恩平15-1油田开发CO_(2)回注封存工程方案研究

Research on CO_(2) re-injection and storage engineering scenario of EP15-1 oilfield development

恩平15-1油田CO_(2)回注封存项目是中国首个海上超百万吨级CO_(2)回注封存示范工程。该油田部分伴生气CO_(2)含量高达95%,累产约8.3亿m3。为积极响应国家“双碳”目标和要求,中国海油以此油田为试点首次提出了海上回注地层封存方案。本文从CO_(2)浓度对脱水工艺的影响和三甘醇与分子筛脱水工艺比选两方面开展了CO_(2)脱水工艺研究,认为分子筛脱水工艺更适用于海上高含CO_(2)气体脱水;开展了压缩回注设备选型及国产化研究,首次在海上采用超临界大分子三级往复式压缩机,可以适应本油田压缩流量较小、压比较高的工况;采用高温高压釜室内实验研究超临界CO_(2)对碳钢的腐蚀情况,发现在不饱和含水工况下釜内和釜底超临界CO_(2)相中的试样平均腐蚀速率很低;对CO_(2)回注封存环境监测提出了回注前、回注中和停注后的环境监测方案,对于海上CO_(2)回注工程安全具有重要意义;开展CO_(2)回注设施安装方案的比选研究,认为模块化安装有利于恩平15-1CEP平台整体实施进度,形成海上CO_(2)回注封存工程技术体系。恩平15-1油田CO_(2)回注封存示范工程填补了中国海上CO_(2)捕集与封存的技术空白,对于推动中国海上二氧化碳捕集、利用与封存的发展应用具有重要的指导意义。

EP15-1 oilfield CO_(2)re-injection and storage project is the first offshore CO_(2)re-injection and storage demonstration engineering of over million tons in China. The CO_(2)fraction in part of associated gas is as high as 95% with total gas production of 830 million cubic miters. In order to actively respond to national “Double Carbon” goals and requirements, CNOOC proposed the offshore re-injection and storage scenario for the first time based on this oilfield. In this paper, CO_(2)dehydration process is studied from the aspects of CO_(2)concentration impact on dehydration process and the comparison between TEG dehydration process and molecular sieve dehydration process, and it is believed that molecular sieve dehydration process is more suitable for the dehydration of offshore high CO_(2)content gas. Compression re-injection equipment selection and localization is studied and supercritical reciprocating macro-molecular compressor with three stages is selected for the first time, which can adapt to the working conditions of low compression flow and high pressure ratio in this oilfield. The corrosion of carbon steel by supercritical CO_(2)is studied by high temperature and high pressure kettle laboratory experiment, and it is found that under the condition of unsaturated water content, the average corrosion rate of the sample in the CO_(2)phase inside and at the bottom of the kettle is very low. As for CO_(2)re-injection environment monitoring, the scheme of conducting environmental monitoring before re-injection, during re-injection and after re-injection is proposed, which is important for the safety of offshore CO_(2)re-injection engineering. Meanwhile the re-injection facility installation scheme comparison study is carried out and modular installation scheme is proposed, which is more conducive to the overall implementation progress of EP15-1CEP platform. All the above form the offshore CO_(2)re-injection and storage engineering technical system. EP15-1 oilfield CO_(2)re-injection and storage demonstration engineering fills the gap of China’s offshore CO_(2)capture and storage technology, which is of important guiding significance for promoting China’s offshore CO_(2)capture, utilization and storage development and application.