黔东南地区震旦系—二叠系海相优质烃源层的时空分布

Spatiotemporal Distribution of Sinian-Permian Excellent Marine Source Rocks in Southeastern Guizhou Province

黔东南典型古油气藏的精细解剖对黔中隆起周缘乃至南方海相油气勘探研究具有重要意义。研究表明,在早寒武世初期、晚泥盆世早期和二叠纪,本地区均发育优质烃源岩,其中以下寒武统盆地相、斜坡相的黑色页岩发育最好,有机质丰度高(TOC普遍大于2%),类型好(偏腐殖型),厚度大,是麻江古油藏及凯里残余油气藏的主力烃源岩;早二叠世盆地相和澙湖相中发育的优质烃源岩与本层位中的沥青具亲缘关系,显示自生自储的特点。二叠纪烃源岩对黔中隆起及其周缘地区油气成藏具有重要作用。本地区缺乏扬子地区广泛发育的上奥陶统五峰组—下志留统龙马溪组底部那套优质烃源岩。

Good prospecting of nature gas exists in Sinian-Permian marine sedimentary formations in Central Guizhou Uplift and its adjacent areas but complex geological conditions and low degree of exploration are faced, Three series of excellent source rocks including lower Cambrian, upper Devonian and Permian ones are discovered, Lower Cambrian excellent source rock that are black shale of basinal facies or slope facies are characterized by high abundance of organic matter （generally TOC≥2.0%）, good type of organic matter （sapropel type）, large thickness and extensive distribution of source rock, which is the main source rocks of Lower Palaeozoic paleo-reservoirs in Majiang and Kaili anticlines. Excellent Permian basinal-lagoonnal source rock is well correlated with the Permian oil seepages in Majing area. Excellent source rocks formed and locally distributed at the bottom of the Upper Devonian rock in Dushan section, No excellent Ordovician-Silurian source rocks are distributed except the widespread excellent Upper Ordovician-Lower Silurian black shale in Yangtze region.