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Analysis of mechanical strengths of extreme line casing joint considering geometric, material, and contact nonlinearities

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petroleum Science 2024年第3期21卷 1992-2004页

作者： Ji-Yun Zhang Chi Peng Jian-Hong Fu Quan Cao Yu Su Jian-Yun Pang Zi-Qiang Yu petroleum Engineering School Southwest Petroleum University Engineering technology Research Institute of CNPC Southwest Oil and Gas Field Company

To address the challenges associated with difficult casing running, limited annular space, and poor cementing quality in the completion of ultra-deep wells, the extreme line casing offers an effective solution over conventional casings. However, due to its smaller size, the joint strength of extreme line casing is reduced, which may cause failure when running in the hole. To address this issue, this study focuses on the CST-ZT Φ139.7 mm × 7.72 mm extreme line casing and employs the elastic-plastic mechanics to establish a comprehensive analysis of the casing joint, taking into account the influence of geometric and material nonlinearities. A finite element model is developed to analyze the forces and deformations of the extreme line casing joint under axial tension and external collapse load. The model investigates the stress distribution of each thread tooth subjected to various tensile forces and external pressures. Additionally, the tensile strength and crushing strength of the extreme line casing joint are determined through both analytical and experimental approaches. The findings reveal that, under axial tensile load, the bearing surface of each thread tooth experiences uneven stress, with relatively high equivalent stress at the root of each thread tooth. The end thread teeth are valuable spots for failure. It is observed that the critical fracture axial load of thread decreases linearly with the increase of thread tooth sequence. Under external pressure, the circumferential stress is highest at the small end of the external thread, leading to yield deformation. The tensile strength of the joint obtained from the finite element model exhibits a relative error of less than 7% compared to the analytical and experimental values,proving the reliability of the finite element model. The tensile strength of the joint is 3091.9 k N.Moreover, in terms of anti-collapse capability, the joints demonstrate higher resistance to collapse compared to the casing body, which is consistent with the test results where the pip

关键词： Extreme line casing Elastic-plastic mechanics Finite element analysis Tensile strength Collapse strength

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Online Pareto optimal control of mean-field stochastic multi-player systems using policy iteration

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Science China(Information Sciences) 2024年第4期67卷 21-37页

作者： Xiushan JIANG Yanshuang WANG Dongya ZHAO Ling SHI College of New Energy China University of Petroleum(East China) department of Electronic and Computer Engineering Hong Kong University of Science and Technology

In this study, the Pareto optimal strategy problem was investigated for multi-player mean-field stochastic systems governed by It? differential equations using the reinforcement learning(RL) method.A partially model-free solution for Pareto-optimal control was derived. First, by applying the convexity of cost functions, the Pareto optimal control problem was solved using a weighted-sum optimal control problem. Subsequently, using on-policy RL, we present a novel policy iteration(PI) algorithm based on the Hrepresentation technique. In particular, by alternating between the policy evaluation and policy update steps,the Pareto optimal control policy is obtained when no further improvement occurs in system performance,which eliminates directly solving complicated cross-coupled generalized algebraic Riccati equations(GAREs).Practical numerical examples are presented to demonstrate the effectiveness of the proposed algorithm.

关键词： mean-field stochastic systems Pareto optimal control policy iteration scheme $\mathcal{H}$-representation

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Helmholtz decomposition with a scalar Poisson equation in elastic anisotropic media

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petroleum Science 2024年第3期21卷 1597-1610页

作者： Xin-Yu Fang Gang Yao Qing-Qing Zheng Ping-Min Zhang Di Wu Feng-Lin Niu State Key Laboratory of petroleum Resources and Engineering China University of Petroleum (Beijing) Unconventional petroleum Research Institute China University of Petroleum (Beijing) department of Mathematics College of Science China University of Petroleum (Beijing) College of Geophysics China University of Petroleum (Beijing) department of Earth Environmental and Planetary Sciences Rice University

P-and S-wave separation plays an important role in elastic reverse-time migration. It can reduce the artifacts caused by crosstalk between different modes and improve image quality. In addition, P-and Swave separation can also be used to better understand and distinguish wave types in complex media. At present, the methods for separating wave modes in anisotropic media mainly include spatial nonstationary filtering, low-rank approximation, and vector Poisson equation. Most of these methods require multiple Fourier transforms or the calculation of large matrices, which require high computational costs for problems with large scale. In this paper, an efficient method is proposed to separate the wave mode for anisotropic media by using a scalar anisotropic Poisson operator in the spatial domain.For 2D problems, the computational complexity required by this method is 1/2 of the methods based on solving a vector Poisson equation. Therefore, compared with existing methods based on pseudoHelmholtz decomposition operators, this method can significantly reduce the computational cost. Numerical examples also show that the P and S waves decomposed by this method not only have the correct amplitude and phase relative to the input wavefield but also can reduce the computational complexity significantly.

