Reservoir Prediction Of Tight Thin-interbeddings Based On High-resolution Seismic

With the rapid development of exploration and technology, researches of/complexreservoirs attract increasing attentions, like tight thin-interbeddings and seam hole reservoirs.The characteristics of tight thin inter-layer reservoirs is low permeability, it mainlydistribution in the north of Ordos Basin and Songliao Basin. The key point in the study oftight thin-interbeddings is reservoir prediction. In the early days of research work, theapproach to predict reservoirs in the areas with a lot of tight thin reservoirs is under theconstraint of seismic or sediment phase, it is usually not accurate enough. In order to meet therequirement of high resolution of complex reservoirs, we can use the attribution of pre-stackseismic data and some attribution related to frequency. This study is based on the real data oftypical tight thin-interbeddings in the north of Ordos Basin, to carry out the analysis of highresolution seismic prediction.We first make the analysis of characteristics of pre-stack seismic data of target area.Because of tunning effect, the P-wave and S-wave from top and bottom, the multiplereflection wave from every reflection interface and the composite reflection wave will affectthe results of study. Therefore, we can not detect gas and oil only based on “bright spot”. Weget the data from well curve and the results from inversion analysis, build some thin and tightthin-interbeddings models to make the analysis of seismic response. The result shows that, intight thin-interbeddings, seismic response characteristics is complex because of tunning effect,but there still are some rules to help to detect gas and oil.Spectral decomposition technology can help hydrocarbon detection. Low frequencyshadow would appear under tight thin-interbeddings, and the low frequency shadow willdisappear when the frequency increased. We use this characteristic to analysis spectral intarget area, to get the profile in different frequency, then compare the result with well data. Itprove the characteristic of “low frequency shadow disappeared in high frequency” can be used in hydrocarbon detectionWe also get frequency division profiles by Inversion spectral decomposition to analysisdifferent seismic response characteristics in different frequency. The result shows that thechange of frequency can lead the change seismic attribute when the reservoir is pore filling.Dispersion attribute can help reservoir prediction. Then make dispersion analysis for a gasfield, the result is in accordance with the logging data. It further confirm its availability inreal data.Therefore, because of the characteristics of tight thin-interbeddings, the studies on theattributions of pre-stack data and the attributions related to frequency can improve the resultof reservoir prediction.