Fracture Characterization And Effectiveness Logging Evaluation Of The Cretaceous Reservoirs In Bozi-Dabei Area

The Bozi-Dabei Area is located in the Kelasu structural belt of Kuqa Depression.The Lower Cretaceous Bashijiqike Formation and Baxigai Formation have rich oil and gas resources,and the reservoir fractures are relatively developed as a whole.However,the reservoir fracture characteristics have strong heterogeneity,and the fracture distribution is extremely complex.Therefore,it is of great significance to carry out quantitative characterization and effectiveness evaluation of reservoir fractures for guiding oil and gas exploration and development in Bozi-Dabei Area.In this paper,the reservoir fractures of the Bashijiqike Formation and the Baxigai Formation in Bozi-Dabei Area are taken as the research objects,and using data such as cores,casting thin sections,logging,imaging logging,and analytical testing to analyze fracture development characteristics,quantitatively characterize reservoir fracture characteristic parameters,and evaluate fracture effectiveness.The results show that :(1)The fractures in the study area are mainly unfilled high-angle oblique fractures and oblique fractures.When the fractures are developed and the fracture parameter value is larger,the productivity is relatively higher.(2)According to the quantitative evaluation parameters of fracture effectiveness,it is found that among different zones,the central area of Bozi has the best fracture effectiveness,followed by the southern area of Bozi and Dabei area,and the northern area of Bozi is the worst,in different strata,the fractures in the Baxigai Formation have better opening,and fracture effectiveness than those in the Bashijiqike Formation.(3)Cementation reduces fracture effectiveness,and dissolution is conducive to increasing fracture effectiveness.(4)According to the relationship between rock mechanics parameters and fracture effectiveness parameters,the smaller the horizontal stress difference and uniaxial compressive strength,the better the fracture effectiveness;the direction of in-situ stress has a significant impact on the fracture effectiveness.Under the same fracture development level,the smaller the angle between the maximum horizontal principal stress and the main fracture direction(< 30°),the better the fracture effectiveness and the higher the productivity.