The Researches Of Silurian Kepingtage Group-Carboniferous Bachu Group Sequence Deformation In Tahe Oilfield Of Tarim Basin

The target block locates in Tahe oilfield of Tarim basin. The researched formation is clasolite of Silurian Kepingtage group-Carboniferous Bachu group. According to the analysis of the background of the tectonic geology, approximately north-south uplift and depression within Tarim plate formed during the Middle Caledonian movement in middle of Late Ordovician. Afterwards, the early Hercynian movement in late Devonian made Tabei(Shaya) uplift ascending and deforming, suffered maverllous denudation and overlaid approximately earth-west tectonic unit on the north-south one which formed approximately east-west Akekule salience. Those all play an important controlling roll in the distribution of Palaeozoic clasolite in Tahe oilfield.According to the chrono-stratigraphic, rock stratigraphic, biostratum, seismic stratigraphic and researches of other experts, Palaeozoic clasolite in Tahe experenced the evolution of silurian offshore with barrier-Devonian offshore-Carboniferous paralic and offshore with barrier longtitudinally. Offshore with barrier developed in Silurian, and tidal flat developed upwards except for neritic continental shelf depositon in the ingression of late Silurian. The deposition of braided delta-lagoon-salt lake-salty lagoon developed upwards in late Carboniferous.Directed by sequence stratigraphy rules and analysis technique, based on the recognization of deposition system types, the sequence boundary of orogenesis angle disconformity, ascending diaconformity and erosion disconformity is recognized. Silurian Kepingtage group-Carboniferous Bachu group in Tahe is divided into 1 first order sequence, 2 second order sequences and 5 third order sequences, which bottom are all I type sequence. SQ1 equals the lower and middle sections of Kepingtage group. SQ2 equals the upper section of Kepingtage group. SQ3 equals the lower and uper sections of Tataaiertage group. SQ4 equals the Donghetang group of Devonian. SQ5 equals the Bachu group of Carboniferous. The primary controlling factors are analysed and rock sequence system and doposition modes of Palaeozoic clasolite in Tahe is concluded.After sequence stratigraphy, deposition, reserior feather and research of oil and gas are analysed totally, it suggested that there are 4 Palaeozoic clasolite reserior longtitudinally in Tahe. They are Silurian SQ1-LST (lower section of Kepingtage group) tidal sandstone, Silurian SQ2-LST(upper section of Kepingtage group) tidal sandstone, Devonian SQ4-LST (Donghetang group) beach sandstone, Carboniferous SQ5-LST (Glutenite section of Bachu group) braided delta sandstone. Relatively, the best reservior sections is the Silurian upper section of Kepingtage group (asphalt sandstone section) tidal sandstone reservior, then is the beach sandstone of Devonian Donghetang group. The tidal sandstone reservior of Silurian lower section of Kepingtage group and braided delta sandstone reservior of Carboniferous glutenite section of Bachu group are worse.