Increase In Saturation Pressure Research Articles

Study on the Mechanism of Carbon Dioxide Miscible Fracturing Fluid Huff and Puff in Enhanced Oil Recovery

Carbon dioxide (CO2) miscible fracturing huff-and-puff technology now plays a pivotal role in enhancing crude oil recovery rates, particularly in reservoirs with challenging physical properties, strong water sensitivity, high injection pressure, and complex water-injection dynamics. In this study, the oil-increasing mechanism and huff-and-puff effect of CO2 miscible fracturing fluid are investigated through a comprehensive experimental approach. Specifically, experiments on PVT gas injection expansion, minimum miscible pressure, and CO2 miscible fracturing fluid huff and puff are conducted on the G fault block reservoir of the J Oilfield. The experimental findings demonstrate that injecting CO2 into reservoirs leads to an expansion in oil volume, a reduction in viscosity, and an increase in saturation pressure. Crude oil extraction is further enhanced by the addition of solubilizers and viscosity reducers. The use of solubilizers not only increases oil recovery rates but also reduces the minimum miscible pressure required for effective CO2 dispersion. We also found that shut-in times, permeability, and the huff-and-puff method used all have considerable impacts on huff-and-puff recovery rates. This study offers valuable technical insights, supporting the application of CO2 miscible fracturing huff-and-puff technology to enhance oil recovery rates in low-permeability reservoirs.

Flow condensation inside a multiport mini channel and a rectangular mini channel with pin fin array

In this paper, an experimental study of flow condensation was carried out of R134a in a multiport mini channel and a mini channel with pin fin array. The former comprised 20 parallel rectangular channels with an equivalent diameter of 0.64 mm. The latter is a narrow rectangular mini channel containing 10 rows of diamond pin fins with a staggered configuration, and height and longitudinal/transverse pitch of 0.5 mm and 2 mm respectively. To acquire the local value of heat flux and heat transfer coefficient, air jet impingement cooling devices were adopted to condense the vapor of refrigerants. The effects of vapor quality, mass flux, heat flux, and saturation pressure on flow condensation heat transfer coefficient were investigated with the operating conditions: vapor quality from 1 to 0, mass flux from 160 to 450 kg/(m2s), heat flux from 10.0 to 39.8 kW/m2, and saturation pressure from 600 to 1500 kPa. The experimental results indicated that the pin fin array significantly improves the condensation heat transfer coefficient up to nearly 186 % compared to the multiport mini channel in the high vapor quality region. For both channels, the local heat transfer coefficient increases with an increase in vapor quality, mass flux, and heat flux whereas decreases with increase in saturation pressure. The influence of heat flux and mass flux on heat transfer coefficient was more pronounced in the high vapor quality region than in the low vapor quality region. A sensitivity analysis was performed at different vapor quality levels. The most influential parameters in the smooth channel and the pin fin array are saturation pressure and mass flux, respectively. The relative contribution of heat flux is more obvious in the high vapor quality region. Some of the existing correlations have good prediction performance for the smooth channel experimental data in this paper, and the corresponding MAD is within 20 %. However, their deviations are much greater for the applications of pin fin array.

Friction and Wear Characteristics of Bacterial Cellulose Modified by Microcellular Foaming Process

Bacterial cellulose (BC) is a biodegradable, non-toxic, natural substance that can be obtained by culturing bacteria. It can be approached in various ways from physical, chemical, and biological points. BC nanoparticles have been applied as lubricating additives to improve the load capacity, anti-wear, and friction. The microcellular foaming process was created using a technology based on the saturation of the polymer by supercritical CO2 and rapid decompression. An increase in saturation pressure leads to an increase in the molecular potential energy of CO2, which can be more easily compressed into the cellulose matrix. Moreover, the high crystallinity and water content combination contribute to thermal stability. Specimen membranes produced by Komagataeibacter xylinus prepared with a thickness of 2 mm were saturated in supercritical condition, 10 MPa of CO2 for 4 h, and foamed at a temperature of 120 °C in a hot press. After the foaming process, we used dry ice to cool the BC. Before foaming, the friction coefficient continuously increased with the increase in cycles, and after foaming, a stable friction coefficient of 0.3 or less was secured despite the increase in the cycle. The microcellular foaming process significantly reduced and made BC’s coefficient of friction stable.

