地熱「鑿井」的誘震探討

Exploration of Induced Seismicity Activities Associated with Enhanced Geothermal Systems

呂錫民(Shyi-Min Lu)

《臺灣鑛業》 72卷1期 (2020/03) Pp. 41-52

摘要

增強型地熱系統（Enhanced Geothermal System, EGS）有可能為世界能源做出重大貢獻。然而，與EGS相關的一個有爭議的問題是誘發地震活動（induced seismicity）或微震（microseismicity）的影響，這是造成世界上至少兩個EGS計畫延遲和威脅取消的原因。雖然微震實際上對操作或周圍社區幾乎沒有（或沒有）不利的物理影響，但仍然存在公眾對與當前和未來EGS操作相關的地震活動的數量和幅度的擔憂。本文主要目的在於提供有關EGS創建和運營過程中所引發的地震活動的已知信息的最新評論，以及我們的認知差距，這些差距一旦得到解決，應該會帶來改進與了解產生事件的機制。一些案例歷史也說明了一些技術與公眾接受的相關問題。我們得出結論，如果選址得當，社區問題得到妥善處理，運營商了解導致事件發生的潛在機制，EGS引發的地震活動不會對地熱能資源的開發構成威脅。誘發地震活動確實可以證明是有益的，因為它可以用於監測EGS操作的有效性並闡明地熱儲層（geothermal reservoir）探勘過程。

關鍵字

誘發地震活動 ； 增強型地熱系統 ； 間歇泉

並列摘要

Enhanced Geothermal Systems (EGS) have the potential to make a significant contribution to the world energy inventory. One controversial issue associated with EGS, however, is the impact of induced seismicity or microseismicity, which has been the cause of delays and threatened cancellation of at least two EGS projects worldwide. Although microseismicity has in fact had few (or no) adverse physical effects on operations or on surrounding communities, there remains public concern over the amount and magnitude of the seismicity associated with current and future EGS operations. The primary objectives of this paper are to present an up-to-date review of what is already known about the seismicity induced during the creation and operation of EGS, and of the gaps in our knowledge that, once addressed, should lead to an improved understanding of the mechanisms generating the events. Several case histories also illustrate a number of technical and public acceptance issues. We conclude that EGS-induced seismicity need not pose a threat to the development of geothermal energy resources if site selection is carried out properly, community issues are properly handled and operators understand the underlying mechanisms causing the events. Induced seismicity could indeed prove beneficial, in that it can be used to monitor the effectiveness of EGS operations and shed light on geothermal reservoir processes.

並列關鍵字

Induced seismicity ； Enhanced Geothermal Systems (EGS) ； The Geysers