The graph is used to illustrate the distribution of oil and water in a reservoir.
What is the oil pay zone?
The graph depicts a cross-section of an oil reservoir, illustrating the distribution of oil and water saturation. The vertical axis shows the height above the free water level (FWL), and the horizontal axis represents water saturation. The oil pay zone is where pores are filled with recoverable oil, sitting above the water-oil contact (OWC) line.
Below the OWC lies the transition zone, where oil and water mix, transitioning to 100% water saturation at the FWL. The irreducible water saturation (S_wc) indicates the minimum water level in the reservoir's oil-bearing portion.