大庆油田聚合物驱后微生物调剖先导性现场试验研究

Study on pilot test of microbial profile modification after polymer flooding in Daqing Oilfield

针对大庆油田聚合物驱后进一步提高原油采收率的问题,从大庆油田聚合物工业化区块采出液中分离、筛选出DT-1和DT- 2两株微生物调剖菌。菌种性能评价结果表明,所筛选的两种调剖菌不仅能够在聚合物驱后的油藏条件下有效地生长繁殖,而且与地层本源菌有很好的兼容性。物理模拟岩心实验结果表明,调剖菌对聚合物驱后的油层有很好的封堵调剖作用,封堵率可以达到70%以上;聚合物驱后利用微生物调剖,原油采收率可进一步提高3.9%(OOIP)。现场试验证明,聚合物驱后实施微生物调剖,能够有效改善注水剖面,增加吸水层位和吸水厚度,采油井见到明显降水增油效果,为聚合物驱后进一步提高采收率探索了一条有效的途径。

In order to further enhance oil recovery of reservoirs after polymer flooding, two kinds of bacteria named DT-1 and DT-2 used for microbial profile modification have been screened out. The bacteria are separated from fluid sample produced from the commercial polymer flooded blocks in Daqing Oilfield. Evaluation of performance shows that these two microorganisms not only can adapt to the special conditions of reservoirs after polymer flooding, but also can grow well with in-situ microorganisms. Physical simulations of core flooding prove that the formation can be plugged perfectly by injecting fermentation liquor of DT 1 and DT 2, the rate of plugging is more than 70%. Oil recovery can be improved about 3. 9% using microbial profile modification after polymer flooding. The first microbial profile modification field test has been carried out in Sabei Oilfield with a good effect. Pilot tests show that microbial treatment can improve injection profile, and increase water entry and water absorbing thickness. As a result, water cut decreased and oil production increased. It is a good method for enhancing oil recovery after polymer flooding.