蠡县斜坡北段古近系沙河街组一段油气来源分析

Analysis on oil and gas source of 1^(st) member of Shahejie Formation of Paleogene on northern Li County slope

蠡县斜坡是位于冀中坳陷中部饶阳凹陷西部的次级构造,是一个在前古近纪古隆起上发育起来的西抬东倾、北东走向的继承性宽缓沉积斜坡。理清斜坡北段古近系沙河街组油气来源,是油气成藏研究的基础,对该区的勘探开发具有重要的意义。通过对斜坡北段原油及烃源岩地球化学特征分析,选取正构烷烃、甾萜烷等地化指标进行油源综合对比,结果表明,蠡县斜坡北段原油植烷优势明显,伽马蜡烷含量相对较高,形成于咸水还原沉积环境,未熟—低熟的特征,主要来源于沙一下亚段烃源岩层。

Li County slope, the secondary structure located in the western part of Raoyang sag of central Hebei depression, is one of the W-E low-lying, the N-E inheritance of wide flat sedimentary slope developed on pre Paleogene uplife. Sorting out the oil and gas source of northern section of slope in Shahejie formation is the foundation of hydrocarbon accumulation research, and also has important significance to the exploration and development of this area. Through the analysis of the geochemistry characteristics of crude oil and source rocks in the northern slope section, and the comprehensive contrast to the geochemical indicators such as N-alkanes and steranes and terpanes, the results show that the crude of northern Li County slope phytane has obvious advantages and relatively high gamma cerane content. It formed in the sedimentary enviroment of salt water reduction with the characteristics of up？ripe-immature, mainly from the hydrocarbon source rock of the 1st member of Shahejie Formation.