加州波特牧場　甲烷洩漏事件

Methane Leaking Event in Porter Ranch, California

呂錫民(S.-M. Lu)

《鑛冶：中國鑛冶工程學會會刊》 61卷1期 (2017/03) Pp. 9-19

https://doi.org/10.30069/MM.201703_61(1).0001

摘要

位在洛杉磯北部的南加州天然氣公司(Southern California Gas Company)的阿利索峽谷的儲存設施，在8,500英尺深處產生的大量天然氣洩漏，該項洩漏是在2015年10月23日發現的，此一事件不止是一件“不幸的事件”，也不是一場小災難，而是一場大災難。不僅因健康原因，迫使近2,500家波特牧場社區居民重新安置家園，另外還有數千家庭很可能進行另一波搬遷。到2016年2月17日晚上該公司終於將該口井完全封住，封井的方法是利用釋壓井置入水泥替代原先堵井的水和泥漿，使之進入到洩漏井管中，水泥乾固後將井底封住使之永久不再打開使用。Well kill封井技術是利用一長段比重很大的流體（通常是重質泥漿）注入井孔中，造成一很高的水頭高度的靜壓(hydrostatic head)，來對抗地層中儲氣的壓力，一般油氣井大修或油氣井災變應變都會採用。此事件持續約四個月，共有約7萬公噸甲烷洩漏至大氣當中，環境代價相當於每天700萬車輛的排放量，相對地，普遍存在的甲烷洩漏現象對於全球環境已形成一種不可輕忽的人類重大議題。甲烷是天然氣的主要元素，是僅次於二氧化碳的人類活動主要產生溫室氣體。甲烷停留在大氣中的時間，沒有比溫室氣體二氧化碳(CO_2)來得久，但是在捕獲熱量上的效率卻比CO_2高出86倍，這使其成為氣候變化的一個十分重要貢獻因素。

關鍵字

封井技術 ； 天然氣井管 ； 甲烷洩漏 ； 溫室氣體

並列摘要

The Aliso Canyon gas leak at 8,500 feet deep in Southern California Gas Company underground storage facility north of Los Angeles is a major energy, human, and environmental disaster. The major gas leak occurred on October 23, 2015 that forced nearly 2,500 Porter Ranch community residents to relocate their homes, and then thousands more are likely to be forced to relocate as well. By February 17, 2016, the leaky well was completely sealed by the plugging cement transported from a relief well to the leaky well replacing the previously injected plug water and mud. Hopefully, the well is fully plugged and condemned. ＂Well kill＂ technology is the injection of a large proportion of heavy fluid (usually heavy slurry) into the leaky well to counter and suppress the formation gas pressure to stop the gas leak. The gas leak lasted for about four months with about 70,000 tonnes of methane leaking into atmosphere. That was equivalent to a total gas emission from 7 million vehicles per day. This is like widespread global methane leaks that is a major environmental issue that must not be overlooked. Methane is the major component of natural gas that is second only to carbon dioxide in human activities for producing greenhouse gases. Although methane does not stay in the atmosphere as long as carbon dioxide (CO_2), methane captures heat 86 times more than does CO_2 making it a significant contributor to global warming and climate change.

並列關鍵字

Well kill ； Gas well pipe ； Methane leakage ； Greenhouse gas emissions