The Fracture Characteristics Study Of 7th Member Of Yanchang Formation In Changqing Oilfield,Anbian Area

The 7th Member of Yanchang Formation in Ordos Basin has a large potential for oil resources.Because of the reservoir permeability is generally less than 0.1-0.2 md,the study of fracture is essential and important to the reservoir exploration and development.So far,the research on sedimentary sand bodies,reservoir heterogeneity,rock petrophysics are insufficient,and this makes the study of fracture more difficult.It influenced on the exploration and development of this kind of reservoir.In order to predict the prospective exploration area and improve the reservoir reserve,this thesis focus on the fracture study of the heterogeneous reservoir.Combining geology with test,internal material with stress condition and 2D simulation,the author mainly carry out 6 aspects study as following:(1)Through the field investigation of the fracture,the author reach a conclusion about the fracture development direction,and make sure the relationship between the fracture development degree and formation thickness and lithology.(2)As aresult of core oberservation,we get conclusions about the length,interval,aperature,dip angle and filling of the fracture.Then we classified the fractures depending on the mechanical properties and analyzed the availability of fractures.Finally we concluded the relationship between density of fracture and reservoir lithology and evaluate fracture development degree with a estiblished standard.(3)Through focal mechanism solutions,differential strain method,velocity anisotropy,logging,rock acoustic emission method,rock compression experiments and other methods,we draw an an conclusion about the degree and direction of maximum horizontal principal stress,maximum and minimum principal stres.(4)We got the fracture direction and direction of the maximum stress nowadays by FMI data.(5)Through the direcional paleomagnetism,we concluded the fracture combination style and reservoir fracture direction.(6)We predicted the fracture development area of fracture generation period and low migration area nowadays.(7)According to the fuild energy,fracture development degree,sand thickness,porosity and permeability,We indicated the prospective exploration area compositively on the basis of Fuzzy Mathematics.