SPE Production & Operations最新文献

{"title":"A Pilot Demonstration of Flaring Gas Recovery during Shale Gas Well Completion in Sichuan, China","authors":"Ming Xue, Xingchun Li, Xiangyu Cui, Xin Cheng, Shuangxing Liu, Wenjia Xu, Yilin Wang","doi":"10.2118/214665-pa","DOIUrl":"https://doi.org/10.2118/214665-pa","url":null,"abstract":"\u0000 As one of the largest emitters in the world, the oil and gas industry needs to apply more effort to greenhouse gas (GHG) reduction. Methane, as a potent GHG, could largely determine whether natural gas could serve as a bridging energy toward a sustainable future. In the past decade, oil and gas companies in China have significantly enhanced casing gas recovery and reduced large volume flaring (>2×104 m3/d). However, the remaining low- to mid-volume flaring gas was left for further recovery. Shale gas production in China has met a surge in the number of drilling wells. Those new wells were characterized by a relatively low gas production rate (<1×106 m3/d) in comparison with shale gas wells in the US. As a result, flaring gas during well completion needs to be recycled or used to enhance the gas recovery rate. In this study, we carried out a pilot demonstration project of flaring gas recovery to reduce GHG emissions in the Weiyuan shale gas region in Sichuan Province, China. We adopted the technical route of dehydration and natural gas compression. The recycled natural gas was transformed into compressed natural gas (CNG) and transported to the nearest CNG station for further use. The inlet gas pressure was between 2.85 and 5.82 MPa, and the outlet pressure was kept stable at around 20 MPa to meet the standard of CNG. The manufactured device also showed sound flexibility with the recovery rate between 523.22 and 1224.38 m3/h, which was 28–157% of the designed capacity. The combination of the molecular sieve with high capacity, post low-pressure dehydration, and the application of hydraulic piston in the compression system have guaranteed the equipment to meet the designed performance. The equipment applied in the pilot demonstration has well matched with the local transportation, gas composition, and surface engineering of the well completion. It has the potential of popularization and application in the shale gas tight gas regions in China. Other technical routes, such as small-scale gas to chemicals or natural gas hydrate, should be considered for industrial application for gas flowing rate less than 2×104 m3/d to ensure a further drive down of methane emission along the value chain.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123119565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transient Flow Performance of a Vertical Well With Multiple Varying Conductivity Fractures in a Tight Oil Reservoir","authors":"Guoqiang Xing, X. Dou, Xianyong Liu, Wenmin Guo, Mingxian Wang, Ying Tang","doi":"10.2118/214328-pa","DOIUrl":"https://doi.org/10.2118/214328-pa","url":null,"abstract":"\u0000 Due to uneven proppant distribution and varied proppant sizes during hydraulic fracturing, artificial fractures of varying length, asymmetry, and varying conductivity are easily formed near the wellbore. The principal focus of this work is to investigate the pressure transient performance of a vertical well penetrated by multiple asymmetrical fractures with varying lengths and varying conductivities in a tight oil reservoir. A novel fracture flow equation was developed specifically to describe the flow behavior inside the complex artificial fractures mentioned above. By combining with the point source solution of the tight oil reservoir, a semianalytical solution was further obtained to analyze the pressure transient behavior of a vertical well with multiple varying-conductivity fractures in a tight oil reservoir. The accuracy and reliability of the newly-developed solution were verified by comparing with the result of a numerical model. With this new solution, fracture flux distribution for different conductivity modes, namely, linearly declining mode, exponentially declining mode, and elliptically declining mode, shows that the near-wellbore fracture flux of the exponential mode is greater than that of the other two modes, but the flux distribution near the fracture tips is on the contrary. Meanwhile, the transient flow characteristics under the above varying conductivity modes indicate that the exponentially varying conductivity has a significant influence on the early linear flow regimes, while the linear and elliptical mode only has a slight influence on the bilinear flow regime under high conductivity. Parameter sensitivity analysis reveals that the obvious inversion point occurring in the pressure derivative curves of uniform conductivity fractures disappears on the pressure derivative curves of varying conductivity fractures, and a weaker asymmetry, a greater adjacent fracture angle, and a larger fracture number and fracture length ratio are conducive to improve the fracturing stimulation effect. This study deepens our understanding of the transient flow performance of vertically fractured wells and helps to estimate artificial fracture properties and evaluate hydraulic fracturing performance.