Life Cycle Environmental And Economic Assessment Of Deep Brine Exploration

Deep brine is an important mineral resource, containing abundant chemical elements (e.g., Na, K, Ca, C1 and Br), which has been maturely utilized for industry chemicals production (e.g., salty extraction and caustic soda production). Development and utilization of deep brine has wide development prospects under current resources situation. However, the exploration of deep brine has lead to a serious of environment problems (e.g., drilling fluid leakage and un-reasonable drilling waste disposal), which restrict the exploration and utilization of deep brine seriously.Life cycle assessment (LCA) as the most effective tool for environmental management evaluates the environmental impacts of a product or process from cradle to grave scientifically and comprehensively. Life cycle environmental and economic assessment of deep brine can not only quantify the environmental and economic impacts of brine exploration comprehensively, but also provide reliable theory and database basis for management decision-making department.The main contents of this dissertation are as follows:(1) Life cycle inventory analysis of Chinese deep brine well exploration via field investigation, test analysis and literature research,(2) Life cycle assessment of deep brine well exploration via ReCiPe model,(3) Normalization analysis to identify key categories that contribute to the overall environmental burden dominantly,(4) Identification and quantification of key factors (i.e., substances and processes) which have significant contributions to the identified key categories,(5) Sensitivity analysis of the selected life cycle assessment model (ReCiPe),(6) Economic impact quantification of deep brine exploration by life cycle costing analysis,(7) Life cycle environmental and economic integrated analysis of deep brine well exploration.Typical deep brine well exploration engineering of Yellow River Delta was selected for case study. Life cycle inventory of brine well exploration was established based on Chinese situation. LCA results showed that the impacts seen from marine ecotoxicity, human toxicity, freshwater eutrophication, freshwater ecotoxicity, and fossil depletion categories had dominant contributions to the overall environmental burden; whereas the impacts seen from the rest categories were negligible.Analysis results of key processes to the identified key categories presented that steel, electricity, as well as drilling waste made dominant contributions to well drilling process, for exploration and transport of brine, the key factor was electricity. Analysis results of dominant substances to the key identified categories showed that the dominant substances in the marine ecotoxicity and freshwater ecotoxicity categories were vanadium and nickel; for human toxicity category, mercury and arsenic were the dominant substances; for freshwater eutrophication category, the dominant substance was phosphorus; meanwhile, coal made the most significant contribution to fossil depletion category.Sensitivity analysis of LCA method results showed that evaluation results obtained via ReCiPe were reliable in present study. In addition, life cycle costing analysis of deep brine well exploration showed that the dominant factors for well drilling process were steel and labor cost; for the exploration and transport of brine process, the key factor was electricity cost. Life cycle environmental and economic analysis of deep brine well exploration presented that control the consumption of steel was effective win-win implication to reduce both environmental and economic impact generated from well drilling process; meanwhile, improve electricity efficiency was the prior win-win approach for the exploration and transport of brine.