Which of the following best defines primary well control?

The correct definition of primary well control is centered around maintaining hydrostatic pressure above formation pressure. This concept is fundamental in ensuring that the pressure exerted by the fluid column in the wellbore is sufficient to counteract the pressure of the fluids in the surrounding geological formations. When hydrostatic pressure is adequately maintained above the formation pressure, it helps prevent undesired influxes of formation fluids into the well, thereby minimizing the risk of kicks and blowouts.

Balancing formation pressure with surface pressure, while an important aspect of well control, does not encapsulate the broader concept of primary well control, which is fundamentally about maintaining a hydrostatic balance. Similarly, controlling drilling during an influx is a reactive measure that relates to secondary well control techniques rather than the proactive prevention established by primary control measures. Monitoring hydrodynamic stability plays a role in ensuring well integrity but does not specifically define the core concept of primary well control. Overall, maintaining hydrostatic pressure above formation pressure is essential for safe and effective well operations.