Determination of Reservoir Properties From XRF Elemental Data in the Duvernay Formation

Abstract

The Alberta Geological Survey estimates the Duvernay Formation to contain more than 400 TCF of natural gas as well as significant NGLs and oil. In order to exploit this resource to its full potential, cost effective means for acquiring reservoir properties, especially in horizontal production wells, are required. Portable X-Ray Flourescence (XRF) instruments allow a large amount of data to be obtained rapidly, with minimal sample preparation or drilling impact, and at low cost. Rock powders, cuttings, slabs or core faces can be analysed directly using this non-destructive technique. XRF analyses provide highly precise, and if calibrated properly, accurate data on the bulk chemistry. Proprietary normative mineral algorithms are applied in order to convert the elemental chemical data to mineralogy. Mineral abundances determined from the XRF analyses correlate well with those obtained by X-Ray Diffraction, thin section point coounting and SEM analyses. The vast majority of the data fall within the 5% envelope expected from the precision of the XRD analyses when compared with XRF determined mineralogy. Mineralogy in the Duvernay is variable and the most abundant minerals are quartz, calcite, K-spar, illite, kaolinite and pyrite. Mineralogy and trace element data are used to determine reservoir properties through a set of semi-emperical equations. Porosity and mechanical properties, including Poisson's ratio and Young's modulus, determined by XRF algorithms correlate well with values obtained from wireline logs and lab analyses in vertical wells. Formation specific algorithms developed from vertical wells can be applied to cuttings analysed from horizontal production wells, where conventional log analyses are impractical or too expensive. The information obtained is particularly valuable for geosteering purposes if conducted on site in real time or for post well completion planning. Data obtained using portable X-Ray Flourescence instruments provide a cost-effective means for optimization of both completions and production from horizontal wells.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016