Steam Flooding in heavy oil production is improved by higher steam quality from the Once Through Steam Generators (OTSGs). It accomplished through ion-exchange softening of feed water. This work describes efforts related to ion-exchange softening and scaling in OTSGs, optimization of current softening operations in Chevron Field A, brine reduction and increased softener throughput with better resins in Field B, and Reliability, Availability, and Maintainability (RAM) Models to Optimize Water Treatment Process in Field C.<br/>Scales in OTSGs during pigging was evaluated. In Field C, the water softening conditions were noted for the service, backwash, and brining cycle. The deviations were noted and compared against recommended practice. In Field B, current hard shell cation-exchange resins were replaced with shallow shell resin which has better ion-exchange kinetics. The change in throughput and salt consumption in brining was monitored in new and conventional resins over a period of six months. Impact of oil fouling of resins was also noted. The RAM model was applied to Field C Water Plant and collective performance of the softener vessels studied.<br/>The corrections introduced in the optimization study led to reduction in salt consumption by 33%. In Field B, the current strong acid cation-exchange resins were replaced with a shallow shell resin which has better ion-exchange kinetics. The change, noted over a period of 6 months, resulted in additional soft water generation of 30 – 80 % with 15 – 30% lower salt consumption. The RAM model was successfully applied to Field C Water Plant and among multiple features of this model to provide a holistic view of the operations, the Loss Production Opportunity (LPO) in the water plant could identify softener vessels which were least productive.<br/>This study points to the benefits of understanding appropriate residence time in the ion-exchange process and the role of proper backwashing to minimize oil fouling resins. It highlights the need for improved ion-exchange kinetics to reduce brine wastes and salt consumption. Modeling scale predictions will help understand the limits of steam quality concentration factors and therefore relevant treatment requirements to achieve the required feed water quality.

Efficient water softening for steam generation in enhanced oil recovery

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.