APPLICATION OF INDUCED GAMMA-RAY SPECTROSCOPY MEASUREMENTS - CHARACTERIZATION OF A NORTH-SEA RESERVOIR

Implementation of a correct mineral transform model and strategy on el emental chemistry, derived from gamma-ray spectroscopy logging tools, can provide a continuous accurate measurement of mineralogy through a complete reservoir section. Such mineralogy logs are potentially valua ble on their own, especially for the identification of clay minerals i n petroleum exploration; however, they can also be used for the determ ination of other important parameters, such as grain density, porosity , and cation exchange capacity (CEC). In exploration wells where core recovery is poor, such knowledge from nuclear logging can help to exte nd formation evaluation across these poorly defined zones, maximizing reservoir characterization. A set of reservoir cores from the North Se a, (Brent Group) are used to evaluate various models developed for tra nsforming elemental data into geologically meaningful mineralogy. Emph asis is placed on evaluating transform techniques using well constrain ed laboratory data before applying the models to elemental data derive d from nuclear logging tools. This evaluation procedure aims to determ ine the most suitable transform model, as well as quantifying some of the inherent problems with mineral inversion. Strategies for overcomin g such problems are also addressed.