Soaking in CO2 huff-n-puff: A single-nanopore scale study

Moh, Do Yoon; Zhang, Hongwei; Wang, Shihao; Yin, Xiaolong; Qiao, Rui

doi:10.1016/j.fuel.2021.122026

Cited by 40 publications

(28 citation statements)

References 38 publications

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“…In the supercritical state, CO 2 has the characteristics of low viscosity and strong diffusivity, which can enter small pores and promote oil production and thus improve the oil recovery. 20,21 CO 2 flooding can be divided into miscible flooding, nearmiscible flooding, immiscible flooding, and carbonized water flooding. 22−25 Compared with immiscible flooding, the nearmiscible and miscible flooding methods have a better displacement efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…Gas injection production has become the main means of increasing oil production in tight reservoirs. − Especially, CO 2 flooding can not only greatly improve the oil recovery of low-permeability tight reservoirs but also realize the geological storage of CO 2 . − For example, Liu et al (2022) proposed dimethyl ether and propanol as efficient agents in assisting conventional CO 2 flooding for oil recovery while increasing CO 2 storage in reservoirs. , CO 2 -enhanced oil recovery mainly includes reducing viscosity of crude oil, swelling effect of crude oil, wettability alteration, and change of interfacial properties. − When the temperature is higher than 31.1 °C and pressure is higher than 7.38 MPa, CO 2 enters a supercritical state. In the supercritical state, CO 2 has the characteristics of low viscosity and strong diffusivity, which can enter small pores and promote oil production and thus improve the oil recovery. , …”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

Gao

Luo

Xie³

et al. 2022

Energy Fuels

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The microscopic pore structure of tight sandstone reservoirs significantly impacts CO2 flooding characteristics. In this work, two types of realistic sandstone visualization models were selected based on petrophysical properties and the pore structure feature. CO2 flooding experiments under different injection pressures and volumes were carried out using the in-house high-temperature and -pressure visualization flooding system. Then, the characteristics of oil movement and residual oil distribution were quantitatively described and analyzed for two rock types. The results show that the type I model has better physical properties and a more favorable pore structure, thus a higher oil recovery than the type II model. The immiscible CO2 flooding efficiency of the type I model is up to 64.5%. On the other hand, the oil recovery of the type II model increases when the miscible pressure is reached, and the maximum oil recovery is 49.5%. In the high-pressure miscible flooding stage, two types of models have similar oil recovery increments, which are 10.7 and 10.6%, respectively. Additionally, the residual oil distribution varies with the pore structure. The type I model has a small residual oil region and thus a high oil recovery efficiency. In contrast, the residual oil saturation of the type II model is larger, and the final oil recovery decreases. Furthermore, as the injection pressure and volume increase, the residual oil saturation becomes smaller, and oil recovery of both models increases. The occurrence characteristics of residual oil are oil droplet, cluster-shaped residual oil, flake oil, and dead corner oil, and the main influencing factors are capillary force, injection pressure, and pore connectivity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

Gao

Luo

Xie³

et al. 2022

Energy Fuels

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“…The CO 2 -EOR contains different methods such as CO 2 -WAG, continuous CO 2 injection, CO 2 huff-n-puff (H-n-P), and gas-assisted gravity drainage (GAGD). , Furthermore, studies have been conducted to assess the performance of CO 2 -EOR techniques in oil-bearing reservoirs that showed that continuous CO 2 injection during CO 2 -EOR is highly effective for oil displacement and viscosity reduction. , However, this continuous CO 2 injection can cause CO 2 breakthrough that is induced by gravity segregation, thereby causing viscosity fingering and permeability reduction because of inorganic and asphaltene deposition . The GAGD is presented as a powerful CO 2 -EOR technique to improve oil recovery because of the density difference between the injected gas and the crude oil. , The main advantage of GAGD is the huge volume of CO 2 that can be injected into the subsurface formation, which leads to cutting down the large-scale emissions of CO 2 into the atmosphere and boosts the volumetric sweep efficiency. , The basic idea behind GAGD is to inject gas vertically to form a gas cap, then utilize gravity segregation to drive oil and water out of the reservoir by employing situated horizontal wells to extract the oil.…”

Section: Introductionmentioning

confidence: 99%

“…4,12 Furthermore, studies have been conducted to assess the performance of CO 2 -EOR techniques in oil-bearing reservoirs that showed that continuous CO 2 injection during CO 2 -EOR is highly effective for oil displacement and viscosity reduction. 11,13 However, this continuous CO 2 injection can cause CO 2 breakthrough that is induced by gravity segregation, thereby causing viscosity fingering and permeability reduction because of inorganic and asphaltene deposition. 14 The GAGD is presented as a powerful CO 2 -EOR technique to improve oil recovery because of the density difference between the injected gas and the crude oil.…”

