Hasil untuk "Petroleum refining. Petroleum products"

Evgenii Kozhevnikov, Fedor Belkov, Mikhail Turbakov et al.

The exploitation of low-flow oil wells following hydraulic fracturing is often hindered by residual proppant and proppant production during early production phases, which can infiltrate pumps and drastically shorten their service life. Managing proppant reliably and cost-effectively in these wells remains challenging due to the limited understanding of proppant transport mechanisms from the well bottom to the pump intake. This manuscript addresses this critical knowledge gap by presenting novel experimental insights into proppant transport in low-flow oil wells, marking the first elucidation of the underlying mechanism. Through innovative laboratory experiments simulating post-fracturing well conditions, we demonstrate that proppant invariably ascends to the pump intake, driven by a previously unrecognized process: droplets of immiscible hydrocarbon fluids capture and transport proppant particles upward. Comparative analyses using fluids of varying viscosities reveal, for the first time, that the viscosity of the immiscible phase has negligible impact on droplet transport capacity. Additionally, our studies establish that proppant concentration during transport is independent of well flow rate, challenging conventional assumptions. A key novel finding is the pivotal role of free gas bubbles in enhancing proppant transport probability, as they facilitate capture by oil and kerosene droplets; higher gas content correlates directly with elevated proppant concentrations in the flow. These experimental discoveries are validated by field trial data from wells with high free gas content under bottomhole conditions, where reduced pump operational times were observed, confirming the mechanism's real-world relevance. By unveiling this transport mechanism, the manuscript provides a foundational basis for developing targeted proppant management strategies, offering new pathways to enhance pump longevity and operational efficiency in low-flow oil wells.

Qingzhong ZHU, Wei XIONG, Dingwei WENG et al.

Currently, unconventional reservoirs are characterized by low single well-controlled reserves, high initial production but fast production decline. This paper sorts out the problems of energy dispersion and limited length and height of main hydraulic fractures induced in staged multi-cluster fracturing, and proposes an innovative concept of “energy-focused fracturing development”. The technical connotation, theoretical model, and core techniques of energy-focused fracturing development are systematically examined, and the implementation path of this technology is determined. The energy-focused fracturing development technology incorporates the techniques such as geology-engineering integrated design, perforation optimization design, fracturing process design, and drainage engineering control. It transforms the numerous, short and dense hydraulic fractures to limited, long and sparse fractures. It focuses on fracturing energy, and aims to improve the fracture length, height and lateral width, and the proppant long-distance transportation capacity, thus enhancing the single well-controlled reserves and development effect. The energy-focused fracturing development technology has been successfully applied in the carbonate reservoirs in buried hill, shallow coalbed methane reservoirs, and coal-rock gas reservoirs in China, demonstrating the technology’s promising application. It is concluded that the energy-focused fracturing development technology can significantly increase the single well production and estimated ultimate recovery (EUR), and will be helpful for efficiently developing low-permeability, unconventional and low-grade resources in China.

Junliang Li, Lili Ji, Wenbin Jiang et al.

Abstract Multiscale pore-slit structures, non-linear flow and complex lithofacies of continental shale in Dongying Sag present significant challenges for reservoir evaluation and sweet spots identification. This study establishes a comprehensive analytical framework through integrated physical experiments and high-resolution imaging to characterize pore-slit structures and flow dynamics across various lithofacies. Firstly, a novel PSD (pore size distribution) splicing technique is developed by combining multiscale feature extraction and a transformed method, seamlessly uniting nitrogen adsorption data with SEM (scanning electron microscopy) image analysis. Compared with traditional methods, this advanced technique provides a more comprehensive representation of shale pore size distribution and structural characteristics. Three permeability indexes, including the non-Darcy index (K non−D ), anisotropy index (K a ), and slit index (K f ), are proposed to quantify flow behavior based on the cubic-block and matrix permeability experiments. These innovative indexes allow us to explore the complex non-linear flow behaviors, the anisotropic flow properties and pore-slit crossflow characteristics of shale. Comparative analysis reveals distinct pore structure and flow characteristics among different lithofacies: clay-rich shale exhibits high porosity and matrix permeability, while carbonate-rich shale demonstrates stronger nonlinear flow capacity and anisotropic permeability. Finally, the intrinsic relationship between mineral composition, pore structure, and complex flow has been investigated, and the identification charts for porosity and permeability have been established. These findings provide valuable tools for enhanced reservoir evaluation and sweet spot identification in the continental shale formations of Dongying Sag.

