Phase Miscibility Research Articles

Air Injection into Condensate Reservoirs in the Middle and Late Stages Increases Recovery with Thermal Miscible Mechanism

Summary Condensate gas reservoirs in the middle and late stages of development are faced with problems such as formation pressure reduction, serious retrograde condensation, and oil and gas seepage channel plugging, which make it difficult to further improve oil and gas recovery by conventional development methods. For this kind of condensate gas reservoir, in this paper we put forward air injection technology as a development means, taking the K condensate gas reservoir in the Tarim Oilfield as the research object. We explored the thermal oxidation characteristics and displacement efficiency of condensate oil/volatile oil by air injection through the thermal oxidation displacement experiment. In addition, we determined quantitatively the minimum miscibility pressure (MMP) of oil samples at high temperature and the correlation between MMP and temperature through a high-temperature, high-pressure slimtube experiment, and clarified the mechanism of “thermally assisted miscible” through fine full-component numerical simulations under high-temperature and high-pressure conditions, which indoor experiments could not achieve. The results showed that condensate oil/volatile oil can form a stable thermal front by injecting air, and the oil displacement efficiency is more than 90%. The MMP of flue gas produced by condensate oil and oxidation reaction decreases gradually with temperature increase, and the MMP is only 11 MPa at 260°C. The high temperature formed by oxidation heat release forces the oil phase into the gas phase, and the extraction of flue gas makes C2-C4 in the oil phase increase continuously, both of which promote the realization of heat-assisted evaporation miscible phase. This thermal-assisted miscible-phase mechanism makes air injection displacement technology an innovative replacement technology for greatly improving the recovery efficiency of condensate gas reservoirs in the middle and late development stages.

Study on the minimum miscibility pressure and phase behavior of CO2–shale oil in nanopores

In recent years, CO2 enhanced oil recovery has gained traction in shale oil reservoirs. Shale oil reservoirs are characterized by numerous nanopores, where shale oil exhibits unique phase behavior due to nano–confinement effects. Traditional theoretical model and microfluidic experiment often fail to accurately depict the minimum miscible pressure (MMP) of CO2–shale oil in nanopores. In this study, nanofluidic experiments were conducted to investigate the MMP of CO2–alkanes in single pore channels and porous media channels with depths of 30 nm and 100 nm. Additionally, a novel thermodynamic model of gas–liquid–adsorbed phase equilibrium, which considers the capillary force and the shift in the critical property, was developed by integrating simplified local density functional theory. The feasibility of the method was determined by comparing the measured MMP with the MMP obtained using the newly established thermodynamic model, resulting in errors of 10.804 % and 5.545 %. Finally, phase behavior and MMP for two typical oil samples in block A in China were conducted using the newly established thermodynamic model. The results revealed that as the pore radius decreases, the area of the two–phase region enclosed by the phase envelope contracts progressively. In addition, the saturation pressure decreases gradually for shale oil with a higher content of light components as the molar fraction of the injected CO2 increases, whereas for shale oil with higher heavy component content, it increases as the CO2 molar fraction increases. The MMP of CO2–shale oil in 10 nm pores is 70.188 bar at 392.75 K of sample 1 and 83.007 bar at 374.72 K of sample 2. Compared to the bulk phase, the MMP was reduced by 63.76 % and 57.64 %.

From mixing to displacement of miscible phases in porous media: The role of heterogeneity and inlet pressures

From mixing to displacement of miscible phases in porous media: The role of heterogeneity and inlet pressures

Understanding the phase behavior during CO2 flooding by dissipative particle dynamics

Understanding the phase behavior of a CO2-oil–water surfactant system is critical for carbon dioxide flooding engineering. Using dissipative particle dynamics, we investigate how the alkanes in crude oil are extracted after the injection of supercritical carbon dioxide into the formation, and what effect this extraction has on the miscible and immiscible displacement of carbon dioxide and crude oil. The images of the extraction are exhibited at the molecular level, and the effects of temperature and pressure on the extraction are investigated. The phase distribution of carbon dioxide, oil, and water under immiscible phase is simulated using actual reservoir fluid data based on a comprehensive understanding of extraction. Oil tends to be spread at the interface of carbon dioxide and water when it is immiscible. The miscible pictures were generated under conditions of reduced CO2-oil–water miscible pressure by adding surfactants to the CO2-oil–water system, and the fluid distribution characteristics under immiscible and miscible phases were examined. dissipative particle dynamics (DPD) simulation demonstrates that when the molar proportion of carbon dioxide is less than 0.4, the solid phase surface can always create a water film of varied thickness, regardless of whether the surface charge of the solid phase is positive or negative. As the molar fraction of carbon dioxide increases, the water film’s thickness decreases.

