Use of Physical Properties of Shale for Evaluating Reliable Correlation Between Electrofacies and Chronostratigraphic Correlation

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KeshariI Nandan Pande,
ONGC INDIA

Abstract

Informal type of correlation based on physical properties of shale parameters recorded by different types of well logs, and also reservoir formation pressures (RFT data) with respect to depth are able to establish a reliable correlation in multiple sand shale series formations where chronostratigraphic (seismic) is contradictory and reverse to electrofacies correlation. Formation evaluated parameters (saturation of water in unflushed zones (SW) and in flushed zone) (Sxo) maintain an identical relationship in individual types of series. The results of conventional testing data available from different wells and their behavior are ‘also helpful to confirm the mapable correlation. The technique can direct toward a correlation which can be found helpful to develop the area having more prospects for exploration of hydrocarbons, which is not possible by conventional processes of correlation. Besides correlation problems, prediction of high pressure zones, direction and their area can also be evaluated. Field example is from an Indian offshore hydrocarbon structure, where seismic time based correlations are found contradictory (Opposite) to electrofacies correlations and has made exploration for hydrocarbon controversial. The technique described here supported (in particular case) chronostratigraphic correlation and the study is found to be correct after drilling few wells.