WANG Shoujun

Microsphere flooding technology has attracted much attention because it effectively blocks high-permeability channels and improves reservoir flow performance. Based on core flooding experiments and rheological experiments， the dispersion， oil displacement performance， long-term stability， and action mechanism of microspheres in sewage at different concentrations and pH values from Shengli Oilfield were systematically analyzed. The results show that as the concentration of sewage from Shengli Oilfield increases from 0 to 50%， the average particle size of the microspheres increases from 1.2 µm to 2.0 µm， indicating a significant deterioration in dispersion. Under different pH conditions， the average particle size of the microspheres is 2.2 µm in the sewage with a pH of 4， while it decreases to 1.3 µm， showing better dispersion in the sewage with a pH of 9. The core flooding experiments indicate that the oil displacement efficiency of the microspheres is the highest， reaching 50.3%， in sewage with high organic content from Shengli Oilfield. The long-term stability of the microspheres is poor in the sewage at a concentration of 30%， with the average particle size increasing to 2.1 µm after 28 days. The rheological experiments show that microsphere suspensions exhibit shear thickening properties， with a shear stress of 9.1 Pa at a shear rate of 1 000 s-¹. The mechanism analysis reveals that the microspheres interact with impurities and suspended particles in the sewage through electrostatic adsorption， physical adsorption， and chemical adsorption， significantly affecting their dispersion and oil displacement effects.

Shunsuke Nakaya, Jun Matsushima

Net energy - the energy obtained from a resource after accounting for the energy expended in its acquisition - fundamentally determines the capacity of societies to sustain and expand. The extended Energy Return on Investment (EROIext) incorporates not only extraction and refining but also transport and end-use infrastructure, yet its long-term dynamics remain poorly understood. Here, we apply a Single-Cycle Lotka-Volterra (SCLV) model to the global petroleum system, calibrated with historical data from 1965-2012. The model projects trajectories of production, capital, and EROIext to 2100, and integrates an entropy-based indicator to evaluate the system's ability to maintain social order. Results show that oil production peaks around 2041, while EROIext declines continuously and falls below unity by 2081. This marks the point at which oil no longer delivers net energy, coinciding with the peak of capital stock, suggesting unsustainable investment in a diminishing resource. The rising entropy ratio signals declining systemic resilience. These findings underscore the importance of evaluating energy systems not only by quantity or cost but also by thermodynamic quality, with direct implications for balancing short-term energy security and long-term sustainability in policy design.

Ailin JIA, Fangxuan CHEN, Naichao FENG et al.

Taking the Ordos Basin as an example, this paper proposed that the construction of an energy super basin should follow the principle of “more energy, less carbon, and better energy structure”. The modeling workflow of energy super basin was built. Based on the resources/reserves, development status and infrastructures of the Ordos Basin, the development potential of the basin was evaluated, the uncertainties in the construction of energy super basin were analyzed, and the future vision and realization path of the Ordos Energy Super Basin were recommended. This study demonstrates that the Ordos Basin has the advantages of abundant energy sources, perfect infrastructures, well-matched carbon source and sink, small population density, and proximity to the energy consumption areas. These characteristics ensure that the Ordos Basin is a good candidate of the energy super basin. It is expected that the energy supply of the Ordos Basin in 2050 will reach 23×108 t of standard coal, and the proportion of fossil fuels in energy supply will decrease to 41%. The carbon emissions will decrease by 20×108 t compared to the emissions in 2023. The future construction of the basin should focus on the generation and storage of renewable energy, and technological breakthroughs for the carbon capture, utilization and storage.

GUO Shuai, WEI Rongjiang, ZHANG Qiang et al.

