Laboratory measurements and reservoir monitoring of bitumen sand reservoirs [electronic resource]
Keywords: Geophysics

This dissertation focuses on the properties of bitumen sand reservoirs and how they change under various temperature and pressure conditions. The key contributions of this dissertation include a new high-temperature, high-pressure ultrasonic pulse transmission system designed specifically with bitumen sands in mind, and a robust dataset of P- and S-wave velocity measurements for several heterogeneous bitumen sand samples. In addition, modeling was performed to determine which rock physics models, if any, are able to predict bitumen sand reservoir properties under various pressure and temperature conditions. Finally, an inversion methodology using P-to-S converted-wave elastic impedance was applied to bitumen sand reservoirs to more accurately track both temperature changes and steam chamber formation in bitumen sand reservoirs undergoing thermal production. Bitumen sand properties are still poorly understood despite a large push in recent years to measure their properties. Specifically, the change in properties with increasing temperature and pressure is poorly constrained. This is due to the inherent difficulties in measuring soft, highly attenuating bitumen sand samples. To measure and better characterize the properties of bitumen sands I designed and built a novel system which incorporates low impedance piezoelectric transducers. These transducers are optimally matched in order to obtain large amplitude, clean signals through bitumen sands over a wide temperature and pressure range. This allows both the P- and S-wave velocities of these materials to be better characterized, and the results can be used to calibrate and develop rock physics models applicable to bitumen sand. The lack of a robust rock physics model for these materials is the fundamental hurdle that must be overcome in order to better characterize and monitor the production of bitumen sands reservoirs. The dissertation uses the dataset collected to lay the groundwork towards the development of a vigorous rock physics model. The data collected is used to ascertain the utility of several widely accepted rock physics models. Though no one single model has been demonstrated to always predict bitumen sand properties correctly, a handful of models show some promise. This work has also demonstrated that several commonly used models are erroneous in their bitumen sand property predictions and should be avoided. Additionally, I investigated the amount of velocity dispersion and attenuation that can be expected for bitumen sands when comparing measurements over a wide range of frequencies. This is of particular importance if we wish to compare measurements made in the laboratory with seismic measurements made in the field. Seismic characterization and monitoring of bitumen sand reservoirs has been largely inadequate to this point due to the inability to quantitatively evaluate the temperature and presence of steam chambers in the reservoir. This dissertation addresses the problem by employing converted wave seismic data collected at near and far offsets to independently assess both the temperature and steam saturation. This methodology provides the information needed to operate thermal production of these reservoirs in an efficient manner, and provides insight into areas of the reservoir that may yet be untapped.