Experimental investigation on the heat transfer and pressure drop characteristics of R600a in a minichannel condenser with different inclined angles

• The heat transfer and pressure drop of R600a in a compact condenser was studied. • The effect of inclined angle in both horizontal and vertical directions was analyzed. • The calculation method of logarithmic mean temperature difference was modified. • New heat transfer correlation was proposed with a mean average deviation of 9.8%. • New friction factor correlation was proposed with a mean average deviation of 7.3%. The condensation heat transfer and pressure drop characteristics of R600a in a multi-louvered fins compact heat exchanger were studied in detail. Experiments were carried out at saturation pressures from 530 to 620 kPa, mass fluxes from 25 to 41.25 kg∙(m 2 ∙s) −1 , air temperature from 25 to 35 °C and inclined angles from 0° to 180° in horizontal and vertical directions, respectively. The effects of mass flux, saturation pressure, air temperature, and inclined angle were analyzed and discussed. The results indicated that both heat transfer coefficient and pressure drop increased with the increase of mass flux and decreased with the increase of saturation pressure. Both heat transfer coefficient and pressure drop were significantly affected by the inclined angle, while the heat transfer capacity of the condenser was almost independent of the inclined angle. The experimental data were compared with several well-known condensation heat transfer models. Based on analysis results, the modified method to calculate the logarithmic average temperature difference was proposed. This predicted method could decrease the deviations of those models by 15%. In addition, the improved correlations for heat transfer and friction factor were proposed and predicted the present experimental data well with 90% of the data points within the bandwidth of ±15% and ±12%, respectively.

Dissolved Air Flotation with Saturation of Liquid in Spray-Type Saturator

A new method of dissolved air (pressure) flotation with the spraying of liquid is presented in the paper. The liquid to be treated is sprayed in the saturator with a hydraulic nozzle which makes it possible to increase the contact surface between the liquid and the gas in comparison with the traditional sparged-air saturator system. The proposed method increases the gas content of the liquid entering the flotation unit for treatment. The paper presents the results of experimental research in terms of the efficiency of liquid saturation in a pressure vessel using whirl and spiral nozzles. The volumetric method was used to determine the amount of air released during the dissolved air flotation based on which the sparging rate was calculated. It is shown that, when the liquid is sprayed, the amount of dissolved air increases by an average of 33% compared to a sparged-air pressure vessel. The sparging rate increases with the increase of saturation pressure and essentially depends on the area of the flotation unit. At the saturation pressure above 2 bar, the sparging rate in the center of the flotation unit becomes significantly higher than that in the wall-adjacent area.

PREPARATION OF PMMA/MWNTS NANOCOMPOSITE MICROCELLULAR FOAMS BY IN-SITU GENERATION OF SUPERCRITICAL CARBON DIOXIDE

Nanocomposites containing poly(methyl methacrylate) (PMMA) and surface functionalized Multi-Walled Carbon Nanotubes (MWNTs) were synthesized. The dispersion of MWNTs in PMMA was characterized using Transmission Electron Microscopy (TEM).The synthesized nanocomposites were successfully foamed using a simple method based on the in-situ generation of supercritical carbon dioxide (CO2). This method in contrast with conventional methods exempted from high-pressure pump and separated CO2 tank. The effect of MWNTs concentration, saturation temperature and saturation pressure on cellular morphology of the prepared microcellular foams were studied by Scanning Electron Microscopy (SEM), and average cell size and cell density of the prepared foams were studied by image analysis. An increase in cell density, as well as a reduction of cell size, was observed with an increase in the concentration of carbon nanotubes. It was also observed that an elevation of saturation temperature from 90 °C to 100 °C, at constant saturation pressure, leads to a higher cell density and a lower average cell size. Furthermore, an increase in saturation pressure results in a decrease in average cell diameter as well as an increase in cell density. However, the effects of MWNTs concentration on both of average cell size and cell density were proved to be more striking than those of saturation pressure.

