Effect of consortium QZ-10 on crude oil and its application in the removal of oil well paraffin

Abstract:

[Background] Under the high-temperature and-pressure condition,crude oil presents as a single-phase liquid.However,due to variations in temperature,pressure,and flow conditions during the mining and transportation processes,paraffin wax is continuously precipitated from the crude oil and deposits in the wellbore and pipelines.As an emerging technology,microbial wax removal has attracted wide attention.Nevertheless,the specific consortium applied needs to be determined according to the site conditions.[Objective] This study aims to use the consortium QZ-10 screened out from the saline-alkali reservoir environment in Qinghai oilfield to solve the problem of wax deposition in oil wells and investigate the mechanism.[Methods] The performance of QZ-10 was characterized based on surface tension/interfacial tension,EI₂₄ value,viscosity reduction rate,wax prevention rate,and hydrocarbon conversion ability.Finally,field trial was carried out to verify its actual effect on paraffin removal.[Results] The fermentation broth of QZ-10 could reduce the water-kerosene interfacial tension to 1.21 mN/m,and the EI₂₄ value was 91.11%.Besides,the viscosity reduction rate was measured as 92.90%,and the wax prevention rate could reach 90.00%.Furthermore,QZ-10 could degrade the heavy hydrocarbons in the crude oil,and increase the light hydrocarbon components,which would improve the quality of the crude oil.The results of laboratory experiments showed that the consortium QZ-10 reduced the viscosity of crude oil and emulsified the oil,and showed the potential to be applied in wax removal and prevention of oil well.The oil wells with severe wax deposition in Qinghai oilfield were selected for the field trial.After the injection of QZ-10 broth,paraffin wax was removed obviously in 80.95% of the tested oil wells after 140 days,and many of the tested oil wells had a significant increment in oil production,with a cumulative oil increment of 1 100 tons.[Conclusion] we demonstrated that the consortium QZ-10 could effectively remove paraffin wax deposited in oil wells and increase the oil production,which exhibited a broad application prospect.