渤海蓬莱20-2油田原油物性差异及成因

通过对渤海蓬莱20-2油田原油物性和色谱-质谱等实验数据进行成藏综合分析与研究,探讨新近系馆陶组原油物性差异及成因。蓬莱20-2油田原油具有高密度、高黏度、低硫、低蜡和低凝固点的稠油特征,油田南区的原油物性呈现出优于北区和东区的特点。南区的原油来自庙西南洼沙三段烃源岩的贡献,其成熟度较低;而北区和东区的原油分别来自渤东凹陷沙三段和庙西北洼沙一段烃源岩的贡献,其成熟度均较高。油田区原油物性差异的主要原因是原油中蜡组分具有相对较强的抗降解能力,其蜡组分形成的有利条件是来自热演化程度较低、藻类来源丰富的富烃凹陷贡献。

Difference of physical properties and genesis of crude oil in Penglai 20-2 Oilfield,Bohai Sea,China

Based on the comprehensive analysis and study of physical properties and chromatography-mass spectrometry of crude oil in Penglai 20-2 oilfield of Bohai Sea,the differences and causes of crude oil physical properties in Neogene Guantao Formation are discussed and studied.It is indicated that the crude oil in Penglai 20-2 oilfield is characteristic of high density,high viscosity,low sulfur,low wax and low freezing point,and the physical properties of crude oil in the southern part of the oilfield are better than those in the northern and eastern parts.In the southern area,the relatively low maturity crude oil is from the contribution of the Sha 3 Member source rock in the southern subsag of Miaoxi Sag.However,the relatively high maturity crude oil in the north and east regions are thought to be contributed by the Sha 3 Member source rocks in Bodong Sag and Sha 1 Member in the northern subsag of Miaoxi Sag respectively.The main reason for the difference in physical properties of crude oil in the Penglai 20-2 oilfield is that the waxes in crude oil have relatively strong anti-degradation ability,and the favorable condition for the formation of waxes is the contribution of hydrocarbon-rich sag with low thermal evolution degree and rich algae source.