Characteristics Of Crude Oil Research Articles

Analysis of the Spatial Distribution Characteristics of Crude Oils with Different Freezing Points and the Genetic Mechanism of High-Freezing-Point Crude Oils in the Dongying Sag.

The freezing point of crude oils is an important factor affecting the process of exploration, development, and transportation of crude oils. In the Dongying Sag, the freezing point of crude oils varies greatly in space, and high-freezing-point crude oils have been found in many structural belts. The freezing point of crude oils in the Dongying Sag is generally high, ranging from -40 to 80 °C. The distribution of high-freezing-point crude oils in the Dongying Sag is scattered, and they have been found at different depths, layers, and structural belts, with relatively more occurrences in specific areas. Based on the relationship between the wax content and the resin + asphaltene content, the high-freezing-point crude oils in the Dongying Sag can be classified into three types (type A, type B, and type C). Type A, type B, and type C high-freezing-point crude oils are mainly found in the gentle slope zone, depression zone, and uplift zone, respectively. The contents of wax and resins + asphaltenes in crude oils are the key factors controlling the freezing point of crude oils in the Dongying Sag. Oil source correlation using biomarkers and n-alkane carbon isotopes demonstrates that different types of high-freezing-point crude oils are generated from different source rocks, indicating that the source of crude oils is not the only factor controlling the freezing point of crude oils. The hydrocarbon-generating parent material of hydrocarbon source rocks developed in different depositional environments of the Dongying Sag is generally characterized by the dominance of bacteria and algae and is supplemented by terrestrial higher plants. This lays the material foundation for the formation of waxes during the maturation of hydrocarbon source rocks. The change of temperature and pressure conditions during the process of oil expulsion from source rocks and migration in the carrier bed will lead to phase fractionation and composition changes of oils, thus forming type A freezing point crude oils in the slope zone and type B freezing point oils in the depression zone. The increase in resin and asphaltene content caused by biodegradation and water washing in shallower buried oil reservoirs is the reason for the formation of type C high-freezing-point crude oils. The research results indicate that the organic matter composition and hydrocarbon alteration during migration and accumulation jointly control the formation of high-freezing-point crude oils in lacustrine basins. The extensive input of terrestrial organic matter into the source rocks of the lacustrine basin laid the foundation for the formation of high-freezing-point crude oils, and the migration fractionation and biodegradation of the crude oils further promoted the formation of high-freezing-point crude oils.

Molecular dynamics simulation of surfactant induced wettability alteration of shale reservoirs

Shale oil has recently received considerable attention as a promising energy source due to its substantial reserves. However, the recovery of shale oil presents numerous challenges due to the low-porosity and low-permeability characteristics of shale reservoirs. To tackle this challenge, the introduction of surfactants capable of modifying wettability has been employed to enhance shale oil recovery. In this study, we perform molecular dynamics simulations to investigate the influence of surfactants on the alteration of wettability in shale reservoirs. Firstly, surfaces of kaolinite, graphene, and kerogen are constructed to represent the inorganic and organic constituents of shale reservoirs. The impact and underlying mechanisms of two types of ionic surfactants, namely, the anionic surfactant sodium dodecylbenzene sulfonate (SDBS) and cationic surfactant dodecyltrimethylammonium bromide (DTAB), on the wettability between oil droplets and surfaces are investigated. The wettability are analyzed from different aspects, including contact angle, centroid ordinates, and self-diffusion coefficient. Simulation results show that the presence of surfactants can modify the wetting characteristics of crude oil within shale reservoirs. Notably, a reversal of wettability has been observed for oil-wet kaolinite surfaces. As for kerogen surfaces, it is found that an optimal surfactant concentration exists, beyond which the further addition of surfactant may not enhance the efficiency of wettability alteration.

