Potential Investigations of Indigenous Microbiological Properties and Its Enhanced Oil Recovery High-temperature Horizons

Abstract:

The analysis results of reservoir characteristics, properties of fluids and microbiological characteristics of the formation waters of the Kongdian oilfield of the Dagang oilfield demonstrated that this oilfield is a high temperature ecosystem with formation waters characterized by low mineralization. The concentrations of nitrogen and phosphorus compounds, as well as of electron acceptors, are low. Oil and oil gas are the main organic matter sources. The oilfield is exploited with produced water-flooding. The oil reservoir was inhabited mostly by anaerobic thermophilic microorganisms, including fermentative bacteria (102 cells/mL-105 cells/mL) and methanogenic (103 cells/mL) microorganisms. Aerobic bacteria were detected mainly in the near-bottom zone of injection wells. The rate of sulfate reduction aried from 0.002 to 18.9 mg S2-/(L·d), and the rate of methanogenesis from 0.012 mg CH4/(L·d) to 16.235 mg CH4/(L·d). Aerobic thermophilic bacteria were capable of oxidizing oil with formation of biomass, the products of partial oxidation of oil (volatile acids), and surfactants. During growth on the culture liquid of oil-oxidizing bacteria, methanogenic communities produced methane and carbon dioxide, which also had oil releasing capabilities. Using various labeled tracers, the primary filtration flows of injected solutions at the test site were studied. Our comprehensive investigations allowed us to conclude that the method for microbial enhancement of oil recovery based on the activation of the strata microflora can be applied in the Kongdian oilfield.