Mathematical model of salt cavern leaching for gas storage in high-insoluble salt formations

Jinlong Li,Tongtao Wang,Xilin Shi,Hongling Ma,Yinping Li,Chunhe Yang

doi:10.1038/s41598-017-18546-w

Jinlong Li, Tongtao Wang + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-18546-w

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Abstract

A mathematical model is established to predict the salt cavern development during leaching in high-insoluble salt formations. The salt-brine mass transfer rate is introduced, and the effects of the insoluble sediments on the development of the cavern are included. Considering the salt mass conservation in the cavern, the couple equations of the cavern shape, brine concentration and brine velocity are derived. According to the falling and accumulating rules of the insoluble particles, the governing equations of the insoluble sediments are deduced. A computer program using VC++ language is developed to obtain the numerical solution of these equations. To verify the proposed model, the leaching processes of two salt caverns of Jintan underground gas storage are simulated by the program, using the actual geological and technological parameters. The same simulation is performed by the current mainstream leaching software in China. The simulation results of the two programs are compared with the available field data. It shows that the proposed software is more accurate on the shape prediction of the cavern bottom and roof, which demonstrates the reliability and applicability of the model.

Highlights

The usage of natural gas resources strongly fluctuates according to the season, while the gas well production is stable[1,2]
The insoluble substances detached from the salt wall, and accumulated on the cavern bottom as loose insoluble particles with larger volume
For the further development of the construction of salt cavern gas storage in China, this paper proposes a prediction model of the single-well cavern leaching process in high-content insolubles salt formations

Summary

Introduction

The usage of natural gas resources strongly fluctuates according to the season, while the gas well production is stable[1,2]. Li et al.[23] set up a model to simulate the repair process of irregularly shaped salt cavern by re-leaching under gas They conducted indoor experiments and field tests, the simulation results coincide well with the experimental results and field data, while the simulation of insolubles accumulation was not mentioned. Most of these researches only considered the case of cavern form control in pure or low- insoluble salt rock. For the further development of the construction of salt cavern gas storage in China, this paper proposes a prediction model of the single-well cavern leaching process in high-content insolubles salt formations. The comparison of the simulation results and the field data demonstrates the validity and accuracy of the proposed model

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Conclusion