Impact of injection temperature and formation slope on CO2 storage capacity and form in the Ordos Basin, China

Abstract

Carbon dioxide (CO2) storage capacity is the main criterion for assessing CO2 geological storage. Based on actual data from the Shiqianfeng formation in the Ordos Basin, three-dimensional (3D) models were built using the TOUGHVISUAL visualization software and simulated using the TOUGH2 integral finite difference modeling code with the ECO2N fluid property module to explore the impact of formation attributes (formation slope) and controllable factors (injection temperature) on CO2 storage capacity. A total of 16 schemes were designed, with four injection temperatures (24℃, 31℃, 38℃ and 45℃) and four formation slopes (0°, 5°, 10° and 15°). Simulation results showed that the injection temperature and formation slope both had a significant influence on CO2 storage capacity. The impact of injection temperature on the total storage amount was more obvious than that of the impact of formation slope. A higher injection temperature resulted in a greater total storage amount. Increasing the formation slope and injection temperature increased the gas-phase, dissolved-phase and total CO2 storage amounts in the upper left section of the injection well, but decreased them in the lower right part of the injection well. The impact of formation slope on the conversion rate from gas-phase CO2 to dissolved-phase CO2 was more obvious than the impact of injection temperature. A steeper formation slope resulted in a higher conversion rate. A shallower formation slope and a higher injection temperature should be selected to store CO2.

Effects of Injection Temperature and Pressure on CO2 Storage Capacity and Safety in a Sloping Formation

“…Based on the actual dip angle of the Shiqianfeng Formation (1–3°), the dip angle of the other simulation schemes was set to 3°. Based on previous experiences, , and the assurance that the injected CO 2 was in a supercritical state, three injection temperature values (31, 38, and 45 °C) were selected including isothermal and nonisothermal conditions. Considering the fracture pressure of the rock, the maximum safe injection pressure was 1.5 times the hydrostatic pressure (1.5P), ,, and three injection pressure values (1.3P, 1.4P, and 1.5P) were set.…”

“…Greater reservoir depth leads to a higher stored CO 2 amount owing to the increase of pressure and temperature that induce higher density in storage . Many existing studies related to CO2 injections have been performed on the temperature and pressure distribution during CO2 injection. ,,,, Tawiah investigated the effect of temperature on CO 2 injectivity, and they found an inverse relationship between the bottomhole temperature of CO 2 and injectivity with the latter increasing. Ma found that an increase in injection temperature decreased the temperature gradient; injection pressure had a certain effect on the temperature gradient at low pressure, and the bottomhole pressure was effectively regulated by the injection pressure.…”