Characteristics Of Jurassic Sedimentation And Reservoirs In The West Of YanWu Area,Ordos Basin

The Jurassic reservoir is one of the main reservoirs in the Mesozoic of the Ordos Basin,which has the characteristics of good reservoir properties,low saturation pressure,small reservoir size,high storage abundance and high single well production,but at the same time there are relatively low permeability and low reservoir types and other complex problems.In this paper,based on the previous studies,combined with a large number of field and indoor work,the Jurassic strata development characteristics,paleogeomorphic restoration,sedimentary facies type,reservoir characteristics and control factors in the Yan Wuxi area are studied in depth.On the basis of the stratigraphic division and comparison,use Jurassic geologic map,combination of well seismic method and formation thickness impression method to confirm the Jurassic Paleogeomorphic features of the sediments before Yan 10.Its overall appearance is highland,steep hill,river valley coexist face.Based on the systematic analysis of the phase sign,the sedimentary facies types in the study area were determined,and the braided river and lacustrine delta sediments were mainly developed in the YanWuxi area of Jurassic.Due to the influence of the southwest provenance,the sand bodies in the study area generally extend in the south-west and north-east direction,and the sedimentary facies are basically in the form.Through the analysis of core samples and the observation of conventional rock flakes and castings by scanning electron microscopy,the reservoir characteristics and reservoir development control factors were studied,and the reservoirs were comprehensively evaluated.The rock types of the sedimentary rocks of the Yan'an 6 Formation to the Yan'an 10 Formation are mainly medium-grained sandstones,and the cuttings are mainly composed of metamorphic rock cuttings.The interstitial materials are mainly heterogeneous and cements.The reservoir space of sandstone is mainly porosity,To the remaining particles between the main hole.Pore structure is mainly developed in the low drainage pressure-in the thick throat reservoir,sorting good-better,are medium-high quality reservoir.On the basis of the above research,depth analysis of the main factors of reservoir development,it is mainly affected by sedimentation,material composition and diagenesis factors,the development of sedimentary microfacies is controlled by different hydrodynamic and depositional modes,the reservoir sand bodies are mainly medium grained sandstone,with higher quartz and lithic content,the base is relatively small.Compaction largely reduces porosity and thus influences reservoir properties.Cementation is one of the reasons for pore reduction.Dissolution is the main reason for improving physical properties.Metasomatism can also improve physical properties during the formation of authigenic kaolinite,and at last take a comprehensive evaluation of the reservoir.The Yan'an 6 Formation to Yan'an 10 Formation in the study area is generally Grade II ~ III,which is part?reservoir.