頁岩蓋層與固井水泥介面在超臨界二氧化碳環境下密封能力之研究

A Study on Shale Cap Rock and Well Cement Interface Sealing Ability under Supercritical CO_2 Environment

郭俊志(C.C. Kuo) ； 林姿町(T.T. Lin) ； 謝其泰(C.T. Hsieh) ； 王建力(C.L. Wang)

《鑛冶：中國鑛冶工程學會會刊》 59卷4期 (2015/12) Pp. 83-89

https://doi.org/10.30069/MM.201512_59(4).0007

摘要

二氧化碳存入地下以地質封存方式進行減量是一項可行的工程手段。乾燥情況下二氧化碳基本沒有危害。然而在進行地質封存時，氣井通常在地下水層、鹽水層等潮濕的環境下操作，二氧化碳與水結合會形成碳酸，形成一個酸性的環境。本研究模擬既有場址之頁岩蓋層與固井水泥超臨界CO_2 封存環境(70 ℃、20MPa)，分六個反應時間點(0、7、14、28、56、84 天)，對其物理及化學性質進行探討。研究發現，頁岩與經過84 天反應過後，其雲母與長石相均有些微下降的現象，顯示於反應過後應有被些微溶蝕，造成礦物相有相對下降之現象。二氧化碳與水形成碳酸（H_2CO_3），造成固井水泥碳化程度的增加，水泥完整性將被打破。而頁岩蓋層和油井水泥界面觀察到碳酸鈣(CaCO_3) 沉澱使微結構的密度增加，相對滲透率也減少。

關鍵字

二氧化碳 ； 頁岩蓋層 ； 固井水泥

並列摘要

Storing carbon dioxide (CO_2) in underground geological reservoirs is a feasible means to reduce atmospheric greenhouse gases. The CO_2 stored in geological reservoirs combined with water in the reservoirs forming carbonic acid (H_2CO_3) that lowers cement's alkalinity and reduces its compressive strength and sealing ability. This paper attempted to study the shale cap rock and well cement sealing ability under supercritical CO_2 environment (70 °C, 20MPa). The physical and chemical properties were measured at six different time periods (0, 7, 14, 28, 56, 84 days). Results of this study showed that after 84 days, the reaction of metamorphic rock such as mica and perthite was found to create a minor amount of sediment. The carbonic acid (H_2CO_3) formed in-situ carbonized the well cement that to a certain degree compromised the well integrity. Aragonite (CaCO_3) precipitate at shale cap rock and well cement interface increased the density of the micro structure and reduced the relative permeability.

並列關鍵字

CO_2 ； shale cap rock ； well cement