This reference is for an abstract only. A full paper was not submitted for this conference.


There is a common misunderstanding about the transition zone in which both water and oil should be movable.

In this paper we will illustrate that in the transition zone only oil is movable above the Free Water Level (FWL) at normal gravity conditions. Putting wells on production in the transition zone produce dry oil unless the drawdown pressure disturbs the normal gravity conditions.

To avoid any confusion, a new term called the "Wedge Zone B" is introduced. Over this zone water saturation increases down flank towards the oil-water contact as a result of gradual increase in the micropores with bounded water due to diagenesis and cementation. The intensity of the diagenesis (cementation) is related to the timing of oil migration and trapmenttiming.

Four wells that had been drilled in an onshore field in the Middle East, showed the Wedge Zone producing dry oil for the last two years. As result of repositioning the new wells based on the Wedge Zone concept, an extra amount of recoverable oil will be added.

Modeling techniques over this zone have been revised resulting in changing the concept of modeling the transition Zone to that modeling of a Wedge Zone. As consequences, the model prediction of sweep efficiency has some impacts.

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