Fault Activity Characteristic Study Of Fault System In North Peri-cline Area Of The Tazhong Paleouplift

The small scale strike-slip fault was the important control factor of middle-lower Ordovician carbonate reservoir and oil and gas accumulation in north peri-cline area of the Tazhong paleouplift.It is a hot spot of exploration and research in recent years.This paper was guided by the Structural geology,Seismic data interpretation,Petroleum geology,Sedimentary petrology as theory.Combined with seismic data,drilling and logging data,by using the method of fault occurrence analysis,fault distance analysis,fault evolution profile made,and so on,accurately explained the structural style,active period and tectonic evolution history of strike-slip fault,and got the following understandings:The north peri-cline area of the Tazhong paleouplift developed three groups middle-small scale strike-slip faults,mainly the North-East trending strike-slip faults,faults were high angle strike-slip,in profile the differences were large,obviously segmented and along strike presented extensional sag and pressure torsion,closed translation the three kinds of structural styles.NE-trending strike-slip fault actived with three phases: the late period of middle Ordovician to early period of Late Ordovician(middle Caledonian)late Silurian-the middle Devonian(Late Caledonian-Early Hercynian),Permian(Late Hercynian),Permian(Late Hercynian).Amomg them,Silurian-the middle Devonian is the main activity time of NE-trending strike-slip faults.The tectonic evolution history of the study area had four periods: middle Caledonian curtain(initial activity strike-slip faults),middle Caledonian curtain-the early Hercynian(strike-slip faults mainly activity),late Hercynian(strike-slip faults activity again),Yanshan to Himalayan period.The NE trending strike-slip faults controlled the reservoir fracture development in the study area,at the same time,fracture section was the advantageous position of reservoir development and oil and gas migration and accumulation.