Investigation of nanopore confinement on fluid flow in tight reservoirs

Zhang, Yuan; Yu, Wei; Sepehrnoori, Kamy; Di, Yuan

doi:10.1016/j.petrol.2016.11.005

Cited by 56 publications

(13 citation statements)

References 23 publications

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“…This simulation result is summarized as the general correlation between ΔT c and d p /σ LJ , as shown in Equation ( 4). This correlation is widely used in EOS models with shifted critical properties in nanoscale porous media [55][56][57][58][59]. However, lower critical pressures were observed in the following molecular simulation of Lennard-Jones fluids in carbon nanopores with adsorption properties [60,61].…”

Section: Tindy Andmentioning

confidence: 99%

CO2-Fluid-Rock Interactions and the Coupled Geomechanical Response during CCUS Processes in Unconventional Reservoirs

Cai

et al. 2021

Geofluids

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The difficulty of deploying remaining oil from unconventional reservoirs and the increasing CO2 emissions has prompted researchers to delve into carbon emissions through Carbon Capture, Utilization, and Storage (CCUS) technologies. Under the confinement of nanopore in unconventional formation, CO2 and hydrocarbon molecules show different density distribution from in the bulk phase, which leads to a unique phase state and interface behavior that affects fluid migration. At the same time, mineral reactions, asphaltene deposition, and CO2 pressurization will cause the change of porous media geometry, which will affect the multiphase flow. This review highlights the physical and chemical effects of CO2 injection into unconventional reservoirs containing a large number of micro-nanopores. The interactions between CO2 and in situ fluids and the resulting unique fluid phase behavior, gas-liquid equilibrium calculation, CO2 adsorption/desorption, interfacial tension, and minimum miscible pressure (MMP) are reviewed. The pore structure changes and stress distribution caused by the interactions between CO2, in situ fluids, and rock surface are discussed. The experimental and theoretical approaches of these fluid-fluid and fluid-solid reactions are summarized. Besides, deficiencies in the application and safety assessment of CCUS in unconventional reservoirs are described, which will help improve the design and operation of CCUS.

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Section: Tindy Andmentioning

confidence: 99%

CO2-Fluid-Rock Interactions and the Coupled Geomechanical Response during CCUS Processes in Unconventional Reservoirs

Cai

et al. 2021

Geofluids

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“…In this section, we include the different pore size regions with different confined fluid properties to consider the nanopore effects on the history matching, which can obtain a more reasonable simulation model [49]. The diffusion and adsorption were not considered in the history matching process.…”

Section: History Matching With An Actual Well From Eagle Ford Tight Omentioning

confidence: 99%

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Zhang

2019

Energies

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CO2 injection has great potentials to improve the oil production for the fractured tight oil reservoirs. However, Current works mainly focus on its operation processes; full examination of CO2 molecular diffusion and adsorption was still limited in the petroleum industry. To fill this gap, we proposed an efficient method to accurately and comprehensively evaluate the efficiency of CO2-EOR process. We first calculated the confined fluid properties with the nanopore effects. Subsequently, a reservoir simulation model was built based on the experiment test of the Eagle Ford core sample. History matching was performed for the model validation. After that, we examined the effects of adsorption and molecular diffusion on the multi-well production with CO2 injection. Results illustrate that in the CO2-EOR process, the molecular diffusion has a positive impact on the oil production, while adsorption negatively impacts the well production, indicating that the mechanisms should be reasonably incorporated in the simulation analysis. Additionally, simulation results show that the mechanisms of molecular diffusion and adsorption make great contributions to the capacity of CO2 storage in tight formations. This study provides a strong basis to reasonably forecast the long-term production during CO2 Huff-n-Puff process.

