Hasil untuk "Petroleum refining. Petroleum products"

CHEN Qiuyu, ZHAO Zhongcong, LI Daming, ZHAO Xiaolong, ZHOU Pengcheng, XU Depei, SUN Xiaohui, HOU Yanxin, HUA Changjun

The deep volcanic reservoirs of the Huoshiling Formation in the Songliao Basin face severe challenges for economically efficient development due to ultra-low permeability and extreme compactness, while also presenting potential target reservoirs for CO2 utilization and storage under CCUS scenarios. To address this challenge, this study explored and verified a water-rock interaction modification method based on supercritical carbon dioxide (SC-CO2) synergized with formation water. Through SC-CO2 saturation dissolution reaction experiments, combined with X-ray diffraction (XRD) mineral quantitative analysis, field emission scanning electron microscopy (FE-SEM) microstructural characterization, and rock mechanical property testing, the modification effects of SC-CO2 synergized with formation water on the reservoir were systematically investigated. The experimental results showed that SC-CO2 preferentially dissolved minerals such as plagioclase and calcite, leading to a significant reduction in clay mineral content and the formation of microscopic fractures and pore throats. Three-dimensional digital core models constructed from CT scans further revealed that SC-CO2 treatment significantly improved reservoir pore structure: the proportion of dominant flow channels with coordination numbers (CN) >3 increased by approximately 11%, while pore volumes with throat radii >6 μm expanded by over 16.5%. The trends of simulated permeability were consistent with the changes in actual gas permeability measurements, both showing year-on-year increases exceeding 90%. Meanwhile, rock mechanical tests indicated that after SC-CO2 treatment, the compressive strength of rock samples decreased by 19.6%, the elastic modulus decreased by 13.2%, and the Poisson’s ratio increased by 8.7%. Combined with scanning electron microscopy (SEM) observations, these results confirmed that mechanical weakening effectively induced a secondary fracture network. The study indicated that SC-CO2, owing to its nanoscale molecular diffusion capability and zero interfacial tension, could effectively penetrate micro- and nano-scale pores and react with pore-bound water to form carbonates. Through water-rock interactions, it deeply dissolved the interior of the reservoir, effectively overcoming the limitation of traditional acid fluids in accessing micro- and nano-scale pores. This method provides new theoretical foundations and technical pathways for the cost-effective development of deep volcanic reservoirs and for CO2 co-storage and enhanced recovery modification in CCUS technology.

REN YUHANG, WU ZHENGBIN, YANG WENBO et al.

In the development of shale oil, polymer fracturing fluid is one of the key technologies for increasing oil and gas production. However, the molecular weight of the polymer significantly affects its fracturing effectiveness. Excessively high molecular weight may exacerbate polymer retention and aggregation within the reservoir, while overly low molecular weight may result in insufficient fracturing effects. To address this issue, this study aims to investigate the influence of polymer molecular weight and concentration on the retention and aggregation behavior of fracturing fluid in shale oil reservoirs, with the goal of optimizing fracturing fluid formulations, minimizing reservoir damage, and improving fracturing efficiency. Through experimental research and technical analysis, polymer solutions with different molecular weights and concentrations were selected for displacement experiments on shale cores. Micro-CT scanners and scanning electron microscopy (SEM) were employed to observe and compare the cores before and after displacement, analyzing the retention and migration characteristics of polymers within the cores. The results showed that when the polymer molecular weight was below 1 754×10⁴ and the concentration was below 2 g/L 1 and 3, where the concentration was 1 g/L—the retention effect was relatively weak. This was manifested as a porosity loss of less than 8.9%, a permeability reduction of less than 15%, and a retention index below 0.35. When the molecular weight exceeded 1 754×10⁴ and the concentration was relatively high, the retention effect was significantly enhanced, with a retention index exceeding 0.70, especially prone to accumulation near fracture entrances, affecting oil and gas flow. Additionally, the study found that polymer retention in cores was jointly affected by molecular weight and concentration, with molecular weight being the main factor. By determining an appropriate range of polymer molecular weight, this study provides a scientific basis for reducing retention and aggregation of fracturing fluid in reservoirs, thereby mitigating reservoir damage and enhancing fracturing performance. The findings offer a scientific foundation for optimizing fracturing fluid formulations in shale oil development and serve as a useful reference for technological improvements in related fields.

