Events Calendar

Astani Civil and Environmental Engineering Ph.D. Seminar

Speaker: Nima Jabbari and Qin Ba, Astani CEE Ph.D. Students

Talk Title: Groundwater contamination potential from well-casing failure during a hydraulic fracturing operation

Abstract: By: Nima Jabbari

Title: Groundwater contamination potential from well-casing failure during a hydraulic fracturing operation

Abstract:
The introduction of hydraulic fracturing as a new technology for hydrocarbon production from low-permeability geologic formations has revitalized natural gas as an abundant, economic, and cleaner source of energy. Despite the benefits, hydraulic fracturing has raised several environmental concerns, from air pollution and water contamination to potential seismic activities induced by the subsurface fluid injection. Incidents and accidents attributed to this technology could be mitigated by setting more stringent regulations and adding more precautions to the operation steps. This research is aimed to investigate one of the potential risk-pathways of the chemicals used in fracturing slurry toward shallow groundwater. Well-casing failure and leakage near the bottom of fresh aquifer during the high-pressure injection process is selected as the hypothetical scenario of concern. A framework is proposed to characterize the human health risk from ingestion of contaminated water. In this model, hydrogeological and operational parameters are altered stochastically in a way to cover a range of possible worst-case scenarios. The results show that if the well integrity is compromised, high risks to human health are achievable. This work can help the site-managers make appropriate decisions once an underground leakage is detected.

Presenter: Qin Ba

Title: Robustness and optimal control of power grid

Abstract:
For infrastructural network systems (e.g. transportation networks, power grid, water networks, and data networks) small fraction of link failure can cascade and lead to system failure. We study the influence of cascading failure and try to develop decentralized control policies to improve the robustness of power grid. Due to the different underlying physics, cascading failures have different effects on power grid and transportation systems. Firstly, while failure always decreases the throughput of transportation networks, it can increase the performance of power grid. This motivates an optimal control problem in which load shedding is considered as the control action to stop cascading failure in power grid. An finite horizon dynamic program formulation is hence proposed. Secondly, while decentralized control policy can never render maximal robustness of transportation system, it can be maximally robust in certain power grids. For this, we consider control on susceptance of links to maximize robustness of power grid, where the the margin of robustness for a given control policy is defined as maximal perturbations under which the link flows can be asymptotically contained within their specified limits. We proposed decentralized control policies to achieve the maximal robustness of a class of networks with simple topologies. The optimality is proved and shown through simulation results based on a benchmark IEEE network.

Location: Grace Ford Salvatori Hall Of Letters, Arts & Sciences (GFS) - 106

Audiences: Everyone Is Invited

Contact: Evangeline Reyes