Simulation of Drill Cuttings Dispersion and Deposition in South China Sea

Drill cuttings with various characteristics and sizes are produced in any offshore oil and gas exploration and production (EP) drilling of the seabed

Drill cuttings and drilling fluids (muds) transport, fate and effects near a coral reef mesophotic zone

The study was conducted to improve knowledge and provide guidance on reducing uncertainty with impact predictions when drilling near sensitive environments. Near/Far-field hindcast modelling of cuttings/drilling fluid (mud) discharges from a floating platform was conducted, based on measured discharge amounts and durations and validated by ROV-based plume and seabed sampling. The high volume, concentration, and discharge rate water-based drilling mud discharges (mud pit dumps) were identified as the most significant dispersal risk, but longer-range movement was limited by the generation of jet-like plumes on release, which rapidly delivered muds to the seabed (80 m). Effects to the sparse benthic filter feeder communities close to the wells were observed, but no effects were seen on the epibenthic or demersal fish assemblages across the nearby mesophotic reef. For future drilling near sensitive environments, the study emphasized the need to better characterise drilling fluid discharges (volumes/discharge rates) to reduce uncertainty in modelling outputs

Adaptive Underwater Robotic Sampling of Dispersal Dynamics in the Coastal Ocean

To get a better understanding of the highly nonlinear processes driving the ocean, efficient and informative sampling is critical. By combining robotic sampling with ocean models we are able to choose informative sampling sites and adaptively change our path based on measurements. We present models exploiting prior information from ocean models as well as real-time information from in situ measurements. The method uses compact Gaussian process modeling and objective functions to locate informative sampling sites. Our aim is to get a better understanding of ocean processes and improve real-time monitoring of dispersal dynamics. The case study focuses on a fjord located in Norway containing a seafill for mine tailings. Transportation of the deposited particles are studied, and the sampling method is tested in the area. The results from these sea trials are presented.acceptedVersio

Dynamic stochasticmodeling for adaptive sampling of environmental variables using an AUV

Discharge of mine tailings significantly impacts the ecological status of the sea. Methods to efficiently monitor the extent of dispersion is essential to protect sensitive areas. By combining underwater robotic sampling with ocean models, we can choose informative sampling sites and adaptively change the robot’s path based on in situ measurements to optimally map the tailings distribution near a seafill. This paper creates a stochastic spatio-temporal proxy model of dispersal dynamics using training data from complex numerical models. The proxy model consists of a spatio-temporal Gaussian process model based on an advection–diffusion stochastic partial differential equation. Informative sampling sites are chosen based on predictions from the proxy model using an objective function favoring areas with high uncertainty and high expected tailings concentrations. A simulation study and data from real-life experiments are presented.publishedVersio

Development of an Integrated System for the Simulation and Assessment of Produced Water Discharges from Offshore Platforms

Techniques for modeling of marine pollution have been studied for decades. Specialized modeling methods have been used to simulate the dispersions of pollutants from offshore outfalls. Produced water, the largest volume waste stream discharged from offshore oil and gas production activities, is a complex mixture of dissolved and particulate organic and inorganic chemicals including metals and hydrocarbons. In recent years, the growing importance and interest in the ocean environment assessment has urged further evaluation of produced water impacts on the marine ecosystem. This thesis study describes an integrated system for the modeling and assessment of produced water discharges in coastal area. The system integrates ocean circulation simulation, pollutant fate and transport modeling that couples near field mechanisms and far field processes, and risk assessment approaches where exposure risks and probabilistic risks are evaluated. A literature survey is first introduced to review and present capabilities and limitations of the most widely used methods and models associated with assessment of the impact of marine pollution. This review identified the need for an integrated system with configurations of numerical schemes of Princeton Ocean Model (POM) for ocean circulation simulation, a Lagrangian method to simulate near field transport processes in three dimensional cross flows, and a numerical solution for far field transport modeling. The physical models are dynamically integrated to ensure mass and energy conservation. Furthermore to assess risks, a modified Monte Carlo method which uses a statistical model to establish the relationship between uncertainty parameters and output concentrations is integrated with physical modeling system along with risk characterization approaches to map risk levels. Evaluation and field validations are conducted for each individual sub-models and for the overall integrated modeling results. Specifically, the near field model is validated against a field study performed in USA platform located about 100 miles of New Orleans Louisiana. The computational efficiency and accuracy of the far field model are evaluated through test cases in comparison with concentration distribution results generated from an exact analytical solution and a RWPT (Random Walk Particle Tracking) method. Validations of ocean circulation results and the integrated produced water dispersion results are conducted in a case study carried out on the Grand Banks of Newfoundland, Canada. Validations show good performance of the developed modeling system which is used to provide satisfactory 3D simulation of marine pollutant dispersion for effective assessment and management of offshore waste discharges. Finally, a risk assessment is carried out to predict risks associated with predicted lead and benzene concentration resulting from potential future produced water discharges in the East Coast of Canada. This research study provide a tool for the modeling of complex transport processes in the coastal area, and improved methods for risk assessment of produced water impacts on the regional water environment

Marine Oil Spills

Major oil spills attract the attention of the public and the media. This was especially the case after the Deepwater Horizon spill. In recent years, this attention has created a global awareness of the risks of oil spills and the damage they do to the environment. Oil is a necessity in our industrial society, however, and a major component of our lifestyle. This means that the risk of major spills continues as does the interest in spills. The Deepwater Horizon spill began a new series of scientific studies that have greatly increased our understanding of oil spills. This book contains 10 such studies. These studies vary from toxicity studies to social studies of human reaction to spills and risk. Importantly, the book is a sampling of important new topics that have become important after the Deepwater Horizon spill. These new topics include new chemical and tracing techniques, new risk perception techniques, perspectives on human health and spills, and discussion on new fuels. This book makes a significant contribution to the understanding of facets of spills and explores 10 very different facets of oil spills