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115097894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Produced Water Management and Utilization: Challenges and Future Directions","authors":"S. Eyitayo, M. Watson, O. Kolawole","doi":"10.2118/209310-pa","DOIUrl":"https://doi.org/10.2118/209310-pa","url":null,"abstract":"\u0000 Produced water (PW) is an undesirable byproduct generated from oil and natural gas production. Due to the large volume produced, managing its disposal is challenging. Generally, PW is used internally for oil and gas operations while different types of means dispose of the remaining volumes. Recently, there has been a need to repurpose the volume of water customarily disposed of for other industries’ applications. This presents a potential opportunity to reduce excessive freshwater usage in oil and gas operations and reduce water depletion in other industries, thus aiding water conservation as one of the goals for sustainable development. While the external uses are the viable and logical solution, there are challenges relating to PW characterization, treatment technology, and economics of such a project. Therefore, the effective treatment technology, utilization, and disposal of PW remain critical issues for the petroleum industry with consideration of the environment, technical aspects, and economics. There must be collaboration among all stakeholders to harness the potential opportunities and merits of external reuse of PW for cost-effective and environmentally sustainable solutions in treatment technology and every other aspect of PW management. This review presents a comprehensive overview of PW management, current practices in the petroleum industry, and opportunities to be used in other sectors. A detailed account of each disposal method and possible external uses are enumerated with associated challenges, and how these can be mitigated.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"345 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124255881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research and Application of a Controllable Permeability Refracturing Technology in a High-Water-Cut Potential Layer","authors":"M. Qi, E. Yang, Y. Liu, C. Dong, X. Chen","doi":"10.2118/214333-pa","DOIUrl":"https://doi.org/10.2118/214333-pa","url":null,"abstract":"\u0000 The Fuyu oil field is a typical shallow, low-temperature, low-permeability reservoir. At present, the oilfield composite water cut is 95%, artificial fractures interlace with natural fractures, and the distribution of ineffective circulation channels between wells is complex. This paper found that after reducing the permeability of the original fracture, refracturing can effectively improve the longitudinal extension range of the new fracture through numerical simulation. Therefore, a controllable permeability temporary plugging agent is studied, and controllable permeability refracture technology is proposed. The controllable permeability temporary plugging system is composed of elastic particles, quartz sand, and quick-soluble elastic enhancers, which are based on elastic particles that do not age, and long-term plugging can be achieved. Through physical experiments, 0.5–1-mm elastic particles with 70–140 mesh and 16–30 mesh quartz sand were used in different ratios (i.e., 5:5, 6:4, and 7:3). According to the closure pressure and the permeability of the fracturing layer, the ratio chart of elastic particles and quartz sand is established. The controllable permeability refracture technology can select the ratio of the quartz sand and elastic particles according to the closure pressure and the control requirements of the fracturing horizon permeability. Through field applications, we found that, compared with the conventional refracturing technology, the average daily fluid gain per well decreased from 5.0 to 3.9 tons, and the daily oil gain increased from 0.3 to 0.6 tons. The controllable permeability fracturing technology could reduce the permeability of the original fracture and improve the vertical production degree of the reservoir after refracturing. In addition, this method ensures that the original fracture has a certain conductivity and that the high-permeability layer reserves are not lost due to temporary plugging agents, thus expanding the planar sweep volume and effectively improving reservoir recovery. Nevertheless, the chart established is mainly suitable for shallow reservoirs, and the closure pressure is 3–15 MPa in this paper. Further testing and research are needed for deep reservoirs.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128040408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular Dynamics Simulation of CO2 Hydrate Growth in NaCl Aqueous Solution","authors":"Xianwu Jing, Li Zhou, Youquan Liu, Yingying Xu, Wenjian Yin","doi":"10.2118/214332-pa","DOIUrl":"https://doi.org/10.2118/214332-pa","url":null,"abstract":"\u0000 Climate change has brought enormous adverse outcomes to biological activities around the world. The main reason is that too much CO2 has been released into the atmosphere. In recent years, storing CO2 in the form of CO2 hydrate is a research hotspot, the main purpose of which is to reduce carbon emissions to mitigate the greenhouse effect. In this work, we use the molecular dynamics simulation method to study the growth of CO2 hydrate in NaCl aqueous solution with the assumption of induction of CO2 sequestration in the ocean. The temperature is 275 K and the pressure is 10 MPa in this work. Under these conditions, stucture I type (sI-type) CO2 hydrate with a density of about 1150 kg/m3 formed within a very short period of time. The simulation results show that during hydrate growth, Na+ and Cl− are “driven” together and the water molecules remain liquid in this region, where they are near Na+ and Cl−. From the independent gradient model (IGM) based on Hirshfeld partition (IGMH) analysis, Na+ does not bond with any ions/molecules, which hinders the formation of water cages and thus inhibits hydrate growth; Cl− forms multiple H-bonds with neighboring H2O molecules and can participate in the formation of water cages. However, it is worth noting that not all Cl– and the nearby water molecules can form either a five-membered ring or a four-membered ring; even some water molecules and Cl− cannot form a closed ring. Therefore, it is impossible to determine whether the water molecules near the Cl− are all in liquid or solid state.