China has a huge potential for ultra-deep oil and gas resources. To promote ultra-deep oil and gas exploration and achieve breakthroughs in new layers is the key direction for exploring new fields of oil and gas. In order to address potential cable jamming issues in the 10km deep ground well, a finite element mechanical model is developed for the underground cables, including those at the top pulley, bottom pulley, and drum, using the cross-sectional method. The study investigated the impact of factors such as the tensile rod, drum diameter, and lifting speed on the strength of the 10km well cable. The calculation results show that: in order to ensure that the weak point is broken first in the case of continuous cable and to reserve a certain safety factor for the cable, the 5 000lbf pull rod can be selected; the large diameter roller is selected to reduce the cable tension, and the roller with a diameter of 700mm is preferred; the normal lifting speed of the logging cable is 6 000m/h, and the cable tension can reach 61.4kN, meeting the strength requirements. The research results provide basic data for the selection of logging cables, rollers and pull rods for deep 10km wells.

WANG Xuejun, ZHANG Xuejun, LUO Huan et al.

Deep source rocks undergo high degrees of evolution， leading to a significant decrease in biomarker content in crude oil as maturity increases. The decrease affects the reliability of the oil source correlation with conventional biomarker parameters. To better use the δ13CPDB value for identifying deep crude oil sources， authors analyzed the δ13CPDB values of four group components in the soluble organic matter from naturally evolved source rock profiles in Dongying Sag， Jiyang Depression， Bohaiwan Basin and the products of physical experiments on hydrocarbon generation and expulsion. Considering the relative content of alkane， authors discussed the carbon isotope fractionation effects in the crude oil from deep source rock. Additionally， authors proposed the working thought and procedure for identifying the source of deep oil with the δ13CPDB values. The carbon isotope fractionation effects resulting from high thermal maturity are obvious in deep source rocks. The δ13CPDB values of the four group components of soluble organic matter from source rocks （alkane， aromatics， non-hydrocarbon， and asphaltene） exhibit a significant elevation with increasing burial depth. Specifically， the δ13CPDB values of alkane exhibit the most pronounced change， exceeding 5‰， while aromatics show a change of around 4‰. The changes in the δ13CPDB value of non-hydrocarbon and asphaltene are relatively small， ranging from 2‰ to 3‰. As burial depth increases， the alkane contents in soluble organic matter increase from around 40% to over 80%. Correspondingly， the δ13CPDB values of alkane increase from around -30‰ to over -24‰， and the alkane contents show a great correlation with the variations of its δ13CPDB values. Similar results can also be observed from the δ13CPDB values of group components from physical experiments on hydrocarbon generation with the same type of source rock samples. In these experiments， the variations in the δ13CPDB values of alkane can reach 4‰， while those in aromatics， non-hydrocarbon， and asphaltene are relatively low， ranging from 1‰ to 3‰. When utilizing carbon isotopes to identify the source of deep oil， it is essential to first check the correlation between alkane contents and their δ13CPDB values to identify if the carbon isotope fractionation effects derived from thermal maturation exists. Subsequently， the δ13CPDB values of alkane should be properly recovered before utilizing it to identify the source of the oil. According to the abovementioned methods， authors identified the source of light oil from Chepaizi Uplift in the Western region of Junggar Basin. It confirmed the presence of carbon isotope fractionation effects in the light oil derived from thermal evolution. It shows a great possibility that the light oil is sourced from the underlying high-maturity source rock of the Permian， which is of important practical significance in the evaluation and deployment of the petroleum exploration target in this area.

Qin Saibo, Yi Xianzhong, Zhang Xuwen et al.