Rapid Gas Decompression Performance of elastomers – A study of influencing testing parameters

Materials used for the oil and gas industry are exposed to high pressure, high temperature and several aggressive fluids and gases. Concerning the still rising oil and gas product demand the development of new oil and gas valves is indispensable. Therefore, new reliable materials to guarantee facility safety at extreme operating conditions are needed. The presented study deals with a specific failure, the rapid gas decompression failure, which occurs due to the exposure to such extreme conditions. This failure leads to crack initiation, crack growth and in the worst case to the complete fragmentation of the component. For the characterization of this failure a hydrogenated acrylonitrile butadiene based rubber with an acrylonitrile content of 36% was exposed to several temperatures, saturation pressures, gas mixtures and different depressurization rates. Whereas, the rising testing temperature leads to decreasing volume change during the depressurization, the increase in saturation pressure, a higher decompression rate and a higher amount of carbon dioxide clearly lead to an increasing of the maximum observed volume change. Based on the observed volume change and the material ranking, determined using common testing standards NACE International (2003) and NORSOK (2001) a correlation to polymer physical principals was established.

A simple method for preparation of polymer microcellular foams by in situ generation of supercritical carbon dioxide from dry ice

In this work, poly(methyl methacrylate) (PMMA) and PMMA/nanoclay nanocomposite microcellular foams were successfully prepared using a simple method based on in situ generation of supercritical carbon dioxide (CO2) from dry ice. The method was compared with conventional methods exempted from high pressure pump and a separate CO2 tank. Effect of various processing conditions such as saturation temperature and pressure and clay concentration on cellular morphology and hardness of the prepared microcellular foams was examined. State of the clay dispersion in the prepared PMMA/clay nanocomposites was characterized using X-ray diffraction and transmission electron microscopy techniques. Field emission scanning electron microscopy was used to study cellular morphology of the prepared foams. It was observed that elevation of saturation temperature from 85 to 105 °C at constant saturation pressure increased cell density and decreased average cell size of the prepared PMMA foams. Furthermore, an increase in saturation pressure from 120 to 180 bar resulted in a reduction in average cell diameter and an increase in cell density of the prepared PMMA foams. On the basis of the gathered results, optimum conditions for preparation of PMMA microcellular foams were determined and applied for preparation of PMMA/nanoclay microcellular foams. It was shown that incorporation of clay into the polymer matrix resulted in a finer and more uniform cellular morphology in the final microcellular foams. It was also observed that incorporation of nanoclay into the prepared foams, up to 3 wt%, led to a moderate increase in the foam hardness.

Solubility and Rheological Properties of Live Crude Oils

Multiphase transportation of the wellhead product in a single pipeline is widely used in oilfields. The oil samples transported in the multiphase pipeline are often live oils saturated by light alkanes. To support the multiphase pipelining more efficiently, in this paper, the solubility and rheology of Chang10 live crude oils are studied at the pressures range from 0 to 2.0 MPa. It was found that the dissolved gas in the live oils is mainly composed of methane (32.70 vol% at 1MPa), ethane (19.43 vol% at 1MPa), propane (21.42 vol% at 1MPa) and C4+ component (22.50 vol% at 1 MPa). The gas-oil ratio, Rs, of the live oils increases rapidly with the increase of saturation pressure. However, the effect of saturation temperature on Rs is very small. The pour point, abnormal point, WAT, viscosity/equilibrium viscosity and yield stress of the live oils decrease obviously with the increase of saturation pressure, meaning that the rheological properties of the live oils improve greatly by gas dissolving. The rheological properties of the live oils are improved mainly by the dilution effect of the dissolved gas.

