Physical Properties Of Crude Oil Research Articles

Study on Wax Deposition Law in Daqing Gulong Shale Oil

Daqing Gulong shale oil exhibits elevated wax content, a high wax precipitation point, and a high freezing point. However, its oil density and viscosity are relatively low, making it susceptible to wax crystal precipitation. The risk of pipeline clogging is heightened in lower ambient temperatures, posing a hazard to the safe production of shale oil. This study focuses on testing the fundamental physical properties of crude oil. The wax deposition flow loop was employed to replicate wax deposition in extracted fluids under actual high-flow gas-liquid conditions within a pipeline. The deposition patterns were determined based on the experimental findings. The results indicate that, irrespective of whether in single-phase, gas-liquid two-phase, or oil-gas-water three-phase conditions, the deposition mass rises with decreasing oil temperature. Furthermore, the deposition mass rises with an increased temperature difference between the oil and the pipeline wall. Conversely, the deposition mass declines with an increased gas-liquid ratio, and the deposition thickness declines with elevated water content. The observed deposition patterns highlight the significant influence of molecular diffusion and the impact of gas phase shear. These experimental findings offer valuable references and insights for the transportation of Daqing shale oil through pipelines.

Evaluation of matrix energization effect of pre-fracturing method in tight reservoirs- A comparative study of CO2, N2, and water

The exacerbation of the greenhouse effect has created an urgent global demand for large-scale utilization of CO2, making it a significant concern for industries worldwide. During the fracturing process, CO2 possesses unique properties that enable the formation of intricate fracture networks, presenting promising applications. However, the potential of CO2 as a medium for enhancing recovery through fracturing remains largely unexplored. This paper highlights the priority of using CO2 as an energized fluid by comparing the pressure and oil recovery performance with N2 and water. Initially, CO2-oil swelling tests were conducted to assess the impact of CO2 injection on the physical properties of crude oil. Subsequently, the matrix energization performance of the three fracturing fluids was analyzed from two perspectives: pressure augmentation and pressure maintenance. The Online Nuclear Magnetic Resonance (NMR) method is proposed to further evaluate the oil replacement performance of fracturing fluids. The experiment results suggest that nitrogen is more effective in raising reservoir pressure, hydraulic fracturing exhibits superior formation energy maintenance, and CO2 demonstrates favorable performance in both aspects. Meanwhile, CO2 remains capable of recovering the largest amount of oil, with a recovery of up to 10.19%, and the oil recovery for nitrogen and water is 9.39% and 6.37%, respectively. Finally, a field-scale numerical model was developed to evaluate the matrix energization performance and oil recovery efficiency. In contrast to water and nitrogen, CO2 exhibits a heightened capacity for oil recovery. However, this advantage is proved to be constrained when the injection volume of CO2 is limited. CO2 can fully leverage its benefits when a substantial injection volume is employed, and reasonable optimization of CO2 injection amount can maximize the benefits.

Effect of a novel type of water-in-oil nanocomposite viscosity improver on rheological properties of crude oil

The waxy crude oil was routinely transported by means of adding pour point depressants (PPD), which can significantly improve the flow behavior of waxy crude oil. In this study, the physical properties of crude oil were first characterized. Subsequently, a novel variety of W/O nanoemulsion was prepared based on water in an EVA/toluene solution at a 3:1 proportion, and evaluated as a viscosity improver. It was found by virtue of the laser particle size analyzer that the EVA emulsion reaches the nano-scale. EVA nanoemulsion can present a behavior similar to nanocomposite PPD, and form a denser and regular structure with wax crystals via heterogeneous nucleation. Compared with conventional EVA, EVA nanoemulsion further reduces the oil viscosity, gel point and yield value by 52.8%, 0.05 °C and 29.6%. In addition, the impact of particle size of EVA nanoemulsion on the rheology of crude oil was discussed. In combination with DSC curve and POM, the action mechanism of EVA nanoemulsion on crude oil was analyzed.

