海上油田二元复合驱提高采收率关键技术——以埕岛油田埕北1区西部Ng4—5砂层组为例

Study on key techniques of surfactant-polymer flooding for offshore field-case of sand grouqs of Ng4-5 in westem Chengbei 1 block,Chengdao oilfield

化学驱是在平台有限期内提高海上油田采收率的有效手段,相比单一聚合物驱,二元复合驱具有更为快速和更大幅度提高采收率的特点。针对埕岛油田埕北1区西部Ng4—5砂层组,设计了二元复合驱油藏工程优化方案;针对海上平台配注水水质差,离子成分复杂,研制了速溶高效抗盐二元复合驱油体系;针对平台空间狭窄,简化了二元复合驱配注流程,研制了高效小型化设备,不但提高了自动化程度,减少了平台操作,还降低了安全环保风险,形成了高效集约化海上配注工艺;针对先导试验区储层出砂严重,层间矛盾突出,研制了低剪切注聚防砂管,形成了低剪切分层防砂分层注入工艺技术,整套管柱粘度保留率高,分层配注准确,可满足海上安全环保要求;形成了海上油田大幅度提高采收率关键技术,并首次在埕北1区示范工程区开展了二元复合驱先导试验。

The characteristics of offshore field(large well spacing,low well density) mean that the oil recovery is comparatively low dur-ing the operation period of platforms,normally 20 years.The surfactant-polymer(SP) flooding is a potential EOR method for offshorefield.The key challenges of SP flooding offshore are: ①high salinity and high divalent cation concentration of the injection water; ②limited space on the oil platforms; ③severe sanding problem in the pilot reservoirs and serious interlayer contradiction.Regarding tothe sand groups of Ng4-5 in Chengbei 1 block,Chengdao field,the thorough study on the key techniques of offshore SP flooding hasbeen performed,including formulation design,injection allocation,sand control,and plan optimization.Our findings are described asfollows: firstly,a fast dissolving and salt resistant SP system is developed so as to meet the offshore field development requirement; sec-ondly,a series of small injection facilities are set up for automatic process,thus,the high-efficient integrated injection has beenachieved; thirdly,the layered sand control and water injection technique with low shearing is established,and lastly,the reservoir engi-neeringplan of SP flooding is optimized.Our study is significant for improving oil production rateand recovery factor in offshoref ields.