Investigation into the Water Jet Erosion Efficiency of Hydrate-Bearing Sediments Based on the Arbitrary Lagrangian-Eulerian Method

Chen Chen,Lin Yang,Yong Cheng,Bing Li,Dongbin Pan,Chengcai Jin,Han Zhang,Xiuping Zhong,Xitong Li

doi:10.3390/app9010182

Abstract

As an innovative way to exploit marine natural gas hydrates (NGH), the solid fluidization exploitation method is to erode hydrate-bearing sediment (HBS) into fine particles by a water jet and transport the particles to an offshore platform. To investigate the water jet erosion efficiency of HBS under various work parameters, such as jet velocity, standoff distance, and nozzle diameter, the Arbitrary Lagrangian–Eulerian (ALE) method was adopted to establish numerical models based on the characteristics of HBS in the South China Sea, and orthogonal experiments were performed to optimize the work parameters. The results show that the water jet erosion efficiency of HBS increases with the increase in jet velocity and nozzle diameter, however it decreases with the increase in standoff distance. The jet velocity is the most significant factor for the erosion efficiency and there exists a threshold velocity which describes the minimum jet velocity required to erode HBS. In addition, comprehensive analysis of the results of the orthogonal experiments indicates that, when the jet velocity is 150 m·s−1, the standoff distance is 0.5 cm, and the nozzle diameter is 2.5 mm, the maximum erosion volume can be obtained, which is 6.0329 cm3. This research provides valuable theoretical support for the solid fluidization exploitation of marine NGH.

Highlights

Natural gas hydrates (NGHs) are white crystalline compounds formed by the interaction of light hydrocarbons, carbon dioxide, and hydrogen sulfide with water under low-temperature and high-pressure coexisting conditions [1]
The results indicate that the jet velocity, the standoff distance, and the nozzle diameter have an an important influence on the water jet erosion of targets
hydrate-bearing sediment (HBS) byInmeans of numerical simulation, and this paper provides theoretical mechanism this paper, a preliminary attempt was made to reveal the valuable mechanism of water support for the solid fluidization exploitation of marine NGH

Summary

Introduction

Natural gas hydrates (NGHs) are white crystalline compounds formed by the interaction of light hydrocarbons, carbon dioxide, and hydrogen sulfide with water under low-temperature and high-pressure coexisting conditions [1]. NGH is regarded as having the most potential as alternative energy in the 21st century because of its numerous potential resources [2,3]. There has been a worldwide upsurge in the exploration, production, and development of NGH. The safe, efficient, and environmentally friendly exploitation of NGH resources has become a worldwide focus [4,5,6,7]. Common methods of NGH exploitation include depressurization, thermal stimulation, inhibitor injection, and carbon dioxide (CO2 ) replacement [9,10,11,12].

Methods

Discussion

Conclusion