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A Class of Parallel Algorithm for Solving Low-rank Tensor Completion
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作者 LIU Tingyan WEN Ruiping 《应用数学》 北大核心 2025年第4期1134-1144,共11页
In this paper,we established a class of parallel algorithm for solving low-rank tensor completion problem.The main idea is that N singular value decompositions are implemented in N different processors for each slice ... In this paper,we established a class of parallel algorithm for solving low-rank tensor completion problem.The main idea is that N singular value decompositions are implemented in N different processors for each slice matrix under unfold operator,and then the fold operator is used to form the next iteration tensor such that the computing time can be decreased.In theory,we analyze the global convergence of the algorithm.In numerical experiment,the simulation data and real image inpainting are carried out.Experiment results show the parallel algorithm outperform its original algorithm in CPU times under the same precision. 展开更多
关键词 Tensor completion Low-rank CONVERGENCE Parallel algorithm
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Leveraging Machine Learning to Predict Hospital Porter Task Completion Time
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作者 You-Jyun Yeh Edward T.-H.Chu +2 位作者 Chia-Rong Lee Jiun Hsu Hui-Mei Wu 《Computers, Materials & Continua》 2025年第11期3369-3391,共23页
Porters play a crucial role in hospitals because they ensure the efficient transportation of patients,medical equipment,and vital documents.Despite its importance,there is a lack of research addressing the prediction ... Porters play a crucial role in hospitals because they ensure the efficient transportation of patients,medical equipment,and vital documents.Despite its importance,there is a lack of research addressing the prediction of completion times for porter tasks.To address this gap,we utilized real-world porter delivery data from Taiwan University Hospital,China,Yunlin Branch,Taiwan Region of China.We first identified key features that can influence the duration of porter tasks.We then employed three widely-used machine learning algorithms:decision tree,random forest,and gradient boosting.To leverage the strengths of each algorithm,we finally adopted an ensemble modeling approach that aggregates their individual predictions.Our experimental results show that the proposed ensemble model can achieve a mean absolute error of 3 min in predicting task response time and 4.42 min in task completion time.The prediction error is around 50%lower compared to using only the historical average.These results demonstrate that our method significantly improves the accuracy of porter task time prediction,supporting better resource planning and patient care.It helps ward staff streamline workflows by reducing delays,enables porter managers to allocate resources more effectively,and shortens patient waiting times,contributing to a better care experience. 展开更多
关键词 Machine learning hospital porter task completion time predictive models healthcare
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MMCSD:Multi-Modal Knowledge Graph Completion Based on Super-Resolution and Detailed Description Generation
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作者 Huansha Wang Ruiyang Huang +2 位作者 Qinrang Liu Shaomei Li Jianpeng Zhang 《Computers, Materials & Continua》 2025年第4期761-783,共23页
Multi-modal knowledge graph completion(MMKGC)aims to complete missing entities or relations in multi-modal knowledge graphs,thereby discovering more previously unknown triples.Due to the continuous growth of data and ... Multi-modal knowledge graph completion(MMKGC)aims to complete missing entities or relations in multi-modal knowledge graphs,thereby discovering more previously unknown triples.Due to the continuous growth of data and knowledge and the limitations of data sources,the visual knowledge within the knowledge graphs is generally of low quality,and some entities suffer from the issue of missing visual modality.Nevertheless,previous studies of MMKGC have primarily focused on how to facilitate modality interaction and fusion while neglecting the problems of low modality quality and modality missing.In this case,mainstream MMKGC models only use pre-trained visual encoders to extract features and transfer the semantic information to the joint embeddings through modal fusion,which inevitably suffers from problems such as error propagation and increased uncertainty.To address these problems,we propose a Multi-modal knowledge graph Completion model based on Super-resolution and Detailed Description Generation(MMCSD).Specifically,we leverage a pre-trained residual network to enhance the resolution and improve the quality of the visual modality.Moreover,we design multi-level visual semantic extraction and entity description generation,thereby further extracting entity semantics from structural triples and visual images.Meanwhile,we train a variational multi-modal auto-encoder and utilize a pre-trained multi-modal language model to complement the missing visual features.We conducted experiments on FB15K-237 and DB13K,and the results showed that MMCSD can effectively perform MMKGC and achieve state-of-the-art performance. 展开更多
