古风化壳孔隙与裂缝发育特征及其油气地质意义

Characteristics and Petroleum Geological Significance of Pores and Fissures Developed in the Paleo Weathered Crust

通过总结前人研究结果,利用数据整理、薄片观察等方法对古风化壳中孔隙和裂缝的发育规律进行了分析,并探讨了古风化壳结构的油气地质意义。研究结果表明,发育完全的古风化壳具有风化黏土层和半风化岩石的分层结构;半风化岩石中部孔隙和裂缝较发育,向上向下规模逐渐减小,至风化黏土层大孔隙和裂缝不发育。通过实例汇总认为,影响半风化岩石孔缝系统发育程度的主要因素包括风化基岩的岩性、风化的时间和强度、风化壳形成时期的剥蚀厚度和古风化壳的埋藏深度以及裂缝孔隙的充填特征。风化黏土层岩性致密,对油气的保存具有建设性作用;半风化岩层中部的孔缝连通体,既为油气运移的良好通道,也可作为油气聚集的有效储层。

The characteristics of the pores and fissures developed in the paleo weathered crust are analyzed by means of summarizing the achievement of the formers＇ research, sorting data and observing thin section, and the petroleum geological significance of its structure is discussed. The result shows that the developed paleo weathered crust is quantizing structure, which includes weathered clay layer and semi weathered rock; the middle pores and fissures of the sapropelic rock are intermediately developed, the upper and lower gradually decreases, and there is no development in big pore and fissures of weathered clay layer. According to the example analysis, it is summarized that the main factors affecting the development of pores in semi-weathered include lithology of weathered bedrock, weathering duration and intensity, the denuding thickness and the buried depth during the formation period of the weathered crust, and the filling characteristics of the pores and fissures. The compaction of lithology weathered clay layer could play a constructive rule in keeping oil and gas; the pore connectivity in the middle part of the semi-weathered rock is excellent migration pathway and effective reservoir for oil and gas.