As the exploration and exploitation of petroleum gradually shift from land to ocean, from shallow sea to deep sea and then to ultra-deep sea, the conventional onshore iron roughnecks are unable to work directly on deepwater offshore platforms. To address this issue, a new type of iron roughneck arm structure supporting the seabed drilling system was proposed. The numerical simulation method was used for safety analysis on the strength, fatigue strength, stiffness, stability and vibration resistance of the iron roughneck arm structure. According to the research results, when the structure of the iron roughneck arm used in seabed drilling is in a dangerous posture(extending 1.8 m), the maximum von Mises stress is 195.45 MPa(less than the allowable stress [σ]=320 MPa), and the fatigue strength safety factor n=4.63(greater than the allowable safety factor [n]=2.0). The total flexural rigidity and the flexural rigidity in the x, y, and z directions of the iron roughneck arm structure are 1.11×10¹⁰, 1.62×10¹², 2.43×10¹³ and 7.34×10¹⁰ N·m², respectively, meeting the rigidity requirements of the iron roughneck arm structure. The critical buckling load of the iron roughneck arm structure P_cr=915.80 kN, which is 45.79 times the actual load, meeting the stability requirements of the structure. There is a 68.23% probability that the maximum von Mises stress of the iron roughneck arm structure does not exceed 179.77 MPa under random vibration excitation, meeting the material strength safety requirements. The research results have verified the safety and reliability of the designed structure of the new type of iron roughneck arm used in seabed drilling, and provide some reference for the structural design of it.

Jinmin SONG, Shugen LIU, Zhiwu LI et al.

The depositional facies types of the fourth member of the Middle Triassic Leokoupo Formation (Lei-4 Member) in western Sichuan Basin are examined through the methods of sedimentology, lithology and analysis of well-logging data, as well as the special lithofacies indicators such as microbialite, gypsum-salt rock and tempestites, using the data of about 400 wells and 11 outcrop sections. The distribution and evolution and its hydrocarbon geological significances of the bay facies have been discussed. The Lei-4 Member in western Sichuan Basin has an ocean–bay–flat depositional model, with the presence of evaporated tidal flat, restricted tidal flat and paleo-bay facies from east to west. The subfacies such as bay margin, subtidal bay and bay slope are recognized within the paleo-bay, with microbial reef and grain bank microfacies in the bay margin, microbial flat, deep-water spongy reef and hydrostatic mudstone microfacies in the subtidal bay, and tempestites and collapsed deposits in the upper bay slope. The bay boundary covered the Guangyuan-Zitong-Dujiangyan area in the period of the first submember of the Lei-4 Member (Lei-4-1) with falling sea level, regressed westward into the Shangsi-Jiangyou-Dujiangyan area in the period of Lei-4-2, and expanded to the Shangsi-Zitong-Langzhong- Wusheng-Yanting-Chengdu area in the northern part of central Sichuan Basin in the period of Lei-4-3 along with a small-scale transgression. The topographic pattern of “one high and two lows” is confirmed in the Lei-4 Member, corresponding to a configuration of source rocks and reservoir rocks alternated horizontally and superimposed vertically. Two efficient source-reservoir configuration models, i.e. side source & side reservoir, and self-generating & self-storing, are available with the microbial reef and grain bank reservoirs at the bay margin and the high-quality source rocks within the sags on both sides of the bay. The research findings will inevitably open up a new situation for the hydrocarbon exploration in the Leikoupo Formation.

Tairone Paiva Leão

Conductivity of unsaturated porous media to fluids is of theoretical and applied interest to mathematicians, physicists, and chemical, petroleum, civil and agricultural engineers. We explore the expression of unsaturated relative conductivity equations as a regularized incomplete beta function, which implies a beta distribution of the variable of interest. A generalized solution for $n>1$ and $m>0$ is presented. The solution can be implemented without difficulties in most programming languages and simulation software.

Junghyun Koo, Yunkee Chae, Chang-Bin Jeon et al.

Music source separation (MSS) faces challenges due to the limited availability of correctly-labeled individual instrument tracks. With the push to acquire larger datasets to improve MSS performance, the inevitability of encountering mislabeled individual instrument tracks becomes a significant challenge to address. This paper introduces an automated technique for refining the labels in a partially mislabeled dataset. Our proposed self-refining technique, employed with a noisy-labeled dataset, results in only a 1% accuracy degradation in multi-label instrument recognition compared to a classifier trained on a clean-labeled dataset. The study demonstrates the importance of refining noisy-labeled data in MSS model training and shows that utilizing the refined dataset leads to comparable results derived from a clean-labeled dataset. Notably, upon only access to a noisy dataset, MSS models trained on a self-refined dataset even outperform those trained on a dataset refined with a classifier trained on clean labels.

