During a well start-up, fluid distribution within the well changes from a segregated phase (gas-oil-water) column to a flowing three phase mixture. For this transition to be successful, the well has to overcome the additional hydrostatic head associated with the phase segregation. Depending on the well trajectory, flowline pressure, reservoir pressure and watercut, the start-up process can be challenging for some wells as an improper bean-up procedure can result in a situation where the pressure driving force across the well is not able to overcome the hydrostatic head imposed by the liquid column. This can result in a failed start-up and, for such wells, a correct bean-up strategy is important to ensure successful start-up.

In this study, an integrated dynamic multiphase simulator is used to investigate the flow and pressure transients during the start-up of an inactive horizontal oil well which encountered start-up problems after a well intervention job to shut-off high watercut zones.

Sensitivities using dynamic simulations for different start-up procedures showed that the well could be successfully started-up by opening the well at the maximum available beansize and ensuring stable flow thereafter by keeping the bean-back above a threshold beansize. The successful well start-up procedure developed using dynamic simulations was applied in the field and resulted in additional oil production. This study demonstrates the significance of dynamic simulations in optimizing well start-up procedures. In this case, this resulted in major incremental revenue for the operator with more than 1000 BOPD added to overall production. Further, the successful start-up procedure devised using a transient multiphase simulator resorted only to well fluids routing and choke manipulation without the need for expensive rig operations and CAPEX/OPEX expenditure.