Study Of The Relationship Between Tectonics Characteristics And Oil-Gas Accumulation In The South Slope Of Central Uplift Belt,Tarim Basin

Based on the geology,well drilling,well logging,core,2D seismic and other materials in south slope of central uplift belt,using petroleum structural analysis theory and technologies,by means of structural style explanation,fault assemblage,faults classification and fault active stage study,balanced cross section,oil and gas forming conditions of typical failure well,mainly studied the tectonic style,lateral assemblage and distribution characteristics,fault active stage evolution,arcuate tectonic belt formation mechanism and the controlling effect of tectonic evolution to oil and gas reservoir.There develops 4 trends of tectonics,i.e.,NW,NWW,NE,E-W.The tectonic styles are varied in profile,the main structural patterns are basement-involved Type and the cover-decollement pattern on the basis of deformation level,which can be subdivided into 6 types of tectonic styles,i.e.,high-angle fault-propagation folds,middle-low angle fault-propagation folds,positive flower structure,positive inversion structure,shallow detachment fault and deep detachment fault.The tectonic styles is different obviously from east to west in the main fault zone: the eastern part develops mainly bilateral thrusting tectonics combines with some thrust related folds,the middle part mainly develops compression and scissor thrust fault combines with strike-slip fault,the western part develops thrust related folds.The south slope of central uplift belt experienced 4 key tectonic changes: the early Caledon develops a few normal fault under weak stretch,the middle Caledonian First Episodes develops high-angle thrust faults under near S-N trending compressive stress,the middle Caledonian Third Episodes develops a series of fault-related folds and NE-trending slip-thrust faults,the late Caledonian to the early Heisey develops a few NE-NEE trending sinistral strike slip fault.The characteristic of tectonic system,the difference of tectonic activities and the differential evolution is controlled by basin and thrust direction,there are 4 period of the formation and evolution of the arcuate structure: Initial subduction development period,passive thrust forming period,initiative thrust reformation period,overall fold bury adjustment period.The 11 drilling in the south slope of central uplift belt mostly have show of oil and gas,but all failed to form industrial oil and gas flow,reasons are as follows: The character of high quality source rock is not clear,the quality of discovered source rock is poor and the pool-forming period is unknown.The reservoir quality is poor that most of them are under severe densification.It's lack of a good hydrocarbon migration pathway.The tectonic activity is intensive in late Caledon and early Heisey,causing the cap rock destroyed badly.