天然氣管線查漏技術－地下土壤氣體分析方法

An Alternative Detection of Leakages in Natural Gas Pipelines

邱虹梓(Hung-Tzu Chiu) ； 顏炳文(Ping-Wen Yen) ； 康文成(Wen-Cheng Kang) ； 施呈杰(Cheng-Chieh Shih) ； 洪正宗(Cheng-Tsung Hong) ； 康文政(Wen-Chen Kang) ； 林盈志(Ying-Chih Lin)

《石油季刊》 44卷1期 (2008/03) Pp. 65-78

https://doi.org/10.30128/JP.200803.0006

摘要

中油公司煉製研究所和天然氣管線處一起合作，使用地下土壤氣體分析方法，建立一套天然氣管線查漏技術。天然氣管線處頭湖開關站附近因艾利風災淹水，地面上有氣泡冒出，經點火可引燃，此冒出氣體與本研究由地下抽取土壤氣體特性相同。分析結果顯示所有氣體樣品的乙烷、丙烷和丁烷等成份皆非常微量，且其C2/C1、C3/C1和C4/C1比值遠小於管線中天然氣，而與沼氣組成相近。再加上氣體樣品中的二氧化碳隨甲烷濃度增加而增加，此趨勢與沼氣特性相似。天然氣管線處進行升壓查漏作業，測試結果未找出洩漏量隨操作壓力增加而增加的關聯性，所以氣體樣品不含有由管線洩漏的天然氣，而其甲烷成分應該是來自地底下的沼氣。為了安全起見，本研究對頭湖開關站26”管線進行後續查漏監測，地下土壤氣體只含微量甲烷，此結果顯示管線沒有漏氣現象，並且地下土壤氣體含的沼氣比率下降。本研究建立的地下土壤氣體分析方法成功應用頭湖開關站地面冒氣事件，此技術準確度高且安全，所需的設備簡單，並且時間和費用花費少，讓現場人員減少升壓開挖查漏作業。天然氣管線處並且已將此技術應用於通霄配氣站和銅鑼線冒氣事件，此兩案例的氣泡皆是土壤沼氣而非管線漏氣。

關鍵字

天然氣 ； 管線漏氣 ； 氣體分析

並列摘要

An alternative detection of gas leak from natural gas pipelines by use of the underground gas analysis was presented. A sampling method by a vacuum system was designed to take underground gas surrounding the natural gas pipelines. The natural gas from the pipeline, the ignitable gas from the ground surface in Tou-Hu and its underground gas samples were collected, analyzed and compared. The pipeline gas consists of methane (91.3%), ethane (5.1%) and propane (2.4%), while C2H6 and C3H8 do not exist naturally in marsh gas. The following results indicated that the methane in the underground gas samples is from marsh gas, rather than from leakages of natural gas pipelines. (1) The content of C2H6, C3H8 and C4H10 in the underground gas samples were negligible, (2) The ratios of C2/C1, C3/C1, and C4/C1 were almost close to zero, (3) CO2 and CH4 of the underground gas increased with depth, which was similar to the trend of marsh gas, and (4) The components of the gas samples were not altered by elevated pressure. Long-terms monitoring of methane emissions from TC wetland was carried out in order to assure the safety. Significant reduction of CH4 in the gas samples showed that very small amount of marsh gas existed in Tou-Hu. The proposed detection has been successfully applied to methane emission at three sites, and has the advantages of high accuracy, low time consumption, low cost, and easy operation and maintenance.

並列關鍵字

Natural Gas ； Pipeline Leakage ； Gas Analysis