Selectivizing a Singled Bed Reservoir, A Successfully Application to Increase the Vertical Displacement Efficiency in a Heavy Oil Waterflooding Project

Abstract

This paper presents the application of multiple selectives injection zones within a high thickness singled bed heavy oil sand. The results were compared with a single zone completion in the same sand, establishing the differences in several aspects like recovery factor, vertical distribution efficiency, operation styles and completion difficulties. This approach is based on the application of two methods of water vertical irrigation in a heavy oil sand, first, a singled 300’ zone completion and else, a 3-4 selectives zones completion, separating the equivalent injection in spaces of 60’-100’ thickness each. To route the flow, the packers were located next to thin shale planes most as possible. The objective was use this natural inundation surfaces intentionally as vertical permeability barriers looking forward to this works as a vertical flow controllers beyond wells selectivization, means like flooding separators, inside the heart of reservoir. In injector wells 3 types of behavior profile logs were ran several times within more than two years. The reservoir under study it is the sand T2 located at Chichimene field, at the Colombia Llanos Basin. It has 320’/250’r of gross/net thickness, physically looks like a singled bed, it is saturated with high viscosity extra heavy oil of 350 cps, it is located at 9000’ measured depth (6000 - 6800’ TVDSS) the permeability shows a broad permeability range of 5 – 10000 mD. Waterflooding was initiated by 2014, the single zone completions wells, were exposed to a 6000 bls/d rate over very high permeability layer and this produced immediate channelization in thin layers only in some weeks after initiated. Producer wells increased water cut to high values, injection rates were controlled as results of its and finally some of the injectors had to be shut in. In the other set of wells, selective applications got separate the sand by 3 or 4 zones, the reservoir sand were irrigated by the same time, at the same rate of 6000 bls/d, almost 2000 bls/d each zone, this time the trends were simply different, means, producers water cut it was low and more stable. The results shows up about 2-3% of RF by simple zone completion in opposite to 6-10% of RF with selectives completions, evidencing a better vertical irrigation. The case study presented in this paper, it is a successful curiously application of multiple selectives completions within a single sand. This example has been tested in field, it is an effective option in order to increase recovery factor and it will reborn expectations about the use of selectives completions over thick heavy oil sands. This results definitely; it will encourage engineers to think more about mechanical conformance applications in waterflooding.