CO2-based heavy oil recovery processes for post-CHOPS reservoirs

Authors would like to thank the financial support of the Petroleum Technology Research Centre Saskatchewan (PTRC) for this project, and Computer Modeling Group Ltd. for the use of their thermal reservoir simulation software CMG STARSTM. We would also like to thank Jacky Wang for his help and comments on the modeling part of this study.Peer reviewedPostprin

Post-Liquefaction Residual Strength of Saturated and Partially Saturated Soils

Post-liquefaction response and residual strength play important roles in stability assessment of liquefied ground. Considering the recent advancements in application of induced partial saturation for liquefaction mitigation, the state of knowledge in estimating the residual strength should be extended for liquefied desaturated soils. In this thesis, the residual strength response of a clean sand at different saturation levels was investigated using a Ring Shear Device (RSD). Direct air injection was used to desaturate the soil, which helped mitigating the liquefaction under cyclic loading. However, by raising the shear strain level, both saturated and partially saturated soils were liquefied followed by residual strength measurement. Results indicate that the residual strength increased with a reduction of the saturation level due to the change in compressibility and consequent volume reduction. In addition, the strain rate dependency of the residual strength was confirmed, since an increase of shear strain rate resulted in an increase in residual strength both under saturated and partially saturated conditions

Post-Liquefaction Residual Strength of Saturated and Partially Saturated Soils

Post-liquefaction response and residual strength play important roles in stability assessment of liquefied ground. Considering the recent advancements in application of induced partial saturation for liquefaction mitigation, the state of knowledge in estimating the residual strength should be extended for liquefied desaturated soils. In this thesis, the residual strength response of a clean sand at different saturation levels was investigated using a Ring Shear Device (RSD). Direct air injection was used to desaturate the soil, which helped mitigating the liquefaction under cyclic loading. However, by raising the shear strain level, both saturated and partially saturated soils were liquefied followed by residual strength measurement. Results indicate that the residual strength increased with a reduction of the saturation level due to the change in compressibility and consequent volume reduction. In addition, the strain rate dependency of the residual strength was confirmed, since an increase of shear strain rate resulted in an increase in residual strength both under saturated and partially saturated conditions

Element-centric clustering comparison unifies overlaps and hierarchy

Clustering is one of the most universal approaches for understanding complex data. A pivotal aspect of clustering analysis is quantitatively comparing clusterings; clustering comparison is the basis for many tasks such as clustering evaluation, consensus clustering, and tracking the temporal evolution of clusters. In particular, the extrinsic evaluation of clustering methods requires comparing the uncovered clusterings to planted clusterings or known metadata. Yet, as we demonstrate, existing clustering comparison measures have critical biases which undermine their usefulness, and no measure accommodates both overlapping and hierarchical clusterings. Here we unify the comparison of disjoint, overlapping, and hierarchically structured clusterings by proposing a new element-centric framework: elements are compared based on the relationships induced by the cluster structure, as opposed to the traditional cluster-centric philosophy. We demonstrate that, in contrast to standard clustering similarity measures, our framework does not suffer from critical biases and naturally provides unique insights into how the clusterings differ. We illustrate the strengths of our framework by revealing new insights into the organization of clusters in two applications: the improved classification of schizophrenia based on the overlapping and hierarchical community structure of fMRI brain networks, and the disentanglement of various social homophily factors in Facebook social networks. The universality of clustering suggests far-reaching impact of our framework throughout all areas of science

Modeling solvent enhanced gravity drainage from a single matrix block in fractured oil reservoirs

Peer reviewedPostprin

100 GHz electrically tunable planar Bragg grating via nematic liquid crystal overlay towards reconfigurable WDM networks

Novel liquid crystal-based integrated optical devices with >140GHz electrical tuning are presented for application towards reconfigurable wavelength division multiplexing (WDM) networks. Initial results with Bragg wavelength tuning covering five 25GHz WDM channel spacing have been achieved with 170V (peak-to-peak) sinusoidal voltages applied across electro-patterned ITO-covered glass electrodes placed 60µm apart. These prototype devices were fabricated using direct UV grating writing, with an evanescent field coupling into a liquid crystal overlay through an etched window. Electrically controlled liquid crystal birefringence modifies the waveguide effective index, resulting in Bragg wavelength shift. Merck 18523 nematic liquid crystals are used, exhibiting compatible refractive index values to that of silica (no=1.44, ne=1.49 at lambda=1550nm). Homeotropic alignment of the liquid crystal is provided by application of a surfactant layer.The inherent refractive index sensitivity of our etched direct-UV-written structures allows observation of previously unreported liquid crystal surface-behaviour, such as multi-threshold points during variation of the applied field. Continued optimisation based on evanescent field penetration, electrode layout, and surface interaction will allow implementation towards a variety of novel liquid crystal applications and devices. For example, a cascaded architecture of these integrated liquid crystal devices operating at different Bragg wavelengths would pave the way towards true colorless add/drop modules for dense optical networks