Pore-scale probing CO2 huff-n-puff in extracting shale oil from different types of pores using online T1–T2 nuclear magnetic resonance spectroscopy

CO2 huff-n-puff shows great potential to promote shale oil recovery after primary depletion. However, the extracting process of shale oil residing in different types of pores induced by the injected CO2 remains unclear. Moreover, how to saturate shale core samples with oil is still an experimental challenge, and needs a recommended procedure. These issues significantly impede probing CO2 huff-n-puff in extracting shale oil as a means of enhanced oil recovery (EOR) processes. In this paper, the oil saturation process of shale core samples and their CO2 extraction response with respect to pore types were investigated using online T1–T2 nuclear magnetic resonance (NMR) spectroscopy. The results indicated that the oil saturation of shale core samples rapidly increased in the first 16 days under the conditions of 60 °C and 30 MPa and then tended to plateau. The maximum oil saturation could reach 46.2% after a vacuum and pressurization duration of 20 days. After saturation, three distinct regions were identified on the T1–T2 NMR spectra of the shale core samples, corresponding to kerogen, organic pores (OPs), and inorganic pores (IPs), respectively. The oil trapped in IPs was the primary target for CO2 huff-n-puff in shale with a maximum cumulative oil recovery (COR) of 70% original oil in place (OOIP) after three cycles, while the oil trapped in OPs and kerogen presented challenges for extraction (COR < 24.2% OOIP in OPs and almost none for kerogen). CO2 preferentially extracted the accessible oil trapped in large IPs, while due to the tiny pores and strong affinity of oil-wet walls, the oil saturated in OPs mainly existed in an adsorbed state, leading to an insignificant COR. Furthermore, COR demonstrated a linear increasing tendency with soaking pressure, even when the pressure noticeably exceeded the minimum miscible pressure, implying that the formation of a miscible phase between CO2 and oil was not the primary drive for CO2 huff-n-puff in shale.

A Multiphase and Multicomponent Model and Numerical Simulation Technology for CO2 Flooding and Storage

In recent years, CO2 flooding has become an important technical measure for oil and gas field enterprises to further improve oil and gas recovery and achieve the goal of “dual carbon”. It is also one of the concrete application forms of CCUS. Numerical simulation based on CO2-EOR plays an indispensable role in the study of the mechanism of CO2 flooding and buried percolation, allowing for technical indicators to be selected and EOR/EGR prediction to be improved for reservoir engineers. This paper discusses the numerical simulation techniques related to CO2 flooding and storage, including mathematical models and solving algorithms. A multiphase and multicomponent mathematical model is developed to describe the flow mechanism of hydrocarbon components–CO2–water underground and to simulate the phase diagram of the components. The two-phase P-T flash calculation with SSI (+DEM) and the Newton method is adopted to obtain the gas–liquid phase equilibrium parameters. The extreme value judgment of the TPD function is used to form the phase stability test and miscibility identification model. A tailor-made multistage preconditioner is built to solve the linear equation of the strong-coupled, multiphase, multicomponent reservoir simulation, which includes the variables of pressure, saturation, and composition. The multistage preconditioner improves the computational efficiency significantly. A numerical simulation of CO2 injection in a carbonate reservoir in the Middle East shows that it is effective for researching the recovery factor and storage quantity of CO2 flooding based on the above numerical simulation techniques.

Experimental study on immiscible and miscible dynamic characteristics of CO2 and crude oil in visual slim tube

CO2 flooding for oil recovery is a dynamic process that requires further investigation of oil-gas interface change characteristics, interfacial mass transfer processes, and oil-gas composition variation during both immiscible and miscible displacement. Understanding these factors is crucial for better comprehending their impact on CO2-enhanced oil recovery (EOR). This research used a jointly developed CO2 miscible visual flooding experimental apparatus to study the horizontal dynamic characteristics of CO2 and crude oil under different pressures and flow rates in visual slim tube. At 10 MPa, the stratification results of CO2 and crude oil indicate that the experiment is immiscible flooding. The contact angle (7.9°) between the two phases of CO2 and crude oil at the flow rate of 15 cm/min is larger than that (5.2°) at 1.5 cm/min, and the grey scale of CO2 increases at 100 cm/min. The quantity, individual content, and shape of the light and medium hydrocarbon components condensed on the inner wall of the tube vary with different flow rates. At 15 MPa, the appearance of the CO2 and crude oil transition interval proves that the experiment is miscible flooding. At different flow rates, the inclination angle and distribution of black stripes vary. The whole transition interval is divided into 6 intervals, and the transition interval lengthens with increasing fluid velocity. The experiments visually demonstrate the occurrence of the miscible phase, and identify experimental pressure and fluid flow rate as key factors influencing the miscibility of CO2 and crude oil.

