Comparative Economic and Life Cycle Assessment of Water and Wastewater Management in the Oil and Gas Industry

Abstract

The increase in worldwide energy demand continues to reinforce dependence on the petroleum industry, despite the growing adoption of renewable energy technologies. This dependency necessitates investigating sustainable strategies to mitigate the environmental impacts associated with petroleum operations, particularly produced water (PW) management. PW represents the largest volume of wastewater generated during hydrocarbon extraction, necessitating innovative and efficient management solutions to minimize environmental footprints and enhance its reuse potential. A systematic review of Life Cycle Assessment (LCA) applications in wastewater management within the petroleum industry was conducted to identify existing research gaps. The review highlighted several key limitations, including the lack of research on produced water (PW) reuse, the absence of region-specific impact characterization factors, and the lack of sensitivity analyses to account for critical uncertainties. Building upon these insights, the research proposed a novel LCA-based framework coupled with optimization and system dynamics model to evaluate various PW management strategies in oilfield offshore operations. The framework also employs experimental designs incorporating stepwise linear regression and multi-criteria decision analysis (MCDA) to assess diverse reuse scenarios, such as internal reuse for enhanced oil recovery (EOR), cooling systems, drilling operations, and utility services. The findings reveal that recent treatment technologies, particularly the integration of combined fiber coalescence with mechanical vapor compression, offer substantial advantages over conventional methods. These advancements lead to a reduction in environmental impacts by up to 66%, an increase in operational efficiency by 14%, and a decrease in treatment costs by 6.5%. Furthermore, system dynamics modeling indicates that internal reuse strategies can utilize up to 47% of the PW inflow, demonstrating significant potential for external reuse applications. Additionally, optimization modeling highlights that recent treatment methods, coupled with external reuse strategies, effectively minimize toxicity and global warming potential while achieving cost-effectiveness when environmental credits are incorporated. Moreover, policy interventions, including targeted incentives and regulatory measures, play a crucial role in accelerating the adoption of sustainable PW reuse strategies. The analysis shows that external reuse strategies, when supported by policy mechanisms, achieve reductions in marine ecotoxicity and human toxicity up to 99%, significantly outperforming deep-well injection and internal reuse scenarios. These findings underscore the importance of integrating environmental, economic, and social considerations to develop a holistic and sustainable PW management framework. By addressing methodological gaps in LCA applications and incorporating optimization and system dynamics modeling, this dissertation provides a robust framework for policymakers and industry stakeholders. The proposed approach advances sustainable PW management strategies, ensuring alignment with global environmental objectives and promoting resource efficiency within offshore oil and gas operations.

Date of Award	7 May 2025
Original language	American English
Supervisor	MUTASEM El Fadel (Supervisor)