鄂尔多斯盆地马岭油田长8油层组储层特征与油藏分布研究

马岭油田延长组长8油层组是鄂尔多斯盆地老区未来油气勘探和开发的重要补充层系之一。研究资料表明,马岭油田长8油层组油藏的储层属于砂岩型储层,总体上物性较差,属低渗—超低渗储层;储层的分布范围较广,主要位于水下分流河道主干河道部位;成岩作用过程中溶蚀作用对于储层储集性能的改善作用明显。长8油层组上部油藏主要分布于水下分流河道的主河道位置或主河道侧翼位置,具有河道砂岩比较发育、相对较好的物性特征。同时,油藏饱和度与次生溶蚀孔隙的发育具有正相关性。说明马岭地区长8油层组油藏的形成与储层分布和储层发育特征关系密切。同时,三角洲前缘水下分流河道砂体距离油源近,两侧泥岩比较发育,具有形成油藏的有利圈闭等特征,是油气聚集的最有利相带。

Characteristics of Chang-8 Oil Reservoir and Distribution of Oil Reservoirs in Maling Oilfield, Ordos Basin

Chang-8 member of upper Triassic Yanchang Formation in the Maling oilfield of Ordos basin is an important supplementary target for oil exploration and exploitation in the future.The top of Chang-8 oil reservoirs with low permeability and porosity is mainly composed of sandstones,considered as low and ultra-low permeability reservoir.The reservoir is largely distributed in the sites of underwater distributary channel development.During diagenesis process,the dissolution improved obviously the physical property of reservoir.Chang-8 oil reservoirs are mainly distributed in the underwater distributary channels or their flank having sandstone development,with relatively good physical property of reservoir.Meanwhile,there is a positive correlation between saturation and solution pore of reservoir,indicating that the formation of Chang-8 oil reservoir would be closely related with distribution and property of sandstone reservoirs.Sand body of underwater distributary channel of delta front is near the oil source rocks and surrounded by both sides of mudstone.Thus,the underwater distributary channel is the favorable facies belt for oil accumualtion.