Fault Evolution Characteristics Of Wen'an Slope In Jizhong Sunken And Their Oil-Controlling Mechanism

In order to analyze geological significance with regard with effects of differential evolution of faults on oil and gas reservoir in Wen'an Slope,this paper studied geometry features,kinematic features and features of dynamic mechanism from the research area by adopting principles of combining regional research with key dissection.This paper divided fault systems based on the division of structural layers and got two fault systems bounded by reflector T5;this paper analyzed distribution features of faults and their combinations,revealed that distribution features of fault zones at macro level were controlled by growth differences of boundary faults and feature differences of sub-sag texture on the basis of fault banding features;we found there were obvious corresponding relationships between boundary faults and basement faults with tracking distribution features of different fault zones by means of integrated seismic section of the area,meanwhile,as influenced by NW trending basement faults,did deformation features of faults from different fault zones have significant differences.In consideration of regional tectonic evolution features,did growth index cross section and balanced cross section are utilized to determine active faults of the researched area.As a result,this study categorized these active faults into six types;they were faults formed during rifting stage 1 and consumed in the later evolution process,faults formed during rifting stage 1 and developed successively during rifting stage 2,faults which kept active from rifting stage 1 to after-rifting stage 3,faults formed during rifting stage 2 and inactive during after-rifting stage 3,faults formed during rifting stage 2 and developed successively during after-rifting stage 3,faults formed during after-rifting stage 3.This study also showed that the boundary faults of faults zones in the researched area demonstrated feature of out-sync growth by analyzing the growth pattern of these faults,which further suggested the basement faults had significant impact on the fault activities.According to the different angels between stretching direction of the researched area and basement-fault strikes,this area could be divided into two types of zones,which were orthogonal stretching deformation zone and oblique stretching tensional-shear deformation zone;and the deformation zones could be further divided as to get secondary transformation tectonic belts whose developments were controlled by NW trending pre-existing structures.On the basis of deformation zones,the researched area were finally divided into three types of fault zones,which were orthogonal stretching fault zone,oblique stretching tensional-shear fault zone and tectonic transferred fault zone.The oil and gas reservoir of the researched area was mainly accumulated in the fault zones near NW trending transferred structure.The stacking areas of orthogonal stretching fault zones and tectonic transferred fault zones possessed beneficial reservoir condition.To be more specific,relay ramps were conductive to lateral migration of the resources along the inclinations where truck faults extended and bonded together in the inclined fault zones;anticline traps were conductive to accumulation of oil and gas reservoir,which were formed by extension and compression of trunk faults in the counter-inclined fault zones;local deformation in out-sync growth process and evolution degree of the boundary faults in the tensional-shear fault zones determined reservoir enrichment.