Crude Oil Density Research Articles

Analysis of Electric Breakup Characteristics of Emulsion Droplets Based on Dissipative Particle Dynamics Method

Crude oil desalination and dehydration are necessary for storage, transportation, and processing procedures. However, the behaviour of fine emulsion droplets under an electric field has always been questioned. This paper modified the dissipative particle dynamics method (DPD) to study the deformation process of fine emulsion droplets under a high-strength electric field. Compared with the literature data, the reliability of the DPD method is confirmed. The influence of the crude oil properties and the electric field characteristics on the behaviour of the emulsion droplet was analysed, and the effect factors included electric field intensity, electric field frequency, emulsion droplet size, centre distance ratio, conservative force intensity, dissipative strength, and crude oil density. The relationship between critical electric field intensity and emulsion droplet deformation was formulated based on the simulational dates.

Treatment of the Bitumen and Heavy Oil in Zubair Formation/ East Baghdad Field

Bitumen precipitation refers to the separation and settling of heavier, denser hydrocarbon compounds from crude oil, which can occur under certain conditions of pressure and temperature. Crude oils with high viscosity, high density, low API gravity, and high sulfur content are more prone to bitumen precipitation. Understanding these properties is essential in the oil industry for predicting the behavior of crude oils during production, transportation, refining, and storage. The viscosity, density, API, and sulfur content of crude oil were examined as part of this investigation. The viscosity test is achieved by using automated viscometer apparatus with ASTM D 7042 standard, while the sulfur content test is performed by using Sindie 2622 Sulfur Analyzer with ASTM D 7039 standard. However, density and API gravity tests are done depending on manually condition related to mixing, time, method, temperature and percentages until obtained an optimized result. In order to determine the reduction in viscosity and other physical properties of crude oil, which will offer a better solution against the precipitating of asphaltene and Bitumen that essentially lead to plug the production pipe and stop oil production. The chosen solvent was kerosene, which mixed with three samples of crude oil over the course of three periods under standard conditions from the Zubair formation/East Baghdad field [EB-58]. However, the kerosene is selected because it has a high specific gravity which is considered as the best solvent for heavy crude oil and it is inexpensive. Moreover, in experimental work used three percentage of kerosene to mix with crude oil; [6%, 12% and 18%]. The results show that all ratio of kerosene addition will optimize the crude oil properties. The best result was gotten by adding 18 % kerosene to crude oil and the best optimization results were viscosity 89.3%, density 4.27%, API 39.5% and sulfur content 21.2%. In addition to reduce the viscosity of the heavy crude oil, using kerosene for 1 job will minimize the expenses approximately 1,177,000 IQD.

Evaluation of Recoverable Hydrocarbon Reserves and Area Selection Methods for In Situ Conversion of Shale

It is well known that the existing horizontal-well-drilling and hydraulic fracturing technology used to achieve large-scale, cost-effective production from immature to low–moderate-maturity continental shale in China, where the organic matter mainly exists in solid form, is fairly ineffective. To overcome the obstacles, in situ conversion technology seems feasible, while implementing it in the target layer along with estimating the amount of expected recoverable hydrocarbon in such shale formations seems difficult. This is because there are no guidelines for choosing the most appropriate method and selecting relevant key parameters for this purpose. Hence, based on thermal simulation experiments during the in situ conversion of crude oil from the Triassic Chang 73 Formation in the Ordos Basin and the Cretaceous Nenjiang Formation in the Songliao Basin, this deficiency in knowledge was addressed. First, relationships between the in situ-converted total organic carbon (TOC) content and the vitrinite reflectance (Ro) of the shales and between the residual oil volume and the hydrocarbon yield were established. Second, the yields of residual oil and in situ-converted hydrocarbon were measured, revealing their sensitivity to fluid pressure and crude oil density. In addition, a model was proposed to estimate the amount of in situ-converted hydrocarbon based on TOC, hydrocarbon generation potential, Ro, residual oil volume, fluid pressure, and crude oil density. Finally, a method was established to determine key parameters of the final hydrocarbon yield from immature to low–moderate-maturity organic material during in situ conversion in shales. Following the procedure outlined in this paper, the estimated recoverable in situ-converted oil in the shales of the Nenjiang Formation in the Songliao Basin was estimated to be approximately 292 × 108 tons, along with 18.5 × 1012 cubic meters of natural gas, in an area of approximately 8 × 104 square kilometers. Collectively, the method developed in this study is independent of the organic matter type and other geological and/or petrophysical properties of the formation and can be applied to other areas globally where there are no available in situ conversion thermal simulation experimental data.

