Sequence and systems tract of Paleogene Kumugeliemu Group in Western Kuqa Depression, Tarim Basin

Sequence stratigraphy is used for analytical comparison and paleogeographic reconstruction of lithologic sections in Paleogene Kumugeliemu Group in western Kuqa Depression under the framework of sequence and systems tract to establish the reservoir-caprock assemblage and allocation system and to predict the distribution of favorable reservoir sandstones. Two sets of coarse fragment sands are developed in the 3rd order sequences Esq1 lowstand systems tract and Esq2 lowstand to transgressive systems tract. The widely distributed salt and gypsum muddy section of Esq1 and Esq2 has good sealing and forms good reservoir-caprock assemblage with the two reservoirs in the bottom sand section of Kumugeliemu Group. According to the reservoir sandbody distribution, the forwarding fluvial system at mountain front to the north, fan delta at east flank of Wensu uplift to the west, and the downcut valley filling and fluvial delta system at Yingmai low paleo-uplift to the south form favorable reservoir sandbodies. Kelasu-Dabei zone on north margin of the depression, Qiulitage-Quele and its southward parts, and northern and eastern Wensu uplift are the favorable places. Key words: sequence and systems tract, depositional system, reservoir-caprock assemblage, Kumugeliemu Group, Kuqa Depression