Abstract:CO2 flooding is recognized as an efficient method for enhancing shale oil recovery, while CO2-oil MMP (minimum miscibility pressure) in the micro-nanoscale is a crucial parameter. This paper presents a method for calculating the MMPs of pure hydrocarbons (C4H10, C6H14, C8H18, and C10H22) and CO2 systems in nanopores (3 nm to 10 nm) with temperature ranging from 290.15 K to 373.15 K. Firstly, we modify the Peng-Robinson equation of state (PR-EOS) by considering the influence of confinement effect and capillary … Show more
“…It is worth noting that this pressure is 0.55 MPa lower than the value in the 1000 nm confinement under the same conditions, indicating that the MMP in the 30 nm confinement is 4.37% lower than that in the bulk phase. This finding also confirms the existence of confinement effects at the 30 nm scale, as supported by recent studies. ,,− …”
The large-scale development of onshore shale oil is not only an inevitable choice under the current oil and gas resource endowment in China but also a vivid practice to ensure national energy security. The CO 2 Huff-n-Puff method, as one of the main ways to enhance the recovery factor of shale oil, has broad application prospects. In view of the complex interaction mechanism of the CO 2 -hydrocarbon system in the nanospace, which is still poorly understood and lacks experimental means, this paper designs two types of terminal-closed single tubes and porous medium tubes in a nanochip. This design, different from the open-ended single tube, can effectively eliminate the influence of convection and more realistically simulate the fluid mobilization process in the dead-end pores of shale. Based on the nanofluidics experimental, we utilized fluorescence and bright-field imaging to further clarify the gas−liquid miscible process. Additionally, we determined the minimum miscibility pressure (MMP) of CO 2 with seven single-component alkanes and multicomponent mixtures at a high temperature of 70 °C and a scale of 30 nm. Notably, we first discovered that the MMP of a multicomponent mixture composed of C 6 , C 10 , and C 16 in a 10:44:16 molar ratio at a size of 30 nm was 4.37% lower than that in the bulk, providing evidence for the presence of a confinement effect. In addition, we find that the nanofluidics not only has extremely low time cost and minimal sample usage but also has good accuracy (maximum error not exceeding 5%). This effective method, combined with a large amount of MMP values for CO 2 and elemental alkanes as well as multicomponent mixtures at reservoir temperatures, may provide theoretical support for CO 2 -enhanced oil recovery.
“…It is worth noting that this pressure is 0.55 MPa lower than the value in the 1000 nm confinement under the same conditions, indicating that the MMP in the 30 nm confinement is 4.37% lower than that in the bulk phase. This finding also confirms the existence of confinement effects at the 30 nm scale, as supported by recent studies. ,,− …”
The large-scale development of onshore shale oil is not only an inevitable choice under the current oil and gas resource endowment in China but also a vivid practice to ensure national energy security. The CO 2 Huff-n-Puff method, as one of the main ways to enhance the recovery factor of shale oil, has broad application prospects. In view of the complex interaction mechanism of the CO 2 -hydrocarbon system in the nanospace, which is still poorly understood and lacks experimental means, this paper designs two types of terminal-closed single tubes and porous medium tubes in a nanochip. This design, different from the open-ended single tube, can effectively eliminate the influence of convection and more realistically simulate the fluid mobilization process in the dead-end pores of shale. Based on the nanofluidics experimental, we utilized fluorescence and bright-field imaging to further clarify the gas−liquid miscible process. Additionally, we determined the minimum miscibility pressure (MMP) of CO 2 with seven single-component alkanes and multicomponent mixtures at a high temperature of 70 °C and a scale of 30 nm. Notably, we first discovered that the MMP of a multicomponent mixture composed of C 6 , C 10 , and C 16 in a 10:44:16 molar ratio at a size of 30 nm was 4.37% lower than that in the bulk, providing evidence for the presence of a confinement effect. In addition, we find that the nanofluidics not only has extremely low time cost and minimal sample usage but also has good accuracy (maximum error not exceeding 5%). This effective method, combined with a large amount of MMP values for CO 2 and elemental alkanes as well as multicomponent mixtures at reservoir temperatures, may provide theoretical support for CO 2 -enhanced oil recovery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.