Well Selection for CO2 Huff-n-Puff in Unconventional Oil Reservoirs Based on Improved Fuzzy Method

The implementation of CO2 huff-n-puff in unconventional oil reservoirs represents a green development technology that integrates oil recovery and carbon storage, emphasizing both efficiency and environmental protection. A rational well selection method is crucial for the success of CO2 huff-n-puff development. This paper initially identifies eight parameters that influence the effectiveness of CO2 huff-n-puff development and conducts a systematic analysis of the impact of each factor on development effectiveness. A set of factors for well selection decisions is established with seven successful CO2 huff-n-puff cases. Subsequently, the influencing factors are classified into positive, inverse, and moderate indicators. By using an exponential formulation, a method for calculating membership degrees is calculated to accurately represent the nonlinearity of each parameter’s influence on development, resulting in a dimensionless fuzzy matrix. Furthermore, with the oil exchange ratio serving as a pivotal parameter reflecting development effectiveness, recalibration of weighting factors is performed in conjunction with the dimensionless fuzzy matrix. The hierarchical order of weighting factors, from primary to secondary, is as follows: porosity, reservoir temperature, water saturation, formation pressure, reservoir thickness, crude oil density, crude oil viscosity, and permeability. The comprehensive decision factor and oil exchange ratio exhibit a positive correlation, affirming the reliability of the weighting factors. Finally, utilizing parameters of the Ordos Basin as a case study, the comprehensive decision factor is calculated, with a value of 0.617, and the oil exchange ratio is predicted as 0.354 t/t, which falls between the Chattanooga and Eagle Ford reservoirs. This approach, which incorporates exponential membership degrees and recalibrated weighting factors derived from actual cases, breaks the limitations of linear membership calculation methods and human factors in expert scoring methods utilized in existing decision-making methodologies. It furnishes oilfield decision-makers with a swifter and more precise well selection method.

Experimental Study on Carbon Dioxide Flooding Technology in the Lunnan Oilfield, Tarim Basin

The Lunnan Oilfield in the Tarim Basin is known for its abundant oil and gas resources. However, the marine clastic reservoir in this oilfield poses challenges due to its tightness and difficulty in development using conventional water drive methods. To improve the recovery rate, this study focuses on the application of carbon dioxide flooding after a water drive. Indoor experiments were conducted on the formation fluids of the Lunnan Oil Formation, specifically investigating gas injection expansion, thin tube, long core displacement, oil and gas phase permeability, and solubility. By injecting carbon dioxide under the current formation pressure, the study explores the impact of varying amounts of carbon dioxide on crude oil extraction capacity, high-pressure physical parameters of crude oil, and phase characteristics of formation fluids. Additionally, the maximum dissolution capacity of carbon dioxide in formation water is analyzed under different formation temperatures and pressures. The research findings indicate that the crude oil extracted from the Lunnan Oilfield exhibits specific characteristics such as low viscosity, low freezing point, low-medium sulfur content, high wax content, and medium colloid asphaltene. The measured density of carbon dioxide under the conditions of the oil group is 0.74 g/cm3, which closely matches the density of crude oil. Additionally, the viscosity of carbon dioxide is 0.0681 mPa·s, making it well-suited for carbon dioxide flooding. With an increase in the amount of injected carbon dioxide, the saturation pressure and gas-oil ratio of the crude oil also increase. As the pressure rises, carbon dioxide dissolves rapidly into the crude oil, resulting in a gradual increase in the gas-oil ratio, expansion coefficient, and saturation pressure. As the displacement pressure decreases, the degree of carbon dioxide displacement initially decreases slowly, followed by a rapid decrease. Moreover, an increase in the injection rate of carbon dioxide pore volume leads to a rapid initial improvement in oil-displacement efficiency, followed by a slower increase. Simultaneously, the gas-oil ratio exhibits a slow increase initially, followed by a rapid rise. Furthermore, as the displacement pressure increases, the solubility of carbon dioxide in water demonstrates a linear increase. These research findings provide valuable theoretical data to support the use of carbon dioxide flooding techniques for enhancing oil recovery.

