Sequence stratigraphic filling model of the Cretaceous in the western Tabei Uplift, Tarim Basin, NW China

Abstract

Cretaceous formation in the western Tabei Uplift is significant petroleum pay zone in the Tarim Basin, NW China. For the complex relationship between tectonic movement and depositional environment, sequence stratigraphic filling model of the whole Cretaceous formation has not been established yet. Using well logs and seismic data in this article, sequence stratigraphic evolution process and filling model of the Cretaceous are interpreted involving paleo-uplift, sedimentary and water-level. As a first-order sequence, the Cretaceous is subdivided into three second-order sequences, Shushanhe, Baxigai and Bashijiqike Formation. Shushanhe Formation is subdivided into three third-order sequences, KSQ1, KSQ2 and KSQ3 upwards; Baxigai Formation is considered as one single third-order sequence, KSQ4; Bashijiqike Formation is subdivided into three third-order sequences, KSQ5, KSQ6 and KSQ7 upwards. In the early KSQ1, paleo-uplift was aquatic. From KSQ1 to KSQ3, water-level raised and paleo-uplift moved upwards gradually; and water-level raising was faster than paleo-uplift ascending. The accommodations of these three sequences increased. Lacustrine facies mudstones and siltstones were onlap filling sequences towards Xiqiu Paleo-uplift. In the end of KSQ3, the whole region was subaqueous. The water-level and paleo-uplift in KSQ4 were easy steady, and the accommodation in KSQ4 was sustained. Delta depositional system began to prograde from depocenter to distal slope of paleo-uplift. In the high of Xiqiu Paleo-uplift, dominated sediments were fine grains for the sedimentary dynamic force. From KSQ5 to KSQ7 in the Bashijiqike Formation, water turned regression, paleo-uplift raised slowly and the accommodation reduced continually. Because of the progradation deltaic sandstones, downlap sequences were developed towards the Xiqiu Paleo-uplift. Exposed in the Early Paleogene, KSQ7 and part KSQ6 were truncated to form top unconformable boundaries. Established sequence filling model of the Cretaceous in the western Tabei Uplift provides important insights on the stratigraphic characteristics and in turn on the exploration potential of petroleum systems.

Sedimentary characteristics and model of seasonal deltaic sandstone: a case study on the continental red bed from the Cretaceous Baxigai Formation, Tarim Basin, NW China

“…B. et al, 2019). Paleo-uplift were weak in activities, and the accommodation was sustained in the deposition period of the Baxigai Formation (Zhao et al, 2022). Influenced by regional tectonic movement, the paleogeographic pattern of the southeast high and northwest bottom was formed in the study area, which controlled the distribution of sedimentary facies (Su et al, 2020).…”

“…Geological background of the western Tabei Uplift (A) Location map of the Tarim Basin in NW China (modified from Wang et al, 2023). (B) The tectonic location of the study area (modified from Zhao et al, 2022). (C) Map showing geological details of the study area, including the location of oil and gas field, cored wells, and partial key wells (modified from Xu et al, 2016).…”

Seismic Response Variance of Depositional Sequences: Implications for Reservoir Prediction in Lacustrine Basin

“…Previous studies have shown that the Cretaceous Baxigai Formation was deposited in a sedimentary transition period. After the development of the ancient uplift in the Shushanhe Formation sedimentary period, the ancient uplift in the study area began to be submerged, becoming a subaqueous low uplift, and river-dominated delta-lacustrine deposits developed [33,[40][41][42]. Although the previous models have revealed the conceptual model of deltaic deposition, the facies distribution in finer scale and beach bar deposition have not been determined yet, due to limitations in the seismic data resolution.…”