Study On The Structural Features Of The Pre-cenozoic In The South Of Kongdian

This paper makes full use of 3D seismic data and various interpretation results,guided by theoretical knowledge of structural geology,oil and gas reservoir geology,sequence stratigraphy,regional structural geology,and combined with tools such as Landmark workstation and Coreldraw drawing software The fault structure characteristics,types,styles and combinations,superposition methods of the two secondary oil-generating sags and some major structural belts in the southern area of the Kong Dian,namely the Huanghua Depression,as well as the structural evolution history and formation mechanism(mechanical mechanism,sedimentary Equal)conducted research.The Kongnan area is located in the southern part of the Huanghua Depression.It includes two major oil-generating sub-sags: Nanpi sag,Cangdong sag,and some small and medium-sized buried hill structural belts.The structural pattern of the target layer is mainly formed from the Early Middle Ordovician to Sooner or later Cretaceous,namely Caledonian,Hercynian,Indosinian-Yanshanian.The current Cenozoic structure was mainly formed in the Eocene-early Oligocene,that is,the Himalayan tectonic stage,which is the result of the superposition of the Kongdian Formation and Shahejie Formation.The long axis of the entire Kongnan area is north-north-east,the north is adjacent to the Kongdian buried hill structural belt,and the south is adjacent to the Dongguang Uplift.The Xuxi fault and the Cangdong fault control the east and west of the work area respectively.In the study of the structural characteristics,structural style,structural formation period and formation mechanism of the work area,the following points of understanding have been obtained:(1)The formation of the Middle Paleozoic superimposed basin is mainly due to the five major functions of compression,tension,gravity strike-slip,shear and reversal,of which compression and tension play a leading role;the thrust nappe in the work area The structural zone is divided into four major sections according to the distribution characteristics on the plane.(2)There are four relatively complete large-scale shear systems in the work area,all of which are negative flower-like structures.The shear tension and torsion strength is greater than the lateral strike-slip strength.This is the most different place in the southern part of the Huanghua Depression.In the late period due to the Himalayan tectonic movement,the Tan-Lu Fault experienced a right-handed strike-slip,which was manifested as a left-handed twist.In addition to multiple NW-trending strike-slip transition zones,there were also multiple shear-generated faults in the Huanghua Depression.(3)The basin in the Kongnan area is a superimposed basin,which has experienced the evolution of Caledonian,Hercynian,Indochina,Yanshan and even Himalayan large tectonic stages.Generally,there are sedimentary discontinuities and weathering and denudation between various orogenic belts and fold belts.,Making many tectonic cycles eventually become buried hills.(4)The Middle and Paleozoic structures in the Huanghua Depression of the Kongnan area are distributed as follows: The main body of the Lower Paleozoic is from southeast to northwest imbricated thrust,which is the so-called basement-involved type.The deformation strength is stronger in the south than in the north,and the upper Paleozoic is the reason.The northwest to southeast overburden-thrust detachment nappe is the so-called caprock detachment type,and the deformation strength is stronger in the west than in the east.At present,the urgent problems to be solved are: establish a typical structural model,clarify the Mesozoic tectonic evolution process and the distribution of stratified prototype basins,clarify key time-bound structural events,establish a kinematic model;clarify the influence factors of Mesozoic tectonics on hydrocarbon accumulation,and establish Oil and gas accumulation model,indicating potential zones for oil and gas exploration.