Effect of dopants addition on the displacing phase properties in a polymer flooding process using computed tomography scanning

This study evaluated the impact of the four most used dopants in core-flooding tests, supported by computed tomography, on the behavior of polymer viscosity. Initially, the minimum concentration of each dopant required to achieve an adequate contrast between phases was estimated by varying the amount of dopant in solution and comparing the CT number of polymer solution and oil to guarantee a differential highest than 300 CT. Afterward, the effect of adding the different dopants on the polymer solution viscosity was determined through Brookfield viscosimeter. Subsequently, the polymer concentration to counteract the viscosity reduction was quantified by adding different polymer amounts. The results showed that sodium iodide achieved the highest attenuating effect between phases with the lowest dopant concentration. Moreover, this dopant caused the lowest polymer viscosity diminution and required the smallest increase in polymer concentration to reach the base case viscosity, making this dopant the most suitable agent to be used in polymer injection experiments at the conditions evaluated. Finally, the impact of crude oil density on the lowest amount of dopant required to achieve sufficient differentiation between phases was analyzed, and as a result, a correlation was found that could be used in future experiments at similar conditions to evaluate polymer flooding in a porous medium by means computed tomography scan as a visual and non-intrusive technique, reaching the best contrast between crude oil and HPAM.

Study of main factors influencing unsteady-state temperature drop in oil tank storage under dynamic thermal environment coupling

With the increasing oil demand, the construction of oil energy reserves in China needs to be further strengthened. However, given that there has been no research on the main influencing factors of crude oil temperature drop in storage tanks under actual dynamically changing environments, this paper considers the influence of dynamic thermal environment and internal crude oil physical properties on the fluctuating changes in crude oil temperature. A theoretical model of the unsteady-state temperature drop heat transfer process is developed from a three-dimensional perspective. According to the temperature drop variation law of crude oil storage tank under the coupling effect of various heat transfer modes such as external forced convection, thermal radiation, and internal natural convection, the external dynamic thermal environment influence zone, the internal crude oil physical property influence zone, and the intermediate transition zone of the tank are proposed. And the multiple non-linear regression method is used to quantitatively characterize the influence of external ambient temperature, solar radiation, wind speed, internal crude oil density, viscosity, and specific heat capacity on the temperature drop of crude oil in each influencing zone. The results of this paper not only quantitatively explain the main influencing factors of the oil temperature drop in the top, wall, and bottom regions of the tank, but also provide a theoretical reference for oil security reserves under a dynamic thermal environment.

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.

Computational Fluid Dynamics Simulation of Oil-Water Batch Transport in a Pumpless Virtual Flow Loop

Summary Batch transportation of oil and water is a new transportation method in oil and gas gathering and transportation pipelines. Its corrosion inhibition effect has been preliminarily verified in a horizontal pipe experiment. However, achieving overall visualization in traditional loops is difficult, resulting in limited flow pattern classification and analysis of influencing factors. Combining the advantages of the traditional flow loop and the wheel flow loop, we introduce in this paper a round-head straight pipe loop and analyze the influence of key factors on the evolution of the flow pattern of the oil-water interface and the dimensionless length of the oil-water film (L~o, L~w) on the pipe wall through computational fluid dynamics (CFD) numerical simulation. The results show that the batch transportation of oil and water using the round-head straight pipe loop is more in line with the flow characteristics of oil and water two-phase flow in gathering pipelines. Three distinct three-layered flow patterns were identified, which are Flow Pattern I (oil-in-water in the upper layer, annular flow in the middle layer, and oil as the annular phase, water as the core phase, and oil-in-water in the lower layer, abbreviated as DW/O-AN-DW/O), Flow Pattern II (oil phase in the upper layer, annular flow in the middle layer, water as the annular phase, oil as the core phase, and oil in the lower layer, abbreviated as O-AN-O), and Flow Pattern III (oil phase in the upper layer, water-in-oil dispersion flow in the middle layer, and oil in the lower layer, abbreviated as O-DO/W-O). Additionally, parametric analysis reveals that the velocity of the rigid body (ν) has the greatest influence on the coverage rate of the oil film on the pipe wall, followed by the viscosity of crude oil. The density of crude oil has the least influence. The round-head straight pipe loop model offers an accurate simulation of the process of oil and water batch transportation in actual production pipelines. Therefore, the corrosion mitigation efficiency increases with the increase in oil viscosity when the viscosity of the oil lies within the range of 0.01–1 Pa·s. This increase is due to the formation of a more stable oil film on the pipe wall at higher viscosities. When the speed of the rigid body ranges from 0.5 to 1 m/s, due to the small fluid velocity, the erosion effect on the oil film on the pipe wall is relatively small, and the corrosion mitigation efficiency remains stable within a wide range.

