Prediction of favorable geological storage areas based on sedimentary characteristics: A case study on the northeastern Ordos Basin, China

Abstract

The Ordos Basin is a large cratonic basin with stable deposition in Northwest China. Given its mostly stable subsidence background and the urgent need for saline water disposal and carbon dioxide storage in the coal mining and coal chemical industries, the Ordos Basin has been chosen as a pilot demonstration site for carbon dioxide and saline water storage in China. However, few studies have been made to evaluate the sedimentary and sequence stratigraphy characteristics of this region, as well as their influence on carbon dioxide and saline water storage potential. To address this research gap, we conducted a sedimentary study of the Lower Triassic Liujiagou Formation in the northeastern Ordos Basin utilizing the stratigraphy theory, laboratory test analysis, and pilot project demonstration, to evaluate the area's viability for the deep geological storage of gas and liquid waste. We studied the tectonic setting, petrological features, and sedimentary characteristics of the favorable strata and predicted favorable areas based on sequence stratigraphy theory. The lithology predominantly consists of feldspathic graywacke, with a fine grain size and mostly fine-to-medium-grained sandstone. The distribution of thick-grained sandstone and fine-grained sediment was identified by dividing the sequence, and a favorable reservoir-cap assemblage configuration was formed. It's concluded that the Lower Triassic Liujiagou Formation exhibits suitable characteristics for the deep geological storage of carbon dioxide and saline water. This study demonstrates the importance of basic theory in guiding practical applications and provides a reference for the scientific selection of favorable areas for deep basin storage.

Keywords

• Ordos Basin
• Liujiagou Formation
• Sedimentary facies
• Sequence stratigraphy
• Geological storage