Study On The Sedimentation And Diagenesis Of The Ma 5 _1-4 Sub-members In The Zhao 54 Well Area, Sulige East District

Eastern Sulige gas field of Ordos Basin is located in the lower Paleozoic Ordovician weathering crust,to find out the reservoir layer distribution characteristics and gas reservoir distribution is base of the effective development of Paleozoic natural gas,how to find Potential reservoir for the block of the long-term stable production has important significance.Combined with scanning electron microscope,cast thin section,cathodoluminescence,mercury intrusion analysis,conventional and test analysis technology,using professional software Stone Culture and Geomap and other tools,through the detailed study of Majiagou group five sub-section of the first to the fourth layer deposition phase and diagenesis of Sulige eastern region,summarized the sedimentary phases and diagenesis control factors of reservoir,comprehensive evaluation and prediction of reservoir development advantageous area.1.The Strata denudation degree of the M51-4 submember varies from place to place.In general,the layers in north and west part of Sulige region have been subjected an intensive erosion,the layer exposed more older,and the southeastern parts relatively intact.That the overall geomorphic characteristics of the study area is high in the east low in the west,the uneven distribution of stratigraphic thickness.2.The sedimentary environment of the study area belongs to the Ordovician continental sea carbonate rock platform evaporative tidal phase,Including three subfacies and several microfacies.Among them,the gypsum dolomitization flat in the supratidal zone is the most favorable reservoir development zone;secondly the dolomitization flat in the intertidal zone,the argillaceous dolomitization flat of the sublittoral is the more unfavorable development zone.3.The study area reservoir development process has experienced a variety of types of diagenesis,such as dolomitization and compaction,pressure dissolution and quasi with gypsum growth and metasomatism and recrystallization,dolomitization and mineral filling effect etc.The advantage of storing layer development into diagenesis mainly dolomitization and supergene karstification,burial stage dissolution etc.;and effect of mineral filling,recrystallization and dedolomitization is less favorable reservoir diagenesis.According to the research shows that the pore evolution of gypsum,The main storing space in the study area type is gypsum core pore and Intergranular pore,containing dissolved pore mud crystal dolomite porosity and reservoir property is the best.Combination various types of information and data collection,and on the results of previous studies,and sedimentary facies,diagenesis and pore evolution process research,consider that sedimentary microfacies and diagenesis and paleokarst landform for storage layer is the major control factors of petrology and reservoir physical property and reservoir space.Finally,through the comprehensive analysis of the reservoir control factors and plane distribution,the study area M51-4 submember is divided into ?,?,? three types of block for evaluation and prediction of favorable areas,and the next development direction.