大港孔店油田本源微生物代谢产物监测分析

应用放射性同位素示踪剂技术研究了大港孔店北二断块水动力学关系,结果表明该区块注水井和采油井之间具有紧密的水动力学连通关系。在本源微生物驱油试验阶段,对试验区微生物及其代谢物在地层中的分布状况进行了3年连续监测,表明本源菌激活期间菌数增加102~105倍,原油部分氧化,使得低分子脂肪酸(乙酸盐,甲酸盐,丁酸盐等)含量约增加10~100倍,碳酸氢盐从0·4~0·6g/L增加到0·7~1·8g/L,产生的生物表面活性剂使地层水平均表面张力降低至48~33·3mN/m,地层水相对石蜡平均界面张力降至25~13·7mN/m,产生的生物多糖代谢物使地层水平均粘度增至0·76mPa·s,最高达0·83mPa·s。这些变化改变了油层物理化学和生态环境,改善了原油流动性,尤其是水动力学连通关系最好的井地层水组成的改变和增油降水效果最为明显。试验区监测结果表明,微生物及代谢物随注入水主流动方向运移,生物表面活性剂和低分子脂肪酸及生物聚合物的作用是提高原油采收率的主要机理。

Monitoring the Metabolic Product of Indigenous Microbial Enhancement of Oil Recovery in Dagang Kongdian Oilfield

A radioactive isotopic tracer is used to study the hydrodynamic relation in the Block Bei 2 of Dagang Kongdian Oilfield. The result shows that there exists a close hydrodynamic relation between water injector and producer in the block. The directions of the distribution of micro-organisms and their metabolites in Kongdian Oilfield were monitored in production wells in the past three years of biotechnological trial. During the period of activation of formation microflow in the oilfield, biotransformation of oil resulted in the increase of lower fatty acids (the concentration of acetate, formate and iso-butyrate increase 10~100 times) in formation water, an increase in the concentration of soluble carbonates is recorded (HCO~-_3 from 0.4~0.6 to 0.7~1.8 g/L). During the pilot trial, surface tension of formation water decreases and viscosity increased in all production wells in the experiment based on the production of boisurfactant and biopolymer, average values are in a range 48~33.3 mN/m, average values of interfacial tension against paraffin decreased to 25~13.7 mN/m, average viscosity increased from 0.70 to 0.76 mPa.s (the highest viscosity as 0.83 mPa.s ) are registered in some wells. Then these deep subsurface physico-chemical cosystems and the filtration properties of the fluids produced are well modified, especially for those wells with strong hydrodynamic links, the changes in composition of formation water and the results of the increase of oil production and the decrease of water cut are obvious. The data show that micro-organisms and their metabolites are moved along with the main flow direction of the injection water, and the influence of lower fatty acids, microbial surfactants and biopolymers could be the possible mechanism of the enhanced oil recovery in the experimental oilfield.