Study On Reservoir Geological Characteristics Of Sandy Conglomerate Body In Near Source Steep Slope Belt,Bohai Bay Basin

In recent years,as the deep exploration wells were transferred to steep slope belt in Bohai Offshore,the composite reservoir of sandy conglomerate body in near source steep slope belt has become one of the most important exploration and development fields in Bohai Bay Basin.However,the research on The formation background and reservoir development condition of sand-gravel body is little.Aiming at the characteristics of complex connectivity of sand bodies and strong reservoir heterogeneity,We re-studied sedimentation model?reservoir genetic mechanism?each time sandbody depiction and favorable reservoir prediction,put forward reasonable suggestions for super thick conglomerate reservoir development,to ensure the reliability of oilfield development program,and reduce the risks of oilfield development.The main achievements of this study are as follows:1.Subtle stratigraphic formwork of the E₃d₃?Paleogene?has been established based on highresolutionsequencestratigraphy,the method of stratum thicknessand Borehole-seismic cycle calibration.The E₃d₃ Stratum has been divided into Low Stand System Tract?LST?and Transgressive System Tract?TST?,LST has been divided into 3quasi-sequence sets,6 quasi-sequences,TST has been divided into 3 quasi-sequence sets,5 quasi–sequences.A detail stratigraphic framework of E₃d₃ Formation has been established.2.According to sedimentary micro-facies markers and detailed depiction of internal sedimentation unit of fan delta concluded that the regressive fan delta deposits were developed in near source steep slope belt,3 sub-phases and 11 micro-facies are identified:and 3 kinds of sub-micro-facies named fan delta plain,fan delta front and prodelta.The fan delta plain included braided channel glutenite micro-facies,super-aqueous mudslides conglomerate micro-facies,interchannel sand-mudstone micro-facies.The fan delta front can be divided into underwater braided channel sandstone micro-facies,sub-aqueous mudslides glutenite micro-facies,underwater inter-channel sand-mudstone micro-facies,the prodelta can be include pro-fan delta siltstone micro-facies,pro-fan delta mudstone micro-facies.3.According to the theory of"source-sink"spatio-temporal coupling sand control,a"ditch-slope-trough"sand control model is put forward,and the sand body detailed characterization technology in the sand-rich area of steep slope zone with geophysical method is used to depict the sand body distribution controlled by paleo-geography.4.Four different porosity-permeability relationships are established with a conclusion of lithology as the main controlling factor to the rock properties,followed by diagenesis.Seismic facies attributes and amplitude attributes based on waveform classification is used to identify two stages of sand bodies and characterize the plane distribution range of fan delta dominated reservoirs in the E₃d₃,1 well block.This research systematically reviewed the challenges whichever have been existed for many years in prediction of glutenite reservoir in steep slope zone,the study has been using to support exploration and evaluation over quite a few oilfields,and lay a strong foundation for subsequent well planning,adjustment,optimization in water injection pattern etc..In addition,this study also provides technical and methodological references for detail description and development to giant thick sandy conglomerate reservoirs with similar geological and data conditions in the Bohai area.