Hydrate Remediation during Well Testing Operations in the Deepwater Campos Basin, Brazil

Abstract

Abstract One of the most common challenges in deepwater environments is hydrate formation during drilling or well testing operations. A hydrate is generated in the presence of a combination of the following four elements: water, natural gas, low temperatures and elevated pressures. The hydrate has the appearance of ice structures and can form very quickly. Hydrates are normally generated during operations such as startup, shutdown, blowdown, and bleeding. In the deepwater oilfields of Brazil, operators have been faced several challenges during hydrate remediation interventions, including:Effectively removing the hydrate plug formed in the riser without damaging the tubing, downhole valves, and subsea tools across the blowout preventerReducing risk of hydrate formation due to unpredictable behavior because the hydrates can be very hard and very strong, holding high-differential pressures, potentially making a projectile of the formerly plugged objectLimiting pressure losses through the umbilical and maintaining injection rates of methanol and monoethylene glycol (MEG)Resuming well testing operations with the least amount of lost rig time. From a drillship, we applied a combination of chemicals pumped through a high-pressure rotating nozzle deployed with coiled tubing (CT). The hydrate plug was breached in less than 4 hr. This cleaning operation effectively removed the hydrate plug and cleaned the tubing, enabling the Operator to resume pressure/volume/temperature testing operations of the deepwater well.