生物标志化合物成熟度参数有效性——以伊通盆地烃源岩为例

Analysis on Validity of Maturity Parameters of Biomarkers:A Case Study from Source Rocks in Yitong Basin

选取伊通盆地有机质类型为Ⅱ型和Ⅲ型的15个不同成熟度（Ro分布在0.5%-1.5%）的烃源岩样品,开展有机地球化学特征分析,系统分析饱和烃和芳烃化合物成熟度参数的适用范围。研究结果表明：生物标志化合物成熟度参数C29甾烷ββ/（ββ＋αα）、莫烷/藿烷、MPI-1和DPR可能都比前人所报道的适用范围更宽。αααC29甾烷20S/（20S＋20R）和C32藿烷22S/（22S＋22R）在Ro达到0.8%时达到平衡值,无法指示更高成熟的烃源岩和原油成熟度。C29甾烷ββ/（ββ＋αα）、Ts/（Ts＋Tm）、DNR-1以及TNR-1可以用于评价Ro〈1.2%的烃源岩和原油成熟度,当Ro〉1.2%时,这些成熟度参数可能出现倒转。莫烷/藿烷、MPI-1、DPR、4-MDBT/1-MDBT、MBDTI以及3-MCH/1-MCH在Ro为0.5%-1.5%范围内都能与Ro保持较好的正相关性,应该能够用来评价高成熟烃源岩和原油成熟度。成熟度参数MPI-1、DPR、DNR-1、TNR-1、4-MDBT/1-MDBT和3-MCH/1-MCH在一定程度上受有机质类型的影响。

The organic geochemical characteristics of 15 source rock samples of different maturity from Yitong Basin whose organic matter type is type Ⅱ and type Ⅲ （Ro is from 0.5% to 1.5% ） ,and the suitable range of the maturity parameters of saturated hydrocarbon and aromatic hydrocarbon compounds were systematically analyzed. It is shown that, the suitable range of biomarker maturity parameters C29 sterane [ββ/（ [ββ ＋ αα）,moretane/hopane, MPI-1 and DPR may have wider suitable range than that previously reported, αααC29 sterane 20S/（ 20S ＋ 20R）and C32 hopane 22S/（ 22S ＋ 22R）reach to equilibrium value when Ro is 0.8%, and they could not indicate the source rocks and crude oils of higher maturity. C29 sterane ββ/（ββ＋ αα） ,Ts/（ Ts ＋ Tm）, DNR-1 and TNR-1 can be used for the maturity evaluation of the source rocks and crude oils whose Ro is less than 1.2%, and when Ro is greater than 1.2%, these maturity parameters may be reversed. Moretane / hopane, MPI-1, DPR,4-MDBT/1-MDBT, MBDTI and 3-MCH/1-MCH can keep a good positive correlation with vitrinite reflectance when Ro ranges from 0.5% to 1.5% ,so they can be used for the maturity evaluation of the source rocks and crude oils of high maturity. The maturity parameters MPI-1 ,DPR,DNR-1 ,TNR-1,4-MDBT/1-MDB and 3-MCH/1-MCH may be affected by the type of organic matter to a certain extent.