Characteristics and Mechanisms of CO2 Flooding with Varying Degrees of Miscibility in Reservoirs Composed of Low-Permeability Conglomerate Formations

The reservoir type of the MH oil field in the Junggar Basin is a typical low-permeability conglomerate reservoir. The MH oilfield was developed by water injection in the early stage. Nowadays, the reservoir damage is serious, and water injection is difficult. There is an urgent need to carry out conversion injection flooding research to improve oil recovery. The use of CO2 oil-flooding technology can effectively supplement formation energy, reduce greenhouse gas emissions, and improve economic benefits. In order to clarify the feasibility of CO2 flooding to improve oil recovery in conglomerate reservoirs with low permeability, strong water sensitivity, and severe heterogeneity, this paper researched the impact of CO2 miscibility on production characteristics and mechanisms through multi-scale experiments. The aim was to determine the feasibility of using CO2 flooding to enhance oil recovery. This study initially elucidated the oil displacement characteristics of varying degrees of miscibility in different dimensions using slim tube experiments and long core experiments. Subsequently, mechanistic research was conducted, focusing on the produced oil components, changes in interfacial tension, and conditions for pore mobilization. The results indicate that the minimum miscibility pressure (MMP) of the block is 24 MPa. Under the slim tube scale, the increase in the degree of miscibility can effectively delay the gas breakthrough time; under the core scale, once the pressure reaches the near mixing phase, the drive state can transition from a non-mixed “closed-seal” to a “mixed-phase” state. Compared to the immiscible phase, the near-miscible and completely miscible phase can improve the final recovery efficiency by 9.27% and 18.72%. The component differences in the displacement products are mainly concentrated in the high-yield stage and gas breakthrough stage. During the high-yield stage, an increase in miscibility leads to a higher proportion of heavy components in the produced material. Conversely, in the gas breakthrough stage, extraction increases as the level of mixing increases, demonstrating the distinct extracting characteristics of different degrees of mixed phases. The core experiences significant variations in oil saturation mostly during the pre-gas stage. CO2 miscible flooding can effectively utilize crude oil in tiny and medium-sized pores during the middle stage of flooding, hence reducing the minimum threshold for pore utilization to 0.3 μm.

Correction to “A correlation between morphology and mechanical performance of injected‐molded PE/EVA/clay nanocomposites: Insight into phase miscibility and interfacial phenomena”

Correction to “A correlation between morphology and mechanical performance of injected‐molded <scp>PE</scp>/<scp>EVA</scp>/clay nanocomposites: Insight into phase miscibility and interfacial phenomena”

Polypyrrole@Pd solar-thermal catalyst for eco-friendly and scalable multiphasic Suzuki coupling reactions

Solar-thermal materials enable the heating of reaction solutions in organic reactions without consuming fossil fuels or electricity. In this study, nanostructured polypyrole@Pd was utilized with solar-thermal, catalytic, and Pickering emulsifier functionalities to successfully demonstrate eco-friendly and scalable Suzuki coupling reactions. Pd-catalyzed multiphasic Suzuki coupling reactions were accelerated with high conversions through solar-thermal heating and the formation of Pickering emulsions in a phase-separated, highly concentrated reaction mixture using polypyrole@Pd. Increasing the interfacial area by forming a Pickering emulsion facilitates mass transfer between the two miscible liquid phases, which is crucial for multiphasic reactions. Gram-scale synthesis under solar illumination over an area of 3.14 cm2 was successfully achieved, and the multiple usability of polypyrrole@Pd was demonstrated over 20 cycles.

Cellulose- and Saccharide-Based Orally Dispersible Thin Films Transform the Solid States and Dissolution Characteristics of Poorly Soluble Curcumin.

