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Geomechanics involved in gas hydrate recovery

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Chinese Journal of Chemical Engineering 2019年第9期27卷 2099-2106页

作者： Zhiqiang Liu Yunxiao Lu Jiuhui Cheng Qiang Han Zunjing Hu Linlin Wang State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum-BeijingBeijing 102249China College of Petroleum Engineering China University of Petroleum-BeijingBeijing 102249China Downhole service Company of Sinopec Shengli Oilfield service Corporation China

Gas hydrate is regarded as a promising energy owing to the large carbon reserve and high energy ***,due to the particularity of the formation and the complexity of exploitation process,the commercial exploitation of gas hydrate has not been *** paper reviews the physical properties of gas hydratebearing sediments and focuses on the geomechanical response during the *** exploitation of gas hydrate is a strong thermal–hydrological–mechanical–chemical(THMC)coupling process:decomposition of hydrate into water and gas produces multi-physical processes including heat transfer,multi-fluid flow and deformation in the *** physical processes lead to a potential of geomechanical issues during the production *** occurrence of sand production is the major limitation of the commercial exploitation of gas *** potential landslide and subsidence will lead to the cessation of the production and even serious *** researches have been conducted to investigate the geomechanical properties of gas hydrate-bearing sediments and to assess the wellbore integrity during the *** physical properties of hydrate have been fully studied,and some models have been established to describe the physical processes during the exploitation of gas *** the reproduction of actual conditions of hydrate reservoir in the laboratory is still a huge challenge,which will inevitably lead to a bias of *** addition,because of the effect of microscopic mechanisms in porous media,the coupling mechanism of the existing models should be further *** efforts,however,are still required for a comprehensive understanding of this strong coupling process that is extremely different from the geomechanics involved in the conventional reservoirs.

关键词： Gas hydrate Phase transition THMC coupling Wellbore integrity Sand production

Effects of rainfall on the weekday traffic flow in major cities of the Beijing-Tianjin-Hebei region, china, in 2021

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Advances in Climate Change Research 2022年第6期13卷 858-867页

作者： Ming-Ming XIONG Zhen-Yu HAN Bo LU Jun GUO Shu XU Yan-Juan YANG He HUANG Tianjin Climate Center Tianjin Meteorological ServiceTianjin 300074China National Climate Center China Meteorological AdministrationBeijing 100081China Tianjin Meteorological Observatory Tianjin Meteorological ServiceTianjin 300074China

Rainfall can bring uncertainties to the traffic flow and influence the normal function of urban transportation *** impact of precipitation on the urban traffic flow,especially the different impacts among cities and areas within a city,is worth ***,we analysed the impact of precipitation on the traffic flow in the urban areas of the Beijing-Tianjin-Hebei region by comparing the traffic flow in non-precipitation and rainy weather with different hourly precipitation intensities in *** increase in the travel time index(TTI)is chosen to represent the influence of precipitation on the transportation *** results show that the maximum of the average TTI increases on the city scale under various rainfall intensities by 3.3%,6.6%and 10.8%in Beijing,Tianjin and Shijiazhuang,*** general,the increase in the TTI contributed by precipitation is the greatest at morning and afternoon peak hours,and the traffic congestion degree increases with the rainfall ***,in the morning peak,afternoon peak and midday hours in Beijing and Tianjin,the influences of the weak rainfall intensity on the traffic flow are generally great,whereas the traffic congestion degree caused by heavy precipitation is relatively ***,in morning peak hours,the congestion reduction reaches approximately 2%,which may be related to the spatial difference in the impacts of precipitation on the traffic flow and the changes in people's travel intention under different rainfall *** findings can help better understand the relationship between rainfall and urban traffic flow characteristics and also potentially contribute to the development of impact-oriented climate predictions.

关键词： Rainfall intensity Urban traffic flow Beijing-Tianjin-Hebei region Auto Navi map road condition data

Spatiotemporal changes of biogenic elements in the Changjiang River Estuary and adjacent waters in summer over the last decade

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Acta Oceanologica Sinica 2023年第1期42卷 83-90页

作者： Lu Yang Yujia Zhang Xiaoli Wang Qiulu Wang Long He Xiao Li National Marine Data and Information service Tianjin300171China

The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this *** concentrations of dissolved inorganic nitrogen(DIN),soluble reactive phosphate(PO_(4)^(3−))and silicate(SiO_(3)^(2−))were generally stable,with a slight decrease of DIN and PO_(4)^(3−),and a slight increase of SiO_(3)^(2−),which mainly occurred in the estuarine *** grey correlation analysis was carried out between biogenic elements and chlorophyll a(Chl-a).Results showed that compared with the absolute values of biogenic elements,the correlations between the concentration ratio of nitrogen to phosphorus(N/P),ratio of silicon to nitrogen(Si/N)and Chl-a were closer,indicating the important influence on phytoplankton by the structure of biogenic *** study area was generally in a state of potential P limitation,and could have potential impact on the phytoplankton community,triggering the shift of red tide dominant species from diatoms to dinoflagellates.