Key Parameters Influencing Microcellular Polystyrene Cell Morphology Blowing with Supercritical CO<sub>2</sub>

Polystyrene microcellular foams blowing with supercritical CO2 were prepared with a novel polymer foam processing simulator. Key parameters influencing Polystyrene cell morphology were investigated. The effect of processing temperature and saturation pressure on cell morphology was observed by scanning electron microscope and the average cell diameter and cell size distribution was calculated. The results show that the cell density decrease and cell size increase with the increase of foaming temperature. The cell density increase and cell size decrease with the increase of saturation pressure. And the cell size distribution shows a narrow distribution at lower foaming temperature and higher saturation pressure.

Sorption and diffusion of carbon dioxide in wood‐fiber/polystyrene composites

AbstractIn this study, sorption and diffusion of carbon dioxide (CO2) in wood‐fiber/polystyrene composites were investigated. The effects of gas pressure and fiber content on the solubility and diffusion coefficients were evaluated. A statistical analysis indicated that pressure is more important than fiber content in determining the solubility and diffusivity of CO2. An increase in saturation pressure causes an increase in the solubility and diffusion coefficients, whereas inclusion of the fibers decreases both of these properties. Models were developed to predict the uptake and diffusion coefficients of CO2 in the composite samples as functions of pressure and fiber content. A theoretical model based on Henry's law and the Langmuir equation compared favorably to the experimental data for CO2 solubility. This dual mode model also described both the transient sorption and desorption data, but only if the concentration‐dependent value of diffusivity was treated as a history‐dependent parameter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 723–735, 2002

The heterogeneous nucleation of microcellular foams assisted by the survival of microvoids in polymers containing low glass transition particles. Part II: Experimental results and discussion

AbstractThe experimental data obtained for the nucleation of microcellular foams are compared with the theoretical model developed in the first part of this paper. Polystyrene (PS) with rubber particles as nucleation sites is used as an exploratory system. Nitrogen is used as a physical blowing agent to nucleate the bubbles. The influence of process variables, such as saturation pressure, foaming temperature, and concentration and size of rubber particles, is discussed. Results indicate that all these variables play important roles during the nucleation process. A nucleation mechanism based on the survival of microvoids against the resisting surface and elastic forces has been modeled to obtain the cell nucleation density. Increase in saturation pressure increase the cell density to a critical pressure. Beyond this critical pressure, there is no increase in bubble number, indicating that all microvoids are activated. The effect of temperature is more complex than the effect of pressure. Increase in concentration of the rubber particles increase the nucleation cell density. In general, the experimental data are well described by the nucleation model presented in Part I.

Environmentally assisted fatigue-crack growth in 7075 and 7050 aluminum alloys

Tests of 7050-T7451, 7050-T651 and 7075-T651 aluminum alloys show that these alloys exhibit similar fatigue-crack-growth kinetics in water vapor. The kinetics conform with the model for transport-controlled crack growth. The saturation water vapor pressure for the 7075-T651 alloy is lower than that for the 7050-T651 and 7050-T7451 alloys because tha latter alloys have rougher fracture surfaces. A slight increase in saturation pressure for 7050-T7451 compared to 7050-T651, on the other hand, is attributed to the difference in yield strengths. Good agreement between the experimentally determined saturation pressures and those predicted by the model provides further confirmation for the model for transport-controlled fatigue crack growth and its applicability to high-strength aluminum alloys.

