From Elemental X-Ray Fluorescence Analyses to Reservoir and Mechanical Properties of Unconventional Reservoirs: A Montney Story

Abstract

Optimal placement of multistage hydraulic fractures is key for efficient hydrocarbon recovery, which requires a continuous profiling of the reservoir and mechanical properties along a horizontal well. Coring horizontal wells and subsequent analyses are expensive, time-consuming, and impracticable. As an alternative, drill cuttings are readily available for routine laboratory analyses such as x-ray diffraction (XRD) and x-ray fluorescence (XRF) analyses to determine mineralogical and geochemical compositions. Geochemical tests are timely and cost-effective and are commonly used to model reservoir and mechanical properties. However, the applied geochemical models have not been rigorously tested and the question remains of the reliability in calculating mechanical properties from XRF data. This study investigates cores and cuttings of multiple Montney wells in west central Alberta. Routine core analyses, mechanical properties tests, and XRF analyses are conducted on cores and cuttings of the selected wells. Several methods are applied to construct the mineralogy and TOC from XRF data, which is calibrated to directly tested XRD and SRA data. Mechanical properties (brittleness index, hardness, and Young's modulus and Poisson's ratio) are calculated using the XRF derived mineralogy and constrained with available data tested directly on cores and cuttings, which are further compared with petrophysical log interpretations. The calibrated XRF mineralogy and mechanical property models are applied to another subset of studied wells to test the validity and applicability of the derived models. The results show that the mineralogy derived from XRF analyses is well consistent with XRD mineralogy although some disparities remain especially for some trace and clay mineral phases. The XRF model is reliable in predicting TOC profiles and gamma ray curves, but is dependent on high quality XRF data. Acceptable rock mechanical properties are also predicted, but uncertainties are relatively high because rock mechanical properties depend not only on mineralogical composition but also on the fabric and texture. Overall, the results show that the XRF mineralogy and mechanical properties models constrained with laboratory core and cutting analyses alone or in combination with petrophysical logs can lead to a better understanding of the reservoir and mechanical properties of the Montney Formation in the study area and can be very useful for optimizing well stimulation programs.

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