REVIEW ON POUR POINT DEPRESSANTS FOR WAXY CRUDE OIL ISSUES

Crude oil contains heavy paraffin molecules that cause the deposition of solid wax. Wax deposition is a criticalproblem in the petroleum industry, which results in various production problems. Pour Point Depressant (PPD) is a chemical additive that prevents wax deposition. PPD is employed to lower the pour point temperature allowing crude oil to flow at a significantly lower temperature. Several types of PPD include polymer, nano-composite and a natural organic compound. This review paper provides insights regarding different types of chemical additives to solve waxy crude oil issues. The effectiveness of these chemical additives is compared based on the changes in pour point value in degrees Celsius, as it is one of the physical properties of crude oil. Ultimately, this paper provides information regarding the performance of different PPDs in reducing pour point temperature to solve wax deposition issues.Keywords: Flow assurance, paraffin wax, wax deposition, mechanism of wax deposition, chemical additives, pour point depressant

Study on heat flow transfer characteristics and main influencing factors of waxy crude oil tank during storage heating process under dynamic thermal conditions

In response to the energy conservation and emission reduction targets proposed by China's Fourteenth Five-Year Plan, it is necessary for oilfield enterprises to achieve the purpose of reducing energy consumption and carbon emissions of crude oil storage under the premise of ensuring safe production of oil depots. As the preferred oil storage facility for crude oil depots, the internal heat flow transmission process of storage tanks plays a vital role in the overall energy consumption of oil depots. In this paper, a three-dimensional theoretical model of the heating process of large waxy crude oil tank storage is established, and the influence law of the circumferential effect of the coil on the heating process of waxy crude oil is put forward. The external environment influence area, the internal temperature rise heat flow influence area and the transition area are put forward. The multi-nonlinear regression method is innovatively used to establish the main influencing factor model for each influence area so as to realize the quantitative characterization of the influence mechanism between the heat flux at the tank boundary and the dynamic thermal environment and the variable physical properties parameters of crude oil. The results show that the convective heat transfer of oil in the tank bottom area is greatly influenced by the circumferential effect of the coil, and the circumferential effect of the coil is enhanced with the gradual proximity of the coils on both sides, and the low temperature area at the tank bottom is obviously improved. The heat loss of the storage tank is mainly concentrated at the boundary of the tank. According to the change of heat flux in each boundary area, the external environment influence area, the internal heating heat flow influence area and the transition area are divided. Among them, the top of the storage tank forms an external environmental impact area dominated by solar radiation heat transfer, supplemented by natural convection of temperature difference, and the bottom of the storage tank forms an external soil impact area dominated by heat conduction to the external soil. Due to the effect of the thermal insulation layer, the influence of the external dynamic thermal environment on the position of the tank wall is weakened, and only the influence area of the internal temperature rise heat flow dominated by the natural convection of crude oil is formed. At the same time, there is a transition area with different thickness between the internal and external influence areas, which is affected by the external dynamic thermal boundary conditions and the physical properties of crude oil. The internal heat transfer direction is different, which causes the influence weight of each factor to fluctuate, and with the reduction of the external dynamic thermal environment, the transition area becomes the external condition influence area.

Developing new correlations for asphaltene deposition involving SARA fractions and colloidal instability index

Asphaltene deposition in pipelines disrupts the normal transportation of the fluid produced. The deposition within the pipeline depends on the content of saturates, aromatic, resin, and asphaltenes (SARA) in crude oil. SARA analysis is used in the petroleum industry to estimate the stability of asphaltenes. In this study, a new set of correlations has been developed using regression analysis and the MATLAB curve fitting tool. The SARA fractions and the colloidal instability index (CII) are correlated with density, viscosity, and the combination of density and viscosity. SARA analysis data from 310 crude oil samples were used to develop the correlations while field data from 29 unique crude oils were used for validation. The best-fit correlations are selected based on statistical indicators such as the correlation coefficient (R2), the root mean square error (RMSE), and the average absolute relative error (AARE). Asphaltene stability plots were also developed for the new density-based CII (DBCII), viscosity-based CII (VBCII), and the density-and-viscosity-based CII (DVBCII). Based on statistical indicators, analysis of results shows that the density-based correlations for the SARA fractions are relatively more accurate than the viscosity-based correlations. The R-squared value for the DBCII is 0.7031 compared to 0.3234 for the VBCII and 0.6875 for the DVBCII. However, the percentage accuracy of 83% for the DVBCII is higher than the accuracy of the existing methods. The newly developed deposition envelopes are divided into stable and unstable regions that can be used to determine the stability of the asphaltene based on the physical properties of crude oil. The newly developed correlations for each SARA fraction based on the oil density eliminate the requirement for the laborious and time-consuming SARA analysis. Therefore, it is useful to predict the stability of asphaltene based on the physical properties of crude oil.