关键词 Multi-modal knowledge graph knowledge graph completion multi-modal fusion
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Point-PC:Point cloud completion guided by prior knowledge via causal inference
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作者 Xuesong Gao Chuanqi Jiao +2 位作者 Ruidong Chen Weijie Wang Weizhi Nie 《CAAI Transactions on Intelligence Technology》 2025年第4期1007-1018,共12页
The goal of point cloud completion is to reconstruct raw scanned point clouds acquired from incomplete observations due to occlusion and restricted viewpoints.Numerous methods use a partial-to-complete framework,direc... The goal of point cloud completion is to reconstruct raw scanned point clouds acquired from incomplete observations due to occlusion and restricted viewpoints.Numerous methods use a partial-to-complete framework,directly predicting missing components via global characteristics extracted from incomplete inputs.However,this makes detail re-covery challenging,as global characteristics fail to provide complete missing component specifics.A new point cloud completion method named Point-PC is proposed.A memory network and a causal inference model are separately designed to introduce shape priors and select absent shape information as supplementary geometric factors for aiding completion.Concretely,a memory mechanism is proposed to store complete shape features and their associated shapes in a key-value format.The authors design a pre-training strategy that uses contrastive learning to map incomplete shape features into the complete shape feature domain,enabling retrieval of analogous shapes from incomplete inputs.In addition,the authors employ backdoor adjustment to eliminate confounders,which are shape prior components sharing identical semantic structures with incomplete inputs.Experiments conducted on three datasets show that our method achieves superior performance compared to state-of-the-art approaches.The code for Point-PC can be accessed by https://github.com/bizbard/Point-PC.git. 展开更多
关键词 causal inference contrastive alignment memory network point cloud completion
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Effects of aerobic or resistance exercise during neoadjuvant chemotherapy on tumor response and therapy completion in women with breast cancer:The randomized controlled BENEFIT trial
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作者 Martina E.Schmidt Siri Goldschmidt +6 位作者 Charlotte Kreutz Jana Müller Andreas Schneeweiss Anne M.May Friederike Rosenberger Joachim Wiskemann Karen Steindorf 《Journal of Sport and Health Science》 2025年第6期67-75,167,共10页
Background The potential of exercise as a concurrent therapy for actively treated primary tumors has been suggested by emerging preclinical and observational studies.However,clinical trials regarding this question are... Background The potential of exercise as a concurrent therapy for actively treated primary tumors has been suggested by emerging preclinical and observational studies.However,clinical trials regarding this question are scarce.Therefore,we conducted a randomized controlled trial investigating the effects of aerobic or resistance exercise concomitant to neoadjuvant chemotherapy(NACT)on tumor size.Methods In the BENEFIT study(German title:Bewegung bei neoadjuvanter chemotherapie zur verbesserung der fitness),patients with breast cancer scheduled for NACT were randomly assigned to supervised resistance training(RT,n=60)or aerobic training(AT,n=60)twice weekly during NACT or to a waitlist control group(WCG,n=60).The primary outcome,“change in tumor size”,as well as the secondary clinical outcomes pathologic complete response(pCR),type of surgery(breast conserving/mastectomy),axillary lymph node dissection(ALND,yes/no),premature discontinuation of chemotherapy(yes/no),and relative dose intensity(RDI)were derived from clinical records.Due to the highly skewed distribution,the primary outcome was categorized.Multiple(ordinal)logistic regression analyses were performed.Results Overall,there was no significant difference in post-intervention tumor size between RT or AT and