[clv101]

When a barrel of 'fluid' is pumped to the surface it isn't all oil. Some is water. The oil is held in permeable rock, the pressure is increased by injecting high pressure water under the oil layer, forcing it up.

Since the oil is more viscous than water, some of the water slips past the oil and end up being pumped out. When the water does get past the oil, the remaining oil becomes stranded... and pretty much imposable to get out.

A high water cut indicates the death of a heavily pushed oil field.

[0mar]

Stranded oil is usually recovered through tertiary recovery methods. It is difficult to reclaim however, simply because the pressure isn't there and probably takes more energy to take out by the pumping of steam, blowing the rocks up, injecting water etc etc that the oil would be worth.

As for Ghawar, I don't think we have enough information regarding the geographic structure to make a claim about the decline of water cuts. It just may be that new wells were dug into an unknown or unavailable portion of the field. Ghawar is a massive field. Whole countries don't have the reserves that Ghawar does. Hell, if it wasn't a huge basin, it probably would have been several gigantic fields instead of the King of all Kings.

[BabyPeanut]

I thought it was "water cut" not "oil cut"? Is the author who used "oil cut" in their text trying to be funny? (like a doctor who says "we found a little blood in your alcohol stream")