Study of a Possible CO2 Flood in Rangely Field

Summary A study program for CO2 injection in the Rangely field, Rio Blanco County, CO, is reported. The work used laboratory measurements as well as compositional-model calculations to investigate the phase behavior of mixtures of Rangely reservoir oil and CO2 with two different quantities of light gas contamination. The results showed that a CO2 flood in the field is technically feasible under current reservoir pressure and that a 10 mol 070 nitrogen content in the CO2 was detrimental to the process. Introduction The Rangely field was discovered in 1933; waterflooding was begun in 1958. The original oil-in-place (OOIP) in the Rangely Weber Sand Unit was approximately 1.6 billion STB (250×106 stock-tank m3). The work reported in this paper was aimed at evaluating the potential of tertiary CO2 flooding in the reservoir. Because some of the possible CO2 sources contain nitrogen, the effect of flooding on process efficiency was investigated. Another objective was to determine the effect of CO2 slug size on oil recovery. Three types of laboratory studies were conducted:measurement of the phase behavior of the CO2 gas/Rangely reservoir oil system,core displacement experiments at 160°F (71°) and 2,600 psi (17.9 MPa) using Rangely Weber cores that were conditioned with regard to wettability by an aging process, andslim tube experiments to determine minimum miscibility pressure between CO2 gas and reservoir oil. Each study was performed with two different CO2 gases. The first gas was about 95 mol % CO2 and 5 mol % CH4. The second gas contained 85 mol % CO2, 5 mol % CH4, and 10 mol % N2. Rangely Reservoir Oil/CO2 Physical Property Measurements The physical property data were obtained from constant composition expansion (CCE) and vapor/liquid equilibrium experiments (VLE). CCE experiments were conducted to determine the phase envelope (bubble point/dew point envelope). VLE experiments yielded vapor /liquid equilibrium constants (K-values). Both CCE and VLE experiments were performed using Rangely reservoir oil and two different CO2 gases, designated Gases 1 and 2. The compositions of the gases and Rangely-reservoir oil are shown in Table 1. CCE Experiments Figs. 1 and 2 show the pressure/composition diagrams for Rangely oil/Gas 1 and Rangely oil/Gas 2 systems, respectively, at 160°F (71°C). Both systems exhibited a larger single-phase region below 3,000 psi (21 MPa) than a previous system studied.1 Saturation pressure (bubble- and dew-point pressures) for the Gas 2/reservoir oil system were substantially higher than those for the Gas 2/reservoir oil system. This increase is due to 10 mol % N2 in Gas 2. The maximum percent increase in saturation pressure due to N2 contamination occurred at 70 mol % gas concentration. At that concentration, bubblepoint pressure for Gas 2 was 4,720 psi (32.5 MPa) compared with 2,690 psia (18.5 MPa) for Gas 1. These data and those given in Ref. 1 show that the light gases CH4 and N2 decrease the solubility of CO2 in reservoir oils at a given pressure. Rangely Reservoir Oil/CO2 Physical Property Measurements The physical property data were obtained from constant composition expansion (CCE) and vapor/liquid equilibrium experiments (VLE). CCE experiments were conducted to determine the phase envelope (bubble point/dew point envelope). VLE experiments yielded vapor /liquid equilibrium constants (K-values). Both CCE and VLE experiments were performed using Rangely reservoir oil and two different CO2 gases, designated Gases 1 and 2. The compositions of the gases and Rangely-reservoir oil are shown in Table 1. CCE Experiments Figs. 1 and 2 show the pressure/composition diagrams for Rangely oil/Gas 1 and Rangely oil/Gas 2 systems, respectively, at 160°F (71°C). Both systems exhibited a larger single-phase region below 3,000 psi (21 MPa) than a previous system studied.1 Saturation pressure (bubble- and dew-point pressures) for the Gas 2/reservoir oil system were substantially higher than those for the Gas 2/reservoir oil system. This increase is due to 10 mol % N2 in Gas 2. The maximum percent increase in saturation pressure due to N2 contamination occurred at 70 mol % gas concentration. At that concentration, bubblepoint pressure for Gas 2 was 4,720 psi (32.5 MPa) compared with 2,690 psia (18.5 MPa) for Gas 1. These data and those given in Ref. 1 show that the light gases CH4 and N2 decrease the solubility of CO2 in reservoir oils at a given pressure.