A common method of obtaining fluid saturations is from measurements taken on core

samples using water-based mud. Unfortunately, the fluid content in the core is altered by two processes:

1. the flushing of mud and mud filtrate into the adjacent formation, and

2. the release of confining pressure as the core is pulled to surface.

But to minimize the effects above and get a better results, use oil-based mud as the coring fluid.

Then, you can use the experimental data to calculate the oil saturation analytically.