Study on the basic physical conditions of CO2 geologic sequestration reservoir in the Majiagou Formation in the Ordos Basin

Carbon dioxide capture and storage is one of the important ways to achieve large-scale CO2 emission reduction and enhance the oil recovery. The site selection and potential assessment of CO2 geological storage requires a systematic study of the basic physical conditions of the geological storage layer in the storage area, and the site selection and storage potential evaluation of CO2 geological storage first require a systematic study of the basic physical conditions in the areas for CO2 storage. Because of the insufficient research on the basic physical conditions of the Majiagou Formation in the Ordos Basin, this study mainly studies the top burial depth, ground temperature, formation pressure, and the density of CO2 of the Majiagou Formation in the Ordos Basin. The research shows: (1) The top burial depth of the Majiagou Formation is a simple slope with high in the east and low in the west in the Ordos Basin. The temperature on the top of the Majiagou Formation gradually increases from 66–73 °C in the east to 132–140 °C. The pressure on the top of the Majiagou Formation gradually increased from 20–30 Mpa in the east to 30–40 Mpa in the west, which indicates that the modern underground pressure field of the Majiagou Formation belongs to the normal pressure system, and the temperature field belongs to the medium-low temperature system, which provides favorable geotemperature and pressure conditions for CO2 injection and storage. (2) The CO2 density on the top of the Majiagou Formation gradually rose from 740–790 kg/m3 in the east to 950–1000 kg/m3 in the west, which provides data support for CO2 storage potential evaluation and provides methodology for the study of basic physical conditions of other CO2 geological storage layers.