Laboratory Test of Fluid Physical Property Parameters of Well Fluid Containing CO2

Change regulation of the physical properties of fluid is key to accurately predicting multiphase fluid flow in the production wellbore of CO2 flooding reservoirs. Given the characteristics of significant changes in pressure, temperature, and CO2 content in the whole wellbore of production wells in CO2 flooding reservoirs, this paper systematically studied the change rules of volume factor, viscosity, density, and solubility of well fluid for pressure 5~30 MPa, temperature 20~120 °C, and CO2 content 10~90% through single degassing PVT experiments. According to the experimental results, the volume factor of crude oil increases first and then decreases with the pressure increase. At the bubble point pressure (20 MPa), the volume factor of crude oil can reach 1.89 at high temperatures. The volume factor can be increased from 1.28 to 1.44 at 8 MPa when the temperature increases from 20 °C to 120 °C. Under the bubble point pressure, the increase in pressure increases the solubility of CO2, and the viscosity of crude oil decreases rapidly. In contrast, above the saturation pressure, the increase in pressure increases the viscosity of crude oil. Under the freezing point temperature (24 °C), the viscosity of crude oil decreases sharply with increase in temperature. In contrast, above the freezing point temperature, the viscosity change of crude oil is not sensitive to temperature. The wellbore temperature has a significant impact on the density of the well fluid. At 5 MPa, the temperature increases from 20 °C to 120 °C, which can reduce the density of high CO2 crude oil from 0.93 g/cm3 to 0.86 g/cm3. The solubility of CO2 in crude oil is sensitive to pressure. When the pressure increases from 5 MPa to 15 MPa at 20 °C, the solubility increases by 36.56 cm3/cm3. The results of this paper support the multiphase fluid flow law prediction of CO2 flooding production wells with a high gas–liquid ratio.

Enrichment factors of movable hydrocarbons in lacustrine shale oil and exploration potential of shale oil in Gulong Sag, Songliao Basin, NE China

The geological characteristics and production practices of the major middle- and high-maturity shale oil exploration areas in China are analyzed. Combined with laboratory results, it is clear that three essential conditions, i.e. economic initial production, commercial cumulative oil production of single well, and large-scale recoverable reserves confirmed by the testing production, determine whether the continental shale oil can be put into large-scale commercial development. The quantity and quality of movable hydrocarbons are confirmed to be crucial to economic development of shale oil, and focuses in evaluation of shale oil enrichment area/interval. The evaluation indexes of movable hydrocarbon enrichment include: (1) the material basis for forming retained hydrocarbon, including TOC>2% (preferentially 3%–4%), and type I–II1 kerogens; (2) the mobility of retained hydrocarbon, which is closely related to the hydrocarbon composition and flow behaviors of light/heavy components, and can be evaluated from the perspectives of thermal maturity (Ro), gas-oil ratio (GOR), crude oil density, quality of hydrocarbon components, preservation conditions; and (3) the reservoir characteristics associated with the engineering reconstruction, including the main pore throat distribution zone, reservoir physical properties (including fractures), lamellation feature and diagenetic stage, etc. Accordingly, 13 evaluation indexes in three categories and their reference values are established. The evaluation indicates that the light shale oil zones in the Gulong Sag of Songliao Basin have the most favorable enrichment conditions of movable hydrocarbons, followed by light oil and black oil zones, containing 20.8×108 t light oil resources in reservoirs with Ro>1.2%, pressure coefficient greater than 1.4, effective porosity greater than 6%, crude oil density less than 0.82 g/cm3, and GOR>100 m3/m3. The shale oil in the Gulong Sag can be explored and developed separately by the categories (resource sweet spot, engineering sweet spot, and tight oil sweet spot) depending on shale oil flowability. The Gulong Sag is the most promising area to achieve large-scale breakthrough and production of continental shale oil in China.

