The Dolomite Genesis Mechanism Of Oridovician Zhuozishan Formation In The North Part Of Tianhuan Depression,Ordos Basin

Dolomite is one of the high quality reservoirs of oil and gas in the study area.Therefore,dolomite and its genesis play an important role in the study of carbonate reservoirs.The dolomite is a hot area favorable for oil and gas exploration in the northwest of Ordos Basin.This paper is based on sedimentology,reservoir geology and geochemical theory,combined with regional geological data,core,sheet and other information.Sedimentary facies and geochemical characteristics,the Zhuozishan formation mechanism and other related research,made the following points:1)The composition of the lithology of the Zhuozishan formation has been microscopically identified and classified according to the genesis-structure.The dolomite of the Zhuozishan formation mainly has powder-microcrystalline dolomite,Residual sand fine crystal cloud and fine-medium dolomite,dolomite mainly flat crystal surface from the crystal-its crystal,the cathode light overall dark.2)The formation temperature of dolomite is not high by Ordinary,trace element,rare earth element,C-O isotope,Sr isotope geochemical data and inclusions uniform temperature.The Tianhuan depression dolomite fluid is seawater or has source fluid characteristics.3)According to the sample analysis test data,it is indicated that the dolomite dolomite of the table is affected by the freshwater of the atmosphere during the quasi-syngenetic period.After the burial compaction of the overlying strata,the pressure of the Mg2 + and the western thrust belt is provided to make the Mg2 +,It is mainly due to the transformation of the source sea source fluid.The mainly cause of mixed water dolomitization and burial dolomitization...