关键词： Changjiang River Estuary biogenic elements spatiotemporal changes

Sea level rise along china coast in the last 60 years

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Acta Oceanologica Sinica 2022年第12期41卷 18-26页

作者： Hui Wang Wenshan Li Wenxi Xiang National Marine Data and Information service Tianjin 300171China

Based on long-term tide gauge observations in the last 60 years,the temporal and spatial variation characteristics of sea level change along the coast of china are *** results indicate that the sea level along the coast of china has been rising at an increasing rate,with an estimated acceleration of 0.07 mm/*** rise rates were 2.4 mm/a,3.4 mm/a and 3.9 mm/a during 1960–2020,1980–2020 and 1993–2020,*** the last 40 years,the coastal sea level has risen fastest in the South china Sea and slowest in the Yellow *** sea levels all show an upward trend but rise faster in winter and spring and slower in *** level change along the coast of china has significant periodic oscillations of quasi-2 a,4 a,7 a,11 a,quasi-19 a and 30–50 a,among which the 2–3 a,11 a,and 30–50 a signals are most remarkable,and the amplitude is approximately 1–2 *** coastal sea level in the most recent decade reached its highest value in the last 60 *** decadal sea level from 2010 to 2019 was approximately 133 mm higher than the average of 1960–*** orthogonal function analysis indicates that china’s coastal sea level has been changing in a north-south anti-phase pattern,with Pingtan and Fujian as the demarcation *** difference was especially obvious during 1980–1983,1995–1997 and 2011–*** coastal sea level was the highest in 2016,and this extreme sea level event was analyzed to be related mainly to the anomalous wind field and ENSO.

关键词： sea level long-term change tide gauge records spatial and temporal variability

Effects of different plasma expanders on rats subjected to severe acute normovolemic hemodilution

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Military Medical Research 2021年第2期8卷 183-195页

作者： Guo-Xing You Bing-Ting Li Zhen Wang Quan Wang Ying Wang Jing-Xiang Zhao Lian Zhao Hong Zhou Institute of Health service and Transfusion Medicine Beijing 100850China

Background:Plasma expanders are widely used for acute normovolemic hemodilution(ANH).However,existing studies have not focused on large-volume infusion with colloidal plasma expanders,and there is a lack of studies that compare the effects of different plasma ***:The viscosity,hydrodynamic radius(Rh)and colloid osmotic pressure(COP)of plasma expanders were determined by a cone-plate viscometer,Zetasizer and cut-off membrane,*** male rats were randomized into five groups with Gelofusine(Gel),Hydroxyethyl Starch 200/0.5(HES200),Hydroxyethyl Starch 130/0.4(HES130),Hydroxyethyl Starch 40(HES40),and Dextran 40(Dex40),with 12 rats used in each group to build the ANH *** was performed by the withdrawal of blood and simultaneous infusion of plasma ***-base,lactate,blood gas and physiological parameters were ***:Gel had a lower intrinsic viscosity than HES200 and HES130(P<0.01),but at a low shear rate in a mixture of colloids,red cells and plasma,Gel had a higher viscosity(P<0.05 or P<0.01,respectively).For hydroxyethyl starch plasma expanders,the COP at a certain concentration decreases from 11.1 mmHg to 6.1 mmHg with the increase of Rh from 10.7 nm to 20.2 nm.A severe ANH model,with the hematocrit of 40%of the baseline level,was established and accompanied by disturbances in acid-base,lactate and blood gas *** the end of ANH and 60 min afterward,the Dex40 group showed a worse outcome in maintaining the acid-base balance and systemic oxygenation compared to the other *** systolic blood pressure(SBP),diastolic blood pressure(DBP),and mean arterial pressure(MAP)decreased significantly in all groups at the end of *** DBP and MAP in the Dex40 group further decreased 60 min after the end of *** the process of ANH,the Dex40 group showed a drop and recovery in SBP,DBP and *** DBP and MAP in the HES200 group were significantly higher than those in the other groups at some time points(P<0.05 o

关键词： Acute normovolemic hemodilution Plasma expander Acid-base Lactate Blood gas Physiological arameters

Transportation and sealing pattern of the temporary plugging ball at the spiral perforation in the horizontal well section

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Petroleum Science 2024年第5期21卷 3288-3297页

作者： Qing-Hai Hu Wan Cheng Zun-Cha Wang Yu-Zhao Shi Guang-Liang Jia Faculty of Engineering China University of GeosciencesWuhan430074HubeiChina Sinopec North china Oilfield service Corporation Zhengzhou445007HenanChina

Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However,the transportation and sealing law of temporary plugging balls(TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of *** the fracturing fluid injection rate from low to high can control the position of the TPBs,improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.

