V.I. Shegai, A.V. Tolstikov
Upper Miocene and Pliocene deposits of north-eastern shelf of Sakhalin Island: new seismic data on structure and petroleum potential
Key words: Sea of Okhotsk region; Sakhalin Island; paleofacies analysis; Nutovsky and Pomyrsky horizons; reservoir; oil; gas.
For citation: Shegai V.I., Tolstikov A.V. Upper Miocene and Pliocene deposits of north-eastern shelf of Sakhalin Island: new seismic data on structure and petroleum potential. Geologiya nefti i gaza. 2022;(3):67–83. DOI: 10.31087/0016-7894-2022-3-67-83. In Russ.
Simultaneous analysis of new seismic and well data allowed creating a single geoseismic framework of north-eastern shelf of Sakhalin Island, which made a basis for studies of structural and tectonic evolution features in the area and sedimentogenesis patterns of Upper Miocene and Pliocene deposits. The conducted investigations demonstrated the key role of the ancient North Sakhalin Trough; its depocentres (Piltunsky and Chaivinsky-Veninsky) materially affected the features of accumulation of Late Miocene deposits. The activity of East Sakhalinsky, East Odoptinsky, and supposedly Shmidtovsky provenance areas is established, which made possible the formation of Later Miocene-Pliocene reservoirs in the region of western shoulder of Deryuginsky and East Sakhalinsky troughs, as well as all along the East Sakhalin mountain system. Prospecting for non-anticlinal traps could be the main area of research to discover new hydrocarbon pools and replace reserves. Settings most favourable for these objects formation in Miocene and Pliocene time were dominant in the region of the eastern shoulder of East Sakhalinsky and Deryuginsky troughs, as well as all along the eastern shelf of Sakhalin Island from Nabil Bay to Cape Patience. The investigations conducted showed that it is possible to identify them in seismic data. Amplitude attributes allow identifying both fans, which are characterised by an amplitude distribution contrasting against the background of host rocks, and their feeding channels clearly visible in the Coherence attribute. These observations can be taken as basic prospecting indicators of stratigraphic traps in this region.