Effect of CO2 Huff and Puff Rounds on Crude Oil Properties

In view of the deterioration of oil well liquid supply capacity and oil increase effect after multiple rounds of carbon dioxide (CO2) huff and puff, according to the actual conditions of the Ng12 reservoir in the XA oilfield, an indoor physical simulation experimental model was established. The experimental parameters were determined, five rounds of CO2 huff and puff experiments were carried out, and the crude oil produced in the water flooding stage and different rounds of CO2 huff and puff were collected. The effects of CO2 huff and puff rounds on crude oil viscosity, density, composition, paraffin content, and gum asphaltene content were studied. The results show that with the increase in CO2 huff and puff rounds, the viscosity and density of produced crude oil decrease. The content of light component (C2∼C6) and intermediate component (C7∼C10) increased, while the content of heavy component (C11+) decreased. CO2 has the strongest extraction effect on light components and the weakest extraction effect on heavy components. At the same time, the content of paraffin and gum asphaltene in the produced crude oil is reduced. For oil wells with multiple rounds of CO2 huff and puff, colloidal asphaltene precipitation inhibitor and scavenger should be considered to reduce the impact of colloidal asphaltene on formation permeability and liquid supply capacity.

Molecular Dynamics Study of Interfacial Properties for Crude Oil with Pure and Impure CH4

Gas injection has received increasing attention as one of the key technologies to enhance oil recovery. When gas is dissolved in crude oil, it will accelerate the flow of crude oil by reducing the density, viscosity, interfacial tension (IFT), and other properties of crude oil, so IFT is one of the main factors affecting the recovery of the gas drive. The interfacial properties of CH4, one of the principal associated hydrocarbon gases, with crude oil remain unclear. In this study, molecular dynamics (MD) simulations were used to determine the IFTs of pure and impure CH4 with n-decane as well as the IFTs of the ternary systems CH4 + n-hexane + n-decane and CH4 + n-decane + n-nonadecane. Additionally, investigating factors including pressure, temperature, gas composition, and crude oil composition reveals the mechanisms affecting the interfacial properties of CH4 and crude oil. The results demonstrate that CO2 significantly lowers the IFT of CH4 + n-decane; the effect of crude oil components on IFT varies with the properties of the crude oil and, generally speaking, IFT is greater for crude oils containing heavy components than for those containing light components; the effect of temperature on the IFT of the CH4 + n-decane system is more pronounced at low pressure and decreases with increasing pressure. This study contributes to understanding the behavior of CH4 and oil systems in the formation and could be used to enhance the oil recovery technology.

Numerical Study of Leakage and Diffusion of Underwater Oil Spill by Using Volume-of-Fluid (VOF) Technique and Remediation Strategies for Clean-Up

An oil spill accident will cause serious harm to marine ecology and the environment. Rapid response and effective prevention methods are required to minimize the damage of oil spill accidents. The critical problems that marine emergency rescue teams face are when the spilled oil reaches the sea surface, the extent of the spilled oil, and how far they are from the drilling platform. However, there is no reliable model to predict the diffusion distance of spilled oil. Accurately predicting the diffusion characteristics of underwater spilled oil can provide timely and accurate information for the treatment of oil spill accidents and guide the correct implementation of emergency treatment. In this paper, the computational fluid dynamics (CFD) method was used to establish a two-phase flow model for the diffusion of a submarine oil spill. The volume-of-fluid (VOF) technique was implemented to track the interface between oil–water phases. The effects of different parameters on leakage and diffusion characteristics were investigated by adjusting spilled oil velocity, ocean current velocity, crude oil density, and crude oil viscosity. The logarithmic velocity profile was adopted for ocean currents to conform to the actual flow near the sea surface. A user-defined function (UDF) was developed and applied for CFD modeling. The focus was on analyzing the diffusion range (rising height Hp and lateral migration distance Wp) from full-field data. The results indicate that the oil spill velocity, ocean current velocity, crude oil density, and crude oil viscosity impact the viscous shear force, the oil spill’s inertia force, and the current shear effect. The formula for calculating the lateral migration distance of spilled oil under different working conditions was obtained by fitting. The results of this study can provide a scientific basis for formulating an emergency treatment plan for offshore oil spill accidents and minimizing the harm to marine ecology and the environment.

