The Study On Reservoir Characterization Technology Based On Pre-stack Seismic Inversion

The analysis of oil/gas reserve in the Chinese continental in the recent year shows，lithologic reservoir occupying from20%in the early1990s to55%in the current out of thetotal discovery, indicating that lithologic reservoir is very important for reserve increasing.Lithologic reservoir is one of the four key area in the oil/gas exploration of Chinese continental,the other three are foreland thrust belt reservoir，middle-lower assemblage superimposed basinand fine exploration in the old oilfiled. These four areas are the important pratical areas inincreasing the current oil/gas reserves. The stratigraphic-lithologic reservoir exploration needsurgently the ancillary techniques of seismic reservoir characterization. In order to extractingmore information from seismic data for reservoir characterization, we need not only to studythe post-stack seismic data, but also to study the pre-stack seismic data. Especially in the recentyears, with the deepening of oil/gas exploration and the development of wide-azimuthacquisition technique, we can obtain more new geological information using of large-offsetprestack gathers, which provides more broad prospects in solving complex reservoir.In order to describe the interbedded sand-shale reservoirs precisely in Dongpudepreression, I use the finer geostatistical inversion instead of the conventional deterministicinversion，and use the pre-stack simultaneous inversion instead of post-stack inversion. By adetailed study of the key technologies of any inversion method, I use WenDong as a test area todescribe the reservoir lithology，shape as well as oil/gas properties. I achieve the main results asthe follows: Using the method of the dip scanning through independent programming toinprove S/N of pre-stack CRP gather, and using the method of sparse pulse combining thetechnology of “well controlled techniques to inprove the resolution” to broaden the frequencybandwidth of seismic data effectively, I establish the detailed processing flow for the pre-stackseismic data optimization. These jobs provide a good basical data for pre-stack simultaneousinversion; I establish the rock physical model for the target area，obtaining a more preciseS-wave logging curve in the framework to provide the necessary basic data, and eatablish therock physical template to provide a precise characterization cutoff value and slope forquantitative interpretation of the inversion results; Using the mothod of forword modelling todetermine the AVO characteristics of target area, and using the method of fluid substitution tocarry out the test of elastic parameters sensitivity of different fluids and of different lithology, Ifinally obtain the sensitive elastic parameters for the characterization of reservoir lithology andfluid prediction; I analyze each step of parameters of pre-stack inversion in detail and ensurethe reasonableness of the inversion property using a variety of quality control; Bydetermining the reference marker layer，the analysis window of attributes and the fusion manner,I desicibe spatial distribution characteristics of sandstones and analysis hydrocarbon potentialbased on rockphysical analysis combining of geological knowledge. I suggest two favorabletarget areas through the results combining with geological knowledge.