Characterizing Shale Rock Properties and Gas Storage Potential
Ye Xu, Zhenxue Jiang, and Zhuo Li
Unconventional Nature Gas Institute, China University of Petroleum, Beijing, China
Shale gas has become a significant unconventional hydrocarbon resource around the world. A work flow for systematic shale rock characterization using a number of advanced micro-scale observation to identify the shale rock properties and to discuss the gas storage potential in shale gas plays. The shale rock properties, including organic matter abundance and type, maturity, static and dynamic mechanical properties (brittleness), silt content, micr/macro-fabrics, porosity, permeability, petrophysical properties and anisotropy, are important for shale gas evaluation. non-destructive petrophysical methods are conducted before destructive measurement was performed. Quantitative mineralogy were performed using XRD and XRF, and clay chemical reactivity via cation exchange capacity (CEC) and grain size by centrifugation, Scanning Electron Microscopy (SEM) and X-ray Computed (micro-) Tomography (X-ray CT) at low and high resolution. Surface area and Mercury Injection Capillary Pressure (MICP) for porosity and pore throat distribution were performed. Shale strength has previously been shown to be related to CEC, which is inversely correlation to silt content. Anisotropy of shale properties is both intrinsic and stress-induced. Low and high field nuclear magnetic resonance can be used to distinguish clay-bound, free water and adsorption of organic components and to screen for wettability. High and low field NMR techniques are combined to show that illitic shales tend to be strongly water wet while the presence of kaolinitic clays imparts a tendency for shales to become oil wet with likely consequences for oil/gas recovery strategy, production flow efficiency and drilling design.
AAPG Datapages/Search and Discovery Article #90180©AAPG/SEPM/China University of Petroleum/PetroChina-RIPED Joint Research Conference, Beijing, China, September 23-28, 2013