Measurements of the Density and Viscosity of Heavy Oil and Water-in-Oil Emulsions Over a Wide Temperature Range

Density and dynamic viscosity of extra viscous heavy crude oil and water-in-oil (W/O) suspensions based on Ashalchinskaya (Tatarstan, Russian Federation) oil have been measured as a function of temperature and concentration of water at atmospheric pressure. The measurements were made at temperatures from (293 to 463) for density and from (293 to 367) K for viscosity with various concentrations of water (from 0 % to 30 % volume fraction). Measurements were made using modified hydrostatic weighing for density and falling body techniques for viscosity. The combined expanded uncertainty of the density, viscosity, pressure, and temperature measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated to be $$U\left( \rho \right)$$ = 0.16 % and $$U\left( \eta \right)$$ = 1.0 %, $$U\left( P \right)$$ = 1.0 %, and $$U\left( T \right)$$ = 0.02 K, respectively. The reliability and accuracy of the new experimental method and correct operation of the modified experimental apparatus was confirmed with measurements using different methods (pycnometric, capillary flow, commercial standard instruments, Brookfield rotational viscometer). The effect of temperature and concentration of water on the measured values of density and viscosity of W/O suspensions were studied. Using crude dry oil, the effective viscosities of several synthetic W/O emulsions are measured at atmospheric pressure using a commercial standard instrument, Brookfield rotational viscometer and falling body technique for different shear rates, temperatures and volume fractions of the dispersed phase. The various correlation equations for describing viscosity as a function of temperature and dispersed phase volume fraction is developed. A number of factors such as water content, shear rate, shear stress, and temperature and their effects on the density and dynamic viscosity of dry crude oil and W/O emulsions were assessed.

Multi-well dynamic liquid-level prediction method of pumping well based on dynamic and static information feature fusion neural network

In a rod pumping system, accurate prediction of dynamic liquid level is a key to rational optimization of pumping system parameters. At present, it is difficult to use a uniform prediction model for dynamic liquid-level prediction in different rod pumping systems. To this end, a method for predicting the dynamic liquid level of multiple wells in a pumping well based on dynamic and static information feature fusion (DSIFF) neural network is proposed in this paper. According to the principle of dynamic liquid-level calculation, suspension displacement, suspension load, pumping rod parameters, formation crude oil density, surface crude oil density, oil pressure, and casing pressure are used as inputs. The subnetwork feature extraction method is proposed for the problem of large network structure caused by the high dimension of the important dynamic data of suspension displacement and suspension load. The Huber loss function is used as the loss function of the prediction model for the case of abnormal data in the large amount of data required for model training. Finally, the results of comparative analysis show that the proposed method solves the problem of unified establishment of dynamic liquid-level prediction model for multiple oil wells and has better robustness for abnormal data.

Simulation of Change in Density and Viscosity of Crude Oil When Mixing

The deviation of density and viscosity values of oil mixtures from those calculated according to the additivity rule has been examined. Mathematical models have been developed for determining the properties of mixtures with different compositions taking into account the group composition of the source components. Mixtures containing components with a high content of alkanes and a low content of arenes have been found to be characterized by extreme deviations of density towards the maximum and kinematic viscosity towards the minimum. The created models were validated and compared with existing methods of describing the oil physicochemical properties. An approach to the creation of optimal from a technological point of view formulation for compounding oil of different types is proposed.

Physical properties of lacustrine shale oil: A case study on the lower member of the Lucaogou Formation (Jimusaer Sag, Junggar Basin, NW China)