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123831004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Real-Time Optimization and Decarbonization of Oil and Gas Production Value Chain Enabled by Industry 4.0 Technologies: A Critical Review","authors":"Harpreet Singh, Chengxi Li, Pengyu Cheng, Xunjie Wang, Ge Hao, Qing Liu","doi":"10.2118/214301-pa","DOIUrl":"https://doi.org/10.2118/214301-pa","url":null,"abstract":"\u0000 The presence of silos in data and technology of the oil and gas (O&G) production value chain prevents the optimal utilization of resources to enhance production, improve efficiency, and reduce carbon emissions in the O&G production value chain. Real-time optimization of O&G production value chain (ROOPVC) can be used to achieve the above-described objectives. Specifically, ROOPVC allows for i) integration of various elements of the O&G production value chain to create a single reference truth of the system, ii) prediction of unified behavior of the single reference truth using physics-based models and data-driven algorithms, and iii) holistic optimization via single unified digital twin (DT).\u0000 Based on recent advances, this study reviews system-level and component-level technologies required to implement ROOPVC. Specifically, the study reviews in detail the two major elements of ROOPVC, which are i) DT technology and ii) modeling, simulation, and optimization, respectively. The study also summarizes field experiences in the deployment of ROOPVC. The key challenges, lessons learned, and recommendations for the deployment of ROOPVC are also discussed.\u0000 The major findings from this review suggest that ROOPVC i) can enable higher stable production while simultaneously allowing significant carbon savings, ii) is suitable for deployment on a field of any size, and iii) can be deployed quickly due to its modular (microservices) approach.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125915068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Case Studies and Operation Features of Long Horizontal Wells in Bazhenov Formation","authors":"T. Yushchenko, E. V. Demin, R. Khabibullin, K. S. Sorokin, M. Khachaturyan, I. V. Baykov, R. I. Gatin","doi":"10.2118/206482-pa","DOIUrl":"https://doi.org/10.2118/206482-pa","url":null,"abstract":"\u0000 In this study, unique field data analysis and modeling of operating wells with an extended horizontal wellbore (HW) and multistage hydraulic fracturing (MHF) in the Bazhenov formation were conducted. Moreover, a large amount of long horizontal well data obtained from the Bazhenov formation field was used.\u0000 Wells with extended HW drilling and MHF are necessary for commercial oil production in the Bazhenov formation. Problems can occur in such wells when operating in the flowing mode and using an artificial lift at low flow rates. This study aimed to describe the field experiences of low-rate wells with extended HWs and MHF and the uniqueness of well operations and complexities. It was also focused on modeling various operation modes of such wells using specialized software and accordingly selecting the optimal downhole parameters and analyzing the sensitivity of fluid properties and well parameters to the well flow.\u0000 The flow rates in wells with extended HW and MHF decrease in the first year by 70–80% when oil is produced from ultralow-permeability formations. Drainage occurs in a nonstationary mode in the entire life of a well, leading to complexities in operation. A comprehensive analysis of field data [downhole and wellhead pressure gauges, electric submersible pump (ESP) operation parameters, and phases’ flow rate measurements] and fluid sample laboratory studies was conducted to identify the difficulties in various operating modes. For an accurate description of the physical processes, various approaches were used for the numerical simulation of multiphase flows in a wellbore, considering the change in the inflow from the reservoir. The complexities that may arise during the operation of wells were demonstrated by analyzing the field data and the numerical simulation results. The formation of a slug flow in low flow rates in a wellbore was caused by a rapid decline in the production rate, a decrease in the water cut, and an increase in the gas/oil ratio (GOR) over time. Based on the results, proppant particles can be carried into the HW and thereby reduce the effective section of the well in case of high drawdowns in the initial period of well operation. Consequently, the pressure drops along the wellbore increased, and the drawdown on the formation decreased. Other difficulties were determined to be associated with the consequences and technologies of hydraulic fracturing (HF). These effects were shown based on the field data and the numerical simulation results of the flow processes in wells. In addition, corrective measures were established to address various complexities, and the applications of these recommendations in the field were conducted.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"241 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132380732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computational Fluid Dynamics Modeling of Pseudotransient Perforation Erosion in a Limited-Entry Completion Cluster","authors":"Brent A. Kebert, J. Miskimins, Gage Soehner, W. Hunter","doi":"10.2118/212366-pa","DOIUrl":"https://doi.org/10.2118/212366-pa","url":null,"abstract":"\u0000 Hydraulic fracturing in limited-entry (LE) completion designs relies on maintaining a high bottomhole treating pressure (BHTP). LE requires high perforation friction to maintain an even distribution of the hydraulic fracturing slurry. As sand exits the perforations, the perforations start to erode. The erosional change in the perforation alters the desired perforation friction and subsequent BHTP. As operators rely on multistage hydraulic fracturing to generate economic production, the issue of perforation erosion becomes inherently repetitive from stage to stage and cumulatively a significant issue. The industry has seen how a perforation can change from a before-and-after perspective with downhole cameras and imaging techniques before and after treatments. However, a more detailed understanding of the dynamic process of perforation erosion can give a better expectation of perforation performance throughout a hydraulic fracturing treatment and not just pretreatment compared to post-treatment.