Feasibility Evaluation of CO2 Sequestration in the Naturally Fractured Undulating Formation of Jurong Oilfield, China

Abstract:

Abstract: The oilfield is one of the most important sites to implement the carbon dioxide (CO₂) capture, utilization (CCU) and sequestration technology (CCUS). This study focused on evaluating the CO₂ injection capacity of the Jurong oilfield, which is a naturally fractured undulating formation located in the important petroleum exploration area of southern China. A three-dimensional geological model of Jurong oilfield was established to evaluate the CO₂ injection capacity of the existing exploration wells. The simulation results indicate that the injection amounts of N3, N10, Rong3 and Jubei1 decreased sequentially when CO₂ was injected in the Longtan reservoir through these wells for 30 years, and the total injection amount through well N3 was three times larger than those of the other three wells. In terms of incremental pressure, the wells Rong3 and N10 due to close to the fracture zones, the pressures had smaller increments after CO₂ injection, while the well N3 caused the highest pressure reaching 95.5 bar. The leakage risk is maximal when the supercritical CO₂ (ScCO₂) was injected through the well Jubei1. The reason is that the well Jubei1 was located in the northwest of the undulating area, which prompt the CO₂ migrate to the major fracture zone. Overall, the existing fracture zones were not predicted to significantly increase the leakage of the ScCO₂, while act as preferential paths for the dissolved CO₂. The effective injection coefficient J was defined to represent the injection capacity of a single well. When evaluating the volume of the study area affected by the ScCO₂ and dissolved CO₂, the J were represented by J_g and J_aq, respectively. According to the averages of J_g and J_aq of the study area, the amounts of CO₂ injection when the outside of study area is not affected by the ScCO₂ and dissolved CO₂ will be 6.65ⅹ10⁷ t and 4.65ⅹ10⁷ t, respectively.