Heavy oil reservoir management using thermal methods is different than conventional reservoir management, especially if the reservoir is highly heterogeneous with limited availability of data. This raises a lot challenges to deal with.

One of these important challenges is timing the conversion of the project from the cyclic steam injection phase to the continuous steam flooding strategy, which allows the steam to contact a larger area of the reservoir, and thus enhancing oil recovery, while optimizing voidage replacement ratio (VRR.) This on the long run increases the project lifetime economically.

Issaran is one of those challenging heavy oil shallow fields in the Middle East, containing reservoirs with heterogeneous properties. Its different reservoirs are managed with different steam strategies. Cyclic steam injection started in 2004 in one of the reservoirs, after that the strategy was converted to continuous steam injection in addition to small cycles in some of the producers to improve communication. Different selected time scenarios of conversion were implemented for each area to enhance sweep efficiency and heat distribution and overcome any undesirable reservoir response such as water encroachment, and deal with highly fractured, highly heterogeneous or low pressure zones.

In this paper, actual field performances will be presented for each formation showing the cyclic steam injection stage and the timing of conversion to continuous steam strategy. A lot of factors will be presented for the steam cycle stage including: voidage replacement ratio (VRR), steam to oil ration (SOR), and the injectivity index performance from cycle to cycle. Then the conversion time from cyclic to continuous steam flooding will be discussed per each area. The relationship between this time with total VRR and the total steam injected in the cyclic stage will be introduced. Spacing between the wells will be mentioned and its effect on the conversion time identified.

Generally the main factors that affect directly on the selected conversion time: communication between the wells, injectivity index and economic factors. The paper will focus on the first 2 factors.

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