因應工業碳排放量等問題，以及全球內閒置及廢棄井的數量劇增之趨勢，廢棄井再利用及碳封存井設置的評估有其重要性。不同類型地層、地層溫度及大地應力會對井結構造成不同程度影響，進而導致井結構失效，因此深井失效風險及其破壞條件評估為設置碳封存井重要之議題。
本研究使用ABAQUS有限分析軟體，設定三種岩層參數，並假設不均向之大地側向應力，分析在碳封存過程時金屬套管內部從0增壓至100 MPa對井結構之應力影響及結構中金屬套管及水泥護套臨界破壞條件。本研究並分析在封存時井結構對於地層溫度的承受能力，因此設置60-210℃區間內六種環境溫度來加以觀測其應力變化。
研究結果表明在非均向大地應力下，水泥護套所受偏應力會比金屬套管高，在楊氏模數較高岩體中最高達18.3%，且應力集中在較弱側向應力軸向，增加該方向的破壞風險；隨著套管內壓增加，不同楊氏係數的岩層對水泥護套的最小主應力產生不同影響：楊氏係數低的岩體會導致水泥護套產生環向張應力，增加剪切破壞風險，楊氏係數高的岩體則使環向壓應力增加，減少剪切破壞可能性；在封存壓力20 MPa下，地層溫度高於60°C不會導致水泥護套或金屬套管破壞，但較低地層溫度下水泥護套會有張應力產生，若低於50°C，楊氏係數低的岩體中的水泥護套可能發生張力破壞，楊氏係數高的岩體中井水泥護套則對低溫有較高抵抗性；工程上普遍設置碳封存井之岩體環境較接近於一號岩體且套管內壓為20 MPa，此壓力下井結構無剪切破壞風險但需提防地層低溫所帶來之水泥護套張力破壞。

With rising industrial carbon emissions and an increasing number of idle and abandoned wells worldwide, evaluating the reuse of abandoned wells and establishing carbon sequestration wells is crucial. Different formation types, temperatures, and lateral stresses impact well structures, potentially causing failure.
This study uses ABAQUS finite element analysis to model three rock formations under anisotropic lateral stress, assessing the impact of internal casing pressurization from 0 to 100 MPa on well stress and the failure conditions of the casing and cement sheath, and examines well integrity across six temperatures from 60°C to 210°C.
The results reveal that, under anisotropic lateral stress, the cement sheath experiences up to 18.3% higher deviatoric stress than the metal casing, with stress concentrated along the weaker lateral stress axis, which increases the risk of failure in this direction. As internal casing pressure rises, rock formations with lower Young's modulus cause the cement sheath to experience tensile hoop stress, raising the risk of shear failure. In contrast, formations with higher Young's modulus induce compressive hoop stress in the cement sheath, reducing shear failure risk. At a storage pressure of 20 MPa, formation temperatures above 60°C do not lead to failure of the cement sheath or metal casing. However, at temperatures below 50°C, low Young's modulus formations increase the likelihood of tensile failure in the cement sheath, while high Young's modulus formations offer better resistance to low-temperature stress conditions. Carbon sequestration wells are typically established in formations similar to Formation 1, with an internal casing pressure of 20 MPa. While this pressure poses no shear failure risk, caution is required to prevent tensile failure of the cement sheath under low formation temperatures.

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