Hasil untuk "Oils, fats, and waxes"

Xiangchun Zhang, Xin Zhang, Bing Liu et al.

Abstract Improving oil recovery from ultra-tight reservoirs remains a critical challenge due to their inherently low permeability, restricted pore connectivity, and poor sweep efficiency. This study presents a systematic experimental investigation of water-based enhanced oil recovery (EOR) techniques applied to core samples from the Tarim Basin. Coreflooding tests were conducted using conventional methods (waterflooding, CO₂ injection), hybrid strategies including Water Alternating Gas (WAG), Gas Alternating Water (GAW), and Alkali–Surfactant–Polymer (ASP), and advanced chemical-assisted schemes, including four Carbonated Water Alternating Gas (CWAG) variants and a novel Active Carbonated Water Alternating Gas (ACWAG) method. Results showed that ACWAG achieved the highest oil recovery (85.3%) and the lowest residual oil saturation (15.7%), outperforming all other techniques. Key performance indicators such as pressure behavior, wettability alteration, and slug size sensitivity confirmed the importance of injection sequencing and chemical formulation. This study provides new insights into the design of EOR strategies for ultra-tight formations and introduces a promising hybrid approach that could be scaled for field application.

TANG Haijun, QIU Xingdong, LIU Yisheng et al.

The adsorption behavior of methane in kerogen is of great significance for shale gas reserve evaluation and production prediction. However， there is still a lack of clear understanding of the hysteresis phenomenon and its micro-causes in the process of methane desorption. Therefore， based on the real kerogen model， the grand canonical Monte Carlo and molecular dynamics （GCMC-MD） coupling method was used to systematically investigate the adsorption-desorption behavior of methane under different conditions and the pore structure evolution characteristics of kerogen. The results show that the volumetric strain of kerogen shows a continuous growth during the methane adsorption process. This positive feedback mechanism of “adsorption， expansion， and readsorption” effectively expands the available pore space and significantly improves the methane storage capacity of the kerogen. Under the same pressure conditions， the methane’s absolute adsorption amount in the depressurization stage is higher than that in the pressurization stage， thus showing a significant hysteresis loop on the isothermal adsorption-desorption curve. The fundamental mechanism is that the kerogen skeleton undergoes partial irreversible structural deformation， making the thermodynamic path of the adsorption-desorption process do not coincide. The increase of temperature will weaken the interaction between methane molecules and pore wall， reduce the adsorption capacity， and alleviate the hysteresis in the desorption process. Under high temperature conditions， the overall deformation response ability of kerogen decreases. Compared with the type III-A kerogen， the type II-A kerogen has a higher proportion of micropores， which leads to a higher energy barrier to methane in the desorption process， thus aggravating the difficulty of desorption.

