The Researches Of Silurian Kepingtage Group-Carboniferous Bachu Group Sedimentary Facies And Sequence Deformation In Tuputai District Of Tarim Basin

The study aera locates at the end of Akekule bump of Shaya uplift in Tarim basin, borders on the main body of Tahe field in the north-east, connects with Halahatang concave in the north-west, and next to Shuntuoguole low uplift. The study layers are Lower Silurian Kepingtage Group to Lower Carboniferous Bachu Group. Akekule bump developed from the mid-Caledonian Event, displaying a bump like a nose from north to south. And it evolved into a large nose bump where mostly Silurian-Devonian, mid-upper Ordovician and part lower Ordovician are absent.Directed by sedimentary basic theory, according to the integrated analysis of facies marks, such as lothology feather, sediment structure and palaeontology, logging curves and seismic facies, etc, combined former study results, this paper defines that barrier shore tidal flat occurs in the lower Silurian Kepingtage group lower and upper segments and Tataaiertage group; shallow sea shelf facies occurs in the lower Silurian Kepingtage group medium segment; shore without barrier beach facies occurs in Devonian Donghetang group; braided river delta occurs in the lower Carboniferous Bachu group glutenite segment, and barrier shore lagoon and salina facies occurs in the lower mudstone segment. Through the research of analysis of individual well facies and comparison of well tie section, combined the palaeogeographic framework, seismic facies and logging facies feather, the distribution and evolution of Silurian Kepingtage group-Carboniferous Bachu group sedimentary system is analyzed.Using classic stratigraphy theory of sequence stratigraphy, on the basis of seismic analysis data and relative geographic information, integrated former study results, this paper fulfills the sequence boundary identification and sequence stratigraphy division and comparison to the Silurian Kepingtage group-Carboniferous Bachu group in the study area, and 5 third order sequence boundaries: SB1, SB2, SB3, SB4, SB5, and 4 sequence inner boundaries: TS1, TS3, TS5, MFS, are identified. SB1 and SB5 are uplifting erosion (parallel) unconformity, and SB2 and SB3 are erosion unconformity, and SB4 is orogenesis erosion unconformity; TS1, TS3 and TS5 are the original flooding surface, and MFS is the maximum flooding surface. The target layer is divided into 5 third order sequence: SQ1 (lower Silurian Kepingtage group medium-lower segment), SQ2 (lower Silurian Kepingtage group upper segment), SQ3 (lower Silurian Tataaiertage group), SQ4 (upper Devonian Donghetang group), SQ5 (lower Carboniferous Bachu group). The third order sequence feather is analyzed, and lateral variation of sequence is concluded, and region sequence evolution model is built up.Integrating sequence and sediment, combining hydrocarbon evidence evaluation and former study results, this paper analyzes the reservoir feather of target layer in the study area, and concludes two sets consociation related to sequence: 1. composed of SQ1-LST (Kepingtage group lower segment) (reservoir)—SQ1-TST (Kepingtage group medium segment) (seal); 2. composed of SQ2-LST (Kepingtage group upper segment), SQ3 (Tataaiertage group), SQ4-LST (Donghetang group), SQ5-LST (Bachu group glutenite segment) (reservoir)—SQ5-TST (Bachu group lower mudstone segment), SQ5-HST (Bachu group two-summit limestone segment) (seal). There are 5 sets of Silurian-Carboniferous clasolite reservoir vertically in the TPT area: Silurian SQ1-LST (Kepingtage group lower segment) tidal sandstone; Silurian SQ2-LST (Kepingtage group upper segment) tidal sandstone; Silurian SQ3 (Tataaiertage group) tidal sandstone; Devonian SQ4-LST (Donghetang group) beach sandstone; Carboniferous SQ5-LST (Bachu glutenite) braided delta sandstone.