The Structural Styles And Petroleum Distribution In Bachu Area Of Tarim Basin

In this study area Bachu uplift is located in the Western central uplift of Tarim Basin.Fault belts are very developed in the Bachu uplift. The development and the distribution of structures in the local region are related to fractures or faults.Anticline,faulted anticline and faulted nose are the basic structural types of study area. Detailed study on the structural framework,development and distribution of fault zones,structural styles,distribution and styles of traps,formation and evolution of fault zones (active stage, development model) and their relationships,which is of great significance to the exploration and development of the area.Studies suggest that The tectonic framework of Bachu area presented as "west-easterentiation and north-south dissimilitude".The uplift developed faults and complex fault system. It can be roughly divided into eastern and the western tectonic deformation zones by A Qia fault - Gu Dong Shan fault - Niao Shan fault zone (tectonic transformation zone).Tectonic units can be divided into four part: the western fault-fold zone,the central depressed area, northeast of fault-fold zone and the southeast fault-fold zone.Bachu uplift experienced multi-phase,multi-tectonic stress during the Caledonian, Hercynian,Indo-Yanshan,Himalayan period which resulted in complex superimposed structural styles. The structural styles which are composed of high-angle basement involved type and cap slipping type were dominated by the former. Basement-involved style long-term developed in Bachu uplift,and had an obvious fault slip characteristics.Different faults zone or different sections of the fault zone of Bachu uplift have the quite difference in the formation time, active stage, the nature, intensity and modes. Fault zones started to move from the middle and late Caledonian event,a strong active stages are in the late Hercynian and Himalayan period. Hercynian faults may have experienced the evolution of earlier extensional and later compressional;The Markit slopes and a strong central uplift mainly formed in the late Himalayan by the strong compressional and uplifting process.The southern fault zone of Uplift is a long-term oil and gas migration area, back-thrusting,slip the upper and lower superimposed composite structural style is favoured of oil and gas gathering and effective preservation in a strong deformation settings. Ancient paleo-structural traps,the structural traps of Cambrian salt and structural trap under the thrust fault which along the lines of Paleogene gypsum mudstone,Cambrian rock salt layer is the important exploration area.Through research results in Bachu uplift tectonic evolution,structrual styles,types of trap,unconformity and the tectonic stress field distribution, sedimentary facies,reservoir and cap rocks and source rocks,we evaluated the tectonic evolution and hydrocarbon accumulation conditions of Bachu area,and pointed out the favorable region of oil and gas accumulation zone.