QIU Kang, WANG Lihua, CUI Qiang, WANG Ying, WANG Xiaoshan, XIONG Zhenyu

The Qiongdongnan Basin is located in the northwestern part of the continental shelf in the northern part of the South China Sea, which is a Cenozoic highly-overpressured, transformed, and extended basin with abundant oil and gas resources. The Qiongdongnan Basin is also a typical offshore HTHP basin in China, and is one of the world’s top 3 offshore HTHP areas, with the highest reservoir temperature of over 240 ℃ and the highest formation pressure coefficient of 2.3, which makes it one of the most difficult areas for domestic and international drilling operations. The complex genesis mechanism of abnormal high pressure in the Qiongdongnan Basin of the South China Sea results in great difficulty and low accuracy of pre-drilling pressure prediction, which seriously compromises drilling safety. Block 64/07 of Lingshui structure in Qiongdongnan Basin was taken as the research object. Through analysis of tectonic evolution and loading/unloading mechanisms, the coupling genesis mechanisms of abnormal high pressure in this block were revealed, a multi-mechanism coupling pressure prediction method was specifically established, and formation pressure profiles of drilled wells and a 3D regional formation pressure model were constructed, systematically analyzing the vertical and horizontal pressure systems of this block. The Qiongdongnan Basin has experienced many rounds of tectonic evolution since the Paleocene, forming a huge thickness of Paleocene-Neocene and Quaternary sediments. From the perspective of the depositional history of the Qiongdongnan Basin, the sedimentation rate of the whole basin is relatively high, with two distinct peaks. The first peak occurred in the fracture to fracture-argument period, with a subsidence rate exceeding 600 m/Ma. The second appeared during the post-fracture rapid subsidence period, with the Yinggehai Formation reaching 600~1 700 m/Ma. Both rates exceeded the 150 m/Ma threshold for overpressure, and these periods were prone to the formation of anomalous high pressures with undercompaction mechanisms. These processes were the basis of the overpressure prevalent across the entire basin, and were manifested as loading-type anomalous high pressures. Meanwhile, the FS fracture zone in this region had the ability to transmit oil and gas, forming a two-way hydrocarbon supply pattern between the main depression and the secondary depression in western Lingshui. The hydrocarbons had two large-scale hydrocarbon discharge periods (15 Ma and 5 Ma), and the Meishan~Sanya Formation underwent prolonged effective charging, creating conditions for high pressure caused by fluid charging, which was the most probable auxiliary cause of anomalous high-pressure formation in this region. Using the logging data of the drilled wells, the rock density-sound wave velocity crossplot of the stratified sections was established, and the Meishan Formation showed a composite mechanism of loading and unloading. Combined with the tectonic evolution history, it could be inferred that the anomalously high pressure of Yinggehai and Huangliu Formations was attributed to the undercompaction mechanisms, and the anomalously high pressure of Meishan Formation resulted from the coupling mechanism of undercompaction and fluid filling. To address the high-pressure coupling genesis mechanism of this block, this study developed a multi-mechanism coupling pressure prediction method. The upper Yinggehai Formation and Huangliu Formation under-compacted strata were evaluated using the conventional Eaton method, and the lower Meishan Formation and Sanya Formation stratigraphic over-pressure zones were analyzed using the multi-parameter effective stress method, thereby overcoming the limitations of single-method prediction and improving prediction accuracy. Based on this method, a high-precision three-dimensional stratigraphic pressure body was constructed in Lingshui tectonic block 64/07, revealing the vertical and horizontal distribution patterns of stratigraphic pressure in this block. The results showed that the high pressure in formations above Huangliu Formation in this area was caused by undercompaction mechanism, while below Meishan Formation it was caused by the coupling mechanism of undercompaction and fluid charging. Vertically, pressure began to increase in the middle and lower part of Yinggehai Formation, Huangliu Formation served as the pressure transition zone, and Meishan and Sanya Formations entered the overpressure zone, with the highest pressure coefficient reaching 2.10. Horizontally, it generally presented the characteristics of “low in the west and high in the east, low in the north and high in the south”. These research findings were applied to well L5-1. The core of this method lay in addressing the coupling genesis of formation pressure in the Meishan Formation by establishing a multi-parameter effective stress method. Parameters such as shale content, porosity, and effective stress of the lower high-pressure layer were introduced, avoiding the difficult problem of determining original sedimentary loading and subsequent unloading, thereby achieving accurate prediction of reservoir high pressure. During the drilling process of well L5-1, a combination of pre-drilling pressure prediction, logging monitoring, logging constraints on seismic layer velocity and MDT pressure correction were used to follow up and monitor the trend of pressure change throughout the entire process in real time. The entire pressure monitoring process could be divided into four stages: (1) determining the starting pressure layer at the pre-drilling design stage as the bottom of Ledong Formation and the top area of Yinggehai Formation; (2) adjusting the starting pressure depth from 2 100 m to 1 850 m based on the three-opening single-root gas pressure and the pressure monitoring profile with drilling; (3) using the four-opening electroacoustic constraints to recalibrate the extracted layer velocity, combined with the MDT pressure measurements, to correct the parameters of the prediction model; (4) conducting five-opening monitoring and the DST test after completion of drilling to complete the real drilling pressure evaluation. Using this method, the average accuracy of pre-drilling formation pressure prediction was 87.1%. During actual drilling, based on logging and test data, prediction results were timely corrected, and the prediction accuracy of lower formation pressure was improved to 98.8%, meeting the requirements for drilling design and field construction.

AbdulQoyum A. Olowookere, Adewale U. Oguntola, Ebenezer. Leke Odekanle

Early detection of energy losses, theft, and operational inefficiencies remains a critical challenge in oil and gas production systems due to complex interdependencies among wells and facilities, evolving operating conditions, and limited labeled anomaly data. Traditional machine learning approaches often treat production units independently and struggle under temporal distribution shifts. This study proposes a spatiotemporal graph-based deep learning framework for anomaly detection in oil and gas production networks. The production system is modeled as a hierarchical graph of wells, facilities, and fields, with additional peer connections among wells sharing common infrastructure. Weakly supervised anomaly labels are derived from physically informed heuristics based on production, pressure, and flow behavior. Temporal dynamics are captured through sequence modeling, while relational dependencies are learned using a Temporal Graph Attention Network. Under time-based evaluation, the proposed model achieves an ROC-AUC of about 0.98 and anomaly recall above 0.93, demonstrating improved robustness and practical potential for proactive monitoring in real-world energy operations.

