Applying 3D Close the Loop and Probabilistic Seismic Inversion Techniques on the Tibr Asset in Petroleum Development, Oman

In Petroleum Development Oman (PDO), a seismic driven 3D Close the Loop workflow has been successfully applied for the first time to the Tibr asset. The business objective was to delineate channel sands with challenging rock properties at a relatively deep target by better predicting the distribution of sands and shales within the Upper Gharif and Al Khlata reservoir sequences. As a result, we were able to reduce subsurface uncertainties leading to improved reserve estimates. 3D Close the Loop workflows allow for better predictions of layer thickness, reservoir properties and velocity away from the wellbore by optimal integration of seismic amplitudes with all other reservoir data. A pre-existing static reservoir model describing reservoir properties through geo-statistical algorithms served as main input. Rock and fluid property models were derived from existing well data. By relating reservoir properties such as net-to-gross, porosity and hydrocarbon saturation to acoustic properties, the 3D model s were converted to a synthetic seismic volume, which could then be compared to measured seismic data. In the final stochastic inversion, reservoir properties were updated until synthetic and seismic data matched within an acceptable error range defined by the signal to noise ratio.