海上油田在线组合调驱提高采收率技术——以渤海C油田E井组为例

针对渤海C油田E井组层间非均质性严重、层内非均质性强的问题,结合海上油田空间有限、快速开发等特点,提出以在线交联体系作为调剖段塞、在线非均相体系作为调驱段塞的在线组合调驱思路。利用不同渗透率双管填砂模型,考察了乳液聚合物与交联剂浓度分别为1 500 mg/L、1 650 mg/L和3 000 mg/L、3 300 mg/L的两种交联体系的调剖能力,结果表明,注入0.5 PV的交联体系并侯凝5 d后,低浓度对应的双管模型上,低渗砂管的分流量由0%变为40%;高浓度对应的双管模型上,高、低渗砂管的分流量相对于前期水驱阶段发生逆转,低渗砂管的分流量由0%变为84%,有效抑制了水驱"优势通道",调整了层间吸水矛盾。利用均质岩心物理模型,在乳液聚合物、微球聚合物和预交联凝胶颗粒总浓度保持4 000 mg/L的条件下,考察了水驱后不同非均相体系驱油效果;并与乳液聚合物单独使用时的实验结果进行了对比。结果表明,不同配方的非均相调驱体系均大幅提高了采收率,提高采收率幅度随着预交联颗粒在体系中所占浓度的提高而增大。2016年3月5日,在线组合调驱体系在C油田E23井开始注入。先后注入3 440.8 m~3的交联体系和10 997 m~3的非均相体系。根据生产情况分析,调驱开始后E24、E27、E36、E28H1、E18、E22取得显著降水增油效果,截至2016年8月初,通过净增油法计算,已经实现累积增油5 937.1 m~3。

EOR Technology by Online Combination Displacement Method for Offshore Oil Field - Take Well Group E of Bohai C Oilfield as an Example

Contraposing the several problems such as the limited service life of offshore platform, limited platform space and the serious reservoir heterogeneity in C oil field, online combination displacement method which composed by online crosslinking system as profile control slug and online heterogeneous system as flooding slug was put forward. Using double tube model of sand pack, two groups of profile control experiments was conducted with crosslinking system. The concentration of emulsion polymer and crosslinking agent in the two experiments was 1500 mg/L, 1650 mg/L and 3000 mg/L, 3300 mg/L, respectively. The results showed that when 0.5PV low concentration crosslinking system was injected and was put for 5 days, the fractional flow of low permeability tube in double-sand pack tube was changed from 0% to 40% and it was changed from 0% to 84% in the experiment with high concentration crosslinking system. Dominant flow channel was effectively restrained and the injectivity profile and interlayer contradiction was modulated. Using physical model of homogeneous core, five groups of displacement experiments with different heterogeneous flooding system was conducted while total concentration of emulsion polymers, polymer microspheres and preformed gel particle was 4000 mg/L. Effect of enhanced oil recovery in each group was compared to the result in the group with pure emulsion polymer. It showed that oil recovery was improved in all groups and the enhanced range was increased as the concentration of preformed gel particle was increased. On March 5, 2016, online combination displacement system was tested in E well group of Bohai C oilfield. 3440.8 m3 crosslinking system and 10997 m3 heterogeneous system was injected. Based on the analysis of production data, the obviousSwaterSprecipitationSreduction andSoilSincrease wereSachievedSin production well of E24, E27, E36, E28H1, E18 and E22. And 5937.1m3 oil was increased until August 2016 through net increased oil method.