Dehao Dai, Ding Ma, Dou Liu et al.

Forecasting crude oil prices remains challenging because market-relevant information is embedded in large volumes of unstructured news and is not fully captured by traditional polarity-based sentiment measures. This paper examines whether multi-dimensional sentiment signals extracted by large language models improve the prediction of weekly WTI crude oil futures returns. Using energy-sector news articles from 2020 to 2025, we construct five sentiment dimensions covering relevance, polarity, intensity, uncertainty, and forwardness based on GPT-4o, Llama 3.2-3b, and two benchmark models, FinBERT and AlphaVantage. We aggregate article-level signals to the weekly level and evaluate their predictive performance in a classification framework. The best results are achieved by combining GPT-4o and FinBERT, suggesting that LLM-based and conventional financial sentiment models provide complementary predictive information. SHAP analysis further shows that intensity- and uncertainty-related features are among the most important predictors, indicating that the predictive value of news sentiment extends beyond simple polarity. Overall, the results suggest that multi-dimensional LLM-based sentiment measures can improve commodity return forecasting and support energy-market risk monitoring.

Vali Mehdipour, Ahmad Reza Rabbani, Ali Kadkhodaie et al.

Abstract The primary purpose of this study is to identify the high reservoir quality area for drilling and perforation of new wells using interrelated geological, petrophysical, and seismic data. Various datasets such as, core analysis data (two wells), petrophysical logs (twenty wells) and 3D seismic cube were used to consider different scenarios for optimum well placement based on the availability and accuracy of the data. Considering four criteria (structure, reservoir property, fracture network, and heterogeneity), various data were combined to assess reservoir potential. A static reservoir model was constructed to reduce the uncertainty of the well location determination. A range of scenarios were implemented based on this static reservoir model or by relying only on the available seismic data. Electrofacies analysis was conducted to establish representative facies with which to guide the forecasting of locations suitable for drilling the new wells. Six facies were determined based on multi-resolution graph-based clustering (MRGC) method. In parallel, 3D seismic data was applied to determine seismic facies and seismic attributes to identify high-quality reservoir areas for well placement. As high fracture intensity is an essential feature required for high oil/gas production rates, a continuous fracture model (CFM) was constructed, and average intensity fracture maps were developed to determine the best production locations and to avoid low-productivity (or potential loss-of-circulation zones) from a drilling perspective. Some structural issues, such as distances from transition zones and/or faults, were also considered for well-placement purposes. Coefficient of variation (as a heterogeneity criteria) was also taken into account for well-placement decision-making. The results indicate that applying the developed integrated approaches reduces well-placement uncertainty and delineates high-quality reservoir zones (or sweet spots) with more confidence.

Yaqian Chen, Hanxue Gu, Yuwen Chen et al.

Body composition assessment using CT images can potentially be used for a number of clinical applications, including the prognostication of cardiovascular outcomes, evaluation of metabolic health, monitoring of disease progression, assessment of nutritional status, prediction of treatment response in oncology, and risk stratification for surgical and critical care outcomes. While multiple groups have developed in-house segmentation tools for this analysis, there are very limited publicly available tools that could be consistently used across different applications. To mitigate this gap, we present a publicly accessible, end-to-end segmentation and feature calculation model specifically for CT body composition analysis. Our model performs segmentation of skeletal muscle, subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) across the chest, abdomen, and pelvis area in axial CT images. It also provides various body composition metrics, including muscle density, visceral-to-subcutaneous fat (VAT/SAT) ratio, muscle area/volume, and skeletal muscle index (SMI), supporting both 2D and 3D assessments. To evaluate the model, the segmentation was applied to both internal and external datasets, with body composition metrics analyzed across different age, sex, and race groups. The model achieved high dice coefficients on both internal and external datasets, exceeding 89% for skeletal muscle, SAT, and VAT segmentation. The model outperforms the benchmark by 2.10% on skeletal muscle and 8.6% on SAT compared to the manual annotations given by the publicly available dataset. Body composition metrics show mean relative absolute errors (MRAEs) under 10% for all measures. Our model with weights is publicly available at https://github.com/mazurowski-lab/CT-Muscle-and-Fat-Segmentation.git.

