--> Fluvial Channels and Boundary Conditions in Relation to the Success of CO2 Geological Storage Into Deep Saline Aquifers at the Shenhua Site, Ordos Basin

AAPG ACE 2018

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Fluvial Channels and Boundary Conditions in Relation to the Success of CO2 Geological Storage Into Deep Saline Aquifers at the Shenhua Site, Ordos Basin

Abstract

The Shenhua Carbon Capture and Storage (CCS) project at the Shenbei Slope injection site in North Yulin is the first 100,000 ton/year scale CCS pilot project in China with an injection operation lasting nearly 3 years. While the project turned into an operational success with 300,000 tons of CO2 being sequestered, several aspects of reservoir dynamic behavior and the role of reservoir heterogeneity are not clearly understood. For example, although there was an initial period of wellhead pressure (WHP) increase at the injection well, WHP incrementally declined for most of the time. The majority of CO2 was received by the topmost sandstone of the Liujiagou formation in the injection interval instead of the lowermost limestone of the Majiagou formation, suggesting strong reservoir heterogeneity. Knowledge of the key reservoir processes and properties that resulted in these observations would help for predicting long-term storage safety and aiding the design of a larger-scale CCS operation at the same site. In this study, we investigate various fluvial channel models and important boundary conditions to determine aspects of heterogeneity that have the most impact on pressure behavior at the injection well and the observed plume dynamics after injection. Simulation results suggest a system of interconnected fluvial channels providing large connected volumes may have allowed such high injectivity into the topmost sandstone Liujiagou formation, leading to relatively small pressure buildup throughout injection operations. In addition to connected volumes, we also find the possibility of leakage at the boundary of our model, which potentially contributed to the fact that 300,000 tons of CO2 were successfully injected.