南堡凹陷滩海地区古近系砂岩孔隙类型、分布及其控制因素

Types,distribution of sandstone pore of Paleaogene and its controlling factors in beach area,Nanpu sag

利用铸体薄片、阴极发光、扫描电镜观察，结合大量物性资料统计，对低勘探程度的南堡凹陷滩海探区古近系的砂岩孔隙类型、分布规律及其主控因素进行分析。结果表明：研究区古近系砂岩储集层在2．5km以上以原生残余孔隙为主，2．7km以下开始发育次生孔隙，主要为碳酸盐、长石溶蚀成因，其次为岩屑溶蚀；纵向上对应2．9—3．3km和4．0km左右深度存在两个次生孔隙发育段；较低的地温梯度以及晚期快速受热过程是南堡凹陷孔隙保存的有利条件，通源断裂活动改善了东一段储集层的孔隙空间，有机质降解形成的有机酸控制了次生孔隙的形成；南堡1号构造带、2号构造带以及4号构造带为研究区内最有利的储集空间发育区。

Pore types, distribution and its controlling factors of the Palaeogene sandstone in beach area, Nanpu sag with low degree of prospecting were studied by using casting thin section analysis, cathodeluminescence and SEM combined with phys- ical property data. The results show that primary residual pores are mainly in depth less than 2.5 km, and secondary pores derived from carbonate, feldspar and cutting dissolution are developed over 2.7 km. There are two secondary pore developed zones of 2.9 - 3.3 km and around 4 km in study area. Lower geothermal gradient and higher heat rating are two advantage factors to pore preservation. And the organic acid derived from organic matter degradation maturation controlled the amount of secondary pore. The quality of shallow reservoirs in the formation of Ed1 was improved because organic acid came from deep maturation beds along activity fault. Three most favorable reservoir development areas are No. 1, No. 2 and No. 4 structural belts of Nanpu sag.