Alvise Ferrari, Giovanni Laneve, Raul Alejandro Carvajal Tellez et al.

Methane (CH4) is a potent greenhouse gas, and its detection and quantification are crucial for mitigating the greenhouse effect. This study presents a comparative analysis of methane emissions observed using near-simultaneous observations from hyperspectral imaging spectrometers hosted aboard different satellite platforms (PRISMA, EnMAP, EMIT and GHGSat). Methane emissions from oil and gas facilities and landfills are analyzed to evaluate the consistency and precision of the sensors and temporal variability of the source. Landfills, characterized by diffuse and stable emissions, and dynamic oil and gas facilities, subject to operational variability, provide contrasting use cases for emission monitoring. Emission rates are quantified using the Integrated Mass Enhancement (IME) model and validated across satellites with overlapping acquisitions. This study highlights the advantages and limitations of each satellite system, emphasizing the critical role of multi-sensor integration in bridging temporal and spatial observation gaps. Insights derived here aim to enhance global methane monitoring frameworks and guide future satellite design for improved emission quantification.

Sajid Muhammad, Munir Hassan, Rasul Fahd et al.

Safflower (Carthamus tinctorius L.) is one of the edible oilseeds crops which is neglected due to its spiny nature that poses difficulties in field operations; however, this problem can be sorted out by introducing non-spiny safflower cultivars. Hence, a 2-year study (2020–2021 and 2021–2022) was planned to assess the production potential of spiny (5 accessions) and non-spiny (5 accessions) safflower germplasm and an experiment was laid out using randomized completed block design (RCBD) under semiarid conditions of Faisalabad (Pakistan). Agronomic and oil traits were targeted during study. In 2021, non-spiny safflower accession PI-198990 gave the highest seed yield and oil percentage as compared to spiny safflower. However, the highest linoleic concentration was noted in spiny PI-199829 accession whereas the greatest oleic acid percentage was determined in non-spiny PI-235660 accession. Principal component analysis unveiled two components accounting for 39.5% and 25.7% of total variation. Biplot graph indicated that seed oil content, seed yield and 1000-seed weight had the highest correlation in the 2nd group while in the 3rd group plant height, days to maturity and oleic acid were correlated. These targeted characters can be considered as suitable index for selection of safflower elite accessions for semi-arid conditions. In general, non-spiny safflower accession responded 19%, 4.3%,10.7%, 21.6%, 6.2% and 77.9% greater in plant height, number of branches, number of heads (capitula), 1000-seed weight, seed yield and oleic acid respectively. From the data of this 2-year studies, we concluded that spiny safflower accessions exhibited 1.2% and 16.3% more oil and linoleic acid content respectively.

Wenzhi ZHAO, Congsheng BIAN, Yongxin LI et al.

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.

Ahmed Farid Ibrahim, Ruud Weijermars

Abstract Accurate estimation of fracture half-lengths in shale gas and oil reservoirs is critical for optimizing stimulation design, evaluating production potential, monitoring reservoir performance, and making informed economic decisions. Assessing the dimensions of hydraulic fractures and the quality of well completions in shale gas and oil reservoirs typically involves techniques such as chemical tracers, microseismic fiber optics, and production logs, which can be time-consuming and costly. This study demonstrates an alternative approach to estimate fracture half-lengths using the Gaussian pressure transient (GPT) Method, which has recently emerged as a novel technique for quantifying pressure depletion around single wells, multiple wells, and hydraulic fractures. The GPT method is compared to the well-established rate transient analysis (RTA) method to evaluate its effectiveness in estimating fracture parameters. The study used production data from 11 wells at the hydraulic fracture test site 1 in the Midland Basin of West Texas from Upper and Middle Wolfcamp (WC) formations. The data included flow rates and pressure readings, and the fracture half-lengths of the 11 wells were individually estimated by matching the production data to historical records. The GPT method can calculate the fracture half-length from daily production data, given a certain formation permeability. Independently, the traditional RTA method was applied to separately estimate the fracture half-length. The results of the two methods (GPT and RTA) are within an acceptable, small error margin for all 5 of the Middle WC wells studied, and for 5 of the 6 Upper WC wells. The slight deviation in the case of the Upper WC well is due to the different production control and a longer time for the well to reach constant bottomhole pressure. The estimated stimulated surface area for the Middle and Upper WC wells was correlated to the injected proppant volume and the total fluid production. Applying RTA and GPT methods to the historic production data improves the fracture diagnostics accuracy by reducing the uncertainty in the estimation of fracture dimensions, for given formation permeability values of the stimulated rock volume.