关键词： Anisotropic media Scalar anisotropic Poisson equation Improved elastic wavefield decomposition

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Microfiltration,ultrafiltration and nanofiltration as a post-treatment of biological treatment process with references to oil field produced water of Moran oilfield of Assam

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petroleum Research 2024年第1期9卷 143-154页

作者： Amarjit Rajbongshi Subrata Borgohain Gogoi Brahmaputra Valley Fertilizer Corporation Limited NamrupAssamIndia department of petroleum technology Dibrugarh UniversityAssamIndia

The selection of an apt technology for the treatment of Oilfield Produced Water(OFPW)depends mainly on the quality of OFPW and methods of pre-and post-treatment processes.The most challenging part of the OFPW treatment process is the removal of Suspended Solid(SS),Oil&Grease(O&G)and dissolved organics.SS and O&G pose an acute problem to the membrane filtration system by fouling the membrane surface which increases operation&maintenance costs and decreases the life of the membrane.Fouling of the membrane surface is mainly attributed to the presence of low molecular weight aromatic compounds and naphthenic acids in the suspended and dissolved organic compounds.Thus,the removal of these suspended and dissolved organic compounds before membrane filtration proffers a challenge to the researchers.In this research,bioremediation process has been applied to remove the organic compounds and the performance and fouling behaviour of hollow fibre Microfiltration(MF),Ultrafiltration(UF)and Nanofiltration(NF)membranes after the bioremediation process has been analyzed in detail.The level of toxicity was determined by comparing the pollutants with the safe discharge limit for disposal into the environment set by Central Pollution Control Board(CPCB),India.The research presents its novelty by using a hydrocarbon-degrading bacteria,Pseudomonas aeruginosa for the Reduction of Organic Loads(ROL)from OFPW of Moran oil field of Upper Assam as a pre-treatment to membrane filtration.The Total Sum Corrected Area(TSCA)method through chromatographic analyses was used for this.The organic loads removal from OFPW by the TSCA method was found to be 67-100%,100%and 100%after 7,14 and 21 days of bioremediation respectively.The major parameters in feed OFPW of Moran oil field were found to be pH(7.5-9.3),Total Dissolved Solid(TDS)(1.79-4.75)ppt,O&G(1.78-2.8)ppt,Salinity(2.94-6.98)ppt,Chloride(Cl^(-))(1.6-3.86)ppt,Bicarbonate(HCO_(3)^(-))(2.89-4.03)ppt.It was observed that the ranges of pollutants removal by NF was highest such as TDS(26-86%),sa

关键词： Oilfield produced water Organic compounds Bioremediation Membrane filtration Membrane fouling

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Interpretation and characterization of rate of penetration intelligent prediction model

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petroleum Science 2024年第1期21卷 582-596页

作者： Zhi-Jun Pei Xian-Zhi Song Hai-Tao Wang Yi-Qi Shi Shou-Ceng Tian Gen-Sheng Li College of petroleum Engineering China University of Petroleum(Beijing)Beijing102249China State Key Laboratory of petroleum Resources and Prospecting Beijing102249China Kunlun Digital technology Co. Ltd.Beijing102206China

Accurate prediction of the rate of penetration(ROP)is significant for drilling optimization.While the intelligent ROP prediction model based on fully connected neural networks(FNN)outperforms traditional ROP equations and machine learning algorithms,its lack of interpretability undermines its credibility.This study proposes a novel interpretation and characterization method for the FNN ROP prediction model using the Rectified Linear Unit(ReLU)activation function.By leveraging the derivative of the ReLU function,the FNN function calculation process is transformed into vector operations.The FNN model is linearly characterized through further simplification,enabling its interpretation and analysis.The proposed method is applied in ROP prediction scenarios using drilling data from three vertical wells in the Tarim Oilfield.The results demonstrate that the FNN ROP prediction model with ReLU as the activation function performs exceptionally well.The relative activation frequency curve of hidden layer neurons aids in analyzing the overfitting of the FNN ROP model and determining drilling data similarity.In the well sections with similar drilling data,averaging the weight parameters enables linear characterization of the FNN ROP prediction model,leading to the establishment of a corresponding linear representation equation.Furthermore,the quantitative analysis of each feature's influence on ROP facilitates the proposal of drilling parameter optimization schemes for the current well section.The established linear characterization equation exhibits high precision,strong stability,and adaptability through the application and validation across multiple well sections.

