Research On Characteristics And Reservoir-controlling Of Yangcun Fault Zone In Jinhu Sag

Composed of Yangcun fault and its branch faults,Yangcun faults zone is a extensional strike-slip faults zone between Jinhu depression and Tianchang bulge.With good oil source condition,Yangcun faults zone has advantageous reservoir forming conditions.Under the guidance of the modern oil and gas accumulation theory and using the high resolution seismic data,this paper carries out comprehensive evaluation of structural system with geometry and kinematics as the core.With application of seismic physical,drilling logging,analysis assay data,geological profile of equilibrium and the quantitative evaluation of the fault activity,the paper studies the characteristics of fault controlling reservoir,combined with the structural evolution,fault activity analysis.Then oil and gas accumulation mode is established and favorable exploration area are predicted.As the difference of regional principal stress field,the fault characteristic and structural style are different between eastern and western section of Yangcun fault.Controlling by Dextral transtensional stress field,the western section is Concave and convex in thrown side.It formed a set of nearly EW pinnate fault which intersect the main fault of sharp angles.Controlling by SN tensile stress field,it formed a set of nearly EW faults parallel Yangcun fault in the eastern section,which eventually formed a half graben with small fault step belt.In the middle area it was the most concentrated release of NE extrusion stress place,formed reverse faults.Studies on the tectonic evolution history,tensile strength,activity rate,growth index shows that Yangcun fault in different space and different time has obviously different fault activity.In time,from Wubao to Sanduo period,Yangcun fault activity mainly enhanced,then weakened.In space,from west to east,the fault activity changed from strong to weak?It's strong in Western Qinying and Xiaoguan area,weak in eastern BMY area.The eastern section of associated faults have also obviously different with the western.In the western section,fault activity is stronger in Sanduo period than in Wubao period.In the eastern section,Instead,fault activity is stronger in Wubao period than in Sanduo period.Study shows SN tensile strength of Yangcun fault is stronger in Sanduo period than in Wubao period,in eastern than in western.Research shows that different stress field differenced the activity of the east and west of Yangcun fault.In Dextral transtensional stress field,west fault zone forms extensional strike slip fault system,which activity is weaker than east.In SN tensile stress field,the east formed tensional faults,which activity is stronger.Difference of activity played a role in the control of tectonic framework and structural style.The Difference of tectonic framework and structural style controlled the sedimentary of Yangcun downthrown.So the subsidence and deposition thickness are bigger in east than west,which controlled maturation and distribution of source rocks of E1f2 and E1f4 is better in Longgang sag than Chajian sag.