关键词： Temporary plugging ball Horizontal well Multistage fracturing Spiral perforation Numerical simulation

FOLMS-AMDCNet:an automatic recognition scheme for multiple-antenna OFDM systems

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Journal of Systems Engineering and Electronics 2023年第2期34卷 307-323页

作者： ZHANG Yuyuan YAN Wenjun ZHANG Limin LING Qing Academy of Aeronautical Operations service Naval Aviation UniversityYantai 264001China

The existing recognition algorithms of space-time block code(STBC)for multi-antenna(MA)orthogonal frequencydivision multiplexing(OFDM)systems use feature extraction and hypothesis testing to identify the signal types in a complex communication ***,owing to the restrictions on the prior information and channel conditions,these existing algorithms cannot perform well under strong interference and noncooperative communication *** overcome these defects,this study introduces deep learning into the STBCOFDM signal recognition field and proposes a recognition method based on the fourth-order lag moment spectrum(FOLMS)and attention-guided multi-scale dilated convolution network(AMDCNet).The fourth-order lag moment vectors of the received signals are calculated,and vectors are stitched to form two-dimensional FOLMS,which is used as the input of the deep learning-based ***,the multi-scale dilated convolution is used to extract the details of images at different scales,and a convolutional block attention module(CBAM)is introduced to construct the attention-guided multi-scale dilated convolution module(AMDCM)to make the network be more focused on the target area and obtian the multi-scale guided ***,the concatenate fusion,residual block and fully-connected layers are applied to acquire the STBC-OFDM signal *** experiments show that the average recognition probability of the proposed method at−12 dB is higher than 98%.Compared with the existing algorithms,the recognition performance of the proposed method is significantly improved and has good adaptability to environments with strong *** addition,the proposed deep learning-based model can directly identify the pre-processed FOLMS samples without a priori information on channel and noise,which is more suitable for non-cooperative communication systems than the existing algorithms.

关键词： blind signal identification(BSI) space-time block code(STBC) orthogonal frequency-division multiplexing(OFDM) deep learning fourth-order lag moment spectrum(FOLMS)

Practical approach to determining traffic congestion propagation boundary due to traffic incidents

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Journal of Central South University 2017年第2期24卷 413-422页

作者：费文鹏宋国华张凡高永于雷 School of Traffic and Transportation Beijing Jiaotong University Beijing 100044 China china Communications news Beijing 100011 China Beijing Transportation Research Center Beijing 100073 China College of Science Engineering and Technology Texas Southern University Houston Texas 77004 USA

A practical approach for predicting the congestion boundary due to traffic incidents was proposed. Based on the kinematic wave theory and Van Aerde single-regime flow model, a model for estimating the congestion propagation speed for the basic road segment was developed. Historical traffic flow data were used to analyze the time variant characteristics of the urban traffic flow for each road type. Then, the saturation flow rate was used for analyzing the impact of the traffic incident on the traversing traffic flow at the congestion area. The base congestion propagation speed for each road type was calculated based on field data, which were provided by the remote traffic microwave sensors(RTMS), floating car data(FCD) system and screen line survey. According to a comparative analysis of the congestion propagation speed, it is found that the expressway, major arterial, minor arterial and collector are decreasingly influenced by the traffic incident. Subsequently, the impact of turning movements at intersections on the congestion propagation was considered. The turning ratio was adopted to represent the impact of turning movements, and afterward the corresponding propagation pattern at intersections was analyzed. Finally, an implementation system was designed on a geographic information system(GIS) platform to display the characteristics of the congestion propagation over the network. The validation results show that the proposed approach is able to capture the congestion propagation properties in the actual road network.

关键词： kinematic wave model Van Aerde model traffic incident congestion propagation on network

Mineral Components, Texture, and Forming Conditions of Hydrothermal Chimney on the East Pacific Rise at 9°-10°N

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Journal of china University of Geosciences 2007年第2期18卷 128-134页

作者：郑建斌曹志敏安伟 College of Marine Geosciences Ocean University of China china Offshore Environmental service Ltd.

To characterize the hydrothermal processes of East Pacific rise at 9°-10°N, sulfide mineral compositions, textural, and geochemical features of chimney ores were studied using ore microscope,scanning electron microscope, X-ray diffraction analysis, and electron microprobe techniques. Results show that there are three mineral assemblages for the hydrothermal chimney ores, namely：（i） anhydrite ＋ marcasite ＋ pyrite, （ii） pyrite ＋ sphalerite ＋ chalcopyrite, and （iii） chalcopyrite ＋ bornite ＋ digenite ＋ covellite. Mineral assemblages, zonational features, and geochemical characteristics of the ore minerals indicate that ore fluid temperature changed from low to high then to low with a maximum temperature up to 400 ℃. The chimney is a typical black smoker. The initial structure of the chimney was formed by the precipitation of anhydrites, and later the sulfides began to precipitate in the inner wall.

关键词： hydrothermal processes black smoker mineral assemblage exsolution texture ore fluid