陇东地区长9油层组浅水三角洲沉积特征及成藏条件研究

Sedimentary Characteristics and Hydrocarbon Accumulation Law of Shallow-water Delta of Chang 9 Reservoir in Longdong Area

根据岩心中沉积构造的特征及其分布规律,认为鄂尔多斯盆地陇东地区长9油层组为典型的浅水三角洲沉积,其湖平面频繁的升降导致湖岸线在研究区内大幅度的往复摆动。由于湖泊水体较浅,湖平面的变化引起湖域间歇性的频繁暴露和淹没,有利于陆生植物的繁衍而不利于优质烃源岩的发育,其油源主要来自邻近长7、长8油层组烃源岩。湖平面上升期砂体叠置呈连片的板状,主要发育岩性-构造复合型油藏;湖平面下降期砂体多呈孤立的长条状,有利于岩性油藏的发育。

By studying the characteristics and distribution pattern of sedimentary structures in cores,it was considered that the Chang 9 reservoir in Longdong Area of Ordos Basin was a typical shallow-water delta,and frequent lake level lifting in the studied area resulted in reciprocating swing greatly.Because of the shallow water,the lake level changing caused intermittent exposing and flooding frequently,it was beneficial to propagation of terrestrial plant and unbeneficial for the development of high-quality source rocks.The oil sources of Chang 9 reservoir mainly came from Chang 7 and Chang 8 reservoirs in the neighborhood.The sand body stacking in clintheriform in the shake level ascending phase,and lithologic-structural reservoirs are mainly developed in this period.The sand body of strip distributed is separately in the shake level descending phase,and lithologic reservoirs are mainly developed in this period.