| The Daning area is located in the southern section of the Jinxi tortuous belt in the southeastern margin of the Ordos Basin.It shows a transitional type of basin structure type.The reserves of natural resources such as oil,gas and coal are considerable,and the exploration degree is high.—The Taiyuan Formation research is mainly focused on coal seams,but the research on sandstone reservoirs is relatively scarce.Therefore,it is necessary to conduct an in-depth study on the Benxi-Taiyuan Formation sandstone reservoirs in Daning area.This thesis focuses on the Benxi-Taiyuan Formation sandstone reservoirs in the Daning block.Based on the existing data in the study area,it relies on the research methods of comprehensive analysis of macroscopic and microscopic geological data,with reference to sedimentology,petrology,reservoir geology,etc.Disciplinary theory,carrying out a series of studies such as thin slice identification and logging data analysis,and carrying out research on sandstone reservoir pore characteristics,rock composition,and factors affecting reservoir development.Try to characterize the sandstone reservoir sign in Daning block in detail.Through microscopic observation of the sandstone casting slices,it is found that the Benxi-Taiyuan Formation sandstone rock types are mainly medium-fine-grained quartz sandstone and medium-coarse-grained quartz sandstone,with particle sizes ranging from 0.1mm to 1.1mm,and the main particle size is 0.3mm —0.7mm.The component maturity is higher overall but there are differences in different well positions and depths,and the structural maturity is generally better.The inter-particle support method is particle support,the contact method is line contact,and the siliceous cement is developed.The interstitial material is mainly clay minerals.Therefore,it can be judged that the Benxi-Taiyuan Formation sandstone is a set of sea-land transitional phase sand bodies,and the overall deposition environment is a barrier-Tidal flat system.The pore types of sandstone are mainly intergranular dissolution pores,and the pore size varies greatly,ranging from 0.01 mm to 0.5mm.The dissolution pores have different shapes and irregularities.They are abundant in quartz sandstone and have few primary pores.The intergranular pores are formed by dissolution,and micro cracks are more developed.The main controlling factors of the Benxi-Taiyuan Formation sandstone reservoir in Daning area include: sedimentation,diagenesis,and tectonism.Through analysis of sedimentary facies and drilling data,it is proposed that the Benxi-Taiyuan Formation sandstone reservoir in the study area is controlled by the barrier-lagoon-chaoping-Lupeng lagoon sedimentary system.By observing and identifying the thin sections of the rock casting body of the Benxi Formation,it is found that the rock types of the Benxi-Taiyuan Formation sandstone reservoir are mainly quartz sandstone,less detrital sandstone,higher component maturity and structural maturity,and the interparticles are mainly Line contact.The pore types are mainly intergranular dissolution pores,and also contain more micro-cracks and intergranular pores.No primary pores were found.The Benxi-Taiyuan Formation sandstone mainly experienced compaction and dissolution during diagenesis.Among them,compaction is multi-faceted for reservoir development,on the one hand,it is not conducive to the development of primary pores in the reservoir,on the other hand,it is helpful to the formation of fractures in the Benxi Formation sandstone reservoir with high quartz content,and has a positive significance for reservoir development.The dissolution has a positive significance for the increase of reservoir porosity.The sandstones in the study area are mainly quartz sandstones,with less debris content,and no micro-cracks are found in the debris,so the micro-cracks are mainly caused by the strong tensile stress formed by the overburden pressure and tectonic movement.It has positive significance for improving reservoir permeability and pore connectivity. |
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