印尼库特盆地深海区中北部沉积波动与油气分布特征

Sedimentary undation and hydrocarbon distribution features in northern and central deep-sea area of Kutei Basin,Indonesia

对印尼库特盆地深海区中北部中中新统以上地层开展沉积波动分析及波动与油气分布的关系研究,应用米兰科维奇旋回地层定年方法对研究区内的单井地层进行定年,建立精细地层年代格架,并计算精细沉积速率曲线。应用地质滤波法从精细沉积速率曲线中提取出周期分别约为6,3.7,1.85和0.4 Ma的4个主要波动,它们与成藏要素的形成及油气分布有重要关系。其中,6 Ma周期波动对研究区内的成藏要素形成起主要控制作用,在它控制下形成上、下两套成藏组合,上部成藏组合以下更新统底部—上新统中部泥岩为盖层,以上新统下部—上中新统上部砂岩为储层;下部成藏组合以上中新统中部泥岩为盖层,以上中新统下部—中中新统顶部砂岩为储层。其它短周期波动对6 Ma周期波动控制下的储层与盖层形成过程有一定影响,它们决定了6 Ma周期波动控制下局部位置储层与盖层发育情况。0.4 Ma周期波动是米兰科维奇旋回中0.40 Ma长偏心率旋回,对研究区高频沉积旋回起主控作用。同时,研究结果显示研究区内油气分布受盖层控制,6 Ma周期波动和3.7 Ma周期波动双重控制下的有利盖层发育叠加区之下均是油气发现区或地震反射异常区。

The relationiship between sedimentary undation and hydrocarbon distribution in the formations above the midMiocence in northern and central deep-sea area of Kutei Basin,Indonesia,was idnetified through Milankovitch cycles dating of single wells,construction of chronostratigraphic framework,and calculatin of sedimentation rates in the study area.Four major undation periods（ about 6,3. 7,1. 85 and 0. 4 Ma） that had important relationships with hydrocarbon reservoiring and distribution were recognized on fine sedimentation rate curves by using geological wave filtering methods. The undation period during 6 Ma was considered to control the formation of two plays（ upper and lower）. The upper play had the lower Pliocene-the Upper Miocene sandstone as the reservoirs and the bottom Lower Pleistocene-the middle Pliocene mudstone as the caprocks. And the lower play had the lower Upper Miocene-the top Middle Miocene as the reseservoirs and the middle Upper Miocene mudstone as the caprocks. Other undation periods also contributed to the development of reservoirs and caps controlled by the 6 Ma period. The undation period of 0. 4 Ma was the long-eccentricity cycles among Milankovitch cycles and the major controlling factor for the formation of high-frequency sedimentary cycles. The study also shows that hydrocarbon distribution was controlled by the caprocks in the study area. All areas where favorable caprocks jointly controlled by the undation periods of 6 Ma and 3. 7 Ma superimpose have oil / gas discoveries or abnormal seismic reflections.