关键词: 不整合, 地层接触关系, 岩性配置关系, 底砾岩, 油气成藏, 侧向运移, 柴达木盆地

Abstract: Unconformity plays an important role in petroleum accumulation. It could be a kind of conductor for lateral petroleum migration and could also obstruct petroleum migration to form unconformity reservoirs. This paper analyzes the unconformity between Mesozoic and Cenozoic of west segment of northern margin in Qaidam Basin from the aspects of stratigraphic contact relationship, lithologic allocation relationship, basal conglomerate distribution and thickness, identifying seven kinds of stratigraphic contact relationship and five types of lithologic allocation relationship, and analyzing the effect of different allocation relationship on petroleum accumulation. It summarizes the role of unconformity in petroleum accumulation. First of all, unconformity is the most important lateral and longdistance conductor from source to reservoir. Secondly, existence and formation of unconformity directly affects the petroleum accumulation and distribution. According to the characteristics of unconformity development, considering other accumulation conditions, this paper puts forward that the buried area and Lenghu No.7 area of Saishiteng sag are favorable for exploration

Key words: unconformity, stratigraphic contact relationship, lithologic allocation relationship, basal conglomerate, petroleum accumulation, lateral migration, Qaidam Basin