蓬莱19-3油田未熟—低熟油特征及形成条件

蓬莱19-3油田是中国海域发现的最大油田,该油田所产原油部分为未熟—低熟油。利用大量的原油和烃源岩等实验资料,对蓬莱19-3油田未熟—低熟油的原油物性、族组分和生物标志化合物等特征进行了系统分析,并从烃源岩沉积环境、烃源岩特征和成烃母质等方面对未熟—低熟油的形成条件进行了探讨。研究结果表明:蓬莱19-3油田未熟—低熟油密度高、黏度高、含硫量中等、含蜡量低,具有饱和烃含量低、饱/芳比低、非烃含量偏高、非/沥比高、Pr/Ph低、重排甾烷丰度低和TsTm等特征;半咸水—咸水沉积环境、烃源岩有机质类型好且丰度高、有机质演化程度低是烃源岩生成未熟—低熟油的有利地质条件。

Characteristics and Formation Conditions of Immature and Low-mature Oil at Penglai 19-3 Oilfield

Penglai 19-30ilfield is the largest oilfield found in China＇s offshore area. Part of crude oil produced in this oilfield is immature and low-mature oil. A large quantity of experimental data about crude and source rock were used to systematically analyze the physical properties, group compositions and biomarker compounds of immature and low-mature oil from Penglai 19-30ilfield. The study is made on the sedimentary environment of source rock, characteristics of source rock and organic matter evolution. The results of the study indicate that immature and low-mature crude oil from Panglai 19-3 is characterized with high density, high viscosity, middle sulfur content, low wax content, low saturated hydrocarbon content, low saturation-aromatics ratio, high non-hydrocarbon content and high asphaltenes ratio, low Pr/Ph, low rearrangement sterane abundance and Ts〈Tm. The strong anoxic semi-saline to saline environment, organic rich and oilprone abundance and low evolution degree of organic matter are the favorable geological conditions for immature and low-mature crude oil.