南海某深水气田平台降压开采后,高压放空气20 000 m3/d、低压放空气5 000 m3/d因无法进入湿气压缩机入口外输而被火炬系统燃烧;项目的主要挑战在于低压放空气的回收,进口压力从近乎于0 MPa提升到2.5 MPa,新设备的组合选型和现场调试是项目的难点。为解决以上问题,通过研究和制定高低压放空气回收方案,并进行方案优选,最终采用新增2台凝析油增压泵提升系统压力让气相重新进入到湿气压缩机的高压放空气回收方案,以及组合选型确定为新增设备液环压缩机和射流器对低压气进行回收的低压放空气回收方案。项目实施后,成功完成了预期回收目标,经济效益和社会效益良好;试运行过程中,通过逐一解决低压放空气回收新增设备的各种问题,保证了低压放空气回收组合设备的稳定运行,增加了类似天然气平台的放空气回收再利用的经验积累,有一定的借鉴和指导意义。

After the commencement of production via pressure reduction at a gas platform of a deep-water gas field in the South China Sea, the high-pressure vent gas increased by 20 000 m3/d, while the low-pressure vent gas remained unchanged at 5 000 m3/d. This resulted in a total of 25 000 m3/d of vent gas being burned off in the flare system as they are not able to feed the wet gas compressor suction for export. The main challenge of this project lay in the recovery of low-pressure vent gas, which required boosting its gauge pressure from nearly zero at the suction to 2.5 MPa. The selection and combination of new equipment in the process system, as well as field commissioning on site, posed significant difficulties for the project. To address this issue, a scheme for recovering both high and low-pressure vent gas was researched and developed. After optimizing the scheme, a high-pressure vent gas recovery scheme was ultimately selected: two new condensate booster pumps were installed to increase system pressure, allowing the vapor phase of the condensate system to feed into the wet gas compressor. For the low-pressure gas recovery scheme, the selected equipment system involved adding liquid ring compressors and ejectors to effectively recover the low-pressure gas. After the implementation of the project, the expected recovery targets were successfully achieved, generating significant economic and social benefits. During the trial operation, various issues with the newly added equipment for low-pressure gas recovery were resolved sequentially, ensuring stable operation of the low-pressure gas recovery equipment system. This study has accumulated experience in the recovery and reuse of vent gas at natural gas platforms of the same nature and offers valuable reference and guidance for the oil and gas industry.