Deformation And Evolution Of Fault Structure In The Yunkai Low Uplift,pearl River Mouth Basin

Yunkai low uplift is located in the southwest of Baiyun Sag,Pearl River Mouth Basin,the abundant hydrocarbon shows and great exploration potential is closely related to the abundant fault system developed since Cenozoic,but the deformation characteristics and evolution process of fault structure in the Yunkai low uplift and its adjacent areas are still unclear,and more in-depth study is needed.Based on the 3D seismic and drilling data,the deformation and evolution of fault structure in the Yunkai low uplift are studied through Seismic profile interpretation,analysis of growth strata and subsidence history,statistics of geometry and kinematics parameters and balanced cross section technique,the following conclusions on fracture deformation and evolution characteristics are drawn.Numerous faults have developed in Yunkai low uplift and its adjacent areas since Cenozoic era.The boundary faults is shovel-shaped and the faults in interior of Yunkai low uplift is small and mainly plate type.Yunkai low uplift is divided into three parts from north to south according to whether the boundary fault develop or not,the northern part which shown as fault uplift develop the boundary fault only on the west side,there is no boundary fault in the middle part which shown as anticline,and the boundary faults develop on the both side of the southern which shown as faulted terrace.On the section,faults are mostly distributed in the Paleogene and the Hanjiang Deformation,and there are many combination styles,such as domino,Y,stepped,conjugate,etc.On the plane,the number,dominant trend and development scale of the faults in Yunkai low uplift and its adjacent areas are different on different interfaces with the change of Cenozoic regional stress field,the faults are mainly NEE and near EW strike in the deep part,and gradually change to NWW strike in the shallow part.In addition,through calculating fault activity rate and compiling balanced cross section,the activity characteristics of the faults in Yunkai low uplift and its adjacent areas present as "early strength and late weakness",and combined with fracture deformation characteristics,the fault evolution process can be divided into the following four stages,the strong active period in the Early Paleogene,the weak active period in the Late Paleogene,the reactive period in the Early Miocene,the cessation period after the Middle Miocene.