塔里木盆地深层碳酸盐岩中不同赋存形式芳烃化合物组成

Aromatic Compositions of Different Occurrence States in Deep Carbonate Rocks from Tarim Basin

通过对塔参1井深层(>5700m)碳酸盐岩游离有机质(氯仿沥青"A")和包裹有机质(氯仿沥青"C")中芳烃化合物组成和成熟度参数对比研究发现,芳烃化合物组成中菲和二苯并噻吩系列化合物较为丰富,菲和等系列化合物丰度随埋深增加而增大,而二苯并噻吩、苯并萘并噻吩和芴等系列化合物丰度表现出相反的规律,这反映出不同芳烃系列化合物在高过成熟阶段热稳定性的差异。同一样品两种赋存形式芳烃化合物组成和成熟度参数明显不同,芳烃化合物成熟度参数和烷基化程度都反映出包裹有机质成熟度低于游离有机质,说明包裹有机质的热演化作用受到了抑制。在高过成熟阶段仍有部分芳烃参数仍可以用来表征深层有机质热演化程度,这些参数包括:菲系列烷基化指标(C1-P/C4-P、C1-P/C3-P、C2-P/C4-P、C2-P/C3-P)、以及二苯并噻吩系列化合物中MDR、C1/C3-DBT、2,4/1,4-DMDBT和4,6/1,4-DMDBT参数;虽然DBT/P比值被认为指示沉积环境的有效参数,但塔参1井深层样品研究表明,该参数与热演化程度关系密切,为高过成熟度阶段较好的成熟度参数。

Aromatic compositions and thermal maturity parameters of free organic matter （chloroform bitumen A） and inclusion organic matter （chloroform bitumen C） in deep carbonate rocks （ 〉 5 700 m） from Well Tacan 1 were stud- ied. The relative distributions of phenanthrenes and dibenthiophenes are richer in the aromatic hydrocarbons of deep carbonate rocks, in the meantime, the abundance of phenanthrenes and chrysenes abundance increase with buried depth, but the dibenthiophenes, naphthobenzothiophenes and fluorenes abundance in aromatic hydrocarbons showed reverse trends, this probably refect the different thermal stability of various aromatic hydrocarbons at high and overmature stages. There are obvious differences in aromatic compositions and maturity parameters between two occurrence states of deep carbonate rocks, comparing with free organic matter, the maturity of the inclusion organic matter are lower and retarded in the same source rock. There are some aromatic maturity parameters can still be used to assess maturity during overmatre stages, including alkylation ratios of phenanthrenes （C1-P/C4-P, C1-P/C3-P, C2-P/C4- P, C2-P/C：P）, and maturity parameters for dibenthiophene （ MDR, CJC：DBT,2,4/1,4-DMDBT and 4,6/1,4- DMDBT）. Although DBT/P are thought to an indicator for organic facies, it is showen from this study that this parameter is related to maturation level, which is a good maturity parameter at the same organic facies in high and over maturity stage.