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CO2 flooding has been widely applied in lots of low permeability reservoirs. After extensive CO2 injection, some reservoirs began to show serious gas channeling problems. CO2 foam had been successfully used to solve gas channeling problems due to its advantages of water selective plugging features (not plugging oil). In this paper, a novel CO2 foam system was developed for high temperature and high salinity(HTHS) (85 ℃, 60,000 mg/L) aiming at solving the gas channeling in Changqing Oilfield. Taking the foam half-life as the evaluation standard, the optimum foam system (0.5 wt% EC-1 + 1 wt% SiO2) for the target reservoir was determined. The influences of temperature, salinity and pressure on the CO2 foam performance were studied by high temperature and high pressure(HTHP)method. The ability and mechanism of anti-gas channeling were studied by experiments of sand packed tube and microscopic displacement, respectively. The results showed that the foam system possessed good foam properties at HTHS with pressure. As the concentration of SiO2 nanoparticles increased, the resistance factor of the foam system increased. However, temperature showed an adverse effect on foam stability, the resistance factor decreased with the increase of temperature. The Jamin superposition and emulsion plugging mechanism of foam system was revealed by microscopic displacement experiments.

The outbreak of the COVID-19 epidemic brings huge consequences on the global economy and health. Diverse restrictive policies have been enforced to prevent the novel Coronavirus from spreading. During the COVID-19 pandemic, the express logistics companies transport essential goods among different regions in China, supporting people's normal lives. This study explores the dynamic impacts of COVID-19 epidemic on the intra-provincial and inter-provincial express parcel flows based on the statistical and econometric analysis considering the individual-specific effects of each province. The key results obtained from the unique long-run panel data analysis are: (1) the temporal fluctuation of inter-provincial express logistics flows affected by the epidemic is stronger than that of intra-provincial flows, both of which also show significant spatial heterogeneity; (2) the process of China's fighting against the COVID-19 pandemic is divided into four stages according to the severity of pandemic and implications of restrictive policies, which have moderating effects for the impacts on the express logistics; (3) the dynamic effects of the pandemic on the express logistics are obviously heterogeneous in different stages, confirming the effectiveness of restrictive and support policies; (4) the delayed effects of COVID-19 epidemic on the regional express logistics vary with different setting of time lags. In the short term, the typical restrictive policies and Chinese Spring Festival holidays have significant negative effects on the express logistics. In the long term, the resumption of work and production stimulate the demands of express logistics, presenting significant positive effects in post-epidemic era. This study can provide the policy implications for the logistics planning and management under the public health intervention.

According to the tourism-led economic growth (TLEG) hypothesis, the development of tourism encourages economic growth. However, the effects of TLEG are not obvious in the areas of China predominant...

Microemulsion, because of its excellent interfacial tension reduction and solubilization properties, has wide range of applications in the petroleum industry, especially in improved oil recovery (IOR). Herein, the concept, types and formation mechanism of microemulsion were primarily introduced. Then, the preparation and characterization methods were illustrated. Additionally, several effect factors were elaborated specifically based on the composition of microemulsion. Finally, the application of microemulsion in IOR was addressed, including IOR mechanism analysis based on sweep efficiency and displacement efficiency, injection method (microemulsion flooding, in-situ microemulsion formation) and field tests. Furthermore, the current challenges and prospects of microemulsion on IOR were analyzed.

The coupling and development of cultural industry and tourism industry is the inevitable trend of industrial development in the new era. Based on the cultural industry and tourism industry data of East China in 2000-2017, this paper uses the coupling coordination degree model to calculate the development level of cultural industry and tourism industry, and then derives the coupling type of cultural industry and tourism industry. The results show that: there is a coupling relationship between the cultural industry and the tourism industry in East China, and the development level of the two is increasing year by year; overall, the cultural industry in East China lags behind the tourism industry. Therefore, East China should use tourism resources to develop cultural industries and achieve balanced and coordinated development of cultural industries and tourism industries.

The study aims to investigate the impact of innovation on economic growth among the G7 and BRICS countries. Our data was retrieved from the World Development Indicators database (World Bank 2019) from the period 2000-2017. Innovation is measured by R&D, patents, and trademarks. This research explored how GDP per capita reacts to a shock from R&D, patent, and trademark among G7 and BRICS countries. Stationarity tests are conducted through panel unit-roots tests. The authors employed a GMM style panel VAR estimator to investigate the phenomenon. Our results revealed that R&D, patent, and trademark as the determinants of innovation have a significant impact on GDP per capita also as a determinant of economic growth among G7 and BRICS countries. However, the impact is more among the G7 than the BRICS countries. The impulse response function of the panel VAR estimates shows that the impact of one standard deviation shock in R&D, patent, and trademark on GDP per capita varies from year one to year ten among these variables for both G7 and BRICS countries.

