Tripping time optimization through drill pipe velocity control

Abstract Control of pressure changes within the well during the drill string tripping is challenging. Tripping the drill string at high speeds and accelerations can produce significant pressure changes, causing the well’s inner pressure to fall beyond safe operating limits, and conversely, adopting conservative pipe speeds results in a waste of operational and financial resources. This work proposes a velocity control model for drill string axial moves during well drilling operations, aiming to reduce non-productive time (NPT) and considering operational limitations, constraints imposed on the operational pressure window, and safety requirements. The proposed optimization admits that the fluid flow caused by pipe motion is compressible and transient. As a result, the model generates tripping acceleration and velocity profiles to keep pressure gradients within the operating window. Simulation results using the inner-point method show that the developed model effectively reduces operating tripping time while satisfying the operational constraints.