This study aimed at developing and optimizing the orally dispersible thin film (ODTF) containing a plant-derived drug-curcumin (CUR). CUR belongs to a biopharmaceutical classification system (BCS) class IV compound that requires improving its water solubility and tissue permeability preceding formulation. An ODTF was applied to produce a solid dispersion matrix for CUR to resolve such solubility and permeability problems. The film-forming polymers used in the study were cellulose-based (hydroxypropyl methylcellulose/HPMC and carboxymethylcellulose/CMC) and saccharide-based maltodextrin (MDX). Poloxamer (POL) was also employed as surfactant and solubilizer. The solvent casting technique was applied to produce the films. The ethanolic solution of CUR was mixed with an aqueous solution of POLs and then incorporated into different film-forming polymers prior to casting. The processing of the CUR with POL solution was intended to aid in the even dispersion of the drug in the polymeric matrices and enhance the wettability of the films. The physical state and properties of the films were characterized in terms of their morphology, crystallinity of the drug, and phase miscibility of the mixtures. The dissolution profile of the films was also evaluated in terms of dissolution rate and dissolution efficiency. The obtained ODTF products were smooth and flat-surfaced. Physical characterization also indicated that the CUR was homogeneously dispersed in the ODTFs and no longer existed as crystalline material as revealed by X-ray diffraction (XRD). The CUR was also not phase-separated from the films as disclosed by differential scanning calorimetry (DSC). Such dispersion was achieved through the solubilizing effect of POLs and compact polymeric film matrices that prevented the CUR from recrystallization. Furthermore, the ODTFs also improved the dissolution of CUR by 3.2-fold higher than the raw CUR. Overall, cellulose-based films had favorable physical properties compared with saccharide-based films.

An Indacenodithienothiophene-Based Wide Bandgap Small Molecule Guest for Efficient and Stable Ternary Organic Solar Cells.

The strategic and logical development of the third component (guest materials) plays a pivotal and intricate role in improving the efficiency and stability of ternary organic solar cells (OSCs). In this study, a novel guest material with a wide bandgap, named IDTR, is designed, synthesized, and incorporated as the third component. IDTR exhibits complementary absorption characteristics and cascade band alignment with the PM6:Y6 binary system. Morphological analysis reveals that the introduction of IDTR results in strong crystallinity, good miscibility, and proper vertical phase distribution, thereby realizing heightened and balanced charge transport behavior. Remarkably, the novel ternary OSCs have exhibited a significant enhancement in photovoltaic performance. Consequently, open-circuit voltage (VOC), short-circuit current (JSC), and fill factor (FF) have all witnessed substantial improvements with a remarkable power conversion efficiency (PCE) of 18.94% when L8-BO replaced Y6. Beyond the pronounced improvement in photovoltaic performance, superior device stability with a T80 approaching 400h is successfully achieved. This achievement is attributed to the synergistic interplay of IDTR, providing robust support for the overall enhancement of performance. These findings offer crucial guidance and reference for the design and development of efficient and stable OSCs.

Melittin-Phospholipase A2 Synergism Is Mediated by Liquid-Liquid Miscibility Phase Transition in Giant Unilamellar Vesicles.

The primary constituents of honeybee venom, melittin and phospholipase A2 (PLA2), display toxin synergism in which the PLA2 activity is significantly enhanced by the presence of melittin. It has been shown previously that this is accomplished by the disruption in lipid packing, which allows PLA2 to become processive on the membrane surface. In this work, we show that melittin is capable of driving miscibility phase transition in giant unilamellar vesicles (GUVs) and that it raises the miscibility transition temperature (Tmisc) in a concentration-dependent manner. The induced phase separation enhances the processivity of PLA2, particularly at its boundaries, where a substantial difference in domain thickness creates a membrane discontinuity. The catalytic action of PLA2, in response, induces changes in the membrane, rendering it more conducive to melittin binding. This, in turn, facilitates further lipid phase separation and eventual vesicle lysis. Overall, our results show that melittin has powerful membrane-altering capabilities that activate PLA2 in various membrane contexts. More broadly, they exemplify how this biochemical system actively modulates and capitalizes on the spatial distribution of membrane lipids to efficiently achieve its objectives.

Effect of TiO2 addition on microstructure and mechanical properties of Al2O3 ceramic joints brazed with Ag‐CuO fillers

AbstractIn our work, 0.5 mol.% TiO2 was added to Ag‐xCuO (x = 2, 4, 8 mol.%) fillers whose compositions at 1050°C were in the L2 single liquid phase region, the boundary of the miscible phase region, and the L1+L2 miscible phase region, respectively. The role of TiO2 was derived by comparing the quenching microstructure of the fillers on the Al2O3 ceramics and the effect on the interfacial microstructure and shear strength of the joints before and after the addition of TiO2. The results showed that the TiO2 would dissolve into the CuO‐rich L1 liquid phase of the filler, leading it to spread outside the molten droplet. When brazing with Ag‐4CuO‐0.5TiO2 filler, the CuO at the joint interface almost completely disappeared, and the shear strength of the joint was significantly reduced. In contrast, the joint strength showed a small increase when using Ag‐8CuO‐0.5TiO2 filler, as the excess CuO at the interface of the brazed joint was reduced. When the filler composition was in the L2 single liquid phase region, CuO was diffusely distributed throughout the molten droplet. TiO2 was hardly contacted with CuO and its addition had no significant effect on the interfacial microstructure and the shear strength of the joints.