Geochemical characteristics and origin of crude oil from Carboniferous volcanic rocks in the Hongche Fault Zone of the Junggar Basin of China

In recent years, significant advances have been made in the exploration of Carboniferous volcanic reservoirs in the Hongche Fault Zone of the Junggar Basin of China, showing good prospects for further exploration. However, the large variation in the physical properties of crude oil and the complex distribution rule inhibit the one-step exploration. In this study, the PM scale of the biodegradation of crude oil and source of crude oil were studied using experimental methods that target the properties, bulk properties and biomarker compounds of crude oil. The exploration potential of crude oil in this area was analysed, and an accumulation model of crude oil was established. Based on the differences in biomarker compounds and the degree of biodegradation, crude oils were divided into four groups and seven subgroups. Additionally, the analysis of the biomarker compounds of crude oil combined with the hydrocarbon-generation history of source rocks showed that there were at least two periods of oil charging in this area. The first period was the late Triassic, with crude oil derived from the P1f source rock. Owing to the strong tectonic activity during the late Indosinian movement, the oil reservoirs were distributed in the footwall of the fault zone, and the oil in the reservoir exhibited different degrees of biodegradation, forming crude oils of subgroup I1, II and III1. The second period was Cretaceous, during which the P1f source rock was in the natural gas generation stage, and the P2w source rock was at a mature stage. A small part of the crude oil formed by the P2w source rock migrated to the Carboniferous reservoirs and mixed with the crude oil formed by the earlier P1f source rock, resulting in crude oils of subgroups I2, III2, and IV2. The crude oil in the studied area originated from the source rocks in the sag during the peak of oil generation. As tectonic activity approached stability in the latter period, it is speculated that there may be well-preserved primary oil and gas reservoirs in the footwall and slope areas of the fault, making these potential exploration sites.

Magnetically recoverable poly (methyl methacrylate-acrylic acid)/iron oxide magnetic composites nanomaterials with hydrophilic wettability for efficient oil-water separation

Due to the environmental and production problems of emulsion, it is important to efficiently separate oil-water emulsion to meet the refinery requirement and clean up oil spills. Synthesis of a universal demulsifier is not an easy task because the physical properties of crude oil vary, which makes its characterization and demulsification procedure difficult. To overcome this problem, hydrophilic and magnetically recoverable poly (methyl methacrylate-acrylic acid)/iron oxide magnetic composite nanoparticles ((P(MMA-AA)/Fe3O4 NPs) were developed as an efficient and economical demulsifier via soap-free emulsion polymerization. To characterize the magnetic composite NPs for their appropriate surface morphology and magnetic domain, TEM, FTIR, VSM, and TGA analyses were carried out. The newly synthesized NPs displayed good hydrophilic properties as they migrated quickly to the aqueous emulsion phase, which was also reassured by their water contact angle of 75°. They exhibit strong magnetic characteristics (20 amu/g) in the oil-water emulsion, makings the hydrophilic wettability capable and attractive to the external magnet. Experimental results revealed that the prepared magnetic composite NPs separated 99% of the water from stable emulsion in 30 min and could be recycled 8 times through magnetic separation. The recycled magnetic composite NPs maintain their hydrophilic wettability and efficiency in separating oil-water emulsion, making them economical and commercially viable. The migration of magnetic composite NPs to the aqueous phase in the stable emulsion with a strong magnetic domain explains the coalescence of emulsified water droplets and their quick separation from the stable emulsions through the external magnet.