WCG.However,there was a significant effect modification by hormone receptor(HR)status(P_(interaction)=0.030).Among patients with HR+tumors,results suggest a beneficial effect of AT on tumor shrinkage(odds ratio(OR)=2.37,95%confidence interval(95%CI):0.97‒5.78),on pCR(OR=3.21,95%CI:0.97‒10.61);and on ALND(OR=3.76,95%CI:0.78‒18.06)compared to WCG.The effects of RT were slightly less pronounced.For HR−subtypes,beneficial effects on RDI were found for AT(OR=3.71,95%CI:1.20‒11.50)and similarly for RT(OR=2.58,95%CI:0.88‒7.59).Both AT and RT had favorable effects on premature discontinuation of chemotherapy(OR(no vs.yes)=2.34,95%CI:1.10‒5.06),irrespective of tumor receptor status.Conclusion While there was no significant effect on the primary outcome in the overall group,aerobic and resistance exercise concomitant to NACT seem to beneficially affect tumor shrinkage and pCR,reduce the need for ALND among patients with HR+breast cancers,and prevent low RDI among patients with HR–breast cancers.These results warrant confirmation in further trials. 展开更多
关键词 Supervised exercise Neoadjuvant chemotherapy Tumor response Pathologic complete response Clinical cancer outcomes
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A Transformer-based approach for anomaly detection in intelligent well completions
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作者 ARANHA Esteves Pedro POLICARPO Angelica Nara SAMPAIO Augusto Marcio 《Petroleum Exploration and Development》 2025年第4期1029-1040,共12页
This study introduces a novel methodology and makes case studies for anomaly detection in multivariate oil production time-series data,utilizing a supervised Transformer algorithm to identify spurious events related t... This study introduces a novel methodology and makes case studies for anomaly detection in multivariate oil production time-series data,utilizing a supervised Transformer algorithm to identify spurious events related to interval control valves(ICVs)in intelligent well completions(IWC).Transformer algorithms present significant advantages in time-series anomaly detection,primarily due to their ability to handle data drift and capture complex patterns effectively.Their self-attention mechanism allows these models to adapt to shifts in data distribution over time,ensuring resilience against changes that can occur in time-series data.Additionally,Transformers excel at identifying intricate temporal dependencies and long-range interactions,which are often challenging for traditional models.Field tests conducted in the ultradeep water subsea wells of the Santos Basin further validate the model’s capability for early anomaly identification of ICVs,minimizing non-productive time and safeguarding well integrity.The model achieved an accuracy of 0.9544,a balanced accuracy of 0.9694 and an F1-Score of 0.9574,representing significant improvements over previous literature models. 展开更多
关键词 anomaly detection intelligent well completion interval control valve well integrity oil well monitoring deep learning Transformer algorithm
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Patients with hepatocellular carcinoma achieving a complete response to sorafenib:Three case reports and review of literature
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作者 Hana Lučev Gordan Adžić +1 位作者 Stjepko Pleština Juraj Prejac 《World Journal of Gastrointestinal Oncology》 2026年第1期233-241,共9页
BACKGROUND Sorafenib has been the conventional treatment for advanced hepatocellular carcinoma(HCC)since 2008.While radiological complete responses are extremely rare,improved supportive care and multidisciplinary app... BACKGROUND Sorafenib has been the conventional treatment for advanced hepatocellular carcinoma(HCC)since 2008.While radiological complete responses are extremely rare,improved supportive care and multidisciplinary approaches in clinical practice may explain the recent increase in case reports and retrospective series documenting such responses.CASE SUMMARY This case series describes 3 patients with advanced HCC who achieved durable complete responses using first-line sorafenib therapy,even in the presence of portal vein thrombosis or extrahepatic spread,and highlights the potential for sustained remission in selected patients.Dermatologic toxicity and non-viral etiology may correlate with favorable outcomes;however,reliable predictive biomarkers for sorafenib response are lacking.CONCLUSION Future research into the etiology and molecular differences in HCC is necessary to develop more personalized therapy options. 展开更多
关键词 Hepatocellular carcinoma SORAFENIB complete response Tyrosine kinase inhibitor Case report
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An Evaluation of "Dialogue Completion" in English Testing
