Regional understanding together with good well log and seismic data could help in interpreting the depositional environment including the breaking up of reservoir facies.Petrophysical analysis results in converting well log data in to reservoir properties,which help in estimating volumes and production.Similarly,rock physics translates the petrophysical results in to petro-elastic properties leading to better seismic interpretation.Both petrophysics and rock physics go hand-in-hand with each other and their integration is indispensable for excellent seismic reservoir characterization.The primary application of rock physics is to be a bridge between well and seismic data.It develops relationships between the well logs and seismic data so that the critical reservoir properties such as porosity,saturation and reservoir pressure can be directly derived from seismic reflectivity and inversion data.Since well logs play a crucial role in this entire integrated process,conditioned log data is essential.In this paper,a workflow is demonstrated on a successful discovery in Moray Firth Basin,UK North Sea, where rock physics driven quantitative interpretation has been used to good effect in reservoir characterization from exploration to the development phase.The reservoir is composed of clean to shaly and calcareous sandstones in which the proportions of calcite-dolomite together with clays control reservoir quality.Porosities range from 10 30%with excellent permeabilities allowing for high flow rates.The clay content within the reservoir has strong effect on porosity trends as seen from both bulk and shear moduli data.The existing well data in the field of interest is deemed to be very much geologically representative,and hence a number of key discovery wells were extensively used in the rock physics analysis and seismic inversion exercise.A rock model to obtain porosity trends with respect to clay content and saturation effects was done. The objective was to model what the end product of seismic reflectivity and inversion would be able to offer in discriminating sedimentary facies,and then determine the interpreted seismic responses with modelled lithological and fluid effects. Typical seismic inversion schemes have also been used to simultaneously invert the seismic offset data to produce seismic impedance and facies volumes.The application of seismic inversion properties like acoustic and elastic impedance, extended elastic impedance coupled with rock physics driven models helped delineate new emerging Lower Cretaceous Punt turbidite fairways and identified the low impedance hydrocarbon anomalies.This Quantitative Interpretation and Inversion workflow resulted in a significant improvement in understanding reservoir facies,which helped in locating wells for further exploration and appraisal.Thus,rock physics driven QI and seismic inversion approach has been instrumental in de-risking the amplitude anomaly driven stratigraphic prospect.The feature was originally interpreted but considered as a high-risk and unlikely prospect because of its purely stratigraphic nature.However,reservoir characterization and fluid identification have been significantly enhanced through seismic- petrophysics modelling in the oil-bearing discovery wells whose results are unambiguous due to well control.Thus,AVO and elastic inversion play a key role assisting in locating the wells for the target reservoir in the appraisal and development phase.
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