Abstract

Wells have been drilled using non-conductive mud (NCM) in the deepwater Gulf of Mexico since before the turn of the century. Following the advent of high-quality NCM imagers, advanced image interpretation techniques have evolved to extract quantitative high-resolution facies information that enables deeper insights into reservoir heterogeneity and production ambiguity.

Today’s NCM images capture very fine details of the formation as distributed around the borehole. An image spectrum analysis technique enables us to clearly identify internal-to-bedding features, including distribution of nodules and clasts. The degree of heterogeneity can be measured and computed, similar in principle to that of laboratory grain-size distribution analysis. This heterogeneity analysis technique enables the use of the visual image interpretation in more quantitative method that can be used in accurate microfacies characterization as the subsets of deepwater depositional elements.

Another major development area has been the extraction of lamina and their use to characterize high-resolution deposits. This is a step forward from thin layer detection and improved net pay determination in terms of ranking such heterolithic reservoirs by the degree of laminarity and integrating that information into high-resolution stratigraphic analysis.

The ability to extract such minute facies details and putting those into perspective of larger reservoir units helps in estimating reservoir extent, connectivity, and assets development.