Research On The Sedimentary System And Potential Districts In The Upper Devonian-Carboniferous Of Tabei Uplift

The Bachu formation of Upper Devonian and the Donghetang formation of Carboniferous is the main exploration target in the Tabei uplift. As a theoretical guide to sequence stratigraphy, sedimentology and seismic stratigraphy, this paper studies deeply the sequences and depositional systems of the Devonian and the Carboniferous formation and determines those with combination of logging, mud logging, core, outcrop and two-dimensional seismic data. Based on above, it predicts three potential districts of the Bachu and Donghetang formations.The target formation of Tabei uplift can be divided to 43rd-order sequences (SQ-Ddh, SQ-Cl, SQ-C2 and SQ-C2) and 8 system tracts, those sequences are made up of TST and HST but LST, and sequence SQ-C1 and SQ-C2 are relatively stable in the study area, the sequence SQ-Ddh mainly distributes in the northwest of Halahatang depression, Caohu depression and Hadexun uplift, and the SQ-C3 mainly distributes in the Hadexun uplift and south of Lunnan uplift.The main sedimentary system of the target formation in Tabei uplift includes lagoon, tidal flat, delta, shore beach and carbonate platform. The TST of SQ-Ddh deposited mainly delta and shore beach system and which contains shore beach system in HST, the TST of SQ-Cl deposited mainly shore beach, lagoon, tidal flat and carbonate platform system which contains lagoon and tidal flat system, the TST of SQ-C2 deposited mainly delta, lagoon and tidal flat system which contains delta and tidal flat system, the TST of SQ-C3 deposited mainly tidal flat system which contains carbonate platform system.This paper selected three potential districts. The one in the TST of SQ-Ddh locates in the area between northeast of well X3 and southwest of well LG15 where be between west of well DH8 and the pinch-out of the HST, and the one in the TST of SQ-Cl locates in the area between the well series (LN21-QM2-LN17-LN62-LN60-LN54) and the pinch-out.