The Research On The Correlations Of Structure And Sediments Feature In Central Of Tarim Basin

Based on the theory of tectonics, sedimentology, Sequence stratigraphy and Basin analysis, the paper comprehensive analysis feature of structure and deposition and correlation about them of Tazhong area in Tarim basin by comprehensive utilize various data such as outcrop, core, seismic and well logging data.1,The research of structure background and feature: Based on the region geology background, The paper emphasize analysis structure movement, structure configuration of Tarim basin and fracture feature of center of tarim uplift for region structure movement notably control the evolvement of Tarim basin. The center of tarim uplift locate in the middle of two depressed, it can capture oil and gas easily. Based on the old-uplift background, the center of tarim uplift develops multi-sub-structure zones, and has important features of subarea in east-west, strip in south-north.2, The research Sequence Stratigraphy: Combined with the former achievement, the paper distinguish two â…  grade inconformity, two â…¡ grade inconformity and several â…¢ grade, â…£ grade inconformity from Cambrian-Ordovician of Tazhong area by utilize fully 2-D seismic profile and combine with the well logging and core data. On the basis of that, the author makes divisions of Cambrian-Ordovician sequence stratigraphy of Tazhong area, and builds up the Cambrian-Ordovician general sequence stratigraphic framework through combination of well and seismic and by means of well connection contrasts. The Cambrian-Ordovician formation of the Tazhong area can be divided into two magnitude sequences and eight supper sequences, i.e. Three supper sequences in Cambrian includes three larger cycles of sea level rise and fall, but the amplitude of sea level change is not wide. The facies in Cambrian mostly involves the restricted platform, tidal flat and lagoon of the evaporated platform, thick-bedded gray dolostone and develop dull pelitic gypsum rock. Two supper sequences in Lower Ordovician generally developed on the background of sea level rise. And that the depositional environment came through the evolvement process of tidal flat facies to the restricted platform and then to the open platform, stratigraphic lithology also changes from thick-bedded grayish brown dolostone to thick-bedded brownish gray limestone.3, The research on the features of structure and sediment evolvement: The structure evolvements of central of tarim happened four great subside and rise, which has important control actions to the form of central uplift zones, structure framework and congregate of oil and gas. On the basis of the isochronous stratigraphy framework, the depositional facies and depositional system of Cambrian-Ordovician were researched carefully, the paper summarizes the major types, the deposition sequence the longitudinal evolvement features of Cambrian-Ordovician depositional facies, and the plane distribution rules of the depositional facies of each sequence, and points out the features and distribution of depositional systems are strict controlled by the sea level change, structure and palaeogeography background. Not only structure uplift controlled development of source rock, fractures have different control actions to different areas sediments, furthermore palaeo-relief have important influence to stratum sediments, specially to middle-upper Ordovician stratum.