Heterogeneity Characteristics Of Carbonate Reservoir Of The Upper Majiagou 5^th Formation In Fuxian Area, Northern Shaanxi

The study section of this paper is member ?6 of Ordovician Majiagou Formationrom in Fuxian area. Its reservoir heterogeneity is very strong, and has become a major geological factors affecting exploration arid production. On the basis of field outcrop and core observation, combined with drilling and logging data, regarding marker bed as isochronous surface and applying depositiona! cycle control combined with electric logging curve characteristics, the strata in M54~M6 are classified and correlated. With thin section identification, cathodoluminescence and scanning electron microscopy, electron probe and trace elements, the petrology characteristics?physical characteristics, diagenesis. pore types and structure characteristics were summarized, and the micro and macro reservoir heterogeneity evaluation and control factor was also analvsised.The study shows that the strata in M54?M5?? is relatively intact, while in M5:?M6 the erosion is serious.Only FG2 Well in central area and XF4 well in northeast area preservate Ma6 layer. The reservoir are mainly breccia dolostone.chip gravel dolomite, and fine crystaldo Iomicrite.etc.The reservoir space mainly includes intergranular pore, intergranular dissolved pore?and gypsum mould hole, while M5 j is rich in corrosion pores. The pore structure of Majiagou Formation in Ordos Basin can be divided into 14 types, and the parameter FJZ is established to evaluate the micro heterogeneity. The pore structure mainly contains middle pore.tiny throat, unimodal and multimodal in the study area, which is with strong micro heterogeneity.The coefficient such as mutation coefficient variation coefficient and connectivity of the target bed shows that there are strong heterogeneity in layer,between layer and on flat surface; Ddiagenesis and tectonism are the main factors affecting the reservoir heterogeneity...