V.I. Shegai, Ya.I. Shtein, A.V. Tolstikov
Structural features of Lower and Middle Miocene pay interval (Daginsky Horizon) in the area of the Kirinsky Block, the Sakhalin Shelf
Key words: the Sea of Okhotsk region; Sakhalin; Kirinsky Block; Sequence Stratigraphy; Facies Analysis; Daginsky Horizon, reservoir.
For citation: Shegai V.I., Shtein Ya.I., Tolstikov A.V. Structural features of Lower and Middle Miocene pay interval (Daginsky Horizon) in the area of the Kirinsky Block, the Sakhalin Shelf. Geologiya nefti i gaza. 2022;(2):31–44. DOI: 10.31087/0016-7894-2022-2-31-44. In Russ.
Studies of target Middle and Upper Daginsky subhorizon section (N11–2dg — Early – Middle Miocene, 6а Reflector – 6 Reflector) within the promising Kirinsky License Area on the Sea of Okhotsk Shelf were carried out on the basis of integrated analysis of well and seismic data. Seven depositional cyclothems (SB6–SB0) were identified in the interval under consideration with building facies schemes for each of them. The studies demonstrated that regressive sedimentation prevailed for much of the mentioned period, resulting in the formation of a progradational package of parasequences (SB6–SB2). In the late Daginsky time, the regression changes for aggradation. SB1 cyclothem formed at that time has high net-to-gross and good lateral continuity. The locally occurring transgressive SB0 cyclothem closes formation of the Daginsky series. Area of its occurrence is limited to the western part of the Kirinsky area. These structural features of the Upper Daginsky subhorizon are responsible for mismatch in indexing pay horizons, which is used for the objects in the western part of the study area (Lunskoe, South Lunskoe fields) in the target pay interval subdivision scheme accepted for the Kirinsky, South Kirinsky, and Mynginsky fields in the southern and eastern parts of the area under consideration. Results of the studies presented in the paper allow obtaining a single consistent system that includes all actual data about pay section architecture within this large rapidly-developing gas producing region, which were obtained during the course of geological studies of the fields.