塔河油田奥陶系原油芳烃地球化学特征

GEOCHEMICAL CHARACTERISTICS OF AROMATIC HYDROCARBONS OF CRUDE OILS FROM ORDOVICIAN RESERVOIR IN THE TAHE OILFIELD

芳烃化合物是原油中重要的组分,在判识原油生源环境和成熟度方面应用广泛。塔河油田主体区奥陶系原油遭受过强烈的生物降解作用,常用的饱和烃生物标志化合物指标往往不能正确反映原油成熟度、运移等信息,芳烃化合物能有效抵制生物降解作用,可更好地反映这些地质信息。通过芳烃GC-MS分析,表明塔河奥陶系原油具有高萘、高菲、高硫芴、低氧芴、低联苯等特点,均来自同一油源,生烃母质属还原—强还原环境。烷基萘指数、二苯并噻吩和三芳甾烷等成熟度指标表明,塔河油田奥陶系原油成熟度由西向东、由北向南不断增高,反映出奥陶系油气主要来自沙雅隆起东南部的满加尔坳陷。

Aromatic hydrocarbons as the important components of crude oils are widely used in estimating depositional environment of source rooks and maturity of oil. The maturity and migration informa- tion of Ordovician oil in the main area of Tahe Oilfield can not be exactly inferred by the normal biomarker parameters of saturated hydrocarbon because of strong biodegradation, but it can be indicated by the aromatic hydrocarbon because of its good restrain to biodegradation. The GC--MS analyses of aromatic hydrocarbon indicates the Ordovician oils have rich naphthalene, phenanthrene and dibenzothiophene, but poor dibenzofuran and diphenyl, which demonstrated that all Ordovician oils come from the same source rocks. The environment of parent material is reduction--strong reduction. The maturation degree of Ordovician oil increases from west to east, from north to south, which is proved by alkylnaphthalene index, DBT and triaromatic steroid. As a result, Manjiaer Depression in the southeast of Shaya uplift belt is regarded as the main hydrocarbon kitchen of Ordovician gas and oil.