Nonlinear Analysis of Tropical Waves and Cyclogenesis Excited by Pressure Disturbance in Atmosphere

The horizontal equations of motion for an inviscid homogeneous fluid under the influence of pressure disturbance and waves are applied to investigate the nonlinear process of solitary waves and cyclone genesis forced by a moving pressure disturbance in atmosphere. Based on the reductive perturbation analysis, it is shown that the nonlinear evolution equation for the wave amplitude satisfies the Korteweg–de Vries equation with a forcing term (fKdV equation for short), which describes the physics of a shallow layer of fluid subject to external pressure forcing. Then, with the help of Hirota’s direct method, the analytic solutions of the fKdV equation are studied and some exact vortex solutions are given as examples, from which one can see that the solitary waves and vortex multi-pole structures can be excited by external pressure forcing in atmosphere, such as pressure perturbation and waves. It is worthy to point out that cyclone and waves can be excited by different type of moving atmospheric pressure forcing source.

Pressure-forced meteotsunami occurrences in the eastern Yellow Sea over the past decade (2010–2019): monitoring guidelines

The eastern Yellow Sea meteotsunami occurrences between 2010 and 2019 and guidelines derived using favourable conditions of pressure disturbance (10 min rate of air pressure change) for meteotsunami generation are described. A total of 34 meteotsunami events over the past decade can be classified based on a current meteotsunami monitoring and observation system. 1 min intervals of mean sea level pressure and sea level observations from 89 meteorological stations and 16 tide gauges are analysed. Most of the classified meteotsunami events (76 %, 26/34) in the eastern Yellow Sea are found to be between February and June during the winter-to-summer transition, which shows a strong seasonal trend. The meteotsunami occurrences are spatially frequent at the DaeHeuksando (DH) tide gauge, known as a beacon tide gauge of the observation system. It appears that the specific characteristics (intensity, occurrence rate, and propagation) of the pressure disturbance are in common on extreme meteotsunami events that are classified by applying the hazardous meteotsunami conditions among the 34 events. For a risk level assessment of the eastern Yellow Sea meteotsunami occurrences, favourable conditions of the pressure disturbance for meteotsunami generation are utilized. Overall, this study can provide useful and practical guidelines such as operation period, potential hot spot, and risk level to monitoring system operators when operating the monitoring system of the Yellow Sea.

Numerical Modeling of Coupled Fluid Flow and Geomechanical Stresses in a Petroleum Reservoir

A fully coupled hydro and geomechanical model has been used to predict the transient pressure disturbance, reservoir deformation, and effective stress distribution in both homogeneous and heterogeneous reservoirs. The heterogeneous reservoir is conceptualized by explicitly considering the spatial distributions of porosity and permeability as against assuming it as constant values. The finite element method was used in the coupled model in conjunction with the poroelasticity. Transient pressure disturbance is significantly influenced by the overburden during the production in both homogeneous and heterogeneous reservoirs for all the perforation schemes. Perforation scheme 2 provides the optimum reservoir performance when compared with other three schemes in terms of transient pressure distribution and reservoir subsidence. It also has the ability to overcome both the water and gas coning problems when the reservoir fluid flow is driven by both gas cap and water drive mechanisms. A Biot–Willis coefficient is found to significantly influence both the pressure and stress distribution right from the wellbore to the reservoir boundary. Maximum effective stresses have been generated in the vicinity of the wellbore in the reservoir at a high Biot–Willis coefficient of 0.9. Thus, the present work clearly projects that a Biot–Willis coefficient of 0 cannot be treated to be a homogeneous reservoir by default, while the coupled effect of hydro and geomechanical stresses plays a very critical role. Therefore, the implementation of the coupled hydro and geomechanical numerical models can improve the prediction of transient reservoir behavior efficiently for the simple and complex geological systems effectively.