Influence of heterogeneity on fluid property variations in carbonate reservoirs with multistage hydrocarbon accumulation: A case study of the Khasib formation, Cretaceous, AB oilfield, southern Iraq

Abstract The fluid distribution is considerably influenced by the reservoir homogeneity. This study analyzes carbonate reservoir heterogeneity and hydrocarbon accumulation processes in the Khasib reservoirs in AB oilfield in the Middle East to discuss factors controlling the distribution of fluid and the effects of this distribution on the productivity of single wells. The Khasib reservoirs in the AB oilfield show uniform vertical distributions, with a large difference in the longitudinal pore throats, and the upper part of the reservoir is better than the lower one. Because the hydrocarbon accumulation is multiphasic, the heterogeneity of crude oil is based on whether traps are formed in the early or late stage of source rock formation during accumulation. Moreover, the longitudinal physical differences in crude oil properties are mainly attributed to the longitudinal differences in the pore throats. The difference in the pore throat and physical properties of crude oil affords differences in the productivity of horizontal wells in different subzones.

Study on layer system complementarity technology in Block N

In view of the low permeability of oil reservoir, poor physical properties of crude oil, narrow strip development of channel sand, scattered development of plane sand body and serious heterogeneity in block n, there are some problems in water drive development, such as low well pattern control, low oil production rate, fast water cut rise rate and large production decline, the ideal stimulation effect can not be achieved by conventional measures, which restricts the potential of the block. In block n, 9 water injection wells and 16 production wells are selected to carry out layer series complementarity. Through the layer series complementarity of infill wells and basic well pattern, the well spacing is reduced, the injection production relationship of narrow sand body is improved, the water drive control degree and multidirectional connectivity ratio are improved, and the feasibility of improving the water drive development effect of block n is improved. In this paper, through the analysis of various remaining oil distribution types, the hole filling mode is optimized, so as to obtain better social and economic benefits.

Characteristics of trace elements in crude oil in the east section of the south slope of Dongying Sag and their application in crude oil classification

The east section of the south slope of the Dongying Sag is rich in oil and gas resources, with diverse reservoir types and complex physical properties of crude oil. It has typical characteristics of multi-source and multi-stage accumulation. The classification of crude oil types is the basis of petroleum geology research. By analyzing the content and distribution characteristics of trace elements in typical crude oil samples, combined with mathematical statistics, the effective classification of crude oil types in the study area is realized. The content of alkali metals, alkaline earth metals and transition metal elements in crude oil is significantly higher than that of rare earth elements, and the content of light rare earth elements is higher than that of heavy rare earth elements. There is a good correlation between the total amount of trace elements and the bulk composition of crude oil, while the correlation between the total amount of rare earth elements and the bulk composition of crude oil is relatively poor. The cluster analysis of multiple trace element-related parameters can classify the crude oil into three types, and the biomarker parameters of different type crude oils show obvious differences, indicating that the use of trace elements to classify crude oil types is effective and feasible in the study area. This study shows that the content, distribution characteristics and related parameters of trace elements in crude oil can be used as effective oil source correlation tools, reasonable selection of correlation parameters, and comprehensive analysis of cluster analysis methods can accurately classify the types of crude oil.

Modeling of Overpressure Generation–Evolution of the Paleogene Source Rock and Implications for the Linnan Sag, Eastern China

Subsurface pore pressure affects the direction of hydrocarbon migration, determines the distribution of the hydrocarbon reservoir, and provides scientific reference for drilling planning. Overpressures are widespread in the Paleogene Shahejie Formation in the Linnan Sag, which is closely related to the distribution of oil reservoir. However, the overpressure generation mechanisms are undefined, let alone the relationship between the evolution of paleo-overpressure and hydrocarbon migration in the Linnan Sag, which brings great challenges for the understanding of oil accumulation and future oil exploration. Basin modeling was carried out to solve the issue of quantitative evaluation of overpressure mechanisms and to restore the overpressure evolution of the Paleogene source rocks. The implications for the pore pressure prediction and oil migration in the Linnan Sag were further discussed. The modeling results show that the disequilibrium compaction of mudstones is a dominated overpressure mechanism of source rocks in the Linnan Sag, which accounts for approximately 90% of the measured overpressure in the region. The remainder part of overpressure was generated by hydrocarbon generation; however, the effects of hydrocarbon generation on overpressure evolution were limited in the intervals deeper than 4000 m. The significance of the overpressure mechanism is that the porosity-dependent method will give a satisfactory pressure prediction result in the current exploration depth range (3800–4300 m). The overpressure evolution of the source rock has undergone a cycle of “accumulation-dissipation-reaccumulation,” which corresponds to the age of 45.5–24.0 Ma (Es3-Ed period), 24.6–14.0 Ma (Ed period), and 14.0–0 Ma (Ng-Qp period). The oil potential of the Es3l shows good inheritance with the overpressure in the source rock, indicating overpressure increased the driving force for oil migration. The oil released from the source rock has a trend to migration from the center of the sag to the uplift belt, which is also indicated by the physical properties of crude oil. The knowledge of the generation and evolution of overpressure has great significance for further exploration in the Linnan Sag and other extensional basins.

