Portable X-ray diffraction for unconventional and conventional petroleum exploration

Abstract

X-ray diffraction (XRD) is a well-established technique in the earth sciences as it can be used to identify and quantify minerals and is particularly useful for fine-grained sedimentary rocks. Due to the capital cost, environmental requirements and significant sample preparation, XRD instruments are generally confined to laboratories. Recent advances in XRD sample holders and X-ray sources have allowed for the development of portable XRD (pXRD) devices where the sample preparation is simpler and does not require regular calibrations by a technical expert. This technology was initially developed by NASA for the Mars Science Laboratory rover Curiosity, to perform mineralogical analysis of the Martian surface. Due to its portability, minimal sample preparation, fast collection times, and excellent correlation with laboratory-based XRD devices, pXRD has been shown to be of great use to petroleum geologists and engineers by providing rapid, quantitative mineralogical data. For mudlogging quantitative mineralogy is being used to guide directional drilling towards the target formations and to ensure lateral drilling stays within the target formations. Quantitative mineralogy from the target formation and overburden rock also provides important information regarding the engineering properties of these rocks (e.g. fracturability), and can help determine the most appropriate acid for acid-fracturing stimulation. For conventional petroleum exploration quantitative mineralogy onsite, can be used to understand geophysical responses, and as a screening tool for selecting samples for more detailed analysis.