[ASOC]

200K seems a bit high.

Was it all oil or process water and oil?

[thackney]

Essentially all oil, these were transit lines after the oil/water separation has taken place.

That was part of the problem. As the fields age, the percent of produced water increases, so that if the pumping/lifting remains constant, the amount of produced oil decreases over time.

The pipes were sized for the maximum expected flow of oil. After decades of production the flow of oil from these older fields is greatly reduced. But the volume of pipe stays the same. Consequently the velocity through the pipe is greatly decreased.

This allowed minute amounts of water and crude to more easily fall out and accumulate in low points, where initial the flow rate helped “sweep” the pipes clean.

Not enough pigging was done, but then the slow flow rate makes pigging more difficult.