The SCSSSV Isolation Question
Completions
In some wells with surface controlled subsurface safety valves a landing nipple is used to lock and operate a wireline retrievable downhole safety valve. The wireline retrievable valve can be pulled to allow nearly full-bore access to the wellbore, however it is a question as to whether an isolation sleeve should be run or not. One of the key advantages for installing a wireline retrievable subsurface safety valve is that it can be pulled and allow larger tools to be run on wireline. However, the insert valve has to form a seal with the inside of the tubing in a safety valve landings nipple. This is achieved by running an upper and lower seal assembly made of chevron seals (or o-rings) which form a seal for the hydraulic oil in the control line to pressure up the safety valve. When wirelining, the wire will ride in a certain location (low side) and can create a groove in this sealing area. This groove can lead to the packing elements of the insert valve not forming a hydraulic seal and rendering the valve inoperable. In this particular well, there was a history of sand production, and the completion was more than 40 years old, which are both cause for concern when running slickline across a SCSSSV nipple profile. It was decided during job design to install an isolation sleeve across the landing nipple to prevent damaging the sealing profile.
The SCSSSV Isolation Question
Completions
In some wells with surface controlled subsurface safety valves a landing nipple is used to lock and operate a wireline retrievable downhole safety valve. The wireline retrievable valve can be pulled to allow nearly full-bore access to the wellbore, however it is a question as to whether an isolation sleeve should be run or not. One of the key advantages for installing a wireline retrievable subsurface safety valve is that it can be pulled and allow larger tools to be run on wireline. However, the insert valve has to form a seal with the inside of the tubing in a safety valve landings nipple. This is achieved by running an upper and lower seal assembly made of chevron seals (or o-rings) which form a seal for the hydraulic oil in the control line to pressure up the safety valve. When wirelining, the wire will ride in a certain location (low side) and can create a groove in this sealing area. This groove can lead to the packing elements of the insert valve