著者

田中 敦子 坂本 靖英 眞弓 大介 東野 晴行 坂田 将 中尾 信典

雑誌

日本地球惑星科学連合2015年大会

巻号頁・発行日

2015-05-01

---

化石燃料をエネルギー源とする発電所で燃焼によって発生するCO2や、天然ガス・石油等の精製所から精製の工程で発生するCO2を処理する手段として、CO2地中貯留技術が期待されている。CO2地中貯留技術は、臨界状態の密度の高いCO2を地中に隔離するため、大量のCO2の固定が可能である。CO2地中貯留の対象とされる地層は主にかん水層や枯渇したガス油田である。 CO2地中貯留(CCS)の重要な候補サイトの一つとなっている枯渇油ガス田には、未回収の原油が半分以上残されている。近年眞弓らは、油ガス貯留層内に自然に存在する嫌気性の特定の微生物のメタン生成能力が、CO2分圧の上昇によって活性化されることを見出した 。これは枯渇油ガス田を対象としたCCSサイトにおける、原位置での天然ガス資源創成の可能性を示唆するものと言える。 このような地下環境における微生物活動を考慮した新たな資源創成型のCCS技術を確立するためには、まず、微生物によるメタン生産量とCO2固定量をはじめとする諸元の定量的に評価して便益を把握する必要がある。 我々は、微生物活動を考慮した新たな資源創成型のCCS技術の基本的な便益を明らかにすることを目標に、地層モデルに地下微生物の働きを組み込み、CCSプロセスにおける地層モデルの挙動とメタン産出量の評価を行うとともに、CO2地中貯留にかかわるサイト周辺の環境インパクト評価および産業安全面のリスクアセスメントを進めている。CO2地中貯留サイトの地下の貯留層・地表・注入井坑口周辺の大気環境をとりあげて、CO2漏洩のリスクの評価を進めるとともに、CO2地中貯留リスク評価プログラムを開発中である。本報告ではこれらの取り組みの中から、とりわけサイト周辺のリスク評価について報告する。

著者

藤井 孝志 菅井 裕一 佐々木 久郎 橋田 俊之 當舎 利行 中尾 信典

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.129, no.12, pp.701-706, 2013-12-01 (Released:2014-12-01)

参考文献数

17

被引用文献数

1 1

---

Understanding of interfacial interactions among supercritical CO2 (scCO2), water, and mineral phase is necessary for a precisely prediction of CO2 migration into aquifers. The purpose of this study is to assess the impact of scCO2 on flow property of Kimachi sandstone and Iidate granite in a CO2 rich dense phase i.e., the condition of which scCO2 is expected to displace formation water in the course of CO2 injection. In this experiment, the permeability test for CO2 gas was conducted before and after a CO2 saturation procedure that is filled with scCO2 in pores of rocks. To investigate a mechanical property of rock specimen in the presence of scCO2, the axial strain was also measured using a laser displacement sensor during scCO2 saturation processes. Our results showed that both Kimachi sandstone and Iidate granite samples tested have a more or less decreasing trend of gas permeability with increasing exposure time to scCO2. It was further shown that the axial strain of Kimachi sandstone and Iidate granite increased as scCO2-exposure time increased. Additionally, increases in masses and dimensions of test samples before and after scCO2 saturation processes were clearly observed under atmospheric pressure conditions. It can, therefore be said that Kimachi sandstone and Iidate granite could be capable of swelling and permeability change accompanied by CO2 sorption into their internal structures in the presence of scCO2. Furthermore, the observed significant reduction in permeability cannot fully be explained by two model predictions based on Kozeney-Carman equation and Hagen-Poiseuille law, considering CO2 sorption onto mineral phases. The present results pointed out that CO2 sorption on rocks under geological CO2 storage conditions could have a significantly impact on flow property of rocks during CO2 injection and storage processes.

著者

中尾 信典

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.138, no.1, pp.10-11, 2022-01-31 (Released:2022-01-28)

著者

徂徠 正夫 後藤 宏樹 杉原 光彦 西 祐司 中尾 信典

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.137, no.4, pp.46-50, 2021-04-30 (Released:2021-04-28)

参考文献数

17

---

Toward the implementation of geological CO2 storage, cost reduction of CO2 monitoring during and after injection into targeted reservoirs is the key issue. The continuous gravity measurement using a superconducting gravimeter, which has been applied to the demonstration project site in Japan ahead of the rest of the world, has a potential to resolve the issue from the viewpoint of a complement to the high-cost seismic survey. The concept is such that the continuous gravity measurement is substituted for constant monitoring and that the use of seismic survey could be limited only when any anomaly is detected. The comparison of the monitoring cost after the completion of CO2 injection indicated that applying gravity measurement can reduce costs by up to 15 to 50% of the seismic cost. The current detection limit of gravity change is around 1 μGal based on the application result in the coastal area in Japan. However, the time series analysis using pseudo gravity data suggested the possibility of anomaly detection even below the detection limit. Further improvement of analysis precision would lead not only to more rapid and more reliable anomaly detection but also to contribution to the cost reduction during the CO2 injection period.

著者

加野 友紀 石戸 経士 中尾 信典

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.136, no.12, pp.140-150, 2020-12-31 (Released:2020-12-18)

参考文献数

45

---

Heterogeneity in mudstone/shale layers has significant effects on seal layer integrity. The presence of intralayer sandstone channels in a seal layer may allow the buoyant CO2 to escape from the reservoir, even if the globally averaged permeability of the seal layer seems low enough. On the other hand, multi-layered structures are known to work often as baffles for the upward migration of CO2 in formations. In this paper, we investigate the storage capacity of multilayer formations with discontinuous seals. Numerical simulations are carried out to study the effects of seal layer discontinuity on the long-term behaviour of CO2 injected into deep saline aquifers. To represent a seal layer composed of low permeability rocks intersected by sandstone channels, ‘MINC' doubleporosity model is adopted. Also conducted is sensitivity analysis to investigate the effects of key parameters such as capillary pressure, relative permeability, temperature, and the thickness of the formations. The results show that CO2 injection into a sufficiently deep multi-layered reservoir enables CO2 to be stored and trapped in and around the reservoir without reaching to a shallow aquifer, even though seal layers have discontinuities. The upward movement of CO2 is greatly affected by capillary pressure of sandstone channels in seal layers. The relative permeability and the temperature-dependent CO2 properties have a significant effect on the final plume spread and the amount of CO2 dissolved or fixed by residual gas trapping.