The present paper is a case study of improved oil recovery (IOR) process evaluation for a reservoir in the North Sea that has been particularly diffi-cult to develop by waterflooding — the method of first choice in the area — due to its complex geology and faulting and to the coexistence of regions of very high and very low permeability.

First, a multicriterion analysis based on general IOR experience and the applicability of specific processes in different geophysical conditions was used for a first-order screening of promising IOR technologies. Next, possible development scenarios for a particular stratified formation with high permeability contrast were modelled analytically, using an IOR screening tool developed in-house, and numerically, using a commercial reservoir simulator. Conventional water and gas injection, various horizontal well injection and production scenarios, as well as "traditional" enhanced oil recovery (EOR) methods, such as surfactant and polymer flooding and Water-Alternating-Gas (WAG) injection, all showed limited efficiency for the reservoir in question.

However, the study also showed that novel, in-novative water/gas injection processes and foam-assisted WAG injection, in combination with ho-rizontal production wells, may give considerable improvement of reservoir sweep efficiency. Field model simulations demonstrated high recovery potential of these new processes. The practical applicability in offshore and deep-water completions for these processes were considered with the conclusion that field-scale implementation may be quite feasible.

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