A Comprehensive Risk Management Review Related to the Application of Low Salinity EOR Process in Offshore Carbonates Reservoirs.

Abstract

This paper sheds some light on the emerging EOR recovery mechanism related to modified ionic design of the injected water, sometimes referred to as low salinity or smart water EOR process. Many laboratory water-flooding experiments have been conducted with mixed outcomes on the benefit of the technology. Relative to the existing field applications in sandstones, this technology is less mature in carbonates. Many researchers support the theory that this process is very complex in carbonates and chemical reactions within productions time-scale are not well-understood. The literature lacks the connection between what researchers address in laboratory work and considerations for full-field applications. Therefore, this work aims to bridge some gaps between what is considered in experiments and what is relative to full-field applications. The paper offers a comprehensive review of the risk management framework related to the application of Low Salinity EOR process in offshore carbonates reservoirs in the UAE. Some risks/opportunities related to subsurface, flow assurance, surface facilities and operations will be addressed. The work presents an example of a risk matrix and remedial actions that must be considered during the design phase. For example, the root causes of souring, scaling, anhydrite participation, nepthenate solid precipitation and divalent cation migration will be presented and their possible impact on flow assurance will be addressed during the application of the low salinity flooding on different types of carbonate rocks. Furthermore, uncertainties related to pore-volume contact to reach the threshold salinity, temperature/cooling impact and chemical modelling limitations are addressed and related to the quantifications of the technology benefits as the study evolves from lab work, field trials and eventually to full-field applications. With such visibility of the full spectrum of the technology impact, laboratory experiments can be tuned with the focus to minimize specific risks and maximize benefits to the addressed field.