关键词： Fully connected neural network Explainable artificial intelligence Rate of penetration ReLU active function Deep learning Machine learning

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Multi-Dimensional QoS Evaluation and Optimization of Mobile Edge Computing for IoT:A Survey

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Chinese Journal of Electronics 2024年第4期33卷 859-874页

作者： Jiwei HUANG Fangzheng LIU Jianbing ZHANG Beijing Key Laboratory of petroleum Data Mining China University of Petroleum department of Computer Science and technology China University of Petroleum

With the evolvement of the Internet of things(IoT), mobile edge computing(MEC) has emerged as a promising computing paradigm to support IoT data analysis and processing. In MEC for IoT, the differentiated requirements on quality of service(QoS) have been growing rapidly, making QoS a multi-dimensional concept including several attributes, such as performance, dependability, energy efficiency, and economic factors. To guarantee the QoS of IoT applications, theories and techniques of multi-dimensional QoS evaluation and optimization have become important theoretical foundations and supporting technologies for the research and application of MEC for IoT,which have attracted significant attention from both academia and industry. This paper aims to survey the existing studies on multi-dimensional QoS evaluation and optimization of MEC for IoT, and provide insights and guidance for future research in this field. This paper summarizes the multi-dimensional and multi-attribute QoS metrics in Io T scenarios, and then several QoS evaluation methods are presented. For QoS optimization, the main research problems in this field are summarized, and optimization models as well as their corresponding solutions are elaborated. We take notice of the booming of edge intelligence in artificial intelligence-empowered Io T scenarios, and illustrate the new research topics and the state-of-the-art approaches related to QoS evaluation and optimization. We discuss the challenges and future research directions.

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Adaptation analysis and fusion correction method of CMIP6 precipitation simulation data on the Qinghai-Tibetan Plateau

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Journal of Mountain Science 2024年第2期21卷 555-573页

作者： PENG Hao QIN Dahui WANG Zegen ZHANG Menghan YANG Yanmei YONG Zhiwei School of Civil Engineering and Geomatics Southwest Petroleum UniversityChengdu 610500China School of Geoscience and technology Southwest Petroleum UniversityChengdu 610500China

In order to obtain more accurate precipitation data and better simulate the precipitation on the Tibetan Plateau,the simulation capability of 14 Coupled Model Intercomparison Project Phase 6(CMIP6)models of historical precipitation(1982-2014)on the Qinghai-Tibetan Plateau was evaluated in this study.Results indicate that all models exhibit an overestimation of precipitation through the analysis of the Taylor index,temporal and spatial statistical parameters.To correct the overestimation,a fusion correction method combining the Backpropagation Neural Network Correction(BP)and Quantum Mapping(QM)correction,named BQ method,was proposed.With this method,the historical precipitation of each model was corrected in space and time,respectively.The correction results were then analyzed in time,space,and analysis of variance(ANOVA)with those corrected by the BP and QM methods,respectively.Finally,the fusion correction method results for each model were compared with the Climatic Research Unit(CRU)data for significance analysis to obtain the trends of precipitation increase and decrease for each model.The results show that the IPSL-CM6A-LR model is relatively good in simulating historical precipitation on the Qinghai-Tibetan Plateau(R=0.7,RSME=0.15)among the uncorrected data.In terms of time,the total precipitation corrected by the fusion method has the same interannual trend and the closest precipitation values to the CRU data;In terms of space,the annual average precipitation corrected by the fusion method has the smallest difference with the CRU data,and the total historical annual average precipitation is not significantly different from the CRU data,which is better than BP and QM.Therefore,the correction effect of the fusion method on the historical precipitation of each model is better than that of the QM and BP methods.The precipitation in the central and northeastern parts of the plateau shows a significant increasing trend.The correlation coefficients between monthly precipitation and site-detected precipitation fo

关键词： GCM CMIP6 Precipitation correction BP-QM fusion correction Spatio-temporal characteristics

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A New Heat Transfer Model for Multi-Gradient Drilling with Hollow Sphere Injection

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Fluid Dynamics & Materials Processing 2024年第3期20卷 537-546页