Assessment of asphaltene and resin fractions in crude oil using laser-induced fluorescence spectroscopy based on modified Beer-Lambert (LIFS-MBL)

Crude oil is one of the most significant petrogenic sources of polycyclic aromatic compounds (PACs). These substances play an essential role in the pollution of the marine environment. Therefore, the rapid identification of this pollutant source and its fractions is vital. For this purpose, a fast and on-site method of laser-induced fluorescence spectroscopy based on modified Beer-Lambert (LIFS-MBL) is proposed here using solvent densitometry. Three optical parameters of the self-quenching (K), the extinction (α), and the peak concentration (Cp) are experimentally extracted from MBL graphs. Note that the parameters above are known to be unique characteristics of various crude oils. The corresponding compounds are generally classified into saturate, aromatic, resin, and asphaltene fractions, abbreviated as SARA. Differentiation among these fractions is achieved using the LIFS-MBL method by selecting the optimal excitation wavelength at 405 nm. This line effectively rules out the light aromatic rings and focuses on heavy fractions. The correlation of optical parameters with heavy oil fractions is verified according to analysis of variance. Statistical relations are proposed to calculate crude oil fractions values. The values of light fractions including saturate and aromatic components can also be determined by the heavy fractions. In this method, the test time is notably reduced from four days using the standard methods to less than half an hour according to the presented LIFS-MBL technique.

Application of Ion Mobility Spectrometry-Mass Spectrometry for Compositional Characterization and Fingerprinting of a Library of Diverse Crude Oil Samples.

Exposure characterization of crude oils, especially in time-sensitive circumstances such as spills and disasters, is a well-known analytical chemistry challenge. Gas chromatography-mass spectrometry is commonly used for "fingerprinting" and origin tracing in oil spills; however, this method is both time-consuming and lacks the resolving power to separate co-eluting compounds. Recent advances in methodologies to analyze petroleum substances using high-resolution analytical techniques have demonstrated both improved resolving power and higher throughput. One such method, ion mobility spectrometry-mass spectrometry (IMS-MS), is especially promising because it is both rapid and high-throughput, with the ability to discern among highly homologous hydrocarbon molecules. Previous applications of IMS-MS to crude oil analyses included a limited number of samples and did not provide detailed characterization of chemical constituents. We analyzed a diverse library of 195 crude oil samples using IMS-MS and applied a computational workflow to assign molecular formulas to individual features. The oils were from 12 groups based on geographical and geological origins: non-US (1 group), US onshore (3), and US Gulf of Mexico offshore (8). We hypothesized that information acquired through IMS-MS data would provide a more confident grouping and yield additional fingerprint information. Chemical composition data from IMS-MS was used for unsupervised hierarchical clustering, as well as machine learning-based supervised analysis to predict geographic and source rock categories for each sample; the latter also yielded several novel prospective biomarkers for fingerprinting of crude oils. We found that IMS-MS data have complementary advantages for fingerprinting and characterization of diverse crude oils and that proposed polycyclic aromatic hydrocarbon biomarkers can be used for rapid exposure characterization. Environ Toxicol Chem 2023;42:2336-2349. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Retracted: Geochemical Characteristics of Crude Oil in Member 7 of Yanchang Formation in Yanchang Oilfield

Retracted: Geochemical Characteristics of Crude Oil in Member 7 of Yanchang Formation in Yanchang Oilfield

Oxidation Kinetics Analysis of Crude Oils with Different Viscosities

In order to compare the oxidation kinetics parameters of crude oils with different properties in the process of crude oil oxidation, six different crude oil samples were selected to analyze the oxidation characteristics of crude oils with different properties. In order to study the oxidation of crude oil, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) synchronous analyzer were used for crude oil in the oxygen environment between 25 °C and 900 °C at a heating rate of 20 °C/min. The experimental results were based on crude oil oxidation using TGA and DTG experimental data to evaluate the oxidation mechanism of different crude oils, so as to better understand the situation in the oxidation reaction process. At the same time, the oxidation stage of crude oil was divided according to DSC data. Arrhenius method was used to analyze the oxidation kinetic parameters of crude oils with different properties, and the activation energies and pre-exponential factors of different crude oils were calculated. The experimental results show that the oxidation stage of crude oil can be divided into three stages: low-temperature oxidation, fuel deposition, and high-temperature oxidation. The low-temperature oxidation reaction begins at 280 °C, and the high-temperature oxidation reaction occurs at 400 °C. The low-temperature oxidation activation energy of an oil sample is 39.73–77.74 kJ/mol. The activation energy of the high-temperature oxidation is in the range of 106.27–264.47 kJ/mol. The activation energy of crude oil in the low-temperature oxidation stage increases with the increase of crude oil viscosity and decreases with the increase of crude oil viscosity in the high-temperature oxidation stage. Therefore, during the high-temperature oxidation stage, high-viscosity crude oil is more prone to reactions.