Bjørn Christian Dueholm, Jesper de Claville Christiansen, Benny Endelt et al.

This paper investigates a common rail cylinder lubrication system for large two-stroke marine diesel engines using electronically controlled injectors. The system is studied using the Bosch rate of injection measurement technique The common rail injector has a buildup of mass flow of approximately 1 ms as the injector opens until the nozzle is choked from cavitation. Using a highly viscous fluid, the Bosch rate of injection method is able to predict the injected amount with an error of 5% or lower for nearly the entire tested delivery range of 2 mg to 21 mg. Lubrication of cylinder liners and piston rings is a crucial parameter in operating a two-stoke marine diesel engine efficiently. Both over and under lubrication is harmful for the engine, so the ability to accurately dose the cylinder oil is very important. A mass flow build up time of 1 ms promises high accuracy of dosage even down to 2.5 mg per injection. This paves the way for injecting the oil where and when it is needed, which in turn will improve engine performance and lower harmful emissions.

Yanpeng KANG, Yujia JIAO, Jianfu WANG et al.

The salt rock resource in China is characterized with multiple interlayers, thin salt formation and poor purity. Meanwhile, the conventional single vertical cavern has small volume and low utilization rate of salt formation, which cannot meet the requirements of rapid and efficient storage construction. Multi-step horizontal leaching can improve the utilization rate of salt formation and is suitable for constructing large gas storage in thin salt beds, and the cavern shape is a key factor affecting its volume and stability. Therefore, a physical simulation experiment was performed for the characteristics of horizontal leaching herein. Meanwhile, the effect of leaching parameters such as leaching rate, brine discharge position and back-step length on cavern shape and brine discharge concentration was explored. The results show that the large leaching rate and the high brine discharge position can reduce the brine concentration, and the effect is more significant in the early leaching stage. The small step length will form a hump cavern roof, while the large step length and use of blanket will form a flat cavern roof, and the alternate injection by two wells will form large body at both ends and small body in the middle. The cavern shape obtained by experiment is basically consistent with the numerical simulation result, which verifies the accuracy of experiment result. In addition, reference values were provided for such parameters as leaching rate and step length of multi-step horizontal leaching on site based on the experiment results, so as to build a hump-shaped horizontal cavern, further improving the stability and gas storage capacity of cavern.

Sun Yongtao, Hu Houmeng, Bai Jianhua et al.

The vent valve for offshore thermal recovery cannot be opened or closed normally under high temperature and high pressure(HTHP)conditions due to the damage of hydraulic control pipeline.To solve this problem,a normally open high-temperature vent valve was designed.It adopts all-metal sealing to ensure its sealing reliability under the high-low temperature alternating working condition ranging from normal temperature to 350 ℃,which was verified by high-low temperature laboratory tests.Its opening at atmospheric pressure and closing at high pressure prevent the downhole tools and pipeline from long-term exposure to HTHP,thus improving its opening/closing reliability.The force analysis of the valve was conducted in the states of opening and closing.Based on the Hertz contact theory,a theoretical model of globe-cone contact mechanics between valve and lower joint was established.Based on the sensitivity analysis of spherical radius,cone angle and hydraulic control pressure,the working performance parameters of surface closing pressure and sealing pressure were optimized to ensure its closing liability in case of emergency.The optimization design of theoretical model shows that it has the best sealing performance at spherical radius of 8.2 mm and cone angle of 4.6°.In addition,the closing pressure charts under different annular pressures were obtained.The high-low temperature tests indicate that the normally open high-temperature vent valve can be opened and closed flexibly and reliably,and it has reliable sealing performance at 60～350 ℃,which meets the requirements of long-term steam injection and oil production of offshore thermal recovery wells.The normally open high-temperature vent valve is suitable for long-term use in offshore thermal recovery wells under normally open and high-low temperature alternating working conditions.It is recommended to be applied in offshore three-cycle huff-and-puff wells and displacement wells.

