Research on the Degradation of the Crude Oil after the Polymer Flooding in the North of the Xing4 ～ 6 Block

The sample of oil and water are from the north of Xing4 ～6 block,which is after the polymer flooded since 2001,The estimation of the 20 days culture solution are as follows: The microorganism in the ②sample were in the good condition,after 20 days the concentration of bacteria reached to 108,after 7 days the diameter of clear zone obtained with the oil spreading reached to 17 cm,the distribution of microbial communities changed and the unpreponderance bacteria activated,the Sphingobacterium,Petrobacter,Paenibacillus in the sample played an important role in the oil recovery.The component percentage of the sample changed,the saturated hydrocarbons raised from 63.11% to 66.27%,the asphaltene decrease from 4.57% to 2.81%,the sample were fractionized and analyzed by GC / MS and gas chromatography.Obtained results were as follows.The peak of saturated straight-chain alkanes raised from C21 to C23,the Pr/ Ph of the sample ① raised from 1.062 to 1.156,the Pr/ nC17 and Ph/ nC18 increased,the ② sample of ∑nC21-/ ∑nC22 + decresaed from 0.915 to 0.685,the homologues of naphthalene and phenanthrene in the aromatics accounted for more than 80%,phenanthrene and it’s homologues accounted for about 52.71%,fluorene,dibenzothiophene,diphenylene-oxide and their homologues accounted for about 11.28%,chrysene,Biphenyl andtheir homologues accounted for about 4.35%,other compands of aromatics accounted for about 4.34%,methyl of branched chain in the PAHs degraded by the microorganism easily.