In this talk, I will focus on comparing behaviors of many carbonate reservoirs around the world (West Texas, Middle East, etc.). I will particularly focus on their oil and water production performance, water cut breakthrough, well water-cut development, and reservoir water movement. I will try to link their behavior to parameters such as:
• Heterogeneity and its impact during primary or secondary recovery.
• Wettability (80% of carbonate reservoirs are oil wet) and its impact on:
• Displacement efficiency.
• Water injectivity.
• Water-cut patterns. Well spacing (West Texas vs. Middle East) and its impact on flow patterns and reservoir performance.
Since most carbonates reservoirs are naturally fractured, the role of fractures will be examined. New seismic methods for detecting fractures and their effectiveness will be discussed in this presentation.

Also, I will show how simplistic simulation models have resulted in overestimation of recovery factor, prediction of longer breakthrough times, and underestimation of the water-cut development.

Application of IOR processes to carbonate reservoirs will be discussed. Because of its complexity, it will be shown why Pilot Testing is needed if one plans to inject water or gas in such fields.