高温岩体システムでの炭酸カルシウム沈積からみたジオリアクターによるＣＯ２地中貯留の可能性

• 柳澤 教雄

  (独)産業技術総合研究所地圏資源環境研究部門

書誌事項

タイトル別名

• Possibility of "georeactor" for CO2 storage considered from precipitation of calcium carbonate of Hot Dry Rock system
• コウオンガンタイ システム デ ノ タンサン カルシウムチンセキ カラ ミタ ジオリアクター ニ ヨル CO2 チチュウ チョリュウ ノ カノウセイ

抄録

  Rock-water interaction in a Hot Dry Rock (HDR) system at Hijiori, Yamagata Prefecture, Northeast Japan, is studied from a view point of “georeactor” effect that is expected to fix CO₂ as Ca carbonates through mineral reactions in the HDR system. Mineralogy of HDR underground and precipitates in wells and pipelines are examined together with fluid geochemistry during a 3-month circulation test from June 1 to August 31, 2002. The study has revealed that, near the injection well, anhydrite in slightly altered granodiorite heat source (HDR) is dissolved in injected river water, which eventually precipitates as calcium carbonates. In HDR-2a well having lower temperatures, the carbonate precipitation using Ca in the produced hot water mainly took place in the pipeline system by degassing near the surface. In HDR-3 well with higher temperatures, Ca concentration in the fluid can be explained assuming calcite precipitation in the underground granodiorite at an amount up to 0.6 ton. Mass balance calculation on CO₂ in the whole system has further revealed that the amount of CO₂ injected into underground HDR was as large as 6 ton during the 3-month circulation test: this amount includes soluble CO₂ initially present in river water used for injection and atmospheric CO₂ absorbed in it. The calculation has shown different behaviors of CO₂ and related species (including calcium carbonate) between HDR-2a and HDR-3 wells. In the HDR-2a well, 67% of CO₂ reached the well has precipitated as calcium carbonate (aragonite and calcite) on pipeline system and 3% was discharged into atmosphere. In the HDR-3 well, the amount of CO₂ discharge is as high as 29% of the whole CO₂ reached there; the fixed CO₂ as calcite is estimated to be around 21%. The result of mass balance calculation indicates that the whole HDR system of the Hijiori site probably contributed mineralization of injected CO₂ associated with the circulation test. Equilibrium geochemical modeling adding extra- CO₂ in the Hijiori HDR system has been carried out to evaluate potential of CO₂ sequestration by the formation of carbonates. The modeling has shown that the potential of CO₂ mineral sequestration depends on the supply of Ca from the HDR, which probably has a strong linkage to the progress of geothermal alteration involving Ca-bearing minerals such as anhydrite and plagioclase.<br>

収録刊行物

• 岩石鉱物科学

  岩石鉱物科学 38 (5), 208-219, 2009

  一般社団法人　日本鉱物科学会

キーワード

• CO₂
• Hot Dry Rock (HDR) system
• Calcite
• Anhydrite
• Ca
• Fluid chemistry
• Scale

詳細情報

• CRID: 1390001206525474176
• NII論文ID: 10025444867
• NII書誌ID: AA1146088X
• DOI: 10.2465/gkk.38.208
• ISSN: 13497979
• ISSN: 1345630X
• NDL書誌ID: 10499505
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I10499505
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可