Log-based prediction of pore pressure and its relationship to compressional velocity, shear velocity and Poisson’s ratio in gas reservoirs; Case study from selected gas wells in Iran

Abstract

A precise identification of pore fluid pressure (PP) is of great significance, specifically, in terms of drilling safety and reservoir management. Despite numerous work have been carried out for prediction of PP in oil reservoirs, but there still exists a tangible lack of such work in gas hosting rocks. The present study aims to discuss and evaluate the application of a number of existing methods for prediction of PP in two selected giant carbonate gas reservoirs in south Iran. For this purpose, PP was first estimated based on the available conventional log data and later compared with the PP suggested by Reservoir Formation Test (RFT) and other bore data. At the end, it has been revealed that while PP prediction is highly dependent on the type of litho logy in carbonates, the effect of fluid type is negligible. Moreover, the velocity correlations work more efficiently for the pure limestone/dolomite reservoirs compared with the mixed ones.