Production decline caused by sand ingress was observed on 2 offshore oil wells in Brunei waters. Both wells were completed with a sub-horizontal openhole gravel pack and were subsequently shut in as the produced sand would likely cause damage to the surface facilities.
In an offshore environment with limited workspace, crane capacity and wells with low reservoir pressures, it was decided to intervene the wells using a catenary coiled tubing (CT) vessel. The intervention required was to clean out the sand build up in the wells and install thru-tubing (TT) sand screens along the entire gravel packed screen section.
Nitrified clean out was necessary due to low reservoir pressures while using a specialized jetting nozzle to optimize turbulence and lift along the deviated section. In addition, a knockout pot was utilized to filter and accommodate the large quantity of sand returned.
The long sections of screens required could not be accommodated inside the PCE stack resulting in the need for the operation to be conducted as an open hole deployment using nippleless plug and fluid weight as well control barrier. A portable modular crane was also installed to assist the deployment of long screen sections prior to RIH with CT.
Further challenges that needed to be addressed were the emergency measures. As the operation was to be conducted using the catenary system, the requirement for an emergency disconnect between the vessel and platform during the long cleanout operations and open hole deployment needed to be considered as a necessary contingency. Additional shear seal BOPs, and emergency deployment bars were also prepared to ensure that the operation could be conducted safely and successfully.