ZHAO Lan

The average porosity and permeability of sandstone of Lower Shihezi Formation of Permian system in Shilijiahan area of Hangjinqi area are of 8.3 % and 0.89×10^-3 μm² respectively, causing the reservior to be a typical tight sandstone reservoir. Meanwhile, the microfractures play an important role in improving the physical properties of tight sandstone reservoir. Therefore, the researches of the reservoir in this area focus on the microfractures. By the observation of the microscopic thin section, and combined with the mercury injection, core physical properties and structural characteristics, the types and genesis, formation stages, control factors and the influence of micro fractures on physical properties in this area have been studied. The results show that the tight sandstone of Lower Shihezi Formation in the study area can be divided into intragranular fracture, grain edge fracture and grain penetrating fracture according to the contact relationship of strata, and can be divided into unfilled fracture, incomplete filled fracture and complete filled fracture according to the filling degree. According to the genetic analysis, there are at least three stages of micro fractures in the study area. Their development degree are controlled by the combination of internal factors （sandstone particle size, rock debris composition, rock debris and interstitial content, contact relationship between particles, etc.） and external factors （tectonic stress）. The microfractures mainly affect the permeability of the reservoir. The multi-factor influence is a basic feature of micro fractured tight reservoir. The average throat radius plays a major role in controlling the permeability of the reservoir.

Gao Junhong, Fu Biwei, Dong Zongzheng

In order to improve the application results of hydraulic radial drilling technology in hydrate exploitation and reservoir stimulation,numerical simulation method was used to study the drilling performance of self-propelled nozzle,which is the core component of hydraulic radial drilling.The drilling performances of three commonly used self-propelled nozzles were compared and analyzed in terms of the propulsion performance and rock-breaking effect.The results show that the jet core length of the straight-rotary mixing jet nozzle is 1.18 times that of the rotary jet nozzle,which enables to eliminate the low-speed zone in the center of the rotary jet.And the tangential velocity and radial velocity of the jet are larger,which enable better shear rock breaking effect.The straight-rotary mixing jet nozzle has obviously larger effective rock-breaking area than that of the straight jet nozzle and it helps to produce larger holes.In addition,there is an optimal operating pressure range for the best drilling performance of the straight-rotary mixing jet nozzle.The study shows that the straight-rotary mixing jet nozzle has good drilling performance with the rock-breaking advantages of both straight jet and rotary jet.The results provide reference for efficient exploitation of marine natural gas hydrate and reservoir stimulation.

DENG Jiasheng, WANG Ziyi, HE Wangda et al.

During the reaction between CO₂ and rocks, there is a synergistic/coupling effect among minerals because the rocks contain quartz, potassium feldspar, albite and other components, which promotes or inhibits the reaction process to a certain extent. The chlorite is an important clay mineral of sedimentary rocks. In order to clarify the chemical behavior and change process of the chlorite in the CO₂ aqueous solution, the state of chlorite reacting with CO₂ respectively for 7 and 30 days at 10 MPa and 60 ℃ are systematically evaluated by means of XRD（X-Ray Diffraction）, XRF（X-Ray Fluorescence）, ICP（Inductively Coupled Plasma）, and SEM（Scanning Electron Microscopy）, focusing on the comparison of the change of the solid elements, the crystal structure and the ion concentration in the reaction solution before and after chlorite powder reaction. Combined with the structural characteristics of chlorite, the mechanism of chlorite change is clarified. The results show that the concentrations of Ca²⁺, Mg²⁺ and Al³⁺ in the liquid phase firstly increase and then decrease after the reaction of the chlorite with CO₂. The concentration of Si⁴⁺ firstly increases and then is stabilized. The crystal planes corresponding to chlorite d（002） and d （004） peaks in the solid phase are destroyed after the reaction, and the mass ratio of Si and Al in the solid element increase from 4.82 to 5.39. Under the acidic conditions, hydroxyl groups in brucite flakes are easier to combine with H⁺ and release cations such as Fe²⁺, Mg²⁺, Al³⁺, etc. Because the brucite octahedron is more prone to ion exchange than silica tetrahedron and alumina octahedron, Mg, Al, Fe and other elements in brucite flakes are dissolved before Si and Al in silica tetrahedron and alumina octahedron.

