天然气低温气浮法在生产水处理中的高效应用

High Efficiency Application of Low Temperature Air Flotation Method in Production Water Treatment

南海某高温高压气田在试生产过程中,生产水处理系统滤芯经常因差压过高而更换,维修频率较高。处理后的生产污水一次性排海含油浓度为35~55mg/L,虽然基本达标,但生产水工艺处理效果不理想。影响生产水处理工艺的主要因素包括地层特性、钻完井返出物、新井投产以及工程施工阶段管线残存杂质。为此,创新引用“低温气浮法”原理,对生产水处理工艺流程进行改造提升。采用平台脱水后并经过节流降温的天然气作为气浮气源,以生产水缓冲罐内部原有冲砂管线作为气泡发生装置,通过不断调整找到比较合理的气浮气量,对生产水实现气浮除油。改造后生产水排海含油浓度可达到30mg/L以下,比改造前降低15mg/L,从满足国家三级海域排放标准,提升至满足国家二级海域排放标准。滤芯更换频次大大减少,创造了可观的环保效益和经济效益。

During the trial production of a high temperature and high pressure gas field in the South China Sea,the filter element of production water treatment system was often replaced due to high differential pres-sure,and the maintenance frequency was high.The oil concentration of the treated production sewage discharged into the sea was 35~55mg/L,which was basically up to the standard,but the treatment effect of the production water was not ideal.The main factors affecting the production water treatment process included for-mation characteristics,drilling and completion returns,new well production and pipeline residual impurities during construction.Therefore,the principle of low temperature air floatation was innovatively introduced to upgrade the production water treatment process.The natural gas dehydrated on the platform and cooled by throttling was used as the air floatation source,and the original sand washing pipeline inside the production water buffer tank was used as the bubble generator.Through constant adjustment,the reasonable air floatation rate was found to achieve the oil removal of production water by air floatation.After the transformation,the oil concentration of the production water discharged into the sea reached below 30mg/L,which was 15mg/L lower than that before the transformation,upgrading from meeting the national third-level discharge standard for sea area to meeting the national second-level discharge standard for sea area.The replacement frequency of filter element was greatly reduced,creating considerable environmental benefits and economic benefits.