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作者 邵阳 《海外英语》 2011年第12X期133-134,共2页
To evaluate the validity of "dialogue completion" item in the language testing, this article explores three contradictions by analyzing aspects of its characters, content, validity and reliability. The findi... To evaluate the validity of "dialogue completion" item in the language testing, this article explores three contradictions by analyzing aspects of its characters, content, validity and reliability. The finding is that "dialogue completion" patten has unpredicted answer and should be avoided in the testing as much as possible. 展开更多
关键词 validity RELIABILITY DIALOGUE completion contradiciton
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Research and application of water jet technology in well completion and stimulation in China 被引量:13
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作者 Li Gensheng Huang Zhongwei Tian Shouceng Shen Zhonghou 《Petroleum Science》 SCIE CAS CSCD 2010年第2期239-244,共6页
In recent years, rapid progress in the use of high pressure water jets (HPWJ) has been made in oil and gas well drilling, completion, and stimulation; and good results have been achieved in field applications. Advan... In recent years, rapid progress in the use of high pressure water jets (HPWJ) has been made in oil and gas well drilling, completion, and stimulation; and good results have been achieved in field applications. Advances in technologies and developments of well completion and stimulation with hydrajet are reviewed in this paper. Experiments were conducted to study the characteristics of abrasive water jetting and to optimize jet parameters, which can provide methods for the well completion and hydrajet fracturing. Deep-penetrating hydrajet perforating can create a 2-3 m clean hole with a diameter of 20-35 mm. Multilayer hydrajet fracturing is a process whereby multiple layers are stimulated in a single run without using mechanical packers, thereby reducing operation procedure and risk. Multilateral radial wells can be drilled using hydraulic jetting up to 100 m in length. The technique to remove sand particles and plugs with rotating self-resonating cavitating water jets in horizontal wellbores has been developed and oilfield-tested, which shows promising, cost effective prospects. 展开更多
关键词 Water jet abrasive jet well completion PERFORATION STIMULATION horizontal drilling with hydrajet
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Imidazolium-Based Ionic Liquids as an Anticorrosive Agent for Completion Fluid Design 被引量:4
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作者 Sugirtha Velusamy Sivabalan Sakthivel +1 位作者 Lakshman Neelakantan Jitendra S.Sangwai 《Journal of Earth Science》 SCIE CAS CSCD 2017年第5期949-961,共13页
Most of the onshore and offshore oil and gas reservoirs are facing operational challenges due to high temperature and high salinity, thus requiring advanced techniques for realizing the ex- pected oil recovery with th... Most of the onshore and offshore oil and gas reservoirs are facing operational challenges due to high temperature and high salinity, thus requiring advanced techniques for realizing the ex- pected oil recovery with the use of specially designed chemicals. During oil and gas well development, completion fluids, which are solids-free liquids, are used to complete an oil or gas well. Completion flu- ids consisting of brines are primarily used for oil and gas well stabilization and are corrosive in nature. There is a need to develop additives to be added with completion fluids to address the corrosive nature. The present investigation involved the usage of two imidazolium ionic liquids (ILs) as corrosion inhibi- tors for mild steel in various completion brine (CaCI2, HCOOCs and ZnBr2) fluids. The study was per- formed using various techniques, such as, potentiodynamic polarization, weight loss measurements and exposure studies. All the above techniques showed promising results which indicated that the ILs as corrosion inhibitors used were of the mixed-type following both physisorption and chemisorption over the mild steel surface. Among the two inhibitors studied here, l-octyl-3-methyl imidazolium chlo- ride ([OMIM]^+[CI]^-) with longer alkyl chain exhibited better inhibition efficiency and much lesser cor- rosion rate than 1-butyl-3-methyl imidazolium chloride ([BMIM]^+[Ci]^-) with a shorter alkyl chain. The results obtained from various methodologies indicate that ionic liquids can be explored to develop anti-corrosive completion fluids suitable for oil and gas reservoirs. 展开更多
关键词 completion fluid corrosion electrochemical ionic liquid inhibition mild steel.