Shale oil generated by the lower member of the Lucaogou Formation, which was deposited under saline lacustrine conditions within the Jimusaer Sag of the Junggar Basin (NW China), is generally characterized by high density and viscosity. However, a strong spatial heterogeneity of physical properties is observed as well. In this paper, these spatial variations and their controlling mechanisms are evaluated from the perspective of the primary depositional environment, source rock thermal evolution and fractionation effects of primary migration. Based on a detailed organic petrological and geochemical characterization of the target interval within the key well JHBE, hydrous pyrolysis experiments conducted on representative source rock samples from well JHBE, as well as established methods of oil-source correlation subjected to oil samples from several regionally distributed producing shale oil wells, a predictive model of density and viscosity changes of crude oil was established. According to the findings of this study, the thermal evolution and sedimentary environment of source rocks are the main factors affecting the quality of crude oil, and the fractionation effect of primary migration has little effect. Crude oil density and viscosity at first increase up to peak oil maturity, followed by a decrease with further increasing thermal evolution of the source rock. Furthermore, if the source rocks experienced similar thermal histories, it was discovered that relatively low density and corresponding viscosity values are characteristic for crudes from source rocks which were formed in a relatively high salinity environment. In contrast, hydrocarbon generation of source rocks formed under relatively low salinity environments is slightly retarded in direct comparison, and the density and viscosity of the generated crude oil are both relatively high. This highlights that a detailed organic petrographical and geochemical evaluation of the target formation is crucial for the assessment of shale oil potential and production sweet spots in alginite-dominated lacustrine sedimentary environments.

Molecular Dynamic Simulation of Crude Oil (SARA) Water Flooding Mechanisms under Different Driving Forces in Oleophilic Pore Channels

This study investigates the variation of crude oil density distribution with water flooding time for different driving force conditions in the oleophilic pore channel. We used molecular dynamic simulations to analyze the dynamic processes of transport and attachment of crude oil molecules in the pore channel under different driving forces. Oil molecule density distribution pattern during water flooding is of great significance to explore the water flooding mechanism. We studied the oil-water and oil-wall interaction energy. The oil-water interaction energy increased slightly with the increase in the driving forces. The oil-wall interaction energy grew with the increase in the driving forces between 0.001 kcal/(mol·Å) and 0.003 kcal/(mol·Å). When the driving forces increased to 0.004 kcal/(mol·Å) and 0.005 kcal/(mol·Å), the oil-wall interaction energy increased with the increase in the driving forces. After 0.003 kcal/(mol·Å), the oil-wall interaction energy decreases to different degrees. Then, we conducted the RDF analysis to compare the changes of peak value on the RDF between the crude oil and the hydrogen atoms in the wall at distinct moments of time for the three driving forces. We can see that the peak is constant between 5 Å and 6 Å as the driving forces increase. We also analyzed the number density of the crude oil and found that the difference in the number density of the crude oil molecules attached to the two sides of the wall becomes more pronounced as the driving forces are accumulated. The plot of the center-of-mass velocity at different driving forces shows the decrease in center-of-mass velocity as the driving forces increase. We also provided graphs of oil density distribution and the velocity distribution at each moment. Those graphs clearly demonstrated that the side of the wall with more crude oil attached attracts oil droplets; then, the water gradually piled the crude oil up to form oil clusters. High-speed water molecules will strip the oil molecules in the middle of the pore.

Acrylate polymer prepared by dispersion polymerization and its crude oil emulsion demulsification performance

AbstractThe development of a new crude oil emulsion demulsifier to replace the block polyether has always attracted attention. In this article, a novel crude oil emulsion demulsifier was prepared by dispersion polymerization using a mixture of ether and water as the dispersion medium and acrylate, methacryloxyethylthrimethyl ammonium chloride (DMC), and acrylamide as the comonomers. Taking the stability and demulsification performance as the index, the effects of acrylate type, ether/water mass ratio, monomer mass ratio, monomer concentration, initiator type, ether type, and reaction temperature on the polymerization results were investigated. The experimental results showed that when the acrylate was butyl acrylate (BA), the mass ratio of BA to DMC was 1:1, and dispersion medium was the mixture of dipropylene glycol methyl ether and water (ether/water mass ratio 1.5:1), monomer concentration was 20 wt%, initiator was V50, reaction temperature was in range of 50 to 55°C, and polymerization reaction was 10 h, the product P (BA‐DMC‐AM) had a good demulsification performance for the crude oil emulsion (crude oil density 0.9625 g/cm3, water content in emulsion 50%). When the dosage of P (BA‐DMC‐AM) was 200 mg/L and the temperature was 75°C, its dehydration was higher than 90% after demulsification for 4 h. This efficiency was similar with the block polyether demulsifier BH133. In addition, interfacial properties showed that P (BA‐DMC‐AM) can adsorb onto the oil–water interface and reduce the strength of W/O interfacial film, thereby achieving demulsification.