黄骅坳陷大中旺地区油源及成藏影响因素分析

Oil source rock and accumulation factors in Dazhongwang area,Huanghua depression

大中旺地区位于黄骅坳陷西部北大港潜山构造带西南倾没端。长期以来对于该区油气成因和油藏特征一直缺少研究。本文研究表明,大中旺地区油气主要分布在沙一段下部的生物碎屑灰岩和云质灰岩段(特殊岩性段),储层溶蚀孔隙发育;圈闭主要为受断层控制的断背斜构造;原油具有高密度、高粘度、中低凝固点、高初馏点、高含硫量和高胶质沥青质等特点,属于未成熟—低成熟油;油源为本地咸水环境下形成的沙一段暗色泥岩。大中旺地区油气藏属于自生自储型,油气分布主要与沙一段烃源岩厚度、特殊岩性段厚度及构造位置有关。大中旺地区进一步勘探应在沙一段沉积环境研究基础上,围绕烃源岩分布范围,选择存在特殊岩性段的有利局部构造进行。

Dazhongwang area is located in the southwest plunge of the Beidagang structure zone, Huanghua depression. There has been a long lack of studies on hydrocarbon origins and accumulation characteristics in this area. Several points can be concluded for the area from this paper study. （1） Hydrocarbon mainly occurs in the lower interval of bioclastic limestone and dolomitic limestone （the special lithologic interval） in Es1 Member,in which solution pores well developed; （2） Traps are mainly anticlines controlled by faults; （3） Crude oil is characterized by high density, viscosity, IBP （initial boiling point） ,sulfur content and gum-sphalt contents and middle to low solidification point, and can be classified as an immature -low mature type; （4） Oil source rock is the dark mudstone in Es1 Member, which deposited in a saline environment. In Dazhongwang area, therefore, hydrocarbon accumulations could belong to a self-generating and self- reservoiring type, and their distribution is controlled by the Es1 source rock thickness, the special lithologic interval thickness and the structural position. The further exploration in the area should select favorable local structures around the source rock zone on a basis of depositional environment studies of Es1 Member.