Characterization of Crude Oil, Formation Water, and Fluid Inclusions of Hydrocarbon-Bearing Strata and Their Hydrocarbon Geological Significance in the Wuliyasitai Southern Sub-sag of the Erlian Basin, China.

The hydrocarbon-bearing inclusions, formation water, and crude oil contain a wealth of information regarding the process of accumulation of oil and gas. Their research has been one of the hotspots in the field of oil and gas geology. Chemical analysis data was systematically employed for the first time to identify the properties of liquid fluids in the oil-bearing system of the Wuliyasitai southern sag in the Erlian Basin. A biased lacustrine algal input was shown by the stable carbon isotopes (δ13C) of whole hydrocarbons, and the morphological characteristics of n-alkanes, isoprenoids, steranes, and terpenes were examined by gas chromatography-mass spectrometry. The δ13C values were determined by the salinity of the sedimentary water body and input of land-sourced materials. The signatures of the n-alkanes' molar fraction arrangement suggest that water washing, crystallization, and wax precipitation are regular occurrences in oil samples. The salinity of formation water and the proportion of characteristic biomarkers (gammacerane, β-carotene) demonstrate that the salinity of the ancient water body ranges from fresh water to brackish water. The correlation between the stratigraphic water's characteristic coefficients and the total dissolved solids (TDS) is strong, particularly for the desulfurization coefficient, which illustrates a better hydrocarbon storage environment when TDS is >6 g/L. The metamorphic coefficients demonstrate that the existing reservoir preservation circumstances are not optimal, and the TDS and concentration degree of formation water are positively connected to the increasing depth, indicating poor longitudinal connectivity. The influence of atmospheric water infiltration is responsible for the fluid inclusions' temperatures of homogenization (60 °C). However, due to deep burial, crude oil has not undergone secondary significant biodegradation despite the percolation of atmospheric water. Besides, the distribution of reservoirs is highly correlated with formation water parameters such as the TDS, which can provide scientific guidance for further exploration of oil and gas in the study area or even in the Erlian Basin.

Crude Oil Density Prediction Improved by Multiblock Analysis of Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Fourier Transform Infrared, and Near-Infrared Spectroscopy Data.

Crude oils are among the world's most complex organic mixtures containing a large number of unique components and many analytical techniques lack resolving power to characterize. Fourier transform ion cyclotron resonance mass spectrometry offers a high mass accuracy, making a detailed analysis of crude oils possible. Infrared (IR) spectroscopic methods such as Fourier transform IR spectroscopy (FT-IR) and near-IR, can also be used for crude oil characterization. The three methods measure different properties of the samples, and different data sources can often be combined to improve the prediction accuracy of models. In this study, partial least squares regression (PLSR) models for each of the three methods (single-block PLSR) were compared to multiblock PLSR and sequential and orthogonalized PLSR (SO-PLSR), with the aim of predicting the density of crude oils. Variable importance in projection was used to identify the important variables for each method, as spectroscopic data often contain irrelevant variation. The variables were interpreted to evaluate their underlying chemistry and to check whether consistency could be found between the variables selected from the spectroscopic data for the single-block and multiblock methods. Combining the different blocks of data increased the prediction abilities of the models both before and after variable selection, and SO-PLSR using a reduced data set resulted in the best-performing prediction model.

Investigation of nano composite heat exchanger annular pipeline flow using CFD analysis for crude oil and water characteristics

This study focuses on the dual-core annular process of crude oil and water. The crude oil exhibits non-Newtonian behavior with high viscosity. The heat transmission flow in pipeline locations is complex. In this process, the cooled water passes through the annular core, experiencing turbulence effects, while the crude oil flows in a laminar manner. The influence of the non-Newtonian behavior is investigated in terms of pipe angles and deformations. In the valve, the inlet velocity flow is set at 1.75 m/s. The flow is executed in downhill orientations in high-velocity locations. The simulation results show CFD variations with a velocity of 3.5 m/s, pressure of 2.33 MPa, pressure gradients of 1.33 MPa, and Reynolds numbers of 1.38 MPa. This study is being conducted for a horizontal pipeline. The CFD solution solvers investigate the volumetric flow characteristics of the fluid as well as the temperature effects. The maximum heat energy has been reduced, resulting in unique flow directions.

