Study On Tectonic Stress Field And Fracture Prediction Of Qingshankou Formation In Northern Songliao Basin

In recent years,important progress has been made in geological evaluation and exploration and development technology of shale oil,and shale oil has been another new field of oil and gas exploration and development.The Upper Cretaceous Qingshankou formation in the Songliao Basin is a typical low-porosity and low-permeability hydrocarbon formation with high platform oil formation and rich shale oil resources,and fractures are the main seepage channels and important storage space for mud shale oil and gas in the Qingshankou formation.The purpose of this paper is to predict the distribution of fractures in the Qingshankou formation using numerical simulation results and provide a basis for further oil and gas exploration in the study area.By collecting and analyzing the basic geological survey and core data of the Qingshankou formation in the northern part of the Songliao Basin,the development characteristics and types of fractures are discussed,and the fracture development in the study area is identified using logging data.The favorable zone of fracture development in the study area was predicted by using the finite element numerical simulation method combined with rock fracture guidelines.Based on the prediction of the favorable zone of rock fracture,the organic carbon content and organic matter maturity distribution map of the Qingshankou formation were used to predict the favorable zone of oil and gas exploration in the study area.The research results are of great significance to the fracture research and shale oil and gas exploration in the shale oil reservoir of the Qingshankou formation in the northern part of the Songliao Basin.The main understanding is as follows:(1)High-angle fractures account for 77% of the fractures in the Qingshankou formation in the northern part of the Songliao Basin,and low-angle fractures are not developed.(2)The mud shale of the Qingshankou formation is dominated by tectonic fractures,while a small number of sedimentary diagenetic fractures are developed.The effectiveness of mud shale fractures is mainly controlled by tectonic and diagenetic effects,and the mud shale fractures of the Qingshankou formation in the Songliao Basin are mainly tectonic in origin.(3)The stress field at the end of the Paleocene and the present day has a significant role in controlling the fracture development of the Qingshankou formation.(4)Based on the simulation results of the stress field combined with the rock fracture guidelines,one Class Ⅰ fracture zone and three Class Ⅱ fracture zones were delineated.The organic carbon content and organic matter maturity distribution map of the Qingshankou formation were integrated,and one class I favorable zone for oil and gas exploration and four class Ⅱ favorable zones for oil and gas exploration were delineated on the basis of the prediction of favorable zones for fracture rate development.