What is another name for initial reservoir pressure, the pressure of a reservoir before it is produced?

• A. Discovery pressure (also virgin pressure)
• B. Static pressure
• C. Bubble point pressure
• D. Reservoir pressure

Answer: (A)

Initial reservoir pressure is the natural pressure inside the reservoir before any production begins. This in-situ pressure is commonly termed discovery pressure, also called virgin pressure, because it is the pressure measured when the reservoir is first encountered during exploration and testing. It reflects the fluids’ state in the reservoir before production alters it, and it serves as a reference point for material-balance calculations and reserve estimation. Bubble point pressure refers to the pressure at which gas comes out of solution, which is a different concept, and static pressure is a broader term that can describe pressure in a non-flowing system, not specifically the initial reservoir pressure observed at discovery. Hence, discovery pressure is the most precise alternate name for initial reservoir pressure.