| The study area of this paper locates in the mid-west of Middle Uplift in Tarim Basin, and the target layer is Cambrian carbonate. According to the tasks and aims of this paper, combined the present study situation of carbonate in and aboard, directed by the theories of Vail's classic sequence stratigraphy, sedimentology, reservoir geology and other subjects, integrated these data of drilling, logging, palaeontology and seismic, the sequence stratigraphy and sedimentary facies researches of Cambrian carbonate in study area are developed, the sedimentary facies constitution and interspace distribution is probed, and the sequence-deposition evolution model is built to discuss the main factors which control the sequence development. On the base of researches, combined the area tectonic features and petroleum geology conditions, the reservoir analysis of Cambrian carbonate in study area is proceeded.Tarim event is the mark of the end of base tectonic evolution of Anti-Cambrian in Tarim basin, and also the mark of the final formation of basin base. It signed the basin entered evolution stage. Affected by that event, on the tectonic background of base uplift in Bachu area, it presented a slow low-uplift. The first act of Caledonian event happened in the end of Sinian and formed a parallel unconformity between Sinian and Cambrian in Bachu-Mid Tarim area, and the seismic boundary is T90. It is an obvious angle unconformity relationship between Cambrian and Anti-Cambrian. The Cambrian on the seismic section is a set of continuous black deflection reflection wave group. The second act of Caledonian event happened in the end of Cambrian, and formed a parallel unconformity between Cambrian and Ordovician. The seismic boundary is T80.According to the macroscopic description of 10 wells Cambrian cores, on the basis of the sedimentary and logging facies fine analysis, combined the analysis of 5 main well-tie section seismic facies and the fossil organism data, three facies, evaporation platform, restricted platform and open platform are confirmed in the study area. The whole Tarim basin appeared the sedimentary frame of west platform-east basin, and Bachu-Mid Tarim lies in the platform area. Affected by the fluctuation of sea level, Yuertusi formation tidal-plat, Xiaoerbulake formation restricted platform and Wusonggeer formation evaporation platform developed respectively in the study area during the early Cambrian; Shayilike formation open-restricted platform and Awatage formation evaporation platform developed respectively during the mid-Cambrian; the Xiaqiulitage formation restricted platform developed during the late Cambrian. According to the available information, sedimentary subfacies and microfacies are further confirmed, and the facies researches are developed systemly.Directed by Vail's classic sequence stratigraphy theory, the Cambrian sequence stratigraphy researches are proceeded in the study area. Combined the analysis of deposition system and tectonic geologic background, the multidisciplinary analysis of mud-logging, well-logging, core-observation, palaeontology and seismic data shows that the Cambrian can be divided into 3 second order super-sequence in Bachu-Mid Tarim area, and each second order sequence boundary is sequence unconformity. And short exposition happened on T90, T82, T81 boundaries. Sedimentary facies planforms are compiled based on second order sequence; sedimentary facies distribution laws are revealed. The paper indicates that the Cambrian carbonate developed successively during each period in study area: the study area showed a shallow upwards carbonate growth succession in lower Cambrian, and evolved a semi-closed restricted-evaporation platform from the early semi-open restricted platform. After short exposition, a small transgression happened in Mid-Cambrian, and the study area evolved a semi-closed restricted-evaporation platform from the early semi-open restricted platform again. During the upper Cambrian, the sea level rose, and a huge set of dolomites deposition restricted platform developed in the study area.On the basis of sequence stratigraphy and sedimentary facies researches, combined the area tectonic features and petroleum geology conditions, it is suggested that in the southwest of Mid Tarim which adhered with Bachu area, north-west rift structure developed exceedingly, providing good conditions for the formation of fracture reservoirs.
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