Shishkin R.A., Saitova E.V., Akhmedov N.L. et al.

Thermobaric conditions have a significant impact on the elastic properties of rocks and their filtration and capacitance characteristics. Taking into account that pressure and temperature are not constant values during the development of a strata, it becomes especially important to correctly predict the mechanical behavior and reservoir potential of rocks. Core studies under different baric conditions with registration of porosity, permeability and elastic characteristics at each stage provide valuable information in solving this problem. Based on this a priori information, it is possible to predict the properties of rocks from borehole studies with modeling the behavior of curves in different thermobaric conditions.

ZHENG Yiqiong, ZHANG Tao, LIU Haiying, RUAN Conghui, ZOU Shuai

Nearly abandoned heavy oil reservoirs present significant challenges for effective reserve utilization using conventional development methods. In-situ combustion technology emerges as a promising solution to enhance recovery from such reservoirs, although its widespread adoption is hindered by high investment costs and economic inefficiencies. This study employs a break-even model and sensitivity analysis within a volume-cost-benefit framework to explore the equilibrium between oil production costs and revenues under varying oil price scenarios from a multidimensional operational perspective. This approach clarifies the critical economic indices of fire-flooding operations and aims to optimize production operations and decision-making effectiveness. The findings reveal significant gaps in pre- and post-operation understanding of the reservoir, where inputs often surpass outputs, coupled with a lack of clear control strategies. These factors contribute to the low cost-effectiveness of in-situ combustion and insufficient grasp of sustained development and operational risks, ultimately impacting investment decisions in reservoir development. The study not only directs improvements in operational efficiency for in-situ combustion but also offers technical support and introduces new management strategies for the effective development of nearly abandoned heavy oil reservoirs.

Tian Chunmeng, Fan Jianchun, Hu Jinqiu et al.

The contact condition of the sealing surface of premium tubing has a significant impact on the sealing performance.The different contact conditions of the sealing surface are difficult to be comprehensively evaluated only by the reflection coefficient in the ultrasonic reflection amplitude stress technology.Therefore,in the paper,by means of collecting the phased array ultrasonic images of tubing sealing surface under different torques and without threaded compound as well as extracting the texture features of the images,the qualitative and quantitative relationship between texture feature parameters and different contact conditions was analyzed.The research results show that as the torque of tubing increases,the greyscale mean,greyscale variance and skewness of the ultrasonic image all decrease; the paragenetic matrix contrast of the ultrasonic image greyscale of tubing sealing surface shows a linear decrease in the 45°,90° and 135° directions with the increase of tubing torque; in the 0° direction,the contrast of ultrasonic image without threaded compound is 2.19 times of that with threaded compound at the same torque; the paragenetic matrix entropy value of the ultrasonic image greyscale of tubing sealing surface shows a linear decrease in the 0°,45°,90° and 135° directions with the increase of tubing torque.The research results provide data support for the qualitative and quantitative characterization of ultrasonic detection images of tubing sealing surface under different contact conditions.

Yansong Peng, Hebei Li, Peixi Wu et al.

We introduce D-FINE, a powerful real-time object detector that achieves outstanding localization precision by redefining the bounding box regression task in DETR models. D-FINE comprises two key components: Fine-grained Distribution Refinement (FDR) and Global Optimal Localization Self-Distillation (GO-LSD). FDR transforms the regression process from predicting fixed coordinates to iteratively refining probability distributions, providing a fine-grained intermediate representation that significantly enhances localization accuracy. GO-LSD is a bidirectional optimization strategy that transfers localization knowledge from refined distributions to shallower layers through self-distillation, while also simplifying the residual prediction tasks for deeper layers. Additionally, D-FINE incorporates lightweight optimizations in computationally intensive modules and operations, achieving a better balance between speed and accuracy. Specifically, D-FINE-L / X achieves 54.0% / 55.8% AP on the COCO dataset at 124 / 78 FPS on an NVIDIA T4 GPU. When pretrained on Objects365, D-FINE-L / X attains 57.1% / 59.3% AP, surpassing all existing real-time detectors. Furthermore, our method significantly enhances the performance of a wide range of DETR models by up to 5.3% AP with negligible extra parameters and training costs. Our code and pretrained models: https://github.com/Peterande/D-FINE.

