潜江凹陷毛场—马王庙地区新沟嘴组下段烃源岩地球化学特征

Geochemical Characteristics of the Source Rocks of the Lower Xingouzui Formation in the Maochang-Mawangmiao Area of the QianJiang Depression

利用大量烃源岩样品有机地球化学资料,系统研究了新沟嘴组下段烃源岩,主要包括烃源岩分布、沉积环境、有机质丰度、有机质类型、有机质成熟度以及生物标志化合物特征。结果表明:研究区新沟嘴组下段烃源岩发育,有机质丰度较高,有机质类型主要为Ⅱ_2型,烃源岩大部分进入成熟阶段。对烃源岩生物标志化合物研究认为,烃源岩形成于半咸水湖相的还原沉积环境,其中不同地区烃源岩沉积环境的水体盐度和还原程度有所差异,生烃母质具有低等水生生物和陆源高等植物双重生源。Pr/Ph、甾烷/藿烷、伽马蜡烷/C_(30)藿烷、C_(35)藿烷/C_(34)藿烷等一系列生标参数的差异可将研究区烃源岩分为两类。

Based on a large number of the organic geochemical data of source rocks,this paper makes a systematic study on the source rocks of the lower Xingouzui formation,including the distribution of source rock,sedimentary environments,organic matter abundance,organicmatter type,organic matter maturity and the characteristics of the biomarkers. The results showed that the lower Xingouzui formation whose organic matter type is Ⅱ2,as is the main period of goodness hydrocarbon source rock development in the study area. Organic matter has evolved to higher stage of maturity. In the research on characteristics of the biomarkers of the source rocks,we consider that the sedimentary environment reduction of the source rocks was half saline reductive lake. There are some differences of source rocks in different areas such as the water salinity and the degree of reduction. Besides that,the hydrocarbon generation materia has the mixed origin of lower aquatic organism and higher terrigenous plants. The source rocks in the area can be divided into two types on the basis of the differences on a series of biomarker parameters,for example,Pr/Ph,steranes/homohopanes,gammacerane/C30-homohopane,C35-homohopane/C34-homohopane,etc.