Abstract
The objective of this paper is to present a novel multiobjective optimization strategy using a weighted optimal Life Cycle Analysis (WOLCA) model to rank environmental performance of Exploration and Production programs. The weighted optimal Life Cycle Assessment (WOLCA) was use to formulate an environmental rank index that incorporates economic tradeoff for selecting best exploration and production (E&P) HSE (Health, Safety, Environment) programs. The application of the model to measure the environmental performance of a typical E & P company based on published HSE data of oil spills and air pollution were weighted statistically and ranked yearly according to their best environmental impact reduction merits over the ten years of operations of the E&P company from 1999-2007. The Environmental impact relating to the impacts of gas flaring and oil spill along pipelines based on the HSE annual report were derived from the concept of the weighted optimal life cycle assessment, the weights being generated using Normal Probability Distributions of the EIU (Environmental Impact Units). The resulting economic and environment and cost multiobjective optimization models were solved using goal-programming (GP) techniques in which the performance index are ranked and then minimized lexicographically. A matrix of deviation from the zero waste targets was formulated using the Jacobean formulation derived from the Liapunov Stability Criteria. A typical E&P HSE program was studied and simulated for the environmental rank and zero target improvement indexes. The results for the E&P case study showed that their environmental performance was poor in 2000 and 2004 with a zero target improvement index being 0.1018 and 0.4151 above zero baselines. Year 2004 exhibited the least environmental performance.The enironmental rank index for year 2000 and 2004 being 0.197165 and 0.198559 having the highest rank fraction in the years spanning 1999-2007. Based on the simulated results, it was possible to rank the environmental performance of E&P Company under a single digit metric. The cost index was derived from the penalties paid as oil spill fines, the cost rank index derived provided a metric of cost associated with the spills and the cost benefits or improvements considered as the economic tradeoffs. This model would be useful to E&P HSE managers, Operators and Regulators to compare the environmental performance of HSE programs of different E& P companies over a common baseline. It would also serves as a useful tool for environmental auditors in providing an informed audit on the actual impact of the E&P Life Cycle operations on the environment.