Study On Fracture Identification And Stress Field Simulation Of Chang 8 Reservoir In Yanchang Oilfield

Yanchang Oilfield is located in the central and southern Ordos Basin,and the southern exploration area is the main exploration and development area of tight oil.Through the collection and analysis of the actual geology,field outcrops and core data in the Chang 8Member tight reservoir of the Yanchang Formation in the southern oil field of Yanchang Oilfield,the development characteristics,fracture types,formation stages and main control of the fractures in the study area were discussed.Factors,etc.At the same time,the logging data was used to identify the fractures and their types in the study area.The numerical simulation technology and method were used to predict the favorable area of fracture rupture in the study area.Based on the selection of favorable areas for rock rupture,combined with the thickness of the sand body in the study area and the relationship between oil production and stress field,the favorable areas for oil and gas exploration and development in the study area are predicted to be tight reservoirs in the Chang 8 Member of Yanchang Oilfield It lays the foundation for fracture research and oil and gas exploration and development.The main conclusions are as follows:(1)The Yanchang Formation Chang 8 tight reservoir is dominated by structural micro-fractures,with three groups of NEE,NWW and NNE fractures.The Yanchang Formation 8 Member NEE-oriented fractures are mainly formed in India.Shear stress field of left-handed strike-slip during the support period.In the Yanshanian period,affected by the southeast~northwest squeezing movement,on the basis of the early NEE-oriented fractures,two groups of NWW and NNE-oriented fractures were superimposed,in which the superposition of fractures in the fold area was strong;(2)Bilateral and induced resistance differences.The qualitative and quantitative interpretation results of the characteristics show that: the fractures in the Chang 8 Member of the Yanchang Formation are relatively developed,which is consistent with the more developed fractures shown by the existing oil and gas drilling;(3)using the results simulated by the tectonic stress field,combined with rock synthesis The rupture rate criterion evaluates the fractures in the Indosinian,Yanshan,Xishan,and Neotectonic periods in the study area,and finally determines the most likely rupture in the Chang 8 member in the study area: a Grade I area and fourGrade II areas Area.At the same time,based on the study of comprehensive fracture attributes,the distribution of oil and gas wells and their production and rock thickness,the maximum and minimum principal stresses and shear stresses in critical periods are thoroughly considered,and a class ?,oil and gas of tight reservoirs in the Chang 8 Member of the study area is comprehensively determined.There are 2 favorable exploration areas in category ?.