作者： Jiangshuai Wang Chuchu Cai Pan Fu Jun Li Hongwei Yang Song Deng School of petroleum and Natural Gas Engineering Changzhou UniversityChangzhouChina CNPC Research Institute of Engineering technology Co. Ltd.BeijingChina National Engineering Research Center for Oil&Gas Drilling and Completion technology BeijingChina College of petroleum Engineering China University of Petroleum(Beijing)BeijingChina College of petroleum Karamay CampusChina University of Petroleum(Beijing)BeijingChina

Multi-gradient drilling is a new offshore drilling method.The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure.In this study,a new heat transfer model is proposed by which the variable mass flow is properly taken into account.Using this model,the effects of the main factors influencing the wellbore temperature are analyzed.The results indicate that at the position where the separation injection device is installed,the temperature increase of the fluid in the drill pipe is mitigated due to the inflow/outflow of hollow spheres,and the temperature drop of the fluid in the annulus also decreases.In addition,a lower separation efficiency of the device,a shallower installation depth and a smaller circulating displacement tend to increase the temperature near the bottom of the annulus,thereby helping to reduce the hydrate generation area and playing a positive role in the prevention and control of hydrates in deepwater drilling.

关键词： Multi-gradient drilling wellbore temperature hydrate separate injection device variable mass

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Numerical Analysis of Phase Change and Container Materials for Thermal Energy Storage in the Storage Tank of Solar Water Heating System

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Journal of Thermal Science 2024年第2期33卷 408-421页

作者： SINGH Shailendra ANAND Abhishek SHUKLA Amritanshu SHARMA Atul Non-Conventional Energy Laboratory Rajiv Gandhi Institute of Petroleum TechnologyJais Amethi229304India

This study evaluates the effectiveness of phase change materials(PCMs) inside a storage tank of warm water for solar water heating(SWH) system through the theoretical simulation based on the experimental model of S.Canbazoglu et al.The model is explained by five fundamental equations for the calculation of various parameters like the effectiveness of PCMs,the mass of hot water,total heat content,and duration of charging.This study simulated eleven PCMs to analyze their effectiveness like Sodium hydrogen phosphate dodecahydrate(SHPD),OM 37,N-Eicosane(NE),Lauric acid(LA),Paraffin wax(PW),OM 48,Paraffin wax C_(20-33)(PW-C20-33),Sodium acetate trihydrate(SAT),Palmitic acid(PA),Myristic acid(MA),and Stearic acid(SA).Among all PCMs,the SHPD has found the highest value of effectiveness factor of 3.27.So,it is the most recommended PCM for the storage tank of the SWH system.The study also includes the melt fraction analysis of all enumerated PCMs corresponding to container materials of stainless steel,glass,aluminum mixed,tin,aluminum,and copper.This melt fraction analysis is performed by making a coding program in the FORTRAN programming language.Through the analysis,copper container material is found to have high melting rate for all PCMs so it is superior to other container materials.

关键词： theoretical model solar water heating system phase change material effectiveness factor melt fraction

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Flow Regimes in Bubble Columns with and without Internals: A Review

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Fluid Dynamics & Materials Processing 2024年第2期20卷 239-256页

作者： Ayat N.Mahmood Amer A.Abdulrahman Laith S.Sabri Abbas J.Sultan Hasan Shakir Majdi Muthanna H.Al-Dahhan department of Chemical Engineering University of Technology-IraqBaghdadIraq Chemical and petroleum Industries Engineering department Al-Mustaqbal University CollegeBabylonIraq department of Chemical and Biochemical Engineering Missouri University of Science and TechnologyRollaUSA

Hydrodynamics characterization in terms ofﬂow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalﬂow regimes established in bubble columns.Some effort is also provided to introduce relevant deﬁnitions pertaining to thisﬁeld,namely,that of“void fraction”and related(local,chordal,cross-sectional and volumetric)variants.Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail.In the second part of the review,the attention is shifted to cases with internals of various types(perfo-rated plates,bafﬂes,vibrating helical springs,mixers,and heat exchanger tubes)immersed in the bubble columns.It is shown that the presence of these elements has a limited inﬂuence on the global column hydrodynamics.However,they can make the homogeneousﬂow regime more stable in terms of transition gas velocity and transi-tion holdup value.The last section is used to highlight gaps which have not beenﬁlled yet and future directions of investigation.

关键词： Hydrodynamics ﬂow regime bubble column heat-exchanging internals

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