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Is Minimizing Flow Completion Time the Optimal Way in Meeting Flow's Deadline in Datacenter Networks 被引量:3
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作者 XU Yakun LUO Hongbin REN Fei 《China Communications》 SCIE CSCD 2016年第S1期6-15,共10页
In modern datacenters, the most common method to solve the network latency problem is to minimize flow completion time during the transmission process. Following the soft real-time nature, the optimization of transpor... In modern datacenters, the most common method to solve the network latency problem is to minimize flow completion time during the transmission process. Following the soft real-time nature, the optimization of transport latency is relaxed to meet a flow's deadline in deadline-sensitive services. However, none of existing deadline-sensitive protocols consider deadline as a constraint condition of transmission.They can only simplify the objective of meeting a flow's deadline as a deadline-aware mechanism by assigning a higher priority for tight-deadline constrained flows to finish the transmission as soon as possible, which results in an unsatisfactory effect in the condition of high fan-in degree. It drives us to take a step back and rethink whether minimizing flow completion time is the optimal way in meeting flow's deadline. In this paper, we focus on the design of a soft real-time transport protocol with deadline constraint in datacenters and present a flow-based deadline scheduling scheme for datacenter networks(FBDS).FBDS makes the unilateral deadline-aware flow transmission with priority transform into a compound centralized single-machine deadlinebased flow scheduling decision. In addition, FBDS blocks the flow sets and postpones some flows with extra time until their deadlines to make room for the new arriving flows in order to improve the deadline meeting rate. Our simulation resultson flow completion time and deadline meeting rate reveal the potential of FBDS in terms of a considerable deadline-sensitive transport protocol for deadline-sensitive interactive services. 展开更多
关键词 DATACENTER NETWORKS DEADLINE PREEMPTIVE scheduling FLOW completion time
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Pitting Corrosion of 13Cr Steel in Oxygen-free Completion Fluids of Organic Salt 被引量:2
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作者 Lining XU Yao MENG +1 位作者 Yunguang SHI Yan LIU 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2013年第3期271-276,共6页
Corrosion behavior of 13Cr steel in oxygen-free completion fluids of the organic salt at 180℃ was studied. Cross-sectional morphologies of the corrosion products were observed by scanning electron microscopy. Energy ... Corrosion behavior of 13Cr steel in oxygen-free completion fluids of the organic salt at 180℃ was studied. Cross-sectional morphologies of the corrosion products were observed by scanning electron microscopy. Energy dispersive spectrum (EDS) was used to study the element distribution of the corrosion product inside and outside the pits. The results show that the organic salt causes severe pitting corrosion of 13Cr steel. The width and depth of the pits increase simultaneously when the test duration prolongs, and potassium enriches inside the pits. 展开更多
关键词 13Cr steel Pitting corrosion Organic salt completion fluids
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A new mathematical model for horizontal wells with variable density perforation completion in bottom water reservoirs 被引量:3
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作者 Dian-Fa Du Yan-Yan Wang +2 位作者 Yan-Wu Zhao Pu-Sen Sui Xi Xia 《Petroleum Science》 SCIE CAS CSCD 2017年第2期383-394,共12页
Horizontal wells are commonly used in bottom water reservoirs,which can increase contact area between wellbores and reservoirs.There are many completion methods used to control cresting,among which variable density pe... Horizontal wells are commonly used in bottom water reservoirs,which can increase contact area between wellbores and reservoirs.There are many completion methods used to control cresting,among which variable density perforation is an effective one.It is difficult to evaluate well productivity and to analyze inflow profiles of horizontal wells with quantities of unevenly distributed perforations,which are characterized by different parameters.In this paper,fluid flow in each wellbore perforation,as well as the reservoir,was analyzed.A comprehensive model,coupling the fluid flow in the reservoir and the wellbore pressure drawdown,was developed based on potential functions and solved using the numerical discrete method.Then,a bottom water cresting model was established on the basis of the piston-like displacement principle.Finally,bottom water cresting parameters and factors influencing inflow profile were analyzed.A more systematic optimization method was proposed by introducing the concept of cumulative free-water production,which could maintain a balance(or then a balance is achieved)between stabilizing oil production and controlling bottom water cresting.Results show that the inflow profile is affected by the perforation distribution.Wells with denser perforation density at the toe end and thinner density at the heel end may obtain low production,but the water breakthrough time is delayed.Taking cumulative free-water production as a parameter to evaluate perforation strategies is advisable in bottom water reservoirs. 展开更多
