A Feasibility Study of the Integration of Enhanced Oil Recovery (CO2 Flooding) with CO2 Storage in the Mature Oil Fields of the Ordos Basin, China

Abstract

Rich in energy resources, China's Ordos Basin Shares many similarities with Wyoming's Powder River Basin. As a result, the experience and expertise pertaining to energy development in the Powder River Basin should prove helpful in the Ordos Basin. The b reserves are ranked fourth. The coal deposits in the Ordos Basin account for 39 percent of total Chinese coal reserves (3.98 trillion tonnes), and six of the thirteen largest coal mines in China are located in the basin. The overlapping development of relatively new coal conversion industries with existing oil and gas industries in northern Shaanxi Province is creating an opportunity to apply the systematic approach developed in Wyoming: the integration of geological CO2 storage and CO2-EOR. The coal conversion industry (i.e., coal-to-methanol, coal-to-olefins, etc.) provides affordable, capture-ready CO2 sources for developing large-scale integrated CO2-EOR and carbon storage projects in the Ordos Basin, China. Compared with other CCUS projects, the ability to use CO2 from the coal- conversion industry for CO2-EOR and subsequent geological CO2 storage will make integrated projects in the Ordos Basin more cost-effective and technologically efficient.The low porosity, low permeability, low oil saturation, anomalously low reservoir pressure, and high reservoir heterogeneity of the target storage formations in the Ordos Basin make using CO2 for enhanced oil recovery much more challenging here than in the US. These reservoir characteristics together constitute a major reason that CO2- EOR is not widely employed in the Ordos Basin, even though sources of highly concentrated CO2 (coal conversion plants) have been available for years. Comparisons of reservoir and crude oil properties in the Ordos Basin with the current US CO2-EOR screening guidelines reveal that gravity, viscosity, crude oil composition, and formation type of the Ordos reservoirs all are favorable for CO2 miscible flooding. The major challenges in deploying EOR result from anomalously low reservoir pressure, low porosity, and higher reservoir heterogeneity.