\u0000 Computational fluid dynamics (CFD) is a quickly emerging tool in the industry. CFD aims to model fluid flow by numerically solving the Naiver-Stokes equations within a specified domain. Along with modeling fluid systems, CFD has the capability to model dispersed particles within the fluid. Once the particles are introduced into the fluid, the domain can also be eroded away within the CFD model. By utilizing the erosional capabilities of CFD, paired with the flow of a hydraulic fracturing slurry, perforation erosion can be investigated transiently throughout an entire hydraulic fracturing stage.\u0000 This work presents a better dynamic understanding of perforation erosion rather than just a “before vs. after” comparison. The CFD modeling methodology used to achieve the correct erosional pattern observed in the field is presented. Throughout this work, four different hydraulic fracturing completion parameters are investigated to determine the respective roles in perforation erosion. The four parameters include proppant size, proppant concentration, fracturing fluid viscosity, and proppant concentration ramping schedules. By investigating the impact that controlled design parameters have on perforation erosion, perforation erosion can be better anticipated to deliver improved completion results.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"351 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116673862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and Evaluation of a Virtual Flowmeter for Multiphase Flow in Production Lines","authors":"G. S. Chaves, H. Karami, V. F. Ferreira Filho","doi":"10.2118/206259-pa","DOIUrl":"https://doi.org/10.2118/206259-pa","url":null,"abstract":"\u0000 Flow rate is a valuable piece of information for the oil and gas industry. High accuracy on flow rate estimation enhances the operations that control and manage production. Recognized as a cost-efficient solution, the virtual flowmeter (VFM) is a mathematical-based technology designed to estimate the flow rates using available field instrumentation. The VFM approach developed in this work combines black-box simulations with mixed-integer linear programming (MILP) problems to obtain flow rates while dismissing the tuning process. The methodology includes a set of multiphase flow correlations. The MILP estimates the flow rate and designates the best-fit model. The VFM is evaluated against 649 well test data. The methodology presents a 4.1% absolute percentage error (APE) for the 25th percentile and 13.5% APE for the 50th percentile of the data. The methodology dismisses the model tuning process, which would require flow rate data. This makes the methodology valuable, particularly in scenarios where historical data are scarce or unavailable.","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"190 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122056585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Semi-Analytical Model of an Off-Center Multi-Wing Fractured Well in a Low-Permeability Gas Reservoir","authors":"Sihan Yang, Xiaoping Li, Qi-guo Liu, You-jie Xu","doi":"10.2118/212858-pa","DOIUrl":"https://doi.org/10.2118/212858-pa","url":null,"abstract":"\u0000 Since there are several hydraulic fractures around a wellbore after a large-scale hydraulic fracturing and the well is not in the center of the reservoir, no corresponding semianalytical model for wellbore pressure analysis has been proposed. To bridge this gap, this paper aims to present a semianalytical model of the off-center multiwing fractured well. With consideration of permeability stress sensitivity, the reservoir model and hydraulic fracture model are established, respectively. The coupling approach of the reservoir model and hydraulic fracture model is used to obtain the wellbore pressure solution. Meanwhile, the off-center multiwing fractured well is verified with a numerical solution. The seven flow regimes can be distinguished according to the characteristics of the pressure derivative curve. Furthermore, the effect of different fracture distributions on wellbore pressure and the derivative curve is discussed and analyzed. Assuming that the fracture wing number is equal to the average length of all fracture wings, the wellbore pressure is lowest before the radial flow regime when the fracture wing has a uniform distribution around the angle and all fracture wings are equal in length. Besides, the influence of other important parameters (fracture wing number, off-center distance, etc.) is discussed. According to the analysis, we conclude that fracture wing number has a significant influence on the pressure and derivative curves before the radial flow regime. The off-center distance has no influence on the pressure and derivative curve before the radial flow regime, but it has an obvious influence on arc boundary reaction time. Finally, the advantages of the semianalytical solution are fast calculation speed and high calculation accuracy (especially in the early flow regime).","PeriodicalId":153181,"journal":{"name":"SPE Production &amp; Operations","volume":"327 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122834832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}