Methodology Research On Geosteering Thin Interbed Interpretation And Reservoir Description

This study analyzed the seismic reflection of the thin interbeds on the numerical models to provide basic gist for thin reservoir interpretation.A special law of the thin interbeds' seismic reflection and formation interference,zero-value time,is found that it has the potential to characterize the thin layer precisely.In this paper,the composite wave formed by the interference of reflection waves at the top and the bottom interfaces of the thin layer is regarded as the layer wavelet.The layer wavelet carries the reflection information of the whole thin layer,which makes the interpretation of the thin layer more geological.The zero-time value is the time when the value of the amplitude of the layer wavelet is zero.When we observe the continuous time slices of the thin interbeds' seismic record,almost all the thin layers in the interbed appear on the slices because of the interference of the wavelet,while the lateral distribution of the corresponding thin layer disappears on the time slice at its zero-time value.This phenomenon can be used to determine the distribution of the thin layer's zero-value time,which is corresponding to the position and thickness of the thin layer.So we can realize the characterization on the thin layers only by the interbeds' seismic record.Zero-value time can be determined directly from the original seismic records,which doesn't require complex processing.It is a direct use of the thin interbeds' geological information.Using the real geological information to guide the thin layer interpretation makes the geosteering significance of the interpretation clearer.Compared with the traditional seismic interpretation only focusing on the changes of longitudinal seismic traces,the zero-value time is determined by the variable characteristics of time slices in horizontal direction,which can make up the deficiency of vertical resolution by using the lateral resolution of seismic records.Compared with the ordinary time slices,the zero-value time slices can show the later distribution of other thin layers in the thin interbed more clearly by reducing the interference of the corresponding thin layer.Comprehensive comparison of different zero slices is beneficial to the study of thin interbedded sedimentary evolution process.In summary,zero-value time has the potential to interpret the thin interbed,but how to make further use of zero-value time or continue to tap new and more efficient special laws of the thin interbeds' seismic reflection and formation interference still needs to be further research.