泌阳凹陷和枣阳凹陷下第三系生油层的孢粉化石颜色及有机质类型

泌阳凹陷和枣阳凹陷位于南襄盆地的东部,同属白垩-第三系沉积凹陷(图1)。经勘探揭示,这两个凹陷不仅在地层发育,接触关系等方面基本一致,而且两者的沉积旋回性质和主要生油层的沉积时期亦近相同。然而,泌阳凹陷的下第三系含油丰富,以“小而肥”著称,而在枣阳凹陷迄今尚未发现任何规模的油气藏。

ON SPORO-POLLEN COLOR AND ORGANIC MATTER TYPES OF LOWER TERTIARY IN BIYANG AND ZAOYANG DEPRESSIONS,NANXIANG BASIN

This paper deals with the visual observation of sporo-pollen color and organic matter types of the 4 wells of the Biyang aad Zaoyang depressions (a total of 57 samples). All of the samples were treated with hydrochloric and hydrofluoric acids to remove carbonates and silicates, then the organic materials contained in them were concentrated by means of heavy liquid ( CdI2 ). Sporo-pollen fossils and other organic matters were observed under transmission microscope. Based on the variations of sporo-pollen color, three organic maturation facies may be distinguished: ( i ) the light yellow and yellow are immature, ( ii ) the yellowish-brown and brown indicate mature to highly mature, and ( iii ) the dark brownish-black and black are metamorphosed. Dry gas and possibly heavy oil could be generated in the immature facies; oil, condensate and wet gas could be found in the mature to highly mature facies; only dry gas could be produced in the metamorphosed facies. Three main types of organic matters in sedimentary rocks can be determined under transmission micros-cope, e.g. sapropel type,humus type and transitional type. In the mature to highly mature facies, the sapropel type and transitional type produce oil, condensate and wet gas,