Research On The Caprock Destroy Degree By Fault In Fangzheng Depression

In this paper, by using geology, seismic and logging data of Fangzheng depression,caprock and fracture as the researching objects, define the caprock and fracture developmentcharacteristics, research on quantitating the caprock destroy degree by fault, analysis on thecaprock and fault matching relation to control the action of hydrocarbon accumulation,predict the directional favorable area for oil and gas production.For researching the caprock characteristics development, selecting representativesingle-well lithology logging data to analysis, can be divided into caprock developmenthorizon; In order to accurate sketch the caprock bordering development and the thicknessdistribution more, using the corresponding relationship between seismic data and well data,tracing mudstone caprock avoidances reflection interface, regional cap rock are covering theentire area and developing in E3b2, the E3b1mudstone and the E1+2x+w upper and lowermudstone as the regional caprock. By analyzing the fracture geometry characteristics,combined with the analysis of the structure-stratigraphic sequence, clear the formation of thefracture evolution process and its characteristics, the fracture formation evolution hasexperienced three big stages:the strike-slip stretching deformatio from E1+2x+w to E2d，thetorsional deformation in E3b and the pressure torsion deformation in N+Q. In order toquantitate the caprocks destroy degree by fault, we put forward this parameter of "juxtaposition thickness ", counting oil and gas showing wells in Fangzheng depression,screening oil and gas reservoirs with the close relationship of the fracture development、formation and evolution, and counting the different caprocks destroy degree by faultdestruction, only juxtaposition thickness greater than0m and caprock thickness greater than40m area can effectively block the lower oil and gas reservoir. By studying the main area ofeastern Daluomi structure and west Zuoshugang, analysis that oil and gas distribution iseastern and western regions, the caprock of eastern regions destroy degree by fault isrelatively high, thin juxtaposition thickness, preventing oil and gas migration, the oil and gasare distributed many vertical layers, respectively in E3b1、E1+2x+w and the bedrock; And thecaprock of western regions destroy degree by fault is relatively low, can prevent oil and gasmigration, oil and gas are mainly distributed in E1+2x+w and the strata below.