Junchuan Gui, Jianchun Guo, Yu Sang et al.

The brittleness index plays a significant role in the hydraulic fracturing design and wellbore stability analysis of shale reservoirs. Various brittleness indices have been proposed to characterize the brittleness of shale rocks, but almost all of them ignored the anisotropy of the brittleness index. Therefore, uniaxial compression testing integrated with geophysical logging was used to provide insights into the anisotropy of the brittleness index for Longmaxi shale, the presented method was utilized to assess brittleness index of Longmaxi shale formation for the interval of 3155–3175 m in CW-1 well. The results indicated that the brittleness index of Longmaxi shale showed a distinct anisotropy, and it achieved the minimum value at β = 45°-60°. As the bedding angle increased, the observed brittleness index (BI2_β) decreased firstly and increased then, it achieved the lowest value at β = 40°–60°, and it is consistent with the uniaxial compression testing results. Compared to the isotropic brittleness index (β = 0°), the deviation of the anisotropic brittleness index ranged from 10% to 66.7%, in other words, the anisotropy of brittleness index cannot be ignored for Longmaxi shale. Organic matter content is one of the main intrinsic causes of shale anisotropy, and the anisotropy degree of the brittleness index generally increases with the increase in organic matter content. The present work is valuable for the assessment of anisotropic brittleness for hydraulic fracturing design and wellbore stability analysis.

Zhang Qilong, Huang Zhongwei, Tan Qiang et al.

Fracturing packing has become a vital completion technique for the recovery of unconsolidated sandstone reservoirs in the Bohai Oilfield.However,the rules governing fracture extension in such unconsolidated sandstones remain unclear to guide the fracturing packing operations.The laboratory experiment and numerical simulation were combined to investigate the mechanism of fracture extension in unconsolidated sandstone,and the grey relational analysis(GRA)was performed to identify the sensitivity of fracturing performance to such parameters as pump rate,reservoir permeability and fracturing fluid properties.The experiment and simulation results show that cross-linked fracturing fluid is more likely to form a single,flat tensile fracture than linear gel fracturing fluid.The fracture length increases with the rising fracturing fluid pump rate and decreases with the increasing reservoir permeability and leakoff coefficient.The fracture width expands with the increasing reservoir permeability and declines with the increasing leakoff coefficient and pump rate.Based on the above results,an optimization method for key parameters of fracturing packing was formed,and it has been satisfactorily applied in more than 170 wells in the Bohai Oilfield.The research findings provide technical guidance and theoretical support for further promoting the fracturing packing technique in unconsolidated sandstone.

Li Cai

In this paper we study the classifying spaces of graph products of simplicial groups and connected Hopf algebras over a field, and show that they can be uniformly treated under the framework of polyhedral products. It turns out that these graph products are models of the loop spaces of polyhedral products over a flag complex and their homology, respectively. Certain morphisms between graph products are also considered. In the end we prove the structure theorems of such graph products in the form we need.

Anas Dakkak, Jan Bosch, Helena Holmström Olsson

For companies developing web-based applications, the Dev and the Ops refer to different groups with either operational or development focus. Therefore, DevOps help these companies streamline software development and operations activities by emphasizing the collaboration between the two groups. However, for companies producing software-intensive products, the Ops would refer to customers who use and operate the product. In addition, companies producing software-intensive products do not only offer products to customers but rather Product Service Systems (PSS), where product-related services play a key role in ensuring customer satisfaction besides their significant revenue contribution. Thus, the context of product-oriented PSS is very different from web-based applications, making it difficult to apply DevOps without considering the role of the services. Therefore, based on a two years participant observation case study conducted at a multinational telecommunications systems provider, we propose a new and novel approach called Development-Services-Operations (DevServOps) which incorporates services as a key player facilitating an end-to-end software flow toward customers in one direction and feedback toward developers in the other direction. Services become the glue that connects the Dev and the Ops, achieved by providing internal services to increase the precision of the development organization and external services to increase the speed of deployment and new content adoption on the customers' side.

