Page 335 - Intelligent Digital Oil And Gas Fields

Smart Wells and Techniques for Reservoir Monitoring 279

while selecting the optimum injection points for water and gas individually
along the well lateral. ICVs and a new mechanical well configuration are
used to enable this continuous injection. The process is called WAGCV.
They set up a numerical model with the new ICV design by injecting gas
and water at different locations in the lateral. These results show that the
proposed process should improve oil recovery significantly compared to
traditional WAG, because:
• Residual oil saturation is significantly reduced in all regions due to more
homogenous oil sweep.
• Water and/or gas breakthrough is substantially delayed.
• As a result, oil-recovery factor increases more than 5% over
traditional WAG.
The well uses two strings, where water is injected through casing and gas
through tubing. The well uses a unique combination of down-hole valves,
sleeves, packers, and fiber optic equipment. Down-hole valves and sleeves
are automatically activated on or off to coordinate the multi-injection
points. The times to activate specific injection points are defined by the opti-
mizer software, which estimates fluid injection volumes (for gas, water, or
both) and slug locations in the reservoir over time.
For illustrative purposes, a reservoir with high heterogeneity in perme-
ability between 10 and 150 md (Fig. 7.19) was set up in a 3D numerical sim-
ulator that predicts the production profiles of water, gas, and oil. Horizontal
wells, an injector and a producer 3000ft apart, are configured in the model,
each well with 4000ft laterals.
The process modeled is described as follows:
A. Water is injected into the reservoir for a long period of time
(Fig. 7.19A). Immediately water starts channeling into the high perme-
ability regions, that is, Regions 1 and 3. All valves are 100% open.
B. After several numerical simulation iterations, the optimizer determines
that a slug of gas should be injected through tubing into Region 1 with a
specified slug size and specified daily rate (Fig. 7.19B). The gas slug is
injected through tubing into Region 1, while water is injected
across the rest of the lateral section. The sleeve in Region 1 is shut
off, allowing gas injection through the tubing and blocking water injec-
tion in Region 1. Water continues to be injected into the rest of the
lateral section.
C. After a period of time, the optimizer determines that additional slugs of
gas should be injected through tubing into Regions 1, 3, and 5 at specific
volumes and injection rates as shown in Fig. 7.19C. The gas slugs are