Elemental Spectroscopy measurements have become a standard component of the logging program in Exploration, Delineation and special Evaluation wells for Saudi Aramco. Elemental Spectroscopy data has proved critical when evaluating complex lithology formations in both siliciclastic and carbonate rocks to produce an accurate mineralogy analysis, resulting in good understanding of the subsurface lithology in a cost effective way.

A rigorous qualification protocol is applied to novel services when they are introduced to Saudi Aramco. New measurements are compared to existing equivalent services if available and to core data if applicable. For the specific case of the new Elemental Spectroscopy device, the elemental outputs were compared to a previous generation tool and to elemental concentrations from core measurements in a wide variety of formations and lithologies in clastic and carbonate reservoirs. Clastic reservoirs were covered in previous publications; in this work we show the results for carbonate rocks.

Initial comparisons between the previous and new generation tools showed good agreement for most of the elements except for Mg (Magnesium) at low concentrations. Several samples were selected from Jurassic carbonate reservoirs to understand better differences at low Mg concentrations. All samples were taken as 1 foot side trims from a full core slab. The samples were crushed and homogenized to minimize the effects of heterogeneity. The prepared samples were analyzed using X-ray fluorescence (XRF) for elemental concentrations and Dual Range Fourier Transform Infrared Spectroscopy mineralogy (DT-FTIR) for mineralogy. The elemental results from both tools and the core samples were then plotted and compared.

While existing measurements work in many areas, there are specific cases where the new technology can generate improved formation evaluation in carbonate formations or increase efficiency by logging faster.

You can access this article if you purchase or spend a download.