坡折带对油气圈闭发育的约束效应——以平湖斜坡带孔雀亭区平湖组为例

Constraints of slope break belt on oil and gas trapping−An example from the Pinghu Formation in the Kongqueting area of Pinghu Slope

  • 摘要: 坡折带对复合岩性圈闭的发育具有重要控制作用。平湖斜坡带孔雀亭地区具备坡折带发育的古地貌背景,研究其类型和对沉积砂体、相带发育及成圈模式的控制,对下一步勘探开发具有重要意义。根据研究区坡折带发育的构造位置及与洼陷的匹配关系,可将研究区划分为高区坡折带、中区坡折带与低区坡折带。按成因机制不同,可在坡折区内进一步细分出三种类型,即断裂坡折、挠曲坡折和侵蚀坡折。高区坡折带以发育侵蚀坡折为主,控制辫状河三角洲平原沉积体系,形成侵蚀沟谷圈闭;中区坡折带以发育断裂坡折和挠曲坡折为主,控制辫状河三角洲平原与前缘沉积体系,发育辫状河道与扇体,形成断块-河道侧向尖灭复合岩性圈闭;低区坡折带发育断裂坡折,控制复合砂坝,形成断块-砂坝复合岩性圈闭。

     

    Abstract: Slope break belt plays critical controlling roles in the formation of complex lithologic traps. The Kongqueting area on the Pinghu slope was a typical slope break belt in terms of paleogeomorphogy. To reveal the tectonic type of the slope break and its control over sand body sedimentation, depositional facies and trapping formation process is very important for the next cycle of oil and gas exploration of the region. According to the structural position of the slope break belt and its matching relationship with depressions, there are three types of slope break belts in the study area including the high stand slope break, the middle stand slope break and the low stand slope break. According to the genetic mechanism, it can be subdivided into faulting slope-break, flexure slope break and erosional slope break. In the high stand slope breaks, the erosional one dominates, which controls the formation of depositional systems of braided river and deltaic plain as well as the erosional valley traps. The middle slope break is dominated by fault slope break and flexure slope break, which controls the formation of the depositional systems of braided river, deltaic plain and deltaic front, and the compound lithologic traps such as braided river channels and fan bodies, and the fault block-river channel laterally pinched sandbodies. The low slope break is developed along the fault steps, where composite sand bar deposits occur, forming the fault block-sand bar composite lithologic traps.

     

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