Results of Proactively Managing a Heavy-Oil Waterflood in South Oman Using Streamline-Based Simulation.

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractStreamline simulation is an ideal reservoir management tool for mature waterfloods since it can identify unswept reserves, quickly evaluate multiple forecast scenarios, and provides novel information like well-pair interactions.The identification of well-pair interactions is particularly useful as it allows for pattern surveillance, quantifying offset production with injection volumes, and identifying efficient vs inefficient areas of injection.The Thuleilat heavy-oil field consists of 120 wells and is geologically complex with stacked reservoirs, multiple oilwater contacts, and numerous faults, making it difficult to identify well interactions and areas of unswept reserves. However, being a dead oil reservoir with the majority of production a result of injection, it is ideally suited for streamline simulation. Several opportunities were identified based on the streamline simulation. These opportunities, which generally apply to all waterfloods, could be divided into well rate target recommendations, pattern optimization, producer-injector conversions, and infill locations.Pattern optimization opportunities resulted in a 10% gain in the offset oil producers. In one of the pattern optimization activities three water injectors were identified for injection rate increase, followed by optimization activities in the associated oil producers which resulted in a significant oil gain. Other pattern optimization activities were to close in high gross rate wells and diverting the flow toward offsets oil producers. One of the trials was to close-in one of the producers in the central area for one week, which resulted in a measurable oil gain in 3 offset oil producer wells. The second activity was closing another producer in the northern sector for two weeks which resulted in an oil gain in 5 offset oil producers. Further use of the streamline model includes the assessment of unswept reservoirs for infill locations and the estimation of water cuts for development locations.