Abstract: The relationiship between sedimentary undation and hydrocarbon distribution in the formations above the mid-Miocence in northern and central deep-sea area of Kutei Basin, Indonesia, was idnetified through Milankovitch cycles da-ting 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 reser-voiring 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.

Key words: undation analyses, Milankovitch cycle, Miocene, Kutei Basin, Indonesia