塞169低渗透油藏微生物活化水驱机理及群落分布规律

Mechanism and Community Distribution of Microbially Activated Water Flooding in Sai 169 Low-permeability Reservoir

针对长庆油田塞169低渗透油藏微生物活化水驱对低渗储层适应性较差的问题,通过气相色谱-质谱等多种检测手段对现场扩培池中微生物活化水的生物表面活性剂、有机酸、生物气等代谢产物种类及含量进行了定量检测,明确其微观驱油机理,并利用双末端测序(Paired-End)方法对22口井采出液的微生物群落分布进行了测序。研究结果表明:微生物代谢产物中酯类质量浓度为1.57~4.98 mg/L,有机酸质量浓度为108.34~133.61 mg/L,生物气体积浓度为18~38 mL/L,油水界面张力降低30%~70%,pH值降低3%~5%,驱油效率提高5.46~11.93个百分点,微生物活化水代谢产物中的生物表面活性剂、有机酸、生物气和生物聚合物发挥了驱油作用;微生物驱过程中,采油井井液中细菌、古菌和产甲烷菌3种菌的基因数量总体增加,井间分布差异逐渐减小;井间微生物群落差异主要与渗透率和注采层位有关。该研究为低渗非均质油藏微生物驱油选层选井和优化注采方案提供重要的理论依据。

In view of the poor adaptability of microbial activated water flooding to Sai169 low-permeability reservoir,Changqing Oilfield,the types and contents of metabolites such as biosurfactants,organic acids and biogas in microbially activated water in the on-field expanding culture insert were quantified by gas chromatography-mass spectrometry and other testing methods,the mechanism of micro oil displacement was clarified,and the microbial community distribution in the produced fluid of 22 wells was sequenced by the paired-end sequencing method.The results of the study showed that the mass concentration of esters in the microbial metabolites ranged from 1.57 to 4.98 mg/L,the mass concentration of organic acids ranged from 108.34 to 133.61 mg/L,the volume concentration of biogas ranged from 18 to 38 mL/L,the oil-water interfacial tension was reduced by 30%to 70%,the pH value was reduced by 3%to 5%,and the oil displacement efficiency was increased by 5.46 to 11.93 percentage points;the biosurfactants,organic acids,biogas and biopolymers in the microbially activated water metabolites played an important role in oil displacement;the gene numbers of bacteria,archaea and methanogens in the fluids of production wells generally increased in the process of microbial flooding,and the differences in distribution between wells gradually decreased;the differences in microbial communities between wells were mainly related to permeability and injection-production horizons.This study provides an important theoretical basis for microbial flooding,formation and well selection,and optimization of injection-production scheme in low-permeability heterogeneous reservoir.