Abstract

Naturally encapsulated, micro to nanoscale fluid filled cavities within rock material retain compositional attributes and physical properties useful for evaluating unconventional plays. We have developed a laboratory workflow for characterization of these fluids and their host rocks (cuttings or core) utilizing a modular approach whereby samples are conveyed sequentially through a series of automated analyzers including: high-resolution UV and visible light photography, trapped volatile analysis by direct quadrupole mass spectrometry, X-ray fluorescence analysis and diffuse-reflectance infrared Fourier-transform spectroscopy. All analyses are performed on the same 0.5g rock sample, preserving interrelationships between rock and fluid, and allowing for multiple data streams to be collected on limited sample volumes. The entire multi-stage analytical cycle lasts 5 days, thus bridging the gap between real-time analyses and longer-term core evaluations. High throughput allows databases to be quickly and cost-effectively generated on fresh or legacy samples of any age, drilled with any mud and bit type.

Data are used for a variety of purposes, but the most practical applications for unconventional plays are ultimately aimed at evaluating vertical wells for horizontal well placement and identifying variability along laterals that can be exploited for more effective completions. In addition to its intrinsic value, whole-wellbore cuttings analysis provides an efficient screening technique that enables appropriate sample selection for more detailed analyses. Examples will be provided from several North American resource plays, including those within the Anadarko, Delaware and Midland Basins.