Mud removal and cement placement during primary cementing of an oil well – Part 2; steady-state displacements

Uncontrolled flows of reservoir fluids behind the casing are relatively common in primary cementing and can lead to any of the following: blowout, leakage at surface, destruction of subsurface ecology, potential contamination of freshwater, delayed or prevented abandonment, as well as loss of revenue due to reduced reservoir pressures. One significant potential cause is ineffective mud removal during primary cementing. Ideally, the drilling mud is displaced all around the annulus and the displacement front advances steadily up the well at the pumping velocity. This paper addresses the question of whether or not such steady-state displacements can be found for a given set of process parameters.