Physico - Chemical Studies of Indian Crude Oil

Abstract: Crude oil is a complex mixture of non-metallic components like Sulphur, Nitrogen, Oxygen, and other elements with hydrocarbons. Crude oil is distinguished by several chemical and physical features that play an essential role in the oil industry. These qualities are critical in making decisions in the exploration and production of crude oil. Heavy crude oil is highly viscous crude oil with high Asphaltene content and API in the range of 10-25. Especially, transportation of Heavy Crude oil is herculean task for Petroleum industry. As a result, the study of physical and chemical properties becomes crucial for the petroleum industry. The current work deals with the investigation of physico-chemical characteristics of Indian crude oil.

A comprehensive assessment for the structural change of waxy crude oils induced by pour point depressant beneficiation

In the petroleum industry, the solid paraffins that precipitate out from a waxy crude oil complicate the low-temperature flow characteristics, causing major difficulties in pipeline transportation. Pour point depressants (PPDs) are often utilized to improve the flow characteristics of crude oils by modifying the morphology and structure of wax crystals, becoming a great technical and economic interest. The improving mechanism of PPDs on the structure of gelled waxy crude oil can be attributed to the nucleation, co-crystallization, and adsorption effect to the precipitated wax crystals, preventing the waxy structure from growing further and forming a volume spanning network. Many previous works about the PPDs’ effect have merely focused on the pour point, apparent viscosity, and yield strength depressing ability, while other structural properties have rarely been comprehensively evaluated. The objective of this study is to comprehensively reveal the change of the wax particle structure in oils benefitted with PPDs. The structure of gelled oils doped with PPDs was found to become less elastic and more susceptible to shear perturbation with a lower linear deformation range of 0.42% and a longer relaxed time scale of 3000 s. Large amplitude oscillatory shear (LAOS) tests show that the nonlinear viscoelastic behaviors can be weakened by PPDs, whereas the third harmonic value obtained by Fourier-transform analysis increases after adding PPDs, indicating that the sensitivity to applied load are strengthened. Meanwhile, the value of yield strain increases to about 8.7%, and the irreversible plastic deformation zone becomes relatively broader (brittleness index I increases to 70.9), which mean a more ductile fracture induced by PPDs would occur when yielding. Although the additive PPDs weaken the structural strength and the non-Newtonian characteristics (kinetic index of n1 increases to 0.8), the characteristic of thixotropy is obviously strengthened, and the doped crude oils exhibit a faster structural breakdown process after yielding. All these novel changes for structural features explored in this paper provide theoretical guidance into understanding the practical engineering problems of accelerated process for the pipeline restart flow benefitted with PPDs.

Experimental study on the effect of high water cut on the emulsifying properties of crude oil

Most waterflooding oilfields have entered the high water cut stage, but significant amounts of crude oil remain in the formation. Therefore, understanding the emulsifying characteristics of crude oil with high water content is crucial. This study investigates the effects of shear time, shear rate, temperature, water content, and re-emulsification at high water content on the emulsifying properties of crude oil. Results indicate that shear time, temperature, and water content play a role in enhancing the emulsifying capacity of crude oil. Additionally, the initial water content of the emulsion affects the solubilization ability of crude oil; lower initial water content leads to stronger solubilization ability, while higher total water content leads to weaker solubilization capacity. Under an optical microscope, the morphology of the emulsion was observed, revealing that an increase in water content resulted in an increase in particle size and quantity of emulsion droplets, leading to more uniform droplets. However, at high water content, the particle size of emulsion decreased, the number of droplets decreased, and the droplets became uneven. Furthermore, the particle size of re-emulsified emulsion was smaller than that of the emulsion with the same moisture content, indicating that re-emulsification can lead to instability. The interfacial characteristics of the emulsion were also analyzed, showing that an increase in water content caused an increase in interfacial tension and expansion modulus of emulsion compared to crude oil. Finally, the study elucidates the influence mechanism of high-water content on the emulsifying performance of crude oil, which includes the destruction of molecular forces on and between interfaces, weakening the steric hindrance effect. Unstable film and non-uniform droplets can promote coalescence and fragmentation of droplets, limiting the emulsifying performance of crude oil. The results of this study provide a better understanding of the formation and fracture process of emulsion under high water cut conditions, offering a theoretical basis for further enhanced oil recovery.