关键词 Bottom water reservoirs Variable density perforation completion Inflow profile Cresting model Cumulative free-water production
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Intelligent Drilling and Completion:A Review 被引量:26
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作者 Gensheng Li Xianzhi Song +1 位作者 Shouceng Tian Zhaopeng Zhu 《Engineering》 SCIE EI CAS 2022年第11期33-48,共16页
The application of artificial intelligence(AI)has become inevitable in the petroleum industry.In drilling and completion engineering,AI is regarded as a transformative technology that can lower costs and significantly... The application of artificial intelligence(AI)has become inevitable in the petroleum industry.In drilling and completion engineering,AI is regarded as a transformative technology that can lower costs and significantly improve drilling efficiency(DE),In recent years,numerous studies have focused on intelligent algorithms and their application.Advanced technologies,such as digital twins and physics-guided neural networks,are expected to play roles in drilling and completion engineering.However,many challenges remain to be addressed,such as the automatic processing of multi-source and multi-scale data.Additionally,in intelligent drilling and completion,methods for the fusion of data-driven and physicsbased models,few-sample learning,uncertainty modeling,and the interpretability and transferability of intelligent algorithms are research frontiers.Based on intelligent application scenarios,this study comprehensively reviews the research status of intelligent drilling and completion and discusses key research areas in the future.This study aims to enhance the berthing of AI techniques in drilling and completion engineering. 展开更多
关键词 Intelligent drilling and completion Artificial intelligence Intelligent application scenarios Literature review Systematic discuss
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Novel Water-Based Drilling and Completion Fluid Technology to Improve Wellbore Quality During Drilling and Protect Unconventional Reservoirs 被引量:24
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作者 Guancheng Jiang Jinsheng Sun +5 位作者 Yinbo He Kaixiao Cui Tengfei Dong Lili Yang Xukun Yang Xingxing Wang 《Engineering》 SCIE EI CAS 2022年第11期129-142,共14页
The efficient exploration and development of unconventional oil and gas are critical for increasing the self-sufficiency of oil and gas supplies in China.However,such operations continue to face serious problems(e.g.,... The efficient exploration and development of unconventional oil and gas are critical for increasing the self-sufficiency of oil and gas supplies in China.However,such operations continue to face serious problems(e.g.,borehole collapse,loss,and high friction),and associated formation damage can severely impact well completion rates,increase costs,and reduce efficiencies.Water-based drilling fluids possess certain advantages over oil-based drilling fluids(OBDFs)and may offer lasting solutions to resolve the aforementioned issues.However,a significant breakthrough with this material has not yet been made,and major technical problems continue to hinder the economic and large-scale development of unconventional oil and gas.Here,the international frontier external method,which only improves drilling fluid inhibition and lubricity,is expanded into an internal-external technique that improves the overall wellbore quality during drilling.Bionic technologies are introduced into the chemical material synthesis process to imitate the activity of life.A novel drilling and completion fluid technique was developed to improve wellbore quality during drilling and safeguard formation integrity.Macroscopic and microscopic analyses indicated that in terms of wellbore stability,lubricity,and formation protection,this approach could outperform methods that use typical OBDFs.The proposed method also achieves a classification upgrade from environmentally protective drilling fluid to an ecologically friendly drilling fluid.The developed technology was verified in more than 1000 unconventional oil and gas wells in China,and the results indicate significant alleviation of the formation damage attributed to borehole collapse,loss,and high friction.It has been recognized as an effective core technology for exploiting unconventional oil and gas resources.This study introduces a novel research direction for formation protection technology and demonstrates that observations and learning from the natural world can provide an inexhaustible source of ideas and inspire the creation of original materials,technologies,and theories for petroleum engineering. 展开更多
关键词 Formation protection Wellbore quality Unconventional oil and gas Drilling and completion fluid BIONICS
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On Accelerated Singular Value Thresholding Algorithm for Matrix Completion 被引量:3
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作者 Li Wang Jianfeng Hu Chuanzhong Chen 《Applied Mathematics》 2014年第21期3445-3451,共7页
