Carbon Dioxide Leakages through Fault Zones: Potential Implications for the Long-term Integrity of Geological Storage Sites

Abstract

Carbon sequestration has recently become more widely recognized as a potential means of reducing atmospheric carbon dioxide levels. Understanding the tectonic relationship of carbon dioxide discharges and the sealing behavior of faults is conducive for predicting the long-term integrity of geological storage formations. Of primary concern is the influence of crustal deformation on the carbon dioxide leakage through fault zones during large-scale underground injection. This paper examines a record of carbon dioxide leakage from a faulted, natural carbondioxide-rich formation, and investigates the crustal tilt in the fault zones. Temporal changes in the crustal tilt reveal pulses of carbon dioxide concentrations ranging from 537.7 up to 1317.1 ppm, and the mean level represents 890.2 ppm. Of particular interest is that each high-frequency pulse coincides with the onset of local solid-earth tide. We show a significant correlation between the crustal tilt magnitude and amount of carbon dioxide leakage. We suggest that carbon dioxide leakage levels increase owing to fracture opening, potentially caused by changes in fault architecture and permeability structure of regions surrounding the faults. Highlights:Carbon dioxide leakages vary with a periodicity controlled by the crustal deformation.Temporal changes in the crustal tilt reveal pulsing of carbon dioxide leakage levels.Carbon dioxide leakages increase as a cause of fracture opening.

Simulation Study on the Mechanical Effect of CO2 Geological Storage in Ordos Demonstration Area

“…With the injection of CO 2 into the subsurface and its long-term storage, the stress field and chemical field in the layer change, triggering a series of changes in geological factors that affect the stability and safety of long-term storage of CO 2 . Yang Duoxing et al found that carbon dioxide-leakage levels and crustal tilt changes vary systematically through time and are highly correlated, indicating increased degrees of carbon dioxide degassing from the fault zone [12]. Xu Lifeng et al conducted five groups of supercritical CO 2 leakage experiments at different initial CO 2 temperatures to study the mechanism of internal and external strain differences caused by the phase transition of supercritical CO 2 leakage along faults [13].…”