Demulsifier Selection Guideline for Destabilizing Water-in-Oil Emulsion for both non-EOR and EOR Application

The most common method for resolving water-in-oil (W/O) emulsions is chemical demulsification. The bottle test is a recommended procedure to analyze a combination of essential parameters such as the demulsifier dosage, residence time, heat, degree of agitation to generate the emulsion and agitation effects after demulsifier injection. It is an extensive and time-consuming selection procedure. Furthermore, the previous demulsifier selection guideline reported in the literature had limitations and was not suitable for the Southeast Asia region. This study describes the development of a new demulsifier selection guideline that relates the demulsifier properties to the crude oil characteristics and is more representative for resolving emulsions in the Southeast Asia environment. In developing the selection guideline, four types of synthetic crude were used, with the crude API ranging from 27˚ to 40˚. Sixteen demulsifiers with a relative solubility number (RSN) ranging from 11 to 21 were evaluated comprising resin alkoxylate and modified polyol base demulsifiers. An emulsion test matrix was developed by creating emulsions with different wax contents, asphaltene content and solid contents in the crude oil; then, the demulsifier was screened for all the matrices. Based on the demulsification bottle test completion for all the test matrices, the demulsifier selection guideline was developed and then validated with the blind test in resolving emulsions from the actual crude. The validation results achieved an 86.7% match rate between the guideline output and the lab experimental result. This proved that good agreement had been established between the demulsifier properties and the crude characteristics.

Effect of clay minerals on asphaltene deposition in reservoir rock: Insights from experimental investigations

This study investigated the effect of crude oil characteristics and the presence of clays on the interaction and precipitation tendency of asphaltenes during solvent washing. As solvent n-pentane was used, hence, in this study, the behavior of n-pentane insoluble asphaltenes was investigated. The asphaltenes precipitation tendency and consequently its impact on formation damage were investigated with several experiments performed on sand samples mixed with two different crude oils, with and without added clays. The samples were then analyzed using various techniques including Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and porosity measurements. The results showed that the presence of clays increased the affinity of asphaltenes towards adsorption onto the clay surfaces, resulting in the plugging of pore spaces and inducing higher asphaltenes precipitation. The surface elemental composition of the samples indicated that the asphaltenes of one crude oil (Oil 1) had a higher concentration of aluminum (Al), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), and silicon (Si), while the asphaltenes of the other crude oil (Oil 2) had a higher concentration of sulfur (S) and vanadium (V). These differences in elemental composition led to different precipitation tendencies and porosity reductions. Accordingly, the interactions of asphaltenes with reservoir rock found more for Oil 1 to Oil 2. The findings of this study provide insights into the factors that influence asphaltene precipitation during solvent washing, which can have implications for oil production and processing.

Microscopic Production Characteristics of Pore Crude Oil and Influencing Factors during Enhanced Oil Recovery by Air Injection in Shale Oil Reservoirs.

