Sedimentary Facies And Favorable Facies Prediction Of The First Member Of Tenggeer Formation On The North Sag In Bayindulan Depression

The Bayindulan depression is one of the important oil and gas areas that belongs to the Erlian basin,it develops three secondary tectonic units that includes the east steep slope,the west ramp zone and the central subsags belt.The period of the sedimentary of the first member of Tenggeer formation,the north sag enter the stage of fault depression,the activity of the eastern boundary faults is frequency,the difference of tectonic movement and the strength change of fault activity,which result in the layer experiences uneven uplifting,each parts suffers from denudation of different degree,especially the south,the center of the subsidence and sedimentary migrated towards north,the bottom of the lake basin develops thick and dark mudstone,which enter the period of extensive deposition of the source rock.Through the systematical observation of the core,combined the data of test analysis,logging,drilling and three-dimensional earthquake,the paper analyses the sedimentary facies and further predicts the favorable reservoir facies belt of the first member of Tenggeer formation on the north sag in Bayindulan depression of the Erlian basin.The north sag of Bayindulan depression undergoes complicated changes of sedimentary environment,producing multiple types and mutually superposed gravel rock mass,controlled by the tectonic activities and terrain,kinds of sand body has the characteristics of close source?small size and short flow extends.The source mainly comes from the eastern bulge that close to the boundary fault,part from the western gentle slope.By the methods of drilling sequence stratigraphy and seismic stratigraphy,divided three sequences of Early Cretaceous strata of Bayindulan depression,establish the isochronous sequence stratigraphic framework,the layer of the first member of Tenggeer formation is divided into upper sub-member and under sub-member,the corresponding sub-member develops transgression systems tract and highstand systems tract respectively.According to sedimentary facies marks,including petrology,logging curve and seismic facies,analysis and investigate the sedimentary facies of the north sag of Bayindulan depression,it develops three types that include nearshore subaqueous fan?fan delta and lake facies,which respectively located in the eastern steep slope?the western gentle slope and the whole lake basin,it also identify the corresponding sedimentary subfacies and microfacies,according to the comparison of the single-well and joint-well facies,determining the plane distribution of the sedimentary facies.By the analysis of the petrology characteristics ? the reservoir property of porosity and permeability,predicting the favorable reservoir facies belt.The rock types mainly include feldspar sandstone and lithic arkoses,the main reservoir space is primarily pores,the reservoir mainly belongs to low porosity-low permeability and low porosity-extra low permeability,the better reservoir distributed in the place of the porosity and permeability is relatively better,the oil and gas shows well,the favorable reservoir facies zone affected by the deposition environment and diagenesis.Through comprehensive analysis,the favorable reservoir facies belts are braided channel of the mid-nearshore subaqueous fan and underwater distributary channel of the front-fan delta,the favorable wells mainly cover three large zone,including the wells that around b92x?b23 and b75,b29,b37 and b27 in the east,b73x?b77x and b79 in the west.