Application of fluid-rock reaction studies to in situ recovery from oil sand deposits,Alberta, Canada—II. Mineral transformations during an experimental-statistical study of water-bitumen-shale reactions

Solution-mineral equilibria were calculated for the aqueous phase, and X-ray diffractograms obtained for the solids, from the factorial experiment reported in Part I of this series of papers, in which a shale from the Lower Cretaceous McMurray Formation in the Athabasca oil sand deposit of Alberta, in the presence or absence of bitumen, was subjected to hydrothermal treatment with aqueous fluids of varying pH and salinity, at two different temperatures, for periods up to 92 hours. Data representing the departures from equilibrium, and normalized X-ray diffraction peak intensities, were studied by statistical analysis of variance. In addition to the dissolution of quartz, montmorillonite was formed probably through a transitional illite-montmorillonite interstratined layer structure, with the reaction being favored by high pH of the aqueous phase. The dissolution of siderite is significantly affected by time, salinity, and the interactions between pH and salinity, time and salinity, and pH, temperature and time. Despite the restrictions imposed by a laboratory investigation, the results demonstrate that mineral dissolution and transformation will be extensive during in situ recovery operations in oil sand deposits.     

Three-dimensional location and waveform analysis of microseismicity in multi-anvil experiments

We present an acoustic emission (AE) monitoring technique to study high-pressure ( P > 1 GPa) microseismicity in multi-anvil rock deformation experiments. The application of this technique is aimed at studying fault mechanisms of deep-focus earthquakes that occur during subduction at depths up to 650 km. AE monitoring in multi-anvil experiments is challenging because source locations need to be resolved to a submillimetre scale due to the small size of the experimental assembly. AEs were collected using an 8-receiver array, located on the back truncations of the tungsten carbide anvils. Each receiver consists of a 150–1000 kHz bandwidth PZT transducer assembly. Data were recorded and processed using a high-speed AMSY-5 acquisition system from Vallen-Systems, allowing waveform collection at a 10 MHz sampling rate for each event signal. 3-D hypocentre locations in the assembly are calculated using standard seismological algorithms. The technique was used to monitor fault development in 3 mm long × 1.5 mm diameter olivine cores during axisymmetric compression and extension. The faults were generated during cold compression to ∼2 GPa confining pressure. Subsequent AEs at 2–6 GPa and 900 °C were found to locate near these pre-existing faults and exhibit high pressure stick-slip behaviour.