陈秋玲，祝芷琦，李咏华，王小妹，梁北梅，温恺嘉，许一靖，曾还雄，林元亨，唐顺之 CHEN Qiuling, ZHU Zhiqi, LI Yonghua,WANG Xiaomei,LIANG Beimei, WEN Kaijia,XU Yijing,ZENG Huanxiong,LIN Yuanheng,TANG Shunzhi

蛋黄卵磷脂样品经微波消解，采用电感耦合等离子体质谱法测定样品中15种金属元素含量，对检测条件进行了优化，并进行了方法学考察。结果表明，在射频功率1.55 kW、载气（高纯氩气）流速 1.03 L/min、等离子气体流速15.0 L/min、蠕动泵转速 0.1 r/s、采样深度 10 mm、重复次数 3 次条件下，通过在线加入内标钪(Sc)、锗(Ge)、铟(In)、铼(Re)元素可校正基体效应和干扰，测定汞元素时，加入金元素可降低测定误差；该方法的15 种金属元素线性关系良好，线性相关系数（R）均大于0.999；方法检出限在0.03～0.65 ng/mL之间，定量限在0.10～1.97 ng/mL之间；仪器精密度良好，RSD在0.45%～4.67%之间；重复性RSD在1.78%～8.72%之间；中间精密度RSD在2.24%～9.45%之间；加标回收率在92.67%～132.90%之间, RSD在1.42%～7.00%之间。样品溶液在2~8 ℃条件下保存72 h，稳定性良好，RSD在0.56%～3.93%之间。该方法快速、准确、灵敏度高, 可用于蛋黄卵磷脂中15种金属元素的同时测定。 Egg yolk lecithin samples were digested by microwave and 15 kinds of metal elements in it were determined by inductively coupled plasma mass spectrometry(ICP-MS). The detection conditions were optimized and the methodology was investigated. The results showed that under the conditions of RF power 1.55 kW, flow rate of carrier gas(high purity argon)1.03 L/min, flow rate of plasma gas 15.0 L/min, peristaltic pump speed 0.1 r/s, sampling depth 10 mm and 3 replications, the internal standard solution with Sc，Ge，In and Re were added online for matrix effect and interference correction, and Au was added when determining the content of Hg to reduce the test error. The linearities for the 15 elements of the method were good with the correlation coefficients（R）above 0.999. The detection limit and quantitation limit of 15 elements were 0.03-0.65 ng/mL and 0.10-1.97 ng/mL, respectively. The precisions of the instrument were good with RSD in the range of 0.45%-4.67%. The RSD of the repeatability test was in the range of 1.78%-8.72%.The RSD of the intermediate precision was in the range of 2.24%-9.45%. The recovery rate of the 15 elements was in the range of 92.67%-132.90% with RSD in the range of 1.42%-7.00%. The stability of the sample solution was good and when it was stored at 2-8 ℃ for 72 h, RSD was in the range of 0.56%-3.93%. The method had advantages of fastness, accuracy and high sensitiveness, and it could be used for simultaneous determination of 15 kinds of metal elements in egg yolk lecithin.

Masoud Hatami Alooghareh, Atefeh Kabipour, Mohamadhosein ghazavi et al.

Application of CO2 gas in foam enhanced oil recovery (EOR) processes has emerged as a win-win strategy for achieving higher oil recovery factor and reducing greenhouse gas emission, which can significantly help the protection of the ozone layer from depletion. However, lower stability of CO2-foam, as compared to the N2- and CH4-foams, has tempted us to examine combinations of CO2 with these gases to not only improve the stability of the produced foam but also have CO2 as the gaseous phase of the foam. In this study, we investigated the effect of different gases and the mixture thereof on the performance of foams in EOR while the aqueous phase of foams is a constant mixture of Cocamidopropyl betaine surfactant (0.03 wt%) and silica nanoparticle (0.1 wt%). To this end, seven different gases, including N2, CO2, CH4, 80% N2 + 20% CO2, 80% CH4 + 20% CO2, 50% CH4 + 50% CO2, 50% N2 + 50% CO2 were used as the gases phase for foam generation and the performance of the produced foams were examined through the following experiments: bulk foam stability tests, apparent foam viscosity measurements and core flooding tests. The results of foam stability tests showed that half-life time for the CO2-, CH4- and N2-foams are 13.5, 17.0 and 44.0 min, respectively. Also, as revealed from apparent viscosity measurements, the N2- and 80% N2+20% CO2 foams have higher apparent foam viscosity values followed by 50% N2+50% CO2 foam. Furthermore, we showed that a combination of 80% N2 + 20% CO2 as the gaseous phase for foam generation could not only improve CO2-foam stability, as compared to other foams, but also can substantially increase ultimate oil recovery (56.6 %OOIP), even more than that for N2 foam (48.6 %OOIP), obtained from core flooding experiments.

