鄂尔多斯盆地杭锦旗地区不整合结构类型及运移特征

Unconformity structure types and hydrocarbon migration characteristics in Hangjinqi area of Ordos Basin

杭锦旗地区地处鄂尔多斯盆地北部边缘,存在上古生界-下古生界、上古生界-元古生界、上古生界-太古界3个不整合面。根据已钻井测井响应特征以及岩心观察和岩屑录井资料,对研究区不整合空间结构特征进行了详细研究,同时结合不整合面上下岩性结构的输导作用以及气藏分布等因素,分析了不整合结构类型的运移特征,指出了优势运移通道的分布区域。研究表明,杭锦旗地区存在9种不整合结构类型:砂-泥-砂、砂-泥-灰、砂-泥-变、砂-变、砂-灰、泥-泥-砂、泥-泥-灰、泥-泥-变和砂-泥-泥结构类型。同时存在3种运移通道类型:双运移通道Ⅰ型、单运移通道Ⅱ1型和单运移通道Ⅱ2型。双运移通道Ⅰ型是优势运移通道,主要分布在3个区域:最大区域位于中东部,其目标圈闭是断裂南侧的十里加汗东圈闭以及断裂北侧的什股壕圈闭,其次是位于西部的新召东圈闭,东部阿镇圈闭面积最小;十里加汗西圈闭双运移通道相对不发育,有利于天然气就近富集成藏。

Hangjinqi Block is located in northern Ordos Basin and has three unconformities including the Upper Paleozoic-Lower Paleozoic,Upper Paleozoic-Paleozoic and Upper Paleozoic-Archean. Logging data,core data and cutting logging data were integrated to study the characteristics of unconformity space structure in detail. In addition,hydrocarbon migration characteristics of various types of unconformity structure were also analyzed in combination with the carriers above and below the conformities and distribution of gas reservoir. It also figured out the distribution area of advantageous migration pathways. The research shows that there are nine unconformity configuration types in Hangjinqi Block,namely sandmud-sand,sand-mud-limestone,sand-mud-metamorphic rock,sand-metamorphic rock,sand-limestone,mud-mud-sand,mud-mud-limestone,mud-mud-metamorphic rock and sand-mud-mud. And there are three kinds of migration pathways,namely double migration pathway I-type,single migration pathway Ⅱ1-type and single migration pathway Ⅱ2-type,among which the double migration pathway I-type is the primary pathway and is mainly distributed in three areas. The largest area is in the central-eastern part of the block,and its target traps are Shilijiahan in the south of fault and Shiguhao Yin the north of fault. And the second area lies in the western block and its target trap is Xinzhao. The smallest area lies in the eastern block and its target trap is Azhen. Double migration pathway is poorly developed in Shilijiahan trap and is favorable for the in-situ enrichement and accumulation of gas.