Volume 04: Proceedings of 11th International Conference on Applied Energy, Part 3, Sweden, 2019

Numerical Investigation on The Erosion Process of Hydrate Materials Using Water Jet Yiqun Zhang, Kexian Zhao, Gensheng Li, Xiaodong Hu, Xiaoya Wu

Abstract

Natural gas hydrate (NGH) is a potential fuel resource. Radial Jet Drilling (RJD), turning sharply in the casing and drilling laterals by using water jet, is a valid approach to solve problems of high cost, low efficiency and formation collapse during the exploitation of NGH resources in permafrost and continental margins. Traditional finite element methods, which tend to produce mesh distortion, cannot accurately depict the water jet drilling efficiency. This paper presents a numerical investigation of Arbitrary Lagrangian Eulerian (ALE) method for analyzing both NGH and Hydratebearing Sediments (HBS) erosion process using water jet. Firstly, a coupled nozzle‐target model is solved by ALE method. The material constitutive models are established based on the characteristics of water, NGH and HBS. After that, several case studies are conducted in air, submerged water and confining pressure environments (different working conditions). Not only the flow field, but also the deformation and erosion of the materials induced by water jet are estimated. Finally, the simulation results, such as damage field, variation of internal material stress and erosion pit characteristic, are compared with each other. The relation curves between erosion depth and hydraulic parameters are consistent with the experimental results. The results show that the ALE method can better simulate the water jet flow field, by which the water jet rock breaking simulation is more in line with the reality and accurately predict the fracture result. Additionally, water jet has obvious destructive/damage effect on NGH and HBS, the presence of confining pressure will inhibit the breaking of materials.

Keywords Natural gas hydrate, Water jet, Erosion, Numerical simulation, Arbitrary Lagrangian Eulerian method

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