Petroleum Physical Properties Prediction Application in Enhanced Oil Recovery Process

The Enhanced Oil Recovery (EOR) process is one of the ways in the petroleum exploitation process so that thick oil can be lifted to the surface and produced. The EOR process referred to in this study is the EOR process carried out in previous studies at the EOR laboratory of UPN Veteran Yogyakarta Indonesia by adding biosurfactants and adjusting the temperature. In laboratory experiments, each time an amount of biosurfactant concentration is added and the temperature is adjusted, the calculation must be done repeatedly to determine the amount of viscosity, interfacial tension (IFT), and density. This experiments takes a long time, requires high cost and variety limitation of the condition. The previous research has succeeded in building a model with multivariate polynomial regression equations to predict the value of the physical properties of crude oil from existing data then classify it into three categories using Naive Bayes, i.e., light oil, medium oil, and heavy oil. The physical properties of petroleum measured in the research are viscosity, interfacial tension, and density. The model uses laboratory data which are taken from the test results of Pertamina's KW-55 well as validation. The validation result shows that Multivariate Polynomial Regression has succeeded in predicting the value of viscosity, interfacial tension, and density with error values ranging from 0% to 1% from the sample data. With a low error value, the application can make forecasting with more variable conditions. The model still cannot be used independently without the Python environment, so to be used easily by more users, the model must be built into an independent application that can be installed on the user's device. In this research, the prediction application of petroleum physical properties has been built. The application is made using the Multivariate Polynomial Regression method according to the model in the previous study to predict the physical properties of petroleum, then uses Naïve Bayes to classify the oil. The application completed the several adjustment to shift from model to application, including user interface, system, and database adjustments.

How Is Ultrasonic-Assisted CO2 EOR to Unlock Oils from Unconventional Reservoirs?

CO2 enhanced oil recovery (EOR) has proven its capability to explore unconventional tight oil reservoirs and the potential for geological carbon storage. Meanwhile, the extremely low permeability pores increase the difficulty of CO2 EOR and geological storage processing in the actual field. This paper initiates the ultrasonic-assisted approach to facilitate oil–gas miscibility development and finally contributes to excavating more tight oils. Firstly, the physical properties of crude oil with and without ultrasonic treatments were experimentally analyzed through gas chromatography (GC), Fourier-transform infrared spectroscopy (FTIR) and viscometer. Secondly, the oil–gas minimum miscibility pressures (MMPs) were measured from the slim-tube test and the miscibility developments with and without ultrasonic treatments were interpreted from the mixing-cell method. Thirdly, the nuclear-magnetic resonance (NMR) assisted coreflood tests were conducted to physically model the recovery process in porous media and directly obtain the recovery factor. Basically, the ultrasonic treatment (40 KHz and 200 W for 8 h) was found to substantially change the oil properties, with viscosity (at 60 °C) reduced from 4.1 to 2.8 mPa·s, contents of resin and asphaltene decreased from 27.94% and 6.03% to 14.2% and 3.79%, respectively. The FTIR spectrum showed that the unsaturated C-H bond, C-O bond and C≡C bond in macromolecules were broken from the ultrasonic, which caused the macromolecules (e.g., resin and asphaltenes) to be decomposed into smaller carbon-number molecules. Accordingly, the MMP was determined to be reduced from 15.8 to 14.9 MPa from the slim-tube test and the oil recovery factor increased by an additional 11.7%. This study reveals the mechanisms of ultrasonic-assisted CO2 miscible EOR in producing tight oils.

