海上CCS场景防CO_(2)腐蚀固井水泥浆体系研究

Research on Anti CO_(2) Corrosion Cement Slurry System for Offshore CCS Scenarios

CCS技术是一项将二氧化碳(CO_(2))捕获和封存的技术,是稳定大气温室气体浓度的减缓行动组合中的一种选择方案。中国海油CCS示范项目利用一口超浅层大位移井,将油田开发过程中高含量二氧化碳原位处置回注至类似“穹顶”地质构造,以达到二氧化碳封存的目的。而高浓度的CO_(2)往往处于超临界状态,其对水泥环的腐蚀能力大大增强,本次研究采用了三大创新水泥浆体系保障了油气田的高效开采:改性硅酸盐长效防腐水泥浆技术,解决常规水泥浆体系长效耐久性问题;CAPLOCK不腐蚀水泥浆体系,解决关键位置水泥环被高浓度CO_(2)腐蚀破坏问题;弹韧性水泥浆体系,增加水泥石抵抗交变应力的能力,保障水泥环完整性。本文通过开展一系列实验,阐释了三项水泥浆体系作用机理及应用优势,研究成果为推进CCS固井技术发展提供一定的科学依据,为揭示海上高碳源场景下水泥环完整性建立理论基础。

CCS technology is a technology that captures and stores carbon dioxide(CO_(2)),and is an option in a combination of mitigation actions to stabilize atmospheric greenhouse gas concentrations.The China National Offshore Oil Corporation(CNOOC)CCS demonstration project utilizes an ultra shallow large displacement well to in-situ dispose of high levels of carbon dioxide during oilfield development and inject it back into geological structures similar to"domes"to achieve carbon dioxide storage.However,high concentrations of CO_(2) are often in a supercritical state,greatly enhancing their ability to corrode the cement sheath.In this study,three innovative cement slurry systems were adopted to ensure the efficient development of oil and gas fields:modified silicate long-term anti-corrosion cement slurry technology,which solves the long-term durability problem of conventional cement slurry systems.CAPLOCK does not corrode the cement slurry system,solving the problem of high concentration CO_(2) corrosion and damage to the cement sheath at critical positions.Elastic and resilient cement slurry system increases the ability of cement stone to resist alternating stress,ensuring the integrity of the cement sheath.This article explains the mechanism and application advantages of three cement slurry systems through a series of experiments.The research results provide a scientific basis for promoting the development of CCS cementing technology and establishing a theoretical basis for revealing the integrity of the cement sheath in high carbon source scenarios at sea.