An Image Is Still Worth a Thousand Words: Heterogeneity Analysis Using Electrical Images, CT-Scans and a Revisited Methodology

Abstract

Summary Carbonate reservoirs commonly exhibit a variety of heterogeneities that can complicate ERD waterflood developments. One such heterogeneity that is commonly observed in carbonate reservoirs is the occurrence of diagenesis where varying degrees of cementation and dissolution can result in complex pore throat systems with varying proportions of primary and secondary porosities. The variability in pore throat systems can result in large variations in permeability and therefore have significant impact on the success of a waterflood development. Therefore characterizing the type of porosity and quantifying the types of porosity observed in the reservoir can lead to significant improvements in permeability prediction, reservoir characterisation and reservoir performance. Classical methods of porosity evaluation through traditional resistivity and neutron-density logs usually lack the vertical and azimuthal resolution to address such complexities in the internal rock fabric variability, and therefore accurate permeability predictions and reconciliation with production data remain elusive. In this case study we present the application of a revisited methodology for the characterisation and quantification of porosity types in heterogeneous reservoirs using borehole images, and whole core CT-Scans. The strength of the study is the iterative approach across multiple cored wells with advanced data acquisition, improving the confidence of propagation to uncored wells.