, and baffles. Similarly, injectivity and injection rate effects on solubility and residual trapping were evaluated. A sensitivity analysis and an uncertainty quantification study were carried out to obtain a probabilistic assessment of the total storage capacity and trapping contributions. The geological evaluation indicates that the area under Riyadh is unsuitable because the Triassic sandstones are too shallow, and the Paleozoic section was entirely removed by erosion during the Carboniferous. Alternatively, the Hawtah area, at 150 km south of Riyadh, is deemed suitable for CO2 sequestration. These sandstones are porous, permeable, tightly sealed, and correspond to hydrocarbon reservoirs in anticlinal structures along the Hawtah, Nuayyim, and Dilam trends. They are favorable for CO2 disposal outside oil and gas fields due to lateral and vertical permeability barriers and up-dip pinch-out against the Batin arch. Simulation results, fifty years after CO2 injection and two hundred fifty years of monitoring, show that the Unayzah Formation satisfies the conditions of capacity, injectivity, and seal efficiency required for technical feasibility. Furthermore, lower injection rates promote higher solubility and residual trapping due to gravity-controlled flow exceeding viscous and capillary forces. Residual trapping contributes ~ 50% to the storage, while solubility adds 10%. The variables that have a higher impact on secure trapping are residual gas saturation, water salinity, and permeability. The current CO2 storage capacity in the area evaluated exceeds 300 Megatons (Mt), and the assessment is still ongoing, with no vertical leakage through the caprocks of the Khuff and Sudair Formations. Overall, the novelty in this research focuses on the unprecedented use of public domain data to construct a detailed geological model of the Unayzah Formation in the Hawtah and Nuayyim area that allowed a better understanding of CO2 flow mechanisms in the reservoir and its capacity to store CO2. This study concludes that the Unayzah reservoir in the Kharj-Hawtah area is a viable candidate for secure CO2 disposal from industrial sources in Riyadh.

Exploring Public Attitudes and Acceptance of CCUS Technologies in JABODETABEK: A Cross-Sectional Study

“…Therefore, this study aims to fill this gap by analysing the social acceptance of CCUS technology and its relationship with various demographic factors. The results of this study provide information on the factors that influence public acceptance of CCUS technology in Indonesia, which could be used as a basis for policy making and industry practises [34,[36][37][38]. Furthermore, the findings could also contribute to the literature on public attitudes towards emerging technologies in developing countries.…”

Advances in Carbon Dioxide Storage Projects: Assessment and Perspectives

“…Some of the said projects includes Frio, Ketzin, Nagaoka, Sleipner, Snøhvit, In Salah, acid-gas injection, and other trial projects . However, in order to effectively store CO 2 into saline aquifer, the formation should contain the following main characteristics: The saline aquifer should contain a depth more than 800 m for effective storage CO 2 It should have a porosity of 10% …”

“…In this case, the aquifer should have good caprock to prevent gas leakage or migration to the formation's lateral extents. 67 In addition, the aquifer should not have any unrecognized faults or fissures that could allow gas to escape. Furthermore, saline aquifers represent potential geological formations and probably contain the largest volume to store CO 2 , but they are associated with high cost or economic standpoint, because of the lack of the existing infrastructures like pipelines, drilled wells, and surface equipment, which need to be developed.…”

“…The displacement will continue until the irreducible water saturation limit has been reached. In this case, the aquifer should have good caprock to prevent gas leakage or migration to the formation’s lateral extents . In addition, the aquifer should not have any unrecognized faults or fissures that could allow gas to escape.…”

Uncertainty Analysis of CO2 Storage in Deep Saline Aquifers Using Machine Learning and Bayesian Optimization

“…CO 2 utilization for enhanced oil recovery and sequestration into aquifers has been practiced for several decades [3], where the focus has been on deep saline aquifers due to their superior storage capacity [14]. In addition, saline aquifers are ubiquitous in many parts of the world, making them available for most existing CO 2 sources [15,16].…”