Shady Galal Ramah, Mohamed Abdalla Othman, Ahmed Z. Nouh et al.

Unified Fracture Design (UFD) bridges the gap between practices and theory in the hydraulic fracturing industry. It represents a technique to design hydraulic fracturing treatment with a particular amount of proppant. This design could provide the maximum fold-of-increase (FOI) in productivity-index (PI) after hydraulic fracturing treatment. The UFD optimization tool is very effective, but it has assumptions like any other model. One assumption of UFD optimization technique; is a single-layer assumption. This assumption does not align with the limited entry fracturing design concept. In limited entry fracturing, the frictional pressure is employed to offset the stress differences between multi-layers reservoirs to attain fluid injection through these layers, intended to deliver an optimal fracture conductivity in all layers. The drawback of this assumption is the underestimation of the actual value of FOI in PI. This paper aims to recast the original unified fracture design approach to extend the optimal UFD to a multilayer reservoir to predict the FOI in PI after limited entry fracturing treatment. The recasting tool for this problem to find the optimum solution is Artificial Neural Networks (ANN). The architected ANN model is based on actual historical data of limited entry fracturing treatments. A statistical comparison between the proposed ANN model and classical UFD technique demonstrates that ANN model solution has a more reliable estimation of FOI in PI with the actual historical data.

SHANG Xiaofei, WANG Mingchuan, LI Meng et al.

The Xujiahe Formation in Xinchang area of western Sichuan Depression has experienced multiple periods of tectonic movement superposition. The stratigraphic deformation is significant, and the whole stratum is characterized by “saddle” shape. In addition, several groups of reverse faults are developed, with different fault broken horizons and diverse fault crosscutting relationships. However, the conventional modeling methods can not accurately describe the complex structure-stratigraphic characteristics of the area, and the model is difficult to meet the actual production needs. Therefore, the VBM modeling method is used to establish the structural-stratigraphic framework model of Xu2 gas reservoir in Xinchang area. Based on the analysis of sedimentary and filling characteristics in the study area, the sequence stratigraphic framework is clarified. Then, the horizon and fault data are obtained based on seismic interpretation data and drilling stratification information to establish the model of fault frame and finely adjust the relation between sectional shape and cross section. The horizon model is used as the input data to calculate the stratigraphic thickness of each sand group, and to restore and construct the original formation model. The present structural-stratigraphic framework model can be established by accurately regulating the relation between faults and horizons by controlling the relevant parameters of them. The results show that VBM method can accurately describe complex structural model through volume conservation principle and tetrahedron grid characterization technology, and better deal with complex formation contact and fault distribution problems. The new stratigraphic framework model has higher grid quality than the traditional corner grid model, and the combination relation and sequence stratigraphic characteristics are maintained in the complex faults. This structural-stratigraphic model provides a more reliable model framework for the subsequent reservoir geological modeling.

Michael J. J. Barry

We prove that a certain family of sums of products of three binomials has alternating behavior modulo a prime $p$. To accomplish this we rewrite these sums as signed sums of products of three binomials, the better to handle $p$, and we give closed-form expressions for two related sums of signed products of three binomials.

Fuwei YU, Zhendong GAO, Wenhao ZHU et al.

To solve the problems of long experiment period and difficult measurement in core imbibition experiments, fracture—matrix microfluidic chips of different sizes, boundary conditions and wettability regulated by surface property modification were designed to research the imbibition mechanisms of oil-water, oil-surfactant solution and oil-Winsor III type surfactant solution. In the oil-water, and oil-wettability modification system imbibition process, oil was replaced from the matrix through Haines jump, the capillary back pressure was the main resistance blocking the flow of oil, the reduction of interfacial tension caused the weakening of Haines jump, reduction of oil discharge rate, and increase of oil recovery. The imbibition of oil-water or oil-surfactant solution with low interfacial tension was a counter- current imbibition process dominated by capillary force, in which all boundaries had similar contribution to imbibition, and the recovery data obtained from this experiment fit well with the classic imbibition scaling equation. The imbibition of oil and Winsor III type surfactant solution was a co-current imbibition process dominated by gravity under super-low interfacial tension, and is essentially the formation and re-balance of neutral microemulsion. The imbibition dynamics obtained from this experiment fit well with the modified imbibition scaling equation.