Section: Introductionmentioning

confidence: 99%

CO₂ Sequestration and Enhanced Oil Recovery via the Water Alternating Gas Scheme in a Mixed Transgressive Sandstone-Carbonate Reservoir: Case Study of a Large Middle East Oilfield

et al. 2022

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The knowledge on CO2 sequestration and CO2 enhanced oil recovery (CO2-EOR) in mature mixed and interbedded hydrocarbon reservoirs are limited. In this vein, the feasibility of CO2-water alternating gas (CO2-WAG) for coupling CO2 sequestration and CO2-EOR in a mature mixed sandstone-carbonate reservoir was investigated using the S1A reservoir. First, core sample analysis and scanning electron microscopy (SEM) were conducted to evaluate the reservoir characterization. Next, a geological model with dual porosity and permeability was developed and transferred to a reservoir simulation model, and 21-year field production data were utilized for history matching and constraining of the reservoir model. Then, continuous CO2 and CO2-WAG injection methods were simulated using newly developed and history-matched geo-models and compared to assess their CO2-EOR and CO2 storage mechanisms and determine their potential in a mixed sandstone-carbonate reservoir. The effect of the anisotropic permeability ratio and hysteresis on CO2 storage mechanisms was addressed in this work. The results indicate that the CO2-WAG scheme can yield a +3% oil recovery factor than the continuous CO2 injection method, and CO2-WAG injection can utilize up to 14 and 12% of the total CO2 injected for residual and solubility trappings, respectively, while a minimal 2.9 and 0.03% was utilized from continuous CO2 injection for residual and solubility trappings, respectively. The WAG ratio of 2:1 could yield a higher recovery factor and greater CO2 utilization for solubility and residual trappings in a mixed reservoir. In mixed and interbedded reservoirs, geological anisotropy can also strongly influence reservoir performance during the CO2-EOR process, in which higher values of the anisotropy ratio (K v/K h) in CO2-WAG can yield greater oil recovery and more CO2 storage; also, hysteresis has great impact on residual trapping. This study provides valuable insights into the potential of CO2-WAG for CO2 sequestration and CO2-EOR in mature mixed and interbedded reservoirs.

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“…In the past decade, the global consumption of fossil energy has tremendously increased, which increases the urgency of the development of new hydrocarbon resources [ 1 , 2 , 3 ]. Among the unconventional sources, shale oil has aroused extensive interest attributed to its abundant reserves, continuous distribution, and easy exploitation in comparison with the existing primary fossil energy [ 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Hexane Displaced by Supercritical Carbon Dioxide: Insights from Molecular Simulations

Song

Zhu

2022

Molecules

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Supercritical carbon dioxide (sCO2) has great potential for displacing shale oil as a result of its high solubility and low surface tension and viscosity, but the underlying mechanisms have remained unclear up to now. By conducting equilibrium molecular dynamics (EMD) simulations, we found that the displacing process could be divided into three steps: the CO2 molecules were firstly injected in the central region of shale slit, then tended to adsorb on the SiO2-OH wall surface and mix with hexane, resulting in loose hexane layer on the shale surface, and finally displaced hexane from the wall due to strong interactions between CO2 and wall. In that process, the displacing velocity and efficiency of hexane exhibit parabolic and increased trends with pressure, respectively. To gain deep insights into this phenomenon, we further performed non-equilibrium molecular dynamics (NEMD) simulations and found that both the Onsager coefficients of CO2 and hexane were correlated to increase with pressure, until the diffusion rate of hexane being suppressed by the highly dense distribution of CO2 molecules at 12 MPa. The rapid transportation of CO2 molecules in the binary components (CO2 and hexane) actually promoted the hexane diffusion, which facilitated hexane flowing out of the nanochannel and subsequently enhanced oil recovery efficiency. The displacing process could occur effectively at pressures higher than 7.5 MPa, after which the interaction energies of the CO2-wall were stronger than that of the hexane-wall. Taking displacing velocity and efficiency and hexane diffusion rate into consideration, the optimal injection pressure was found at 10.5 MPa in this work. This study provides detailed insights into CO2 displacing shale oil and is in favor of deepening the understanding of shale oil exploitation and utilization.

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Soaking in CO2 huff-n-puff: A single-nanopore scale study

Cited by 40 publications

References 38 publications

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

CO₂ Sequestration and Enhanced Oil Recovery via the Water Alternating Gas Scheme in a Mixed Transgressive Sandstone-Carbonate Reservoir: Case Study of a Large Middle East Oilfield

Mechanism of Hexane Displaced by Supercritical Carbon Dioxide: Insights from Molecular Simulations

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Soaking in CO2 huff-n-puff: A single-nanopore scale study

Cited by 40 publications

References 38 publications

Experimental Investigation of the CO2 Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

Experimental Investigation of the CO2 Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

CO2 Sequestration and Enhanced Oil Recovery via the Water Alternating Gas Scheme in a Mixed Transgressive Sandstone-Carbonate Reservoir: Case Study of a Large Middle East Oilfield

Mechanism of Hexane Displaced by Supercritical Carbon Dioxide: Insights from Molecular Simulations

Contact Info

Product

Resources

About

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

CO₂ Sequestration and Enhanced Oil Recovery via the Water Alternating Gas Scheme in a Mixed Transgressive Sandstone-Carbonate Reservoir: Case Study of a Large Middle East Oilfield