Seismic Inversion And Reservoir Prediction In Palaeogene In Kaiping Sag

Study area of this paper is Kaiping sag in pearl river mouth basin and the purpose of this paper is Eocene Wenchang formation and Oligocene Enping formation in Paleogene.Seismic facies analysis,seismic attribute analysis method and seismic inversion methods of reservoir prediction technology are used to study reservoir distribution characteristics and predict oil and gas favorable zones.Nine seismic reflection interfaces and four subsags such as middle subsag,west subsag,southwest subsag and east subsag are found after well to seismic calibration and horizon tracking,adjustment and tie to forty 2D seismic survey lines.T70 seismic reflection interface roughly corresponding to the top of the Enping formation,Tg seismic reflection interface to the bottom of Wenchang formation,T80 seismic reflection interface to the interface of them.Subsags are almost half-graben structures characterized as southern fault accompanied with northern stratigraphic overlap.There are five wells in study area including one oil flow well three oil show well and one dry well,and their distance is not the same as well.Through the study of the relationship between well logging curves and oil show,we found that there is no unified reflection in all study area,but well logging curves such as GR,DT,CNL and RT have the ability to recognize oil and gas to some extent.Seismic facies plans of Enping formation and Wenchang formation are made based on the analysis to the seismic attributes such as amplitude,frequency,continuity and shape of seismic reflection.Ten kinds of seismic facies are found in both Enping and Wenchang formation.Major sedimentary facies in Enping formation maybe includes middle-deep lacustrine facies,shore-shallow lacustrine facies,delta facies and fan deltaic facies according to the analysis while middle-deep lacustrine facies,shore-shallow lacustrine facies,delta facies,fan deltaic facies,slump fan and fluvial facies maybe in Wenchang formation.Fifteen kinds of seismic attributes will be extracted containing amplitude statistics,complex trace statistics,spectral statistics,sequence statistics.Attribution optimization and seismic-lithology analysis should be done to predict oil and gas zone in Enping formation and Wenchang formation.Model based seismic inversion and constrained sparse spike inversion will be applied to study the lateral distribution characteristics of reservoir,characteristics of the underground geological structure and reservoir lithology characteristics.These two methods should be used reasonablely to deal the challenge of the poor quality of2 D seismic data and deep buried depth.Quality control should be done well in pretreatment,parameter selection and modeling,so that the accuracy of seismic inversion can be promoted.Reservoir prediction and six parts of favorable zones are given based on structure characteristics,seismic-lithology analysis,seismic attributes and seismic inversion.