Modified Fibre-Bundle Model to Simulate Induced Seismicity

English Abstract:

An increase in the number of earthquakes in the last ten years or so has been linked to human activity in areas of oil and gas production in the Midwestern United States. This induced seismicity has raised public concerns over the safety of operations of energy-related activities such as wastewater disposal and hydraulic fracturing. Because of the economic effect that the extraction of oil and gas can provide to regions rich in these resources, there has been a significant amount of interest and investment put into these types of operations in Alberta. However, an increased number of earthquakes, including those of larger magnitude, could be problematic when considering critical infrastructure such as industrial facilities, power plants, dams, etc. located in these regions. Here we apply a modified version of the fibre-bundle model to simulate the process of failure leading to an earthquake due to induced seismicity. This model has been successful in simulating the failure processes in various applications, including earthquakes, damage mechanics models, communication networks, and traffic systems. The fibre-bundle model represents a solid material as a collection of fibres in a bundle, similar to cables composed of intertwined wires. An applied stress is distributed to each fibre within a bundle. The failure of these fibres over time provides valuable insights into the failure of solid materials. In the proposed model the interevent times and frequency-magnitude statistics of the model earthquakes are computed over multiple simulations. The model couples the standard fibre bundle with a fluid that is introduced and diffused into the system and is shown to impact earthquake statistics due to the lowering of the critical thresholds of the fibres exposed to the fluid. The resulting change in statistics observed helps to highlight the effect of decreasing the effective stress within the rock and how this relates to induced seismicity.