High-pressure air injection (HPAI) is one of the effective methods to improve shale oil recovery after the primary depletion process. However, the seepage mechanisms and microscopic production characteristics between air and crude oil are complicated in porous media during the air flooding process. In this paper, an online nuclear magnetic resonance (NMR) dynamic physical simulation method for enhanced oil recovery (EOR) by air injection in shale oil was established by combining high-temperature and high-pressure physical simulation systems with NMR. The microscopic production characteristics of air flooding were investigated by quantifying fluid saturation, recovery, and residual oil distribution in different sizes of pores, and the air displacement mechanism of shale oil was discussed. On this basis, the effects of air oxygen concentration, permeability, injection pressure, and fracture on recovery were studied, and the migration mode of crude oil in fractures was explored. The results show that the shale oil is mainly found in <0.1 μm (small pores), followed by 0.1-1 μm (medium pores), and 1-10 μm (macropores); thus, it is critical to enhancing oil recovery in pores less than 0.1 and 0.1-1 μm. The low-temperature oxidation (LTO) reaction can occur by injecting air into depleted shale reservoirs, which has a certain effect on oil expansion, viscosity reduction, and thermal mixing phases, thereby greatly improving shale oil recovery. There is a positive relationship between air oxygen concentration and oil recovery; the recoveries of small pores and macropores can increase by 3.53 and 4.28%, respectively, and they contribute 45.87-53.68% of the produced oil. High permeability means good pore-throat connectivity and greater oil recovery, and the production degree of crude oil in three types of pores can be increased by 10.36-24.69%. Appropriate injection pressure is beneficial to increasing the oil-gas contact time and delaying gas breakthrough, but high injection pressure will result in early gas channeling, which causes the crude oil in small pores to be difficult to produce. Notably, the matrix can supply oil to fractures due to the mass exchange between matrix fractures and the increase of the oil drainage area, and the recoveries of medium pores and macropores in fractured cores increased by 9.01 and 18.39%, respectively; fractures can act as bridges for matrix crude oil migration, which means that proper fracturing before gas injection can make the EOR better. This study provides a new idea and a theoretical basis for improving shale oil recovery and clarifies the microscopic production characteristics of shale reservoirs.

Physico-Chemical Studies on Crude Oil of Western Onshore

Abstract: Crude oil is a complex mixture of hydrocarbons with non-metallic elements such as sulphur, nitrogen, oxygen, and other elements. Hydrocarbons are chemicals that are mostly composed of the elements carbon and hydrogen. Crude oil comprises a variety of hydrocarbon molecules that fall into three categories: alkane, cycloalkane, and aromatic. Crude oil is distinguished by a number of chemical and physical features that play an essential role in the oil industry. These qualities are critical in making decisions in the exploration and production of crude oil. Characteristics like density, specific gravity, API gravity, water content, and sulphur content, to name a few, contribute value to the price of crude before it is transported to markets and refineries, so controlling these parameters significantly saves damage to infrastructure like pipelines and refineries. As a result, the study of physical and chemical properties becomes crucial for the petroleum industry. The current work deals with the investigation of physico-chemical characteristics of crude oil of Western onshore.

New Unit Root Tests in the Nonlinear ESTAR Framework: The Movement and Volatility Characteristics of Crude oil and Copper Prices

New Unit Root Tests in the Nonlinear ESTAR Framework: The Movement and Volatility Characteristics of Crude oil and Copper Prices

Correlation of Neogene Oil and Paleogene Source Rocks in the Middle Huanghekou Sag, Bohai Bay Basin

Several billion-ton Neogene oil fields have been successfully discovered in the middle Huanghekou sag over the past few years. However, the source of the crude oil needs to be clarified, and the relevant oil-source correlation was less carried out. Six source rocks of the third member of the Paleocene Shahejie Formation (Es3) from five wells and sixteen Neogene crude oil samples from nine wells in the middle Huanghekou sag were investigated for the oil-source correlation with the biomarkers and carbon and hydrogen isotopes of saturated hydrocarbon monomers. The distribution characteristics of n-alkanes, C19/C23 ratio of tricyclic terpanes, long-chain tricyclic terpene ratios (ETR), C24 tetracyclic terpane to C26 tricyclic terpene, and distribution characteristics of conventional steranes suggest that the Es3 parent material is of a mixed-source input from terrestrial higher plants and aquatic phytoplankton. The gammacerane to C30 hopane ratio is low, ranging from 0.094 to 0.134, with a mean value of 0.118; the Pr/Ph ratio is less than 1.5. The Neogene oils show the characteristics of a saturated hydrocarbon biomarker similar to Es3. The carbon and hydrogen isotopes of saturated hydrocarbon monomers also corroborate the oil-source correlation from the depositional environment and parent material source, which characterize the low salinity of the water during the Es3 sedimentary period, which was a brackish or a freshwater delta deposition under weak oxidation–weak reduction conditions. The parity dominance of CPI and OEP values (both greater than 1), higher ratios of Ts/Tm (1.174 to 1.383, mean 1.278) and the C29Ts/C29 norhopane, high values of diahopane and diasterane contents (C30diaH/C30H, C27diaS/C27S), and hopane and sterane isomerization parameters (%22S, %20S, %ββ) confirm that the Es3 source rock samples are mature enough to provide crude oil for the middle Huanghekou sag. The biomarker characteristics of regional Neogene crude oil are significantly different from those of Es4 source rocks in the surrounding depressions (sags), indicating the Es4 strata’s absence in the middle Huanghekou sag. Suitable traps need to be discovered around the hydrocarbon-generating center of the Es3 source rock for oil and gas exploration in the future.

