The Study Of The Sequence Stratigraphy And The Sedimentary Facies Of Carboniferous To Lower Permian Of Bachu Area In Tarim Basin

Bachu uplift lies in the southwest of central uplift belt of Tarim Basin. It is a large back-rush fault belt and is about 40000km2. The degree of exploration in Bachu area is very low on the whole, and the oil and gas reservoirs found in recent years mostly concentrated in fracture belt of uplift edge. However there is little oil and gas found in the inner uplift. What are the main reasons? So it is very necessary for us to study systemically the sequence stratigraphy and sedimentary facies of the Bachu area so as to guide the oil and gas exploration .The Carboniferous to Lower Permian are the study intervals in my paper. Basing on the anterior research, at the same time guided by the theory of sequence stratigraphy and combined with the outcrop, drilling, logging data, this paper introduce the standard of sequence stratigraphy to help us achieve unity in understanding it. The result shows that the Carboniferous can be divided into five sequences and the Lower Permian can be divided into two sequences. We analyze the controlling factors of sequence stratigraphy.The research of sedimentary facies is mainly based on the fine stratigrapic classification and correlation. The types of sedimentary facies are fixed by the help of outcrop, well logging and core data. Seven types of sedimentary facies can be identified and these sedimentary facies include evaporate platform, restricted platform, platform-edge bank, tidal fiat, coastal facies, continental shelf facies and delta facies. The result shows that platform-edge bank, inside the beach and clastic tidal flat facies are the most favorable sedimentary facies. Along with the result of sequence stratigraphy, the distribution of sedimentary facies in vertical is controlled by sequence stratigraphy framework. The most favorable sedimentary facies developed in transgression system tract. At the same time, the distribution of sedimentary facies is obviously controlled by marine transgression and regression, sediment supply, topography and water body energy.The result of sequence stratigraphy and sedimentary facies of Carboniferous to Lower Permian in Bachu area can point out the direction in the process of exploration and development in Tarim basin.