Praise Adeyemo, Balazs Szendroi

We study a natural set of refinements of the Ehrhart series of a closed polytope, first considered by Chapoton. We compute the refined series in full generality for a simplex of dimension d, a cross-polytope of dimension d, respectively a hypercube of dimension d<4, using commutative algebra. We deduce summation formulae for products of q-integers with different arguments, generalizing a classical identity due to MacMahon and Carlitz. We also present a characterisation of a certain refined Eulerian polynomial in algebraic terms.

Niclas Heilig, Jan Kirchhoff, Florian Stumpe et al.

Medical diagnosis is the process of making a prediction of the disease a patient is likely to have, given a set of symptoms and observations. This requires extensive expert knowledge, in particular when covering a large variety of diseases. Such knowledge can be coded in a knowledge graph -- encompassing diseases, symptoms, and diagnosis paths. Since both the knowledge itself and its encoding can be incomplete, refining the knowledge graph with additional information helps physicians making better predictions. At the same time, for deployment in a hospital, the diagnosis must be explainable and transparent. In this paper, we present an approach using diagnosis paths in a medical knowledge graph. We show that those graphs can be refined using latent representations with RDF2vec, while the final diagnosis is still made in an explainable way. Using both an intrinsic as well as an expert-based evaluation, we show that the embedding-based prediction approach is beneficial for refining the graph with additional valid conditions.

Xu Yang, Luo Mingzhang, Du Guofeng

The defect monitoring and radial damage evaluation are of great significance for safe operation of oil and gas pipelines. In order to improve the monitoring ability of ultrasonic guided waves for pipeline defects, a new method for radial damage depth evaluation based on the variation trend of guided waves in L(0,2)and L(0,1)modes was proposed. The single-channel exciting-receiving device was used to realize the time reversal method in the way of multiple superimposition synthesis, allow the guided wave energy to be focused at the pipeline defect, enhance the reflection echo amplitude of the defect, and improve the signal to noise ratio of the monitoring signal. The effectiveness of using synthetic time reversal method to improve the ability of ultrasonic guided wave to monitor pipeline defects was proved by specific tests. When the L(0,2)mode guided wave propagated in the pipeline, the mode would convert while encountering defect, and some L(0,2)modes were converted to L(0,1)modes. Combined with the displacement distribution of guided wave in the pipe wall, the influence of the radial damage depth of pipeline defect on the mode conversion from L(0,2)to L(0,1)was analyzed. The test data show that, as the radial damage of pipeline expanded, the reflection coefficients of L(0,2)and L(0,1)modal defects showed regular changes. The study results provide an important reference for evaluating the radial damage depth of pipeline defects and judging whether it reaches half wall thickness or penetration.

ZHANG Zonglin, LYU Guangzhong, WANG Jie

Climate change centering on carbon dioxide（CO₂） emissions and energy security centering on the shortage of oil resources are two major problems restricting the sustainable development of China's social economy. In order to solve the bottleneck of both the CO₂ capture and the great improvement of recovery factor of low permeability reservoir, the related technology researches have been carried out in Shengli Oilfield, forming the supporting technologies such as CO₂ capture, safe long-distance transmission, reservoir engineering optimization design, the injection-production process design, design of surface gathering and oil displacement and environmental monitoring, and building an industrial-scale demonstration project for flue gas CO₂ capture, oil displacement and underground storage of coal-fired power plants. The industrial tests show that the cost of the new MSA technology is 35 % lower than that of the traditional MEA technology. Over 31×10⁴ t of CO₂ have successfully been injected into the reservoir, with the cumulative oil increment of 8.6×10⁴ t, and 28×10⁴ t of CO₂ storaged in G89-1 block. The central well area has increased the recovery rate by 9.5 %, and the recovery rate is expected to reach 17.2 %.