| 摘要: | 將二氧化碳注入地下鹽水層或廢棄的油氣田，是目前認為最有效的地質封存方法。鐵砧山氣田的淺部構造沒有油氣的生產，因此，較難以對其進行研究分析，相關文獻報告也較少。為了準確評估鐵砧山氣田構造封閉區對二氧化碳的封存量，本研究收集井下地質、震測、電測等資料，再依據震測解釋作業流程，繪製淺部目標地層—上福基砂岩、桂竹林層、錦水頁岩及卓蘭層下段等地下構造圖與斷層的分布，再利用蒙地卡羅模擬方法，評估淺層構造二氧化碳的封存量。鐵砧山構造是由通霄背斜與鐵砧山背斜所組成，為一東緩西陡，伴隨著幾支正斷層的構造形貎。桂竹林層至卓蘭層下段等厚圖顯示，位於背斜軸的沉積厚度較薄，分佈在T-20、T-16、T-17、T-21井一帶向外增厚，初步推斷可能受到深部隆起地層，致使鐵砧山構造局部地區變薄。本區桂竹林層為儲集二氧化碳的主要目標層，錦水頁岩與十六份頁岩做為二氧化碳儲存時的蓋層，可有效阻隔二氧化碳的洩漏；且在錦水頁岩之上還有卓蘭層當做二次阻隔。區域性桂竹林層頂部深度約在-1980公尺上下，具有良好的孔隙率，可做為好的儲集層。依據蒙地卡羅模擬方法，鐵砧山氣田淺層可以封存約356億立方公尺(0.64億噸)的二氧化碳，深具經濟規模儲量。同時，鐵砧山構造位於西部海岸平原的地形高區、附近空曠，靠近台灣主要二氧化碳排放來源處，是良好的封存場址。At present, the most effective method to store carbon dioxide (CO2) in geological sequestration is to inject of CO2 directly into saline aquifer or abandoned oil-gas fields. The shallow zones of Tiehchanshan’s (TCS) structure in the TCS gas field, recognized as a region without oil-gas productivity, has not been studied in the past, but holds promising for CO2 sequestration. . In order to accurately estimate the CO2 storage capacity of shallow structure trap, this study collected well, seismic and logging data in the TCS gas field, then followed the standard operating procedure of seismic interpretation to draw structural maps of target formations and the distribution of faults. Monte Carlo simulations was used to estimate CO2 storage capacity in the shallow zones of TCS structure, which include the Sangfuchi Sandstone, Kueichulin Formation, Chinshui Shale and the lower part of Cholan Formation sequence in the shallow zone. The TCS structure is composed of two anticlines, including the Tonsiao anticline and the Tiehchanshan anticline, both verging towards the West and accompanied by normal faults. Isopatch maps of the Kuelchulin Formation and lower part of the Cholan Formation show that stratigraphic thickness is thinner along the anticlinal axis than in other regions of the TCS structure, as showing in wells of T-20, 16, 17 and 21. It can be deduced that the paleo topographic high during the period of sedimentation corresponds to the present anticlinal axis. The late reverse faulting resulted in the eastward migration of the anticlinal axis from surface toward depth.The height of structural closure of the Kueichulin Formation is about -1980 m, this coupled with high porosity and permeability makes the Kueichulin Formation a good reservoir for CO2 sequestration. The relatively impermeable Chinshui and Shihliufen Shale can function as cap rocks. In addition, the overlying Cholan Formation can also act as additional seal that would potentially increase the security of CO2 sequestration. Based upon Monte Carlo simulation, the CO2 storage capacity in TCS gas field is about 356 billion m3 (0.64 billion tons). Moreover, the TCS structure is located in the tableland of Western Coastal Plain, in a relatively undeveloped area and near the main source of CO2 emission in Taiwan; thus the TCS structure is considered as one of the best sites for CO2 geologic sequestration. |
