BASS Division Talk
Determination of Mineralogy and Reservoir Properties from XRF Elemental Data in the Duvernay Formation
Speaker: Ron Spencer, PhD | XRF Solutions Ltd.
February 05, 2020
Location: geoLOGIC Room (2nd Floor), Aquitaine Tower, 540-5th Avenue S.W., Calgary
12:00pm: Talk Starts
*CSPG members can register for free and track their CPD hours!
The Alberta Geological Survey estimates the Duvernay Formation to contain more than 400 TCF of natural gas as well as significant NGLs and oil. Cost effective means for acquiring reservoir properties, especially in horizontal production wells, are essential In order to exploit this resource to its full potential. Portable X-Ray Fluorescence (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 bulk chemistry. XRF analysis can be conducted over an entire vertical well in order to determine a chemical stratigraphy and locate potential areas of interest. Elemental abundances provide a wealth of data that can be used to distinguish various chemical stratigraphic units. Each unit can be distinguished with relative ease using basic elemental abundance suites. The major rock forming elements along with trace elements acquired through XRF methods are excellent for identifying rock formations and sub-units in the subsurface which can be correlated from well to well. XRF analysis of elements. related to gamma can be used to create a spectral gamma suite along with a combined XRF generated gamma signature. Depth shifting can be applied by relating the XRF gamma back to wireline or core gamma. Trace elements related to TOC are used to locate zones with a high source rock potential, even though carbon itself is too light to detect using XRF.
Proprietary normative mineral algorithms are applied in order to convert the elemental chemical data to mineralogy. Mineral abundances determined from the XRF analyses are compared to those obtained by X-Ray Diffraction, thin section point counting and SEM analyses. Lab bias versus mineralogy differences in the Duvernay will be discussed further in the talk. Mineralogy and trace element data are used to determine reservoir properties through a set of semi-empirical equations. Porosity, permeability 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. A reservoir quality log suite from core is shown in Figure 1. Formation specific algorithms developed from vertical wells are applied to cuttings analysed from horizontal production wells, where conventional log analyses are impractical or too expensive. Data obtained using portable X-Ray Fluorescence instruments provide a cost-effective means for acquiring data necessary for the optimization of both completions and production from horizontal wells.
Ron Spencer has over 40 years of geological experience in education and research. He began working with X-ray florescence in 2009 on several research and consulting projects. Ron is the co-founder and Vice President of research and development at XRF Solutions. He ensures data quality and develops sound methods and procedures for X-Ray Fluorescence methodology. Ron began his geology education in Colorado obtaining a Bachelor of Arts in Geology in 1973. He continued with a Master of Science in Geochemistry at the University of Nevada in 1977 and completed his PhD at John Hopkins University in 1981. Ron has been with the University of Calgary since 1981, retiring from teaching in 2009. He continues to hold a Faculty Professor position there engaging in academic research and student supervision.