Numerical analysis on the rate-determining factors of depressurization- induced gas production from methane hydrate cores

Yoshihiro Konno*, Yoshihiro Masuda, Hiroyuki Oyama, Masanori Kurihara, Hisanao Ouchi

*この研究の対応する著者

研究成果: Conference contribution

7 被引用数 (Scopus)

抄録

Depressurization is a gas recovery method to dissociate methane hydrate (MH) by lowering wellbore pressure below the hydrate stability pressure. Depressurization method is considered to be the most promising method because the highest energy profit ratio could be achieved among proposed methods. However, the gas productivity of MH production wells is much different depending reservoir properties such as permeability and temperature. In order to understand the key factors for depressurization method, we performed laboratory scale depressurization experiments using artificial MH cores and analyzed the rate-determining factors of gas production by numerical simulations. There are three major factors to determine the depressurization-induced gas production rate: kinetic of MH dissociation, gas flow through the reservoir, and heat transfer to the dissociating zone. The gas production behavior significantly changes depending on these rate-determining factors. Thus, the analysis on rate-determining factors is crucial to understanding the gas productivity and is applicable for developing the strategy of depressurization-induced gas production. In order to analyze the rate-determining factors, we calculated the potential methane fluxes generated by kinetic of MH dissociation, gas flow and heat transfer, and compared these methane fluxes. We conducted numerical simulations using MH21-HYDRES (MH21 Hydrate Reservoir Simulator) to calculate the potential methane fluxes during MH dissociation. From the calculation and comparison of the potential methane fluxes in the experiments, we concluded that gas productions in the laboratory scale experiments were mainly limited by heat transfer. For a low permeability core, the fluid flow dominated gas production behavior in a very early stage. However, the rate-determining factor transited from the fluid flow to the heat transfer immediately because the permeability increased with time by hydrate dissociation. The kinetic of hydrate dissociation had a limited role in determining the gas production rate from MH hydrate cores. We also discussed the experimental condition required to simulate the gas production behaviors in field scale reservoirs. Analysis on rate-determining factors in field-scale hydrate reservoirs will be an issue in the future; it should give us a clue to 1) understanding the applicable reservoir conditions of depressurization method, and 2) developing the suitable Enhanced Methane Hydrate Recovery (EMHR) method for hydrate deposits expected poor productivity by depressurization.

本文言語English
ホスト出版物のタイトルOffshore Technology Conference 2010, OTC 2010
ページ1157-1166
ページ数10
出版ステータスPublished - 2010 12月 1
外部発表はい
イベントOffshore Technology Conference 2010, OTC 2010 - Houston, TX, United States
継続期間: 2010 5月 32010 5月 6

出版物シリーズ

名前Proceedings of the Annual Offshore Technology Conference
2
ISSN(印刷版)0160-3663

Conference

ConferenceOffshore Technology Conference 2010, OTC 2010
国/地域United States
CityHouston, TX
Period10/5/310/5/6

ASJC Scopus subject areas

  • 安全性、リスク、信頼性、品質管理
  • 海洋工学
  • エネルギー工学および電力技術
  • 機械工学

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