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“…Recently, experimental and theoretical studies have shown the existence of capillary pressure effect in nanopores. In an effort to consider the nanopore confinement effect on the phase behavior in tight oil reservoirs, Zhang et al [23] modified flash calculation with capillary pressure and performed the studies of the phase behavior of CO 2 /hydrocarbons systems in Bakken formations, and the results indicated that the capillary pressure effect cannot be neglected in nanopores. MMP of CO 2 injection decreases with the capillary pressure effect, resulting in the suppression of the resistance of fluid transport.…”

Section: Introductionmentioning

confidence: 99%

“…As mentioned above, nanopore confinement effects including capillary pressure, fluid-wall interaction, and molecule adsorption cannot be ignored in porous media with pore diameters less than 50 nm and greater than 2 nm [32][33][34]. Although numerous models have been proposed to explore the phase behavior in nanopores, they focused on one or both aspects of nanoscale confinement [23][24][25][26][27][28][29][30][31], and there still lack an accurate model that takes into account capillary pressure, fluid-wall interaction, and adsorption effect simultaneously. Additionally, despite methods being there to investigate nanopore confinement effect, only a few of them have studies the influence of nanopore confinement effect on CO 2 injection recovery mechanisms in tight oil reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

Zheng

2021

Geofluids

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The pore sizes in tight reservoirs are nanopores, where the phase behavior deviates significantly from that of bulk fluids in conventional reservoirs. The phase behavior for fluids in tight reservoirs is essential for a better understanding of the mechanics of fluid flow. A novel methodology is proposed to investigate the phase behavior of carbon dioxide (CO2)/hydrocarbons systems considering nanopore confinement. The phase equilibrium calculation is modified by coupling the Peng-Robinson equation of state (PR-EOS) with capillary pressure, fluid-wall interaction, and molecule adsorption. The proposed model has been validated with CMG-Winprop and experimental results with bulk and confined fluids. Subsequently, one case study for the Bakken tight oil reservoir was performed, and the results show that the reduction in the nanopore size causes noticeable difference in the phase envelope and the bubble point pressure is depressed due to nanopore confinement, which is conductive to enhance oil recovery with a higher possibility of achieving miscibility in miscible gas injection. As the pore size decreases, the interfacial tension (IFT) decreases whereas the capillary pressure increases obviously. Finally, the recovery mechanisms for CO2 injection are investigated in terms of minimum miscibility pressure (MMP), solution gas-oil ratio, oil volume expansion, viscosity reduction, extraction of lighter hydrocarbons, and molecular diffusion. Results indicate that nanopore confinement effect contributes to decrease MMP, which suppresses to 650 psi (65.9% smaller) as the pore size decreases to 2 nm, resulting in the suppression of the resistance of fluid transport. With the nanopore confinement effect, the CO2 solution gas-oil ratio and the oil formation volume factor of the oil increase with the decrease of pore size. In turn, the oil viscosity reduces as the pore size decreases. It indicates that considering the nanopore confinement effect, the amount of gas dissolved into crude oil increases, which will lead to the increase of the oil volume expansion and the decrease of the viscosity of crude oil. Besides, considering nanopore confinement effect seems to have a slightly reduced effect on extraction of lighter hydrocarbons. On the contrary, it causes an increase in the CO2 diffusion coefficient for liquid phase. Generally, the nanopore confinement appears to have a positive effect on the recovery mechanisms for CO2 injection in tight oil reservoirs. The developed novel model could provide a better understanding of confinement effect on the phase behavior of nanoscale porous media in tight reservoirs. The findings of this study can also help for better understanding of a flow mechanism of tight oil reservoirs especially in the case of CO2 injection for enhancing oil recovery.

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Investigation of nanopore confinement on fluid flow in tight reservoirs

Cited by 56 publications

References 23 publications

CO2-Fluid-Rock Interactions and the Coupled Geomechanical Response during CCUS Processes in Unconventional Reservoirs

CO2-Fluid-Rock Interactions and the Coupled Geomechanical Response during CCUS Processes in Unconventional Reservoirs

Simulation Study of CO2 Huff-n-Puff in Tight Oil Reservoirs Considering Molecular Diffusion and Adsorption

Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

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