海上油田超临界态高含CO_(2)伴生气回注压缩机选型设计研究

Research on Design of Compressors for Re-injection of Supercritical High-CO_(2)Associated Gas in Offshore Oilfields

海上油气开发中,很多油田所产伴生气中含有CO_(2)。当CO_(2)含量超过30%~40%,伴生气无法用作燃料,且高含CO_(2)气体长距离输送风险与成本较高。为了推动碳达峰碳中和目标实现,某海上油田计划将高含CO_(2)伴生气增压至超临界态后回注埋藏。通过对干气、湿气回注方案进行比选,确定采用干气回注方案;通过对压缩机型式、驱动方式、配置、成橇方法、设计要求等关键因素进行分析,确定选型方案。最终配置2台往复式压缩机,通过三级压缩将高含CO_(2)伴生气增压至超临界态。同时通过将二级、三级间高含CO_(2)伴生气引出橇外,进入分子筛橇脱水的设计,优化2台压缩机橇配置,大幅减少平台占用空间。

Many offshore oilfields see the associated gas with the CO_(2)content when they are brought under development.The associated gas is unable to be used as fuel once the CO_(2)content exceeds 30 to 40 percent.In addition,the high-CO_(2)gas is transmitted over a long distance at high risks and costs.To fulfill the carbon peak and carbon neutrality objective,one of the offshore oilfields planned to pressurize the CO_(2)associated gas to the supercritical state for re-injection and burial.The drygas re-injection scheme was recommended after comparison was made between the dry-gas and wet-gas re-injection schemes.The design of compression process was determined on the basis of analyzing a series of key factors,such as compressor model,driving mode,configuration,skid structuring method and design requirements.Finally,two reciprocating compressors were recommended to pressurize the high-CO_(2)associated gas to a supercritical state through three-stage compression.Meanwhile,the high-CO_(2)associated gas between the second and third stages was drawn out of the kid to enter the molecular sieve skid for dehydration.The skid structure of the two compressors were optimized to substantially reduce occupation of the platform space.