南华北上古生界油气成藏关键条件分析

ANALYSIS OF HYDROCARBON ACCUMULATION CONDITIONS OF THE UPPER PALAEOZOIC SEQUENCE OF THE SOUTHERN NORTH CHINA BASIN

南华北上古生界石炭—二叠系含煤地层是一套良好的烃源岩,但多年勘探一直未能取得油气突破。该文从控制上古生界油气成藏的关键因素出发,立足有效烃源岩与油气保存这2个基本条件的分析,取得了对该区主要凹陷上古生界成烃演化和油气保存条件的重要认识。研究认为,南华北上古生界具有二次生烃的有利条件,并具有油气兼生的特点;太康隆起、鹿邑凹陷、谭庄—沈丘凹陷在燕山中晚期已具备二次生烃条件,而倪丘集凹陷较晚,主要在喜山晚期,是寻找晚生晚成油气藏的重点地区;现今深凹区是二次生烃的主要区,并具有有利的油气保存条件。

The coal-bearing strata of Carboniferous--Permian of Upper Palaeozoic is a set of good source rock in the Southern North China Basin. However, up to now any great exploration breakthrough has not been achieved. Based on analysis of effective source rock and hydrocarbon preservation, starting from the key factors of controlling hydrocarbon accumulation of Upper Palaeozoic, the important recognition on the hydrocarbongeneration evolution and hydrocarbon preservation condition of main sags has been gained in this paper. Three viewpoints by research are as follows. There is advantaged condition of secondary hydrocarbon generation in the Southern North China and the source rock can produce oil and gas. Taikang Uplift, Luyi Sag and Tanzhuang--Shenqiu Sag had secondary-hydrocarbon condition in Mid Late Yanshanian Period, but there is secondary hydrocarbon in Late Himalayan Period in Niqiuji Sag, which is the focus of looking for the hydrocarbon accumulations that hydrocarbon generated late and reservoir formed late. The modern deep sags are the main hydrocarbon-generation areas and they have advantages condition of hydrocarbon preservation in the Southern North China Basin.