For evaluation and design of thermal, thermal-solvent, and thermal-additive (additive can be surfactants or alkaline for example), a gap exists between laboratory scale physical model apparatus and field trials. Laboratory scale models are excellent at evaluating processes at the centimeter to meter scale and can be design to honor force ratios such as gravity to viscous forces. They also allow through comparisons between experiments a determination of how operating strategy can alter the oil production rate and steam-to-oil ratio. Together with matched thermal reservoir models, laboratory scale experiments can be also help to deduce the physics of the processes as well as calibrate uncertain transport parameters e.g. effective diffusion coefficients. The key benefits of laboratory-scaled physical models is that they can be controlled easily e.g. injection rates, pressure, and temperature, and they are orders of magnitude less expensive than field trials.
The key missing capability of laboratory-scale physical models is that they cannot represent 1. geomechanics (the actual reservoir is within an unconfined large domain), 2. mixing that occurs at the length scale of the system e.g. velocity-dependent dispersion and the thickness of the mixing zone within the formation (related to the height of the formation), 3. reservoir heterogeneity e.g. shale layers and depositional settings such as point bar systems, 4. capillary forces i.e. it is difficult to scale gravity, viscous forces, and capillary forces simultaneously, 5. in situ reactions e.g. aquathermolysis and steam-rock reactions, and 6. electromagnetic heating i.e. cannot honor scaling of gravity, viscous, and electric heating phenomena. The big models will also allow minimization of impact on the reservoir behavior due to density of instrumentation ports and due to end effects.
The above discussion sets the stage for an intermediate scale physical model apparatus that honors more scaling criteria than laboratory-scaled physical models yet offers the capability to do repeatable and controlled evaluations of recovery processes at substantially lower costs than that of a field trial.
The proposed project will examine the value and cost of an intermediate scale physical model facility for evaluation of heavy oil and oil sands recovery processes. From a literature review of scaling criteria for thermal and thermal-solvent process, listed in Table 1 below, it is possible to design an intermediate scale physical model apparatus to improve its representation of field-scale recovery processes over that of laboratory-scale physical model devices. The specific project objectives will be as follows:
- Conceptual design of the intermediate physical model facility including size, design features such as loading walls for imposing a representative state-of-stress on the model, sampling points, seismic, and injection and production systems. The footprint of the facility will also be identified.
- Operating procedures for the intermediate physical model facility.
- Rough estimates of capital and operating costs.