Study On Biological Inhibitor And Formula Of Sulfate Reducing Bacteria

Aiming at the high salinity water samples in the water injection system of Qinghai Oilfield,using the biological competition method,this paper puts forward the solutions to the problems of pipeline corrosion and production safety caused by sulfate reducing bacteria.In order to simulate the corrosion of sulfate reducing bacteria in the field of oilfield water injection in the laboratory,the best nutritional system for inhibiting sulfate reducing bacteria was established.Two methods are used to activate nitrate reducing bacteria.One is to screen nitrate reducing bacteria and inhibit sulfate reducing bacteria by adding bacterial solution;The other is to add specific nutrients of nitrate reducing bacteria: nitrate,nitrite,molybdate and nickel to obtain the best formula of biological inhibitors.The experimental results show that:(1)In the process of oilfield water reinjection,the salinity and conductivity of water samples were as high as 120000mg/L and150 m S/cm,and the chemical corrosion of water samples was serious;And the biological corrosion along the reinjection water was serious.The biological corrosion rate of reinjection water in the south line of the pipeline was 0.01025mm/a stronger than that of reinjection water in the north line of the pipeline,which was 0.007869mm/a;(2)The analysis of microbial community structure showed that the bacteria with the highest content in water samples were salt anaerobic bacteria and iron removing bacteria,which accounted for 70% of the total microorganisms in water samples;The species with the highest content of sulfate reducing bacteria were desulfurizing bacteria and desulfurizing salt bacteria,accounting for 7%-9% and 1.6%-2% of the total microorganisms in water samples respectively;The content of nitrate reducing bacteria was very low,which needed to be screened after enrichment or activated by adding specific nutrients to inhibit biological corrosion;(3)The best inhibition system for sulfate reducing bacteria was 80 m L water sample and 20 m L sulfate reducing bacteria medium;(4)Two nitrate reducing bacteria,NRB-7(Paenibacillus sp.)and NRB-12(Bacillus licheniformis),were obtained.In the original water sample and the best inhibition system,the corrosion rates of blank experiment were 0.026 mm/a and 0.036mm/a respectively;The corrosion rate decreased to 0.0116 mm/a and 0.0125 mm/a after adding the culture solution of NRB-7,and 0.0128 mm/a and 0.0136 mm/a after adding the culture solution of NRB-12.The corrosion inhibition rate could reach more than55% by adding nitrate reducing bacteria solution;(5)The results showed that the concentration of nitrate was 56 g/L,the concentration of nitrite was 504 g/L,the concentration of molybdate was 10 g/L,the concentration of nickel salt was 0.010 g/L,and the dosage was 10 μL/100 ml.After adding biological inhibitor,the corrosion rate decreased to 0.009 mm/a.the corrosion inhibition rate of sulfate reducing bacteria reached 68.92% in the original water sample and 76.16% in the best inhibition system.This study puts forward a solution for inhibiting sulfate reducing bacteria in oil field,and establishes a biological method for inhibiting sulfate reducing bacteria.