Trinidad Columbus Basin Petrophysics Field Study Part 1: Volume of Shale and Porosity

Abstract

A Petrophysical Refresh of the bpTT fields in the Columbus Basin in Trinidad has been carried out. The objectives of the Refresh were to provide continuity and consistency in petrophysical interpretations in this mature basin where over the years multiple vendors and differing interpretational approaches have been employed.In an effort to create a more robust core data set, data gaps were identified in the existing core analyses and supplemental analysis performed.The core data set was expanded to include additional porosity and permeability measurements at net mean stress, laser particle size analysis was conducted on shaley intervals from 4 wells to confirm volume of shale method.New models were developed for volume of shale, porosity and net cut-offs and each of these models were calibrated against the robust core dataset. A curvilinear volume of shale was confirmed to be the most appropriate to estimate volume of shale for the bpTT fields. A total porosity model has been recommended, replacing the legacy effective porosity models. Core derived minipermeability profiles were combined with core photos, and log-derived volume of shale and effective porosity log curves to explore the limits of what might constitute net.