In order to evaluate the performance and mechanism of de-emulsification for amphiphilic polymer produced oil in water (O/W) emulsion,the environmentally friendly β-cyclodextrin (β-CD) was chosen as a reverse demulsifier. Viscosity of amphiphilic polymer solution (APP4) and de-emulsification rate of the O/W emulsion were determined by rheometer and stability analyzer. The de-emulsification mechanism of β-CD was explored by measuring the interfacial tension, three-stage rheology and continuous phase viscosity. The results showed that the highest dewatering rate of the O/W emulsion with β-CD could reach 90 %. When the NaCl concentration increases, instability of the O/W emulsion increased. Temperature has little effect on demulsification. The reason for demulsification was that hydrophobic chain of APP4 is included by β-CD. The host–guest inclusion interaction could effectively disassemble the network structure of APP4, resulting in the large decrease of the structural viscosity. APP4 could not be adsorbed on oil–water interface, the droplets tended to grow up quickly. Thus, β-CD could be applied as an effective reverse demulsifier for O/W emulsion formed by amphiphilic polymer.

Blockage is a common problem in the development of water-flooding reservoirs. The key to solve this problem is to determine the composition and distribution rules of the blockage. In this work, the location distribution and components of blockage were analyzed by one-dimensional (1D) and two-dimensional (2D) cores, and x-ray diffraction and differential weight methods. The blockage formation mechanism was also studied. The 1D experimental results show that the blocking locations of the inlet and outlet ends are 3/10 and 8/10, respectively (1D core is divided into 10 equidistant sections; “3/10” refers to the three sections from the inlet end and “8/10” refers to the two sections from the outlet end). The blockage near the inlet is mainly composed of inorganic scale, which is formed by a combination of the carbonate and coarse sand particles. However, the blockage near the outlet is mainly composite scale, which is formed by the fine particles and inorganic scale with heavy oil. In addition, the water sensitivity with clay leads to the decrease in permeability. This work provides a theoretical and scientific basis for the development of technology to effectively prevent reservoir blockage.

Nanoemulsions consist of small particle size, uniform dispersion, and long-term stability, making them suitable for use in enhanced oil recovery for low-permeability reservoirs. In this paper, an ultrastable oil-in-water nanoemulsion was prepared using the emulsification inverse phase method at a constant temperature. Rheology, multiple-light scattering, laser particle size analyzer, and optical microscope were used to determine the effects of the emulsifier and water content, salinity, and reservoir temperature on the stability of the prepared nanoemulsion. The oil washing performance of nanoemulsion was tested by the weight-loss method. Results show that the nanoemulsions tend to be stable with an increase in the emulsifier content (≥8 wt. %). As the water content increases, the viscosity of nanoemulsions gradually decreases as well as its elasticity. The salinity and temperature are found to have minor effects on the stability of nanoemulsions. At the same time, the oil washing efficiency of nanoemulsion can reach as high as 83%. Hence, this study will provide theoretical supports and guidelines for the preparation of highly efficient nanoemulsion flooding systems for low-permeability reservoirs.

Short-term traffic prediction is vital for intelligent traffic systems and influenced by neighboring traffic condition. Gradient boosting decision trees (GBDT), an ensemble learning method, is proposed to make short-term traffic prediction based on the traffic volume data collected by loop detectors on the freeway. Each new simple decision tree is sequentially added and trained with the error of the previous whole ensemble model at each iteration. The relative importance of variables can be quantified in the training process of GBDT, indicating the interaction between input variables and response. The influence of neighboring traffic condition on prediction performance is identified through combining the traffic volume data collected by different upstream and downstream detectors as the input, which can also improve prediction performance. The relative importance of input variables for 15 GBDT models is different, and the impact of upstream traffic condition is not balanced with that of downstream. The prediction accuracy of GBDT is generally higher than SVM and BPNN for different steps ahead, and the accuracy of multi-step-ahead models is lower than 1-step-ahead models. For 1-step-ahead models, the prediction errors of GBDT are smaller than SVM and BPNN for both peak and nonpeak hours.