Sensitivity analysis of hydrate dissociation front conditioned to depressurization and wellbore heating

Study on the relations between controlling mechanisms and dissociation front of gas hydrate reservoirs

A methodology to predict the run-out distance of submarine landslides

The Last Phase

The upper part of the continental slope in the northern South China Sea is prone to submarine landslide disasters, especially in submarine canyons. This work studies borehole sediments, discusses geotechnical properties of sediments, and evaluates sediment stability in the study area. The results show that sediment shear strength increases with increasing depth, with good linear correlation. Variations in shear strength of sediments with burial depth have a significantly greater rate of change in the canyon head and middle part than those in the canyon bottom. For sediments at the same burial depth, shear strength gradually increased and then decreased from the head to the bottom of the canyon, and has no obvious correlation with the slope angle of the sampling site. Under static conditions, the critical equilibrium slope angle of the sediments in the middle part of the canyon is 10° to 12°, and the critical slope angle in the head and the bottom of the canyon is 7°. The results indicate that potential landslide hazard areas are mainly distributed in distinct spots or narrow strips on the canyon walls where there are high slope angles.

Geotechnical properties and stability of the submarine canyon in the northern South China Sea

A large number of submarine landslides with different scales have been identified in the canyon area of the submarine pipeline route of Liwan 3-1 gas field. There is still much chance that submarine slope failures would happen, and the following mass movement would present great risk to the submarine pipeline. In view of this, a numerical prediction method based on Eulerian-Eulerian two-phase flow model is introduced to simulate the mass movement of potential submarine landslides. The sliding soil and ambient water are respectively simulated by Herschel-Bulkley rheology model and Newtonian fluid model. The turbulence is simulated using the k-e model. Compared with both the experiment data and Bing result, the two-phase flow model shows a good accuracy, and its result is more close to the actual situation; the dynamic coupling between soil and ambient water can be effectively simulated and the phenomena of hydroplaning and head detachment can be obtained. Finally, the soil movement of a potential submarine landslide is simulated as an example, according to the seismic profile in the canyon area. The result shows that the hydroplaning occurs during the movement process. The runout distance calculated by the two-phase flow model is 877 m, which is 27.1% larger than the Bing result. However, the peak front velocity of soil is relative small, with a maximum value of 8.32 m/s. The Bing program with a simple and rapid process can be used for a preliminary evaluation, while the two-phase flow model is more appropriate for an accurate assessment.

Runout prediction and dynamic characteristic analysis of a potential submarine landslide in Liwan 3-1 gas field

• Use DeST to simulate the energy consumption in different climate zones. • MARKAL model was proposed for energy coupling and renewable energy ratio. • Total energy consumption was predicted using energy conversion efficiency. • The proportion of renewable energy is expected to be 29.2% by 2050. The building sector is one of the largest energy user and carbon emitters globally. To increase the utilization rate of renewable energy and reduce carbon dioxide emissions, the optimal technical scheme of active public institutions and coupled utilization of renewable energy is studied. In this study, the energy consumption of three types of public institutions in various regions of China was simulated by using DeST building energy consumption software, combined with energy conversion efficiency and data released by the National Bureau of Statistics, and the total energy demand and total energy supply of public institutions were predicted using the load density method. Based on the coupling mechanism of the MARKAL model, the optimal proportion of renewable energy in the energy supply of public buildings in different regions is determined. Through the study of the number of public institutions in various regions of China, energy consumption characteristics, construction area, and other related data, the reverse energy flow method is creatively proposed, and the active and renewable energy coupling algorithm from the energy demand side of public institutions to the energy supply side is established. The results show that the central region has the highest utilization rate of renewable energy in the public sector, reaching 36.18%. The use of renewable energy in public buildings in hot summer and warm winter zones decreased to 35.08%, and it was 12.82% in cold zones. By 2025, the proportion of renewable energy resources in China is expected to reach 29.2%. The energy coupling model and algorithm constructed in this paper can provide a basis for the coupling macro configuration of renewable energy in public institutions in China. 

Jianghui Yang

Papers

Runout prediction and dynamic characteristic analysis of a potential submarine landslide in Liwan 3-1 gas field

The Optimization Research on the Coupled of Active and Passive Energy Supplying in Public Institutions in China