Research of Microbial-gel Combined Flooding Technology of Ba19 Block in Baolige Oilfield

Bal9 fault block is a medium-high temperature (58°C) reservoir in Baolige Oilfield. The crude oil is characterized by poor physical properties which has high wax and high gum content. The oil-water viscosity ratio is high and this leads to a low water flooding efficiency. The reservoir heterogeneity is high and the contradictions between layers are prominent. According to the characteristics of the oilfield, a microbial-gel combined flooding technology with the microbial flooding as the main body and the gel flooding as the auxiliary is developed to improve the overall development effect of the oilfield water flooding. Microorganism can improve the physical properties of crude oil, and appropriate gel flooding should be carried out to enlarge the sweep volume of microorganism work and improve the effect of microbial-gel combined flooding. By continuous application of this technology in Baolige Oilfield, the concentration of microorganisms is maintained at about 106 a/ml, and the whole microbial field is formed. The average annual reduction rate of crude oil is 48.1%. The microbial-gel combined flooding technology is verified to increase the recovery factor by 9.5%. Since the combined flooding was carried out in 2010, the recoverable reserves of the Ba19 block increased by 630,600 tons.

Special Distribution of Crude Oil in the Lucaogou Formation in Jimusaer Sag and Genetic Analysis of Its Physical Difference

The shale oil of the Lucaogou Formation in the Jimusaer Sag of the Junggar Basin was divided into two sweet spots for exploration and development. Crude oil in the upper and lower sweet spots comes from the upper and lower source rocks. After years of exploration, it has been found that the crude oil in the lower sweet spot has worse physical properties than that of the upper sweet spot. In this study, through the physical and geochemical analysis of crude oil in the upper and lower sweet spots, combined with the organic petrological observation of the upper and lower source rocks, the cause of the poor physical properties of the crude oil in the lower sweet spot has been identified. n-Alkanes in the saturated hydrocarbons of crude oil in the upper and lower sweet were complete while odd-to-even predominance was evident, indicating that the poor physical properties of the crude oil are unrelated to biodegradation. In addition, the correlation between the biogenic parameters and the physical properties of crude oil was analyzed, finding that the difference in crude oil is mainly related to the composition of biogenic precursors of upper and lower source rocks. Combined with organic petrological observation, the lower source rock was found to be rich in telalginite (green algae), which is therefore the primary reason for the difference in physical properties. In comparing results from the characteristics of crude oil biomarkers from both the upper and lower sweet spots, crude oils in the upper sweet spot are similar to each other, indicating that the enrichment of crude oil has experienced a certain migration. In contrast, the differences in biomarkers between the crude oils of the lower sweet spot were relatively large and changed regularly with depth, suggesting the self-generated and self-stored characteristics of crude oil enrichment. At the same time, it was found that the crude oil in the lower sweet spot is also affected by the maturity of adjacent source rocks under the condition of a consistent parent material source. Overall, it was determined that the lower the maturity of source rocks, the poorer the physical property of the crude oil produced.

Correlations Between Main Physical Properties of Crude Oils and Their NMR Relaxation Behavior and New User-Friendly Software for Quick Crude Oil Characterization

Correlations Between Main Physical Properties of Crude Oils and Their NMR Relaxation Behavior and New User-Friendly Software for Quick Crude Oil Characterization

Study on the Operation Safety and Reliability of a Waxy Hot Oil Pipeline with Low Throughput Using the Probabilistic Method.

