Determination Of Water Injection Efficiency In The Multi-Layered Garra Field Using The Formation Tester Tools

By

Saad Hassa¹, Ahmed Anwar¹, Moustafa Oraby², Mohamad Samir³, Samir Siso³

(1) Petrobel, Cairo, Egypt (2) Halliburton, Egypt, Cairo, Egypt (3) Petrobel, Egypt, Egypt

 The Kareem formation in Garra field is under water flooding using 40 Kppm salinity water which is different than the formation connate water salinity (330 Kppm). Currently, the Kareem formation is producing oil with 80% watercut with a mixed produced water salinity (80 Kppm).

The Reservoir Description Tool, RDT, was run. Twenty-nine pressure points, many with in-situ compressibility and bubble point measurements were taken, and seven PVT quality fluid samples retrieved to:

1) Obtain pressure data for each layer, 2) Identify fluid contents 3) Obtain water samples for water injection monitoring 4) Examine the existence of gas zones 5) Determine reservoir permeability 6) Obtain PVT samples.

The RDT results show that the upper part of Kareem formation is a high permeability layer with low formation pressure. The water sample from this layer has the same salinity as the injected water, indicating that this layer is completely swept, and that most of the water produced is probably coming from this layer. The lower part of Kareem formation showed higher pressure and lower permeability with sample salinity corresponding to a mix between injected water and formation water.

In the Rudeis formation, the RDT showed the existence of a gas cap with low formation pressure, followed by an oil zone with much higher pressure, and ending with a water zone containing water similar to original formation water.

With the above information, new completion techniques are planned for the Garra field to improve the water injection and reduce water cut.