| The delta-front deposits developed in the Gaotaizi oil formation in the Sabei Development Zone,with small sand size,complex planar phase changes and strong nonhomogeneity,lead to relatively low average recovery rates and high extraction difficulties in this type of reservoirs.To address this problem,a fine prediction is made for the delta front reservoir in the study area,and a combination of well seismic method is used to achieve an accurate portrayal of the depositional phase and analyze the distribution characteristics of the composite river channel.Then,the reservoir configuration and non-homogeneity in the study area are studied to explore the influence of reservoir configuration and nonhomogeneity on the distribution of remaining oil and further guide the tapping of remaining oil in this type of reservoir.In this thesis,taking the delta front reservoir of the Gaotaizi oil formation as the research object,we carried out a targeted study to carve out the sedimentary phases of the GI oil group,compounded the river distribution characteristics,summarized four typical single river sand types in the study area,and divided them into river stages.The delineation of different stage configuration units was completed,and the distribution pattern of sand body internal intercalation was analyzed.The non-homogeneity of different types of sand bodies is described,and finally the influence of reservoir configuration and reservoir non-homogeneity research results on the remaining oil distribution is summarized,and the characteristics of remaining oil distribution in the study area are summarized.The study shows that(1)fine reservoir prediction of the GI oil reservoir in the study area is achieved by the geostatistical seismic inversion method combined with well seismic and seismic attribute techniques.Through the idea of well point fixing phase,attribute fixing and inversion defining boundary,the depositional micro-phase of typical layers in the study area is accurately carved out.For the four typical single channel sand types of nearshore channel(inherited and migrated),mid-shore(water-in type)and far-shore channel(water-out type)developed in the study area,a composite channel phase delineation was carried out,and the distribution characteristics of the channels in the study area were summarized.(2)In the context of delta front sedimentation,the internal channel configuration model was established,and different stages from composite channel(six stages)to internal interlayer(three stages)were delineated for the study area.The dip angle of the internal interlayer of the sand body in the study area is slow,and the logging identifies a density of 1-2 bars/story with a dip angle of 0.8°-1.2°.(3)The pore permeability distribution in the study area is large,and the reservoir is non-homogeneous.The inhomogeneity characteristics of the two-sided accretionary,two-phase lateral accretionary,advancing and receding sand bodies are analyzed,and their influence on the remaining oil distribution is summarized from three aspects: depositional micro-phase,reservoir configuration and inhomogeneity.The two-sided accretionary sands are the most inhomogeneous compared with the two-phase lateral accretionary,incoming and outgoing sands,and the reservoirs of remaining oil are easily formed below the intersection of two single channel sands. |