An accelerated singular value thresholding (SVT) algorithm was introduced for matrix completion in a recent paper [1], which applies an adaptive line search scheme and improves the convergence rate from O(1/N) for SVT... An accelerated singular value thresholding (SVT) algorithm was introduced for matrix completion in a recent paper [1], which applies an adaptive line search scheme and improves the convergence rate from O(1/N) for SVT to O(1/N2), where N is the number of iterations. In this paper, we show that it is the same as the Nemirovski’s approach, and then modify it to obtain an accelerate Nemirovski’s technique and prove the convergence. Our preliminary computational results are very favorable. 展开更多
关键词 Matrix completion SINGULAR Value THRESHOLDING Nemirovski’s LINE SEARCH Scheme Adaptive LINE SEARCH
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Drilling and completion technologies of coalbed methane exploitation: an overview 被引量:7
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作者 Tianshou Ma Jinhua Liu +1 位作者 Jianhong Fu Bisheng Wu 《International Journal of Coal Science & Technology》 EI CAS CSCD 2022年第5期1-31,共31页
Coalbed methane(CBM)drilling and completion technologies(DCTs)are signifcant basis for achieving efcient CBM exploration and exploitation.Characteristics of CBM reservoirs vary in diferent regions around the world,the... Coalbed methane(CBM)drilling and completion technologies(DCTs)are signifcant basis for achieving efcient CBM exploration and exploitation.Characteristics of CBM reservoirs vary in diferent regions around the world,thereby,it is crucial to develop,select and apply the optimum DCTs for each diferent CBM reservoir.This paper frstly reviews the development history of CBM DCTs throughout worldwide and clarifes its overall development tendency.Secondly,diferent well types and its characteristics of CBM exploitation are summarized,and main application scopes of these well types are also discussed.Then,the key technologies of CBM drilling(directional drilling tools,measurement while drilling,geo-steering drilling,magnetic guidance drilling,underbalanced drilling and drilling fuids),and the key technologies of CBM completion(open-hole,cavity and under-ream completion,cased-hole completion,screen pipe completion and horizontal well completion)are summarized and analyzed,it is found that safe,economic and efcient development of CBM is inseparable from the support of advanced technologies.Finally,based on the current status of CBM development,the achievements,existing challenges and future prospects are summarized and discussed from the perspective of CBM DCTs. 展开更多
关键词 Coalbed methane CBM EXPLOITATION DRILLING completion Horizontal well L/U/V-shaped well Multilateral well
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Concise review of relaxations and approximation algorithms for nonidentical parallel-machine scheduling to minimize total weighted completion times 被引量:1
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作者 Li Kai Yang Shanlin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第4期827-834,共8页
A class of nonidentical parallel machine scheduling problems are considered in which the goal is to minimize the total weighted completion time. Models and relaxations are collected. Most of these problems are NP-hard... A class of nonidentical parallel machine scheduling problems are considered in which the goal is to minimize the total weighted completion time. Models and relaxations are collected. Most of these problems are NP-hard, in the strong sense, or open problems, therefore approximation algorithms are studied. The review reveals that there exist some potential areas worthy of further research. 展开更多
关键词 parallel machine SCHEDULING REVIEW total weighted completion time RELAXATION algorithm
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The study of formulation and performance of formate drilling and completion fluid system 被引量:2
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作者 Bingren Wang Zehua Wang +1 位作者 Yuxue Sun Jiuzhou Sun 《Natural Science》 2013年第9期997-1000,共4页
Formate drilling and completion fluid system is a new type of clean organic salt brine system which has been developed from inorganic salt brine drilling fluid system. It is beneficial to protecte and find hydrocarbon... Formate drilling and completion fluid system is a new type of clean organic salt brine system which has been developed from inorganic salt brine drilling fluid system. It is beneficial to protecte and find hydrocarbon reservoir. Due to the solid free system, the damage of solid phase particles on reservoir, especially low permeability oil and gas layer, can be greatly eliminated, at the same time, drilling fluid and completion fluid have greater compatibility. It will avoid that precipitation which is not compatible with drilling and completion fluid and generates damages on reservoir. And because mud cake of the solid free system is thin and resilient, it is conductive to improve cementing quality greatly. Experiments show that the formate drilling and completion system has good rheological property, strong inhibition ability, good lubricating performance, good compatibility with reservoir rocks and formation water at high temperature. 展开更多
关键词 FORMATE DRILLING and completion Fluid SYSTEM Solid Free SYSTEM HYDROCARBON Reservoir Protection
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