Robert Hickingbotham, David R. Wood

Dujmović, Joret, Micek, Morin, Ueckerdt, and Wood [J. ACM 2020] established that every planar graph is a subgraph of the strong product of a graph with bounded treewidth and a path. Motivated by this result, this paper systematically studies various structural properties of cartesian, direct and strong products. In particular, we characterise when these graph products contain a given complete multipartite subgraph, determine tight bounds for their degeneracy, establish new lower bounds for the treewidth of cartesian and strong products, and characterise when they have bounded treewidth and when they have bounded pathwidth.

Febin Sebastian Elayanithottathil, Janis Keuper

Most eCommerce applications, like web-shops have millions of products. In this context, the identification of similar products is a common sub-task, which can be utilized in the implementation of recommendation systems, product search engines and internal supply logistics. Providing this data set, our goal is to boost the evaluation of machine learning methods for the prediction of the category of the retail products from tuples of images and descriptions.

Mahsan Basafa, Kelly Hawboldt

Abstract Reservoir souring is a widespread phenomenon in reservoirs undergoing seawater injection. Sulfate in the injected seawater promotes the growth of sulfate-reducing bacteria (SRB) and archaea-generating hydrogen sulfide. However, as the reservoir fluid flows from injection well to topside facilities, reactions involving formation of different sulfur species with intermediate valence states such as elemental sulfur, sulfite, polysulfide ions, and polythionates can occur. A predictive reactive model was developed in this study to investigate the chemical reactivity of sulfur species and their partitioning behavior as a function of temperature, pressure, and pH in a seawater-flooded reservoir. The presence of sulfur species with different oxidation states impacts the amount and partitioning behavior of H2S and, therefore, the extent of reservoir souring. The injected sulfate is reduced to H2S microbially close to the injection well. The generated H2S partitions between phases depending on temperature, pressure, and pH. Without considering chemical reactivity and sulfur speciation, the gas phase under test separator conditions on the surface contains 1080 ppm H2S which is in equilibrium with the oil phase containing 295.7 ppm H2S and water phase with H2S content of 8.8 ppm. These values are higher than those obtained based on reactivity analysis, where sulfur speciation and chemical reactions are included. Under these conditions, the H2S content of the gas, oil, and aqueous phases are 487 ppm, 134 ppm, and 4 ppm, respectively.

Yong Wang

In this paper, we introduce semi-symmetric metric Koszul forms and semi-symmetric non-metric Koszul forms on singular semi-Riemannian manifolds. Semi-symmetric metric Koszul forms and semi-symmetric non-metric Koszul forms and their curvature of semi-regular warped products are expressed in terms of those of the factor manifolds. We also introduce Koszul forms associated to the almost product structure on singular almost product semi-Riemannian manifolds. Koszul forms associated to the almost product structure and their curvature of semi-regular almost product warped products are expressed in terms of those of the factor manifolds. Furthermore, we generalize the results in \cite{St2} to singular multiply warped products.

Sachindranath Jayaraman, Yogesh Kumar Prajapaty, Shrihari Sridharan

The aim of this manuscript is to understand the dynamics of products of nonnegative matrices. We extend a well known consequence of the Perron-Frobenius theorem on the periodic points of a nonnegative matrix to products of finitely many nonnegative matrices associated to a word and later to products of nonnegative matrices associated to a word, possibly of infinite length. We also make use of an appropriate definition of the exponential map and the logarithm map on the positive orthant of $\mathbb{R}^{n}$ and explore the relationship between the periodic points of certain subhomogeneous maps defined through the above functions and the periodic points of matrix products, mentioned above.

Jang Soo Kim

In 2007 Lam and Pylyavskyy found a combinatorial formula for the dual stable Grothendieck polynomials, which are the dual basis of the stable Grothendieck polynomials with respect to the Hall inner product. In 2016 Galashin, Grinberg, and Liu introduced refined dual stable Grothendieck polynomials by putting additional sequence of parameters in the combinatorial formula of Lam and Pylyavskyy. Grinberg conjectured a Jacobi--Trudi type formula for refined dual stable Grothendieck polynomials. In this paper this conjecture is proved by using bijections of Lam and Pylyavskyy.