生物标志物定量叠加参数恢复法在渤海油田稠油油源对比中的应用

Application of biomarker quantitative superposition parameter recovery method for oil-source correlation of heavy oil in Bohai oilfields

渤海油田绝大部分稠油遭受了严重生物降解,给油源对比带来困难。研究表明,在渤海油田严重生物降解原油中普遍检测到的25-降藿烷系列化合物是由藿烷的微生物脱甲基作用而生成,基于此生成机理及化学加和性原理,提出了生物标志物定量叠加参数恢复法,即将生物降解原油中残余的正常藿烷的质量以及与其对应的25-降藿烷的质量及所脱去甲基的质量求和,从而得到原始原油中正常藿烷的质量参数。利用本文方法对渤海油田不同地区、不同层位、不同降解等级的稠油样品藿烷系列参数进行恢复,进而校正伽马蜡烷指数,并与长链三环萜烷(ETR)指数共同组成区分东营组、沙一段、沙三段原油的有效油源对比指标,最终完成了研究区生物降解原油油源对比,其结果也验证了本文方法在严重生物降解原油的油-油对比和油-源对比研究中的有效性。

Oil-source correlation of heavy oil in Bohai oilfileds is very difficult because of the severe biodegradation.Studies show that the widespread25-norhopane in severe biodegradation crude oil of Bohai oilfields is generated by microbial demethylation of hopane.Based on this generation mechanism of 25-norhopanes and chemical additive property,a biomarker quantitative superposition parameter recovery is proposed,in which the sum of residual normal hopane in biodegradation oil and its corresponding 25-norhopanes,and the methyl demethylated is used to obtain the prime quality of hopane in crude oil.With this method,a series of parameters of hopane of heavy oil with different biodegradation levels in different formations and zones in Bohai oilfields are recovered,then gammacerane index(Gam/C30hopane)is corrected,and an effective oil source correlation index that identifies the crude oil from Dongying Formation,I and III members of Shahejie Formation is formed together with long side chain tricyclic terpanes index(ETR).Finally,the oil-source correlation of biodegradation crude oil in the study area is successful and the results also prove the effectiveness of this method for oil-oil and oil-source correlation of severe biodegradation crude oil.