The Development Regularity Of The Middle And Upper Ordovician Karst Reservoirs In Taiyuan Area

This paper takes karst reservoirs of the middle and upper Ordovician in Taiyuan area as the research object.Based on theoretical foundations such as sedimentary petrology,reservoir geology,paleogeomorphology,logging geology and on the basis of fully absorbing previous research results,using cores,outcrops,drilling logging and so on,macro and micro experimental analysis methods with techniques were used to deeply study the development regularity of the middle and upper Ordovician karst reservoirs in Taiyuan area.Results show that karst reservoir has experienced syngenetic palaeokarst,crust palaeokarst and three stages of buried paleokarst.On the vertical surface,surface phreatic zone,vadose zone and slow flowing belt are developed.The palaeogeomorphology shows the karst slope belt in the north-central and southeast of the study area and karst depression in the south.The main controlling factors of karst reservoir are diagenesis,tectonic activity,paleogeomorphology and sedimentation,such as sedimentation provides the basis for reservoir conditions,the transformation of diagenesis is the condition of formation of karst reservoir,tectonic activity and palaeogeomorphology are the key to the formation of karst reservoirs,diagenesis is karst reservoir forming conditions.A comprehensive study found that the development zone of high quality reservoirs of karst reservoir of the middle and upper Ordovician in Taiyuan area are the composite areas of the lithologic development zone dominated by limestone and dolomite limestone,the diagenetic zone with strong dolomitization,dissolution and tectonic fracture,tectonic uplift exposes the surface of the stratum to the development zone of epigenic karst,as well as the karst slope area with strong karst action and weak cementation.