| 摘要: |
| 目的CCUS井的水泥环长期处于CO2腐蚀环境中,水泥环将被腐蚀导致CO2泄漏,需对腐蚀速率进行预测。然而目前的腐蚀预测模型以井眼和半经验公式为主,导致水泥环腐蚀预测不准确,制约了CCUS井水泥环腐蚀防治技术的研究。 方法针对这一问题,基于CO2和钙质量守恒定律,建立了CO2腐蚀深度预测模型,并利用该模型分析了腐蚀时间、温度、CO2分压、水灰比和耐腐蚀材料加量对腐蚀深度的影响规律,并建立了评价模型,对影响因素的影响程度进行排序。 结果CO2腐蚀深度随腐蚀时间、温度、Cl—浓度、CO2分压、水灰比及含水饱和度增加而增大,随着水泥环密度、耐腐蚀材料加量增加而减少；水泥环中CO2含量随腐蚀深度呈非线性降低。影响因素由强到弱为:含水饱和度>耐腐蚀材料>水灰比>CO2分压>腐蚀时间>水泥环密度>Cl—浓度>温度。 结论研究成果对于CCUS井控制CO2对水泥环的碳化腐蚀保障井筒完整性具有指导意义。 |
| 关键词: CCUS井 CO2腐蚀 水泥环 沉淀 腐蚀深度 |
| DOI：10.3969/j.issn.1007-3426.2024.03.014 |
| 分类号: |
| 基金项目:国家自然科学基金青年科学基金项目“CCUS地质封存井磷铝酸盐水泥固井提高水泥环耐碳化腐蚀机理研究”(52204014)；四川省青年基金项目“废弃高温气藏注超临界CO2开采地热井水泥环劣化机理及控制研究”(2023NSFSC0926) |
|
| Prediction model and influencing factors of cement sheath corrosion in CCUS wells |
|
YANG Chuan1, YU Caijun1, SHI Qing1, WANG Zhigang1,LIU Shibin1, XU Bihua2
|
|
1. CNPC Chuanqing Drilling Engineering Co., Ltd. (CCDC), Chengdu, Sichuan, China;2. School of Petroleum and Natural Gas Engineering, Southwest Petroleum University, Chengdu, Sichuan, China
|
| Abstract: |
| ObjectiveThe cement sheath of CCUS well is exposed to CO2 corrosion environment for a long time, and the cement sheath will be corroded, leading to CO2 leakage. Therefore, it is necessary to predict the corrosion rate. However, the current corrosion prediction models mainly rely on wellbore and semi empirical formulas, which leads to inaccurate prediction of cement sheath corrosion and restricts the research on the prevention and control of cement sheath corrosion in CCUS wells. Methods In response to this issue, a CO2 corrosion depth prediction model was established based on the conservation laws of CO2 and calcium mass. This model analysed the impact of corrosion time, temperature, CO2 partial pressure, water-cement ratio, and corrosion-resistant material dosage on corrosion depth. An evaluation model was also established to rank the degree of influence of these factors. ResultsThe research results indicated that the CO2 corrosion depth increased with the corrosion time, temperature, chloride ion content, CO2 partial pressure, water-cement ratio, and water saturation, and decreased with the cement sheath density and corrosion-resistant material dosage. Additionally, the CO2 concentration within the cement sheath showed a non-linear decrease with the increase in corrosion depth. The strength of the influencing factors was:water saturation > corrosion resistant material > water-cement ratio > cement ring density > CO2 partial pressure > corrosion time > chloride content > temperature. ConclusionThe research results have guiding significance for controlling CO2 carbonization corrosion of cement sheath in CCUS well to ensure well integrity. |
| Key words: CCUS well CO2 corrosion cement sheath sediment corrosion depth |