When the hot oil pipeline is running at a low throughput, it easily enters into an unstable condition, which seriously threatens the safety of the hot oil pipeline operation. In this study, the unsteady heat transfer and flow mathematical models for the hot oil pipeline system were established first by comprehensively considering the uncertainty of parameters during pipeline operation, such as the operating parameters (throughput and oil temperature), physical properties of crude oil (freezing point, viscosity, and thixotropic parameters), and environmental parameters (buried deep soil temperature and soil thermal conductivity). Then, the efficient Latin hypercube sampling (LHS) stochastic numerical algorithm was applied and further developed to quantitatively describe the operation safety of hot oil pipelines with low throughput in the form of probability. On the basis of the abovementioned research, the qualitative relationship between pipeline flowrate and friction loss is obtained. Finally, taking an actual crude oil pipeline as an example, the failure probabilities of the pipeline under different operating conditions were analyzed in detail. Combined with the target safety level of pipeline operation, the minimum allowable throughput of pipelines was determined. This study revealed the flow and heat transfer law of hot oil pipelines with low throughput and determined its operation safety and reliability under different operating conditions.

Numerical study of elbow corrosion in the presence of sodium chloride, calcium chloride, naphthenic acids, and sulfur in crude oil

During the crude oil refining process, the piping system suffers a lot of corrosion damage at the elbows due to complex chemical reactions. This work aimed to investigate the effects of sodium chloride (NaCl), calcium chloride (CaCl2), naphthenic acids, and sulfur compounds, which can be responsible for corrosion in oil refineries due to the rheological and physical properties of crude oils. The corrosion occurs by a cracking operation that depends on the solid–fluid interaction, the temperature, and the crude oil nature. Computational fluid dynamics (CFD) has been used to predict the corrosion behavior based on the velocity profiles, shear stress, the friction factor, and the solid deposition rate of iron(II) chloride (FeCl2), iron(II) acetate (Fe(CH3COO)2), and iron sulfide (FeS) along the elbow. The numerical results proved that the corrosion locations are focused at certain regions, especially the elbow extrados wall outlet. The numerical results provide more solutions to avoid corrosion and improve the operational safety of the refinery.

Origin and migration pathway of biodegraded oils pooled in multiple-reservoirs of the Chepaizi Uplift, Junggar Basin, NW China: Insights from geochemical characterization and chemometrics methods

The Chepaizi Uplift possesses three sets of oil-bearing reservoirs, six sets of source intervals, multiple episodes of hydrocarbon charging, and variable physical properties of crude oils. In this study, based on geochemical characterization source intervals and the biodegradation rank of the crude oils, four oil populations named as group A, B, C, and D (D1, D2) were defined. The combined results of Q-cluster analysis (QCA) and discriminant analysis (DA) indicate that group A occurred mainly in Lower Neogene Shawan Formation (N1s) in the western Chepaizi Uplift and were primarily derived from the Middle-Lower Jurassic Xishanyao, Badaowan, Sangonghe formations (J2x-J1b-J1s) and a little of Paleogene Anjihaihe Formation (E2-3a) of the Sikeshu Sag. Group B occurred essentially in Upper Carboniferous Xibeikulasi Formation (C2x) of the western Chepaizi, and originated mainly from the J1b mudstone of the Shawan Sag. In addition, the crude oils of group C occurred mainly in the Lower Cretaceous Tugulu Group (K1tg) of the eastern Chepaizi and were primarily derived from Carboniferous-sourced oil from the Chepaizi Uplift. The crude oils of groups D (D1 and D2) are mixed with Permian (P1f and P2w) of Shawan Sag and Carboniferous-sourced oil from the Chepaizi Uplift. Based on the reconstruction of the migration history, the oils of group A in the N1s Formation of western Chepaizi migrated predominantly from the south (Sikeshu Sag) to the north and northeast, with wells Su1-2 and C27 as the initial filling points. The oils of group B in the N1s Formation of the western Chepaizi travelled predominantly from the southeast (Shawan Sag) to the north and northwest. The oils of group D1 in the C2x Formation of eastern Chepaizi migrated mainly from the northeast and southeast (Shawan Sag) to the west, with well P661 as the initial filling point. Wells SM011 and C64 are the initial filling points of the K1tg Group in the Hongche Fault Belt. Crude oils of group C in the K1tg Group travelled predominantly from the southeast (Shawan Sag) and northeast to the west into the eastern Chepaizi and from well P68 to the southwest. According to the paleo-oil preferential filling orientations and paleogeomorphology, some favourable targets for petroleum exploration of the Chepaizi Uplift are forecast in this study.