Search results for: Dongqi Ji

Authors: Dongqi Sun, Juan Tao, Yingying Wu

Abstract:

This paper reexamines the appropriateness of contrarian trades as a proxy of informed trades, using high frequency Chinese stock data. Employing this measure for 5 minute intervals, a U-shaped intraday pattern of probability of informed trades (PIN) is found for the CSI300 stocks, which is consistent with previous findings for other markets. However, while dividing the trades into different sizes, a reversed U-shaped PIN from large-sized trades, opposed to the U-shaped pattern for small- and medium-sized trades, is observed. Drawing from the mixed evidence with different trade sizes, the price impact of trades is further investigated. By examining the relationship between trade imbalances and unexpected returns, larges-sized trades are found to have significant price impact. This implies that in those intervals with large trades, it is non-contrarian trades that are more likely to be informed trades. Taking account of the price impact of large-sized trades, non-contrarian trades are used to proxy for informed trading in those intervals with large trades, and contrarian trades are still used to measure informed trading in other intervals. A stronger U-shaped PIN is demonstrated from this modification. Auto-correlation and information advantage tests for robustness also support the modified informed trading measure.

Keywords: contrarian trades, informed trading, price impact, trade imbalance

Procedia PDF Downloads 169

Authors: Dongqi Li, Yunjia Huang, Tomo Inoue, Kohei Inoue

Abstract:

With urbanization, urban cultural heritage is facing the impact and destruction of modernization and urbanization. Many historical areas are losing their historical information and regional cultural characteristics, so it is necessary to carry out systematic color planning for historical areas in conservation. As an early focus on urban color planning, Japan has a systematic approach to urban color planning. Hence, this paper selects five merchant towns from the category of important traditional building preservation areas in Japan as the subject of this study to explore the color structure and emotion of this type of historic area. First, the image semantic segmentation method identifies the buildings, roads, and landscape environments. Their color data were extracted for color composition and emotion analysis to summarize their common features. Second, the obtained Internet evaluations were extracted by natural language processing for keyword extraction. The correlation analysis of the color structure and keywords provides a valuable reference for conservation decisions for this historic area in the town. This paper also combines the color structure and Internet evaluation results with generative adversarial networks to generate predicted images of color structure improvements and color improvement schemes. The methods and conclusions of this paper can provide new ideas for the digital management of environmental colors in historic districts and provide a valuable reference for the inheritance of local traditional culture.

Keywords: historic districts, color planning, semantic segmentation, natural language processing

Procedia PDF Downloads 97

Authors: Chenqi Ge, Dongqi Ji, Yiquan Yan, Zhewei Chen, Zhengdong Lei, Zhangxing Chen, Gang Hui

Abstract:

CO₂ injection has emerged as a promising technique to enhance oil recovery in continental shale reservoirs by addressing challenges such as low sweep efficiency caused by micro-to-nano-scale heterogeneities and rapid production decline due to low reservoir pressure. This study evaluates the potential of CO₂ injection for improving shale oil productivity and sequestration efficiency through numerical simulations that incorporate nano-confined phase behavior, oil displacement mechanisms, water-oil imbibition, cross-scale flow characteristics, and dynamic fracture properties. Two major continental shale oil reservoirs in China, Gulong (pure shale deposition) and Jimsar (mixed deposition), are analyzed to assess the feasibility of CO₂-enhanced oil recovery. The study models spatially dependent fluid phase behavior by differentiating between matrix and fractures, while multiscale fluid flow, ranging from nanopores to fractures and wellbores, is simulated using a hybrid multiple-interacting-continua and discrete fracture network approach. Model validation is achieved through comparison with historical production data, achieving over 85% agreement in production rates. The effects of cross-scale oil flow and CO₂ channeling on sequestration and oil production efficiency are investigated for both reservoirs. The comparative analysis reveals distinct mechanisms governing CO₂-enhanced oil recovery in the two reservoirs. In the Gulong shale, CO₂ injection at high pressure expands bedding fractures, enhancing connectivity between the nano-scale matrix and fractures. Additionally, slow CO₂ diffusion into the tight matrix promotes oil displacement and long-term sequestration. Conversely, in the Jimsar shale, CO₂ injection primarily enhances oil mobility by reducing viscosity from 50 cp to below 5 cp. The relatively larger matrix pore structure and lower minimum miscibility pressure in Jimsar lead to higher sweep efficiency during CO₂ displacement. Simulation results also indicate that CO₂ utilization efficiency in Jimsar surpasses that in Gulong. This study introduces an integrated numerical simulation approach that combines spatially dependent phase behavior with multiscale flow modeling to evaluate the interplay between oil productivity and CO₂ sequestration in shale reservoirs. The findings provide insights into optimizing CO₂ injection strategies for different shale reservoir types, offering a pathway for sustainable CO₂ utilization in enhanced oil recovery operations.

Keywords: shale oil, CO₂ displacement, CO₂ sequestration, enhanced oil recovery

Procedia PDF Downloads 6

Authors: Chenqi Ge, Dongqi Ji, Yishan LIU, Zhengdong Lei, Zhangxing Chen, Gang Hui

Abstract:

Shale oil is the dominant contributor to global unconventional oil resource production. Compared to conventional oil and gas, shale oil productivity is significantly constrained by nano-confinement effects, which hinder oil flow from nano-pores (primary storage locations) to micro-fractures (main flow channels). Besides, the compact micro-fractures of low permeability cannot provide efficient flow channels to production well. These constraints result in inefficient oil displacement and fast production decline. Increasing temperature can simplify the phase change process and potentially enhance micro-fracture permeability by dilation. This study explores the potential of electrical heating enhanced shale oil flow by wind power transition, which can unlock the oil from tight shale oil formations. A non-isothermal numerical simulation approach is developed to model the thermal effects on shale oil flow dynamics. The model integrates nano-confined phase behavior, phase transition mechanics, multi-scale flow processes, heat transfer, and fracture dilation. A modified equation of state accounts for capillary pressure, adsorption, and nano-confinement. A coupled thermo-mechanical phase-field model simulates thermally induced micro-fractures. Model validation is performed by comparing simulation results against nano-scale experimental data. Further validation is conducted by the oil production performance comparison of simulation results and field history. Comparative analysis of the isothermal production method and electrical heating improvement approach in shale oil production confirm that elevated temperature improves oil phase consistency from nano-pores to fractures and increases micro-fracture permeability. As a result, oil flow is accelerated from tight formation to production well and thermal treatment makes a promising approach for shale oil production enhancement. Numerical simulation demonstrates that heat is primarily generated in the zone of high salinity saturation due to its high dielectric values. Meanwhile, the in-situ oil is simultaneously heated by conduction. Computation of energy efficiency provides that 100 % electric power can be transformed into heat in a shale oil formation by the ohm effect. Key results show that pore size dictates the target heating temperature, while shale mineral thermal expansion coefficients influence fracture initiation and dilation. Additionally, simulations indicate that a temperature increase of approximately 100°C significantly enhances shale oil mobility by improving phase change consistency from nano-pores to fractures and micro-fracture permeability. This study provides a computation framework for evaluating the effectiveness of thermal treatment in overcoming shale oil nano-confinement and compact fracture challenges.

Keywords: shale oil, thermally enhance oil recovery, nano-confinement, phase behavior, electric excitation

Procedia PDF Downloads 5