--> Abstract: Power and Limitations of X-ray Fluorescence from Cuttings, a Test in the Utica and Lorraine Shales from Quebec, by Jean-Yves Chatellier, Erik Quartero, Mark Urban, Marianne Molgat, Arnaud Deconinck, and Pierre Francus; #90124 (2011)

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Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Power and Limitations of X-ray Fluorescence from Cuttings, a Test in the Utica and Lorraine Shales from Quebec

Jean-Yves Chatellier1; Erik Quartero1; Mark Urban1; Marianne Molgat1; Arnaud Deconinck2; Pierre Francus2

(1) Talisman Energy Inc, Calgary, AB, Canada.

(2) INRS, Quebec City, QC, Canada.

Shale gas exploration in the Quebec Lowlands is in full swing. The present main target is a roughly 200 m thick Utica shale (carbonate rich); a potential target for the future is the overlying Lorraine shale, which can exceed 2500 meters in thickness. Both shale units are laterally extensive. Whereas the stratigraphy of the Utica is well understood, log analyses of the Lorraine have failed to provide any stratigraphic framework, as the gamma ray is relatively featureless in every well.

The drill cuttings of five wells have been systematically studied using X-ray fluorescence (XRF) at the INRS laboratory in Quebec City. For each studied cutting vial, a series of ten measurements has been taken that gives a representative view of possible compositional variations; this was thought to be essential when considering that the exact depth of each rock sample is only approximate. Data from twenty-two elements has been systematically recorded and analyzed individually, in combination with others, and in ratios. Within the Lorraine shale, the best trends have been expressed by the following elements: K, Mn, S, Si, Ti, Rb, Fe, and Zr. The best ratios for the Lorraine shale are Si/Ti, Mn/S and Al/Cu and by far, the best discriminating displays are ternary diagrams using these three cited ratios. The best diagnostic ratios for Utica shale are different. They are: K/Ca, Rb/Sr and Ca/Ti.

Within the Lorraine shale, five large chemostratigraphic units have been identified and correlated across the study area with no single well presenting the complete sequence; only three chemostratigraphic units have been recognized in most of the studied wells.

In two of the wells, various sieve fractions have been analyzed to understand the influence of the “rock chip / grain size” on the analysis. Some discrepancies in the data are the result of different travel time to surface between finer and coarser fractions, the latter lagging the former.

The X-ray fluorescence study of two of the horizontal wells in the Utica has clearly demonstrated the vast potential of the analysis to accurately identify the position of the borehole within the Utica stratigraphic framework. The results of the integration with a log based structural geology analysis are highly promising, making XRF a very useful tool for the successful development of shale gas resource plays.