Study on the Evolution Law of Temperature, Pressure, and Productivity near the Well for Gas Hydrate Exploitation by Depressurization

Rongrong Qi, Hongfeng Lu (), Chenlu Xu, Lu Yu, Changwen Xiao, Jinwen Du and Yan Li ()
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Rongrong Qi: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China
Hongfeng Lu: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China
Chenlu Xu: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China
Lu Yu: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China
Changwen Xiao: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China
Jinwen Du: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China
Yan Li: Guangzhou Marine Geological Survey, China Geological Survey, Guangzhou 511458, China

Energies, 2024, vol. 17, issue 15, 1-20

Abstract: In this paper, a one-dimensional model of gas–water two-phase productivity for hydrate depressurization is established, which takes into account permeability variation and gas–water two-phase flow. By solving the coupled algebraic equations of dissociation front position, equilibrium temperature, and pressure in an iterative scheme, the movement law of the hydrate dissociation front and the evolution process of temperature and pressure near the well were obtained, and the effects of bottom hole pressure, reservoir temperature, and hydrate saturation on productivity were analyzed. The results show that the hydrate reservoir is divided into a decomposed zone and an undecomposed zone by the dissociation front, and the temperature and pressure gradients of the former are greater than those of the latter. Reducing bottom hole pressure, increasing reservoir temperature, and increasing hydrate saturation all lead to an increase in temperature and pressure gradient in the decomposed zone. Methane gas production is a sensitive function of bottom hole pressure, reservoir temperature, and hydrate saturation. The lower the bottom hole pressure, the higher the reservoir temperature, the lower the hydrate saturation (within a certain range), and the higher the gas production rate. The trend of the water production curve is the same as that of gas, but the value is 3–4 orders of magnitude smaller, which may be due to the large difference in the viscosity of gas and water, and the gas seepage speed is much larger than that of water.

Keywords: gas hydrate; depressurization; dissociation front; productivity (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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