Comprehensive Study On Ordovician Petroleum Geological Characteristics Of LT1 Well In Weibei Area

The Ordovician of Weibei area deposits a set of marine carbonate strata,in Which the exposed surface of the Ordovician strata profile found a lot of bitumen and reefs.Some of the exploration wells in this area also have found gas.Therefore,Weibei area may have a good prospect of natural gas exploration.The purpose of this study is:(1)the establishment of Ordovician strata profile and the source cover combination profile in Linyou-Chunhua area;(2)to understand the development of Ordovician natural gas source rock and evaluate its potential for gas generation;(3)looking for the lithologic gas reservoirs in Ordovician Majiagou Formation and Pingliang formation.According to the core,logging,seismic and paleontological data,the strata of the well area are divided and compared.The sedimentary environment and facies of Ordovician sediments were studied by testing the carbon and oxygen isotopes,trace elements and total rock of LT1 well.It is concluded that the Ordovician belongs to the normal seawater carbonate sedimentary environment,and the main sedimentary facies is carbonate facies-residual basin facies.The qualitative evaluation of the source rocks shows that:the organic matter of the Ordovician Beiguoshan Formation and Pingliang Formation in LT1 well is high,and the organic matter type is mainly type ?and ?1,and it is have high maturity.Source rocks tend to generate natural gas.The lithologic logging can be used to determine the organic matter content in the whole well.It is believed that most of the middle and lower Ordovician are non-hydrocarbon source rocks.The lithology,physical properties,pore structure and reservoir type of the reservoir were analyzed by using the core photo,the casting sheet,the physical property test,the capillary pressure curve,the imaging logging and the conventional logging.Finally,the reservoirs were classified and evaluated.The four elements relationship of the reservoir has established the logging interpretation model of lithology,physical property and gas content of reservoir.Analysis of the development and distribution characteristics of Ordovician cover layer.According to the comprehensive study,the Ordovician source rocks in the LT1 well are mainly distributed in the Beiguoshan Formation and the Pingliang Formation.The reservoirs are mainly distributed in the Pingliang Formation and the Ma5-Ma6 group of Majiagou Formation,The cover layer is mainly distributed in Dongzhuang Formation and upper part of Pingliang Formation.This is the formation of the upper-lower storage and self-storage combination type.