Oceanic mesoscale eddies typically span tens to hundreds of kilometers and last several weeks to months. They are a key dynamic process influencing the distribution of oceanic energy, affecting energy budgets, heat distributions, and material transport. Advances in satellite remote sensing and in situ observation over the past half-century have substantially enhanced our understanding of the statistical properties, energetics, and dynamic mechanisms of mesoscale eddies, establishing this field as a major focus in physical oceanography. This article presents a comprehensive review of recent advancements in 6 key areas of mesoscale eddy research: (a) eddy detection methods and data products (leading automated detection methods and the corresponding eddy datasets and data products currently available), (b) eddy generation and dissipation (eddy generation, development, and dissipation mechanisms), (c) energy cascades (energy cascades between eddies, large-scale circulation and submesoscale processes, the role of these processes in modulating the energy transfer of near-inertial internal and surface waves, and research progress in related parameterization), (d) air–sea interaction (eddy-induced interactions, especially the interaction between eddies and typhoons), (e) interdisciplinary studies (impacts of eddies on biogeochemistry, acoustics, and other related fields), and (f) observation studies (programs dedicated to studying mesoscale eddies through in situ observation). This article also discusses research prospects on mesoscale eddies.

It has been a great challenge for the oil and gas industry to timely identify any electrical submersible pump (ESP) abnormal performance to avoid ESP failure. Given the high cost of the ESP failure, more and more real-time surveillance systems are applied to monitor ESP performance to generate alarms in the case of failures. This paper presents a robust principal component analysis (PCA) model to perform fault detection for ESP systems continuously. A three-dimensional plot of scores of principal components was used to observe different patterns during the stable and failure periods. 47 cases of actual failure events and 40 cases of stable operating events were tested on the robust PCA model to generate prediction results. The testing results demonstrate that the robust PCA model has managed to identify 20 failure events before the actual failure time out of the 47 failure cases and has successfully distinguished all the 40 stable operating wells. This study has concluded that PCA has the potential to be used as a monitoring platform to recognize dynamic change and therefore to predict the developing failures in the ESP system.

During the process of gas production in high-pressure, high-temperature (HPHT) gas wells, the choke valve, as the most vital component of the surface control equipment, plays a significant role in regulating the output and reducing the fluid pressure to ensure the safety of surface gathering and transportation equipment. High-pressure, high-velocity fluid flow and solid-phase particles cause deterioration of the choke valve. With the enhancement of intelligent and digital oilfields, conventional choke valves have been progressively replaced by electric choke valves. Due to the complex structure of the throttle valve, the flow path and the velocity state of the fluid in the throttle valve, and the distribution law of the erosion fraction are quite distinctive from those in the ordinary throttle valve, meriting further research. In this paper, a simulation of computational fluid dynamics (CFD) was conducted to determine the effects of the pressure distribution, fluid state, divergent particle sizes, and sand volume on the erosion rate of the choke valve. Under various valve openings, the fluid state and the location of high-risk points can be ascertained. The large particle size (diameter greater than 6 mm) of sand and gravel is convenient for causing concentrated erosion in the position of the valve hole, which induces the channel diameter to expand. Fine silt sand (diameter from 0.1 mm to 1 mm) gives rise to relatively uniform abrasion to the choke’s current-facing surface. This study can optimize the layout of the choke valve and reduce the cost and number of switching wells, thereby decreasing the frequency of maintenance and the pressure fluctuation’s effect on the formation.

A coupled reservoir/wellbore simulator is essential for solving relevant flow phenomena with dynamic interactions between reservoir and wellbore in two-phase flow systems. A reservoir simulator or wellbore simulator alone fails to solve these transient flow phenomena. This paper summarises a critical review of the coupled reservoir and wellbore simulation. First, a wide application of the drift-flux (DF) models to simulate gas–liquid flow in a wellbore model coupling to a reservoir model was discussed. Then, the mechanisms of the coupled reservoir/wellbore simulator in two-phase flow systems were discussed, including the reservoir modeling, wellbore modeling, and their coupling schemes. Various examples of representative coupled simulators were presented. Finally, some case studies were reported to reveal dynamic interactions between wellbore and reservoir by using the coupled reservoir/wellbore simulators. This study gives the most up-to-date and systematic sights on the relevant research topic of reservoir/wellbore coupling, allowing for a better understanding of the coupled reservoir and wellbore simulation and its application in the oil and gas industry.