Dmitry Anatolievich NOVIKOV

To reveal the equilibrium state of oil and gas and water in a petroliferous basin with a high content of saline water, calculations of water-gas equilibrium were carried out, using a new simulation method, for the Arctic territories of the West Siberian oil and gas bearing province. The water-bearing layers in this area vary widely in gas saturation and have gas saturation coefficients (Cs) from 0.2 to 1.0. The gas saturation coefficient increases with depth and total gas saturation of the formation water. All the water layers with gas saturation bigger than 1.8 L/L have the critical gas saturation coefficient value of 1.0, which creates favorable conditions for the accumulation of hydrocarbons; and unsaturated formation water can dissolve gas in the existent pool. The gas saturation coefficient of formation water is related to the type of fluid in the reservoir. Condensate gas fields have gas saturation coefficients from 0.8 to 1.0, while oil reservoirs have lower gas saturation coefficient. Complex gas-water exchange patterns indicate that gas in the Jurassic–Cretaceous reservoirs of the study area is complex in origin.

Feynman Liang, Liam Hodgkinson, Michael W. Mahoney

While fat-tailed densities commonly arise as posterior and marginal distributions in robust models and scale mixtures, they present challenges when Gaussian-based variational inference fails to capture tail decay accurately. We first improve previous theory on tails of Lipschitz flows by quantifying how the tails affect the rate of tail decay and by expanding the theory to non-Lipschitz polynomial flows. Then, we develop an alternative theory for multivariate tail parameters which is sensitive to tail-anisotropy. In doing so, we unveil a fundamental problem which plagues many existing flow-based methods: they can only model tail-isotropic distributions (i.e., distributions having the same tail parameter in every direction). To mitigate this and enable modeling of tail-anisotropic targets, we propose anisotropic tail-adaptive flows (ATAF). Experimental results on both synthetic and real-world targets confirm that ATAF is competitive with prior work while also exhibiting appropriate tail-anisotropy.

Samyak Prajapati, Amrit Raj, Yash Chaudhari et al.

Remote sensing has become a crucial part of our daily lives, whether it be from triangulating our location using GPS or providing us with a weather forecast. It has multiple applications in domains such as military, socio-economical, commercial, and even in supporting humanitarian efforts. This work proposes a novel technique for the automated geo-location of Oil & Gas infrastructure with the use of Active Fire Data from the NASA FIRMS data repository & Deep Learning techniques; achieving a top accuracy of 90.68% with the use of ResNet101.

Mohamed Mansour, Mohamed Eleraki, Ahmed Noah et al.

Formation damage due to fines migration is a major reason for well productivity decline for oil and gas wells. Formation fines are small enough to pass through pore throats causing pore plugging and permeability decline. Different factors affect fines migration such as flow rate, salinity, pH value, reservoir temperature and oil polarity, as well as changes in chemical environment induced by Enhanced Oil Recovery (EOR) agents. This paper focuses on the effect of flow rates on fines detachment from the grain surfaces, which causing permeability reduction. As the fluid inside the reservoir moves towards the wellbore, the fluid velocity increases, when the fluid reaches the critical flow rate these fines can be picked up into the fluid. These fines captured by thinner pore throats causing pore plugging and permeability reduction. Different concentrations of nanoparticles were used to fix these fines on their sources and prevent their mobilization at high flow rates. The unique technique used in this study is changing the potential surfaces between fines and grain surfaces to prevent fines movement above the critical flow rate. SiO2 and MgO NPs used in this study can be adsorbed on the pore surfaces and reduce the repulsion forces between fines and pore surfaces. SiO2 and MgO nanoparticles at different concentrations (0.25, 0.50 and 0.75 g/L) were used on treating the Abu-Rawash sandstone reservoir using Formation Damage System Cell FDS-350. The experimental studies showed that using MgO NPs would prevent fines detachment from the pore surfaces and decrease the reduction of permeability at high flow rates more than SiO2 NPs. The optimum concentration of MgO NPs was at 0.5 g/L as the permeability remediation at this concentration reaches to 64.83%.