聚合物驱后油藏激活内源微生物驱油现场试验

A field test of activation indigenous microorganism for microbial enhanced oil recovery in reservoir after polymer flooding

针对聚合物驱后油藏内源微生物的生长特点,对大庆油田萨南开发区南二区东部聚合物驱后典型油藏开展了激活内源微生物驱油现场试验。通过优选由玉米浆干粉、硝酸钠和磷酸氢二铵构成激活剂,与保护剂聚合物交替注入,并运用分子生态学末端限制性片段长度多态性方法分析了内源微生物激活前后群落结构的变化规律,研究了利用内源微生物驱油技术的可行性。现场试验结果表明:聚合物驱后油藏中有明显的产气增压效果;油藏驱动压力的动态变化及代谢产物气体组分CH_4和CO_2的δ^(13)C同位素含量波动,验证了激活剂的加入促使油藏内源微生物微氧和无氧代谢交替进行;产出液的各项生化监测指标均有明显变化,激活后优势菌群为Pseudomonas、Thauera和Arcobacter,且丰度增高;试验区阶段累计增油3 068.13t,含水率下降2.2%,驱油增产效果明显。该试验的成功实施证明了聚合物驱后油藏采用激活内源微生物驱油的工艺方法是可行的,并为同类油藏进一步提高采收率提供了可借鉴的方法和途径。

Based on the characteristics of indigenous microbial growth in reservoirs after polymer flooding （RAPFs）, a field test was conducted to activate indigenous microorganisms for microbial enhanced oil recovery （MEOR） in representative RAPFs in the east of Nan-2 district in Sanan development zone, Daqing oilfield. The optimized activator, which consisted of corn steep powder, NaNO3, and （NH4）2 HPO3, was injected alternately with protectant polymer. The changes in indigenous microbial community structure be- fore and after activation were examined using terminal restriction fragment length polymorphism analysis, in order to determine the feasibility for application of indigenous MEOR technique. Results showed that： there existed a significant gas supercharging effect in the RAPFs; Dynamic changes in the driving pressure of RAPFs and substantial fluctuations in the δ13C isotope contents of microbial- ly produced CH4 and CO2 confirmed that the addition of activator promoted alternative micro-aerobic and anaerobic metabolism of in- digenous microorganisms in the reservoirs there were significant changes in the major biochemical parameters of the produced fluid after activation of indigenous microorganisms, the dominant indigenous microbial populations included Pseudomonas, Thauera, and Arcobacter, whose abundance experienced great increases after activation; the incremental oil production was 3 068. 13 t while the water content declined by 2.2%, indicating that MEOR application significantly improved the oil recovery. This work proved that it is feasible to activate indigenous microorganisms for MEOR in RAPFs, which provides an alternative approach for further improving oil recovery in similar reservoirs,