You are encouraged to attend the defence. The details of the defence and attendance information is included below:  

Date: Tuesday, December 2, 2025 

Time: 9:00 AM to 12:00 PM (PT)

Defence mode:  Hybrid 

In-Person Attendance: Senate Chambers, UNBC Prince George Campus  

Virtual Attendance: via Microsoft Teams 

Please contact the Office of Graduate Administration for information regarding remote attendance for online defences. 

To ensure the defence proceeds with no interruptions, please mute your audio and video on entry. The meeting will be locked to entry 5 minutes after it begins: please ensure you are on time.  

Thesis entitled: EXPERIMENTAL AND NUMERICAL STUDY OF MECHANICAL AND TIME-DEPENDENT BEHAVIOR IN TIGHT SEDIMENTARY ROCKS FROM BRITISH COLUMBIA SHALE GAS PLAY 

Abstract: 

Mechanical properties (e.g., elastic modulus and hardness) and creep behaviour of tight rocks are critical in geological and engineering applications, particularly in oil and gas extraction. Compared with conventional compression tests, instrumented indentation is a fast, convenient, low-cost, and sample-efficient method for characterizing elastic and creep responses. This work systematically evaluates the applicability of indentation in heterogeneous and anisotropic tight formations from BC shale gas plays by varying load levels and indenter geometry, and it quantifies their influence on measured responses. It also develops an integrated experimental–computational framework that links instrumented indentation to macroscopic stiffness and time-dependent behaviour in tight formation rocks.

The experimental program applies Brinell and Vickers indentation across controlled force ranges and loading cycles, pairing each indent with derived mineral maps and pore metrics from scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses to quantify indenter-tip effects, loading conditions, and mineralogical features. It further conducts micro-indentation creep on multiple tight formations, complemented by multi-stage uniaxial compression (UCS) creep on pre-fractured samples. The numerical program builds axisymmetric finite-element models of compression and indentation with an elastoplastic constitutive model and a Burgers creep model, and a full-factorial analysis of variance is used to quantify rheological sensitivities and to guide calibration. Simulation-informed machine-learning models (a support vector regression (SVM) for bulk modulus and a multi-output network for creep parameters) are trained on large synthetic datasets and evaluated against independent experiments.

The study shows that indenter geometry and loading conditions materially affect indentation-derived properties; mineralogical context and porosity systematically influence local mechanical response; and a common constitutive framework can represent creep behaviour in uniaxial and contact configurations. The validated simulators and learning models provide a practical pathway for translating rapid indentation measurements into formation-calibrated estimates of macroscopic stiffness and creep inputs, thereby reducing sample demand, cost, and testing time while offering clear guidance for parameter selection and model calibration.

Defence Committee:

Chair: Dr. Ian Hartley, University of Northern British Columbia  

Supervisor: Dr. Wenbo Zheng, University of Northern British Columbia  

Co-Supervisor: Dr. Jianhui Zhou, University of Northern British Columbia  

Committee Member: Dr. Chao Kang, WSP CANADA INC.

Committee Member: Dr. Xiaojun Cui, AGAT Laboratories 

External Examiner: Dr. Biao Li, Concordia University