Characteristics Of Strike-slip Fault And Its Relationship To Oil And Gas In Northern Slope Of Middle Tarim Basin

Northern slope of middle Tarim Basin is located in the footwall of Tazhong No.1 fault belt, crossed in two development uplifts of Shuntuoguole and Guchengxu, with area of about 15000km2. This thesis is mainly on the basis of tectonic geology, petroleum geology and seismic interpretation, combined with the seismic, drilling and regional geological data, its structural characteristics, active periods and genesis are studied, and the Paleozoic evolution process is preliminarily restored, also the influences on reservoir are discussed of the strike-slip fault on the north slope, the conclusions are as follows:1、The tectonic morphology is a slope from Southeast(high) to Northwest(low), and is developed to 7 left lateral strike-slip fault zone with NNE, NEE trending, and is divided into a plurality of different block.2、The main displacement belt of strike-slip fault is in the plane linear extension, and the locally are formed to horsetail fault combinations, extension and the main displacement with large angle of intersection, not long NNW to en echelon normal faults. The structural styles of the strike-slip faults included flower structure, dolphin and riband effects in section, with obvious segmentation along the strike, extrusion forming reverse faults and local extensional normal faults appear alternately formed.3、The strike-slip faults were active mainly during the middle Caledonian(the end of the Middle Ordovician) and the early Hercynian(the end of the Middle Devonian).The early Hercynian tense-shearing strike-slip faults developed based on the middle Caledonian compressive-torsionto typical passive strike-slip faults.4、The trend of effective crack is the same as the strike-slip fault zones, show that fracture tectonic of strike-slip faults fracturing control. Fractures and hydrothermal activities played important roles in the generation of fractures and vuggy reservoirs in Ordovician carbonate rocks.5、The drilling wells accessed to oil and gas are distributed in the strike-slip fault zone or its vicinity, it shows that the strike-slip fault played a vital role on oil and gas accumulation. The strike-slip fault activities controlled the longitudinal distribution and enrichment of hydrocarbon, and the beaded seismic reflection anomalies near to strike-slip faults are the most favorable exploration targets on the Ordovician carbonate rocks area.