Improper zonal isolation can cause production losses and lead to the requirement of additional workover activities throughout the life of a well.

A Russian client discovered the presence of gas in the toe zone of a production casing, most likely caused by bad cementing/micro channeling. The client had previous experience with the use of different swell packers and hydromechanical packers, but neither option was feasible due to a limited swell timing (which carries a risk of swelling/expansion before deployment is complete), and a very low efficiency due to a short sealing element respectively. Furthermore, the high mechanical stress when running tools in the bottom section would also mean that traditional packers with rubber sealing elements were not an option.

In this case, Welltec® approached the client to highlight the issue of crossflow, and proposed a solution to rectify the situation, whereby proper zonal isolation would facilitate an increase in production.

The Welltec® Light Packer (WLP) can be used to prevent gas migration between zones, and on this occasion stop migration from the production interval to the water zone above.

The 812WLP 5k was installed as part of the 7” production casing, 40 – 50 meters from the bottom and below the water zone. In the event there had been any issue reaching TD, the WLP is fully rotatable.

A compensation system at the bottom of the WLP allows the packer to hold up to 5,000 psi – far greater than the pressure difference between the water and production zones – meaning that stimulation of the production zone is also possible without risk of fluid migration.

The setting of the packer was prolonged via the use of an onset valve, helping to prevent setting during circulation or cementing despite pressures up to 4,000 psi.

A sheer-pin valve was used to revert well integrity after the WLP was set.

The job was completed without issue, and the client is now benefitting from a high level of efficiency thanks to the 812WLP 5k.

Crossflows have been eliminated and this has been confirmed by surface sampling and e-line measurements.

The robust WLP has successfully provided multiple benefits, giving cement assurance and delivering cost savings by removing the need for expensive gas-tight cement, improving efficiency and avoiding the need for future workover operations.