Reliability Evaluation of a Dynamic-Pressure Mechanical Seal Based on Liquid Film Vaporization Phase Transition

Aiming at the problem of researching the reliability of dynamic-pressure mechanical seals, this paper proposes a reliability evaluation method for dynamic-pressure mechanical seals based on the Monte Carlo method. Based on the influence of the mass transfer coefficient on vaporization phase transition, a liquid film vaporization model of a hydrodynamic mechanical seal’s end face is established, and the working condition parameters and groove structure parameters are designed using the experimental design method. The vaporization characteristics of the liquid film under various parameters are analyzed, and the functional functions of the vaporization characteristics are obtained by fitting. Combined with the maximum vapor phase volume fraction when the dynamic-pressure mechanical seal changes from the liquid miscible phase to the vapor miscible phase, the limit state equation of the vapor phase volume fraction is obtained. Finally, based on the Monte Carlo simulation method, the sealing reliability under specific groove structure parameters is calculated. Our research shows that this method has practicability and effectiveness for the reliability evaluation of mechanical seals with different working conditions and different groove structures.

Miscibility phase diagram for ternary vesicle compositions with PE lipids

Miscibility phase diagram for ternary vesicle compositions with PE lipids

Concomitant Precipitation of Solid-State Miscible Product-Impurity Phases in Solution Crystallization. Part 1: Theoretical Basis and Workflow for Efficient Impurity Rejection

Concomitant Precipitation of Solid-State Miscible Product-Impurity Phases in Solution Crystallization. Part 1: Theoretical Basis and Workflow for Efficient Impurity Rejection

Phase separation in soft repulsive polymer mixtures: foundation and implication for chromatin organization.

Given the wide range of length scales, the analysis of polymer systems often requires coarse-graining, for which various levels of description may be possible depending on the phenomenon under consideration. Here, we provide a super-coarse grained description, where polymers are represented as a succession of mesosopic soft beads which are allowed to overlap with others. We then investigate the phase separation behaviors in a mixture of such homopolymers based on mean-field theory, and discuss universal aspects of the miscibility phase diagram in comparison with the numerical simulation. We also discuss an extension of our analysis to mixtures involving random copolymers, which might be interesting in the context of chromatin organization in a cell nucleus.

Spin rotons and supersolids in binary antidipolar condensates

We present a theoretical study of a mixture of antidipolar and nondipolar Bose-Einstein condensates confined to an infinite tube. We predict the presence of a spin roton and its associated instability, which triggers a continuous unmodulated-to-supersolid phase transition. We characterize the phase diagram of the binary system, ranging from the quasi-1D to the radial Thomas-Fermi (elongated 3D) regimes. We also present the dynamic formation of supersolids following a quench from the uniform miscible phase, which maintains phase coherence across the system.

Phase homogeneity in ternary amorphous solid dispersions and its impact on solubility, dissolution and supersaturation – Influence of processing and hydroxypropyl cellulose grade

As performance of ternary amorphous solid dispersions (ASDs) depends on the solid-state characteristics and polymer mixing, a comprehensive understanding of synergistic interactions between the polymers in regard of dissolution enhancement of poorly soluble drugs and subsequent supersaturation stabilization is necessary. By choosing hot-melt extrusion (HME) and vacuum compression molding (VCM) as preparation techniques, we manipulated the phase behavior of ternary efavirenz (EFV) ASDs, comprising of either hydroxypropyl cellulose (HPC)-SSL or HPC-UL in combination with Eudragit® L 100–55 (EL 100–55) (50:50 polymer ratio), leading to single-phased (HME) and heterogeneous ASDs (VCM). Due to higher kinetic solid-state solubility of EFV in HPC polymers compared to EL 100–55, we visualized higher drug distribution into HPC-rich phases of the phase-separated ternary VCM ASDs via confocal Raman microscopy. Additionally, we observed differences in the extent of phase-separation in dependence on the selected HPC grade. As HPC-UL exhibited decisive lower melt viscosity than HPC-SSL, formation of partially miscible phases between HPC-UL and EL 100–55 was facilitated. Consequently, as homogeneously mixed polymer phases were required for optimal extent of solubility improvement, the manufacturing-dependent differences in dissolution performances were smaller using HPC-UL, instead of HPC-SSL, i.e. using HPC-UL was less demanding on shear stress provided by the process.