Effects of Pressure and Depressurization Rate of Dissolved CO2 on the Foaming Characteristics of Crude Oil

With the CO2 flooding technique implemented, much CO2 gas is dissolved in the produced fluid. A large amount of CO2 escapes from crude oil due to continual depressurization in the surface pipeline system, leading to massive foam. In this paper, the effects of dissolved-CO2 pressure and depressurization rate on foaming characteristics were investigated by depressurization. To explore the mechanism in depth, CO2 solubility and interfacial characteristics were considered. The results indicated that foamability increases as the pressure increases and increases initially and then decreases with an increase in the rate. Further experimental results showed that when the pressure increases from 1.5 to 3.0 MPa at 30 °C, equilibrium interfacial tension decreases only by 12.78%, while CO2 solubility increases by 81.73%, indicating that CO2 solubility plays a dominant role in foamability. Additionally, it is inferred that when the rate is lower than 18 L/min, it increases at which point the gas that is originally dissolved inside the crude oil transforms to free gas. When it is increased above 18 L/min, the decrease in the solubility and enhancement of disturbance appear. These may be reasons why foamability decreases. Meanwhile, foam stability, the decay degree of foam height over time, was measured immediately after the foam height reached maximum. It was found that foam stability decreases when the pressure increases and increases initially and then decreases when the rate elevates. Further experimental results indicated that when the pressure increases from 1.5 to 3.0 MPa at 30 °C, the bulk viscosity and interfacial dilational modulus decrease by 23.45 and 38.58%, respectively. It is suggested that the role of interfacial viscoelasticity in foam stability is superior to that of viscosity. Additionally, it was inferred the increased rate below 18 L/min makes bubble size smaller, while the weaker structure of the foam film and higher surface energy make foam stability worse with the rate increased above 18 L/min.

A study of blending carbon nanoparticles made of coconut shell (fullerene C60) in vegetable oils on the droplet evaporation characteristics

The droplet evaporation characteristics of crude vegetable oils, including crude coconut oil (CCO), crude palm oil (CPO), crude jathropa oil (CJO), and crude sunflower oil (CSFO) mixed with and without nanocarbon (fullerene C60) were investigated. The nanocarbon was produced from the waste biomass-based coconut shell. The droplet evaporation experiments were performed in an atmospheric chamber using a K type thermocouple and equipped with a Nikon D3300 camera at 60 frames per second. Droplet temperatures were measured in a real-time basis at a sampling frequency of 1 kHz. The crude vegetable oils were mixed with fullerene at 5 mg/L. In this study, the droplet evaporation behaviors of fullerene addition were studied and compared to pure vegetable oils. The results reported that the bubble formation and the flame propagation were formed faster in the cases of crude vegetable oils blended with fullerene by as much as 44% and 22%, respectively. The trend of early bubble formation was CCO5 > CPO5 > CJO5 > CSFO5. However, the initial flame propagation profile was CCO5 > CJO5 > CSFO5 > CPO5. A lot of local hot spots were identified for the blended vegetable oils with fullerene. The micro-explosion mechanism of blended vegetable oils with fullerene was obtained based on the droplet visualization. At a normal temperature, fullerene molecule was well attached to the carbonyl chain. The electronegativity between fullerene and triglyceride influenced the attachment form of fullerene to carbonyl chain with respect to droplet temperature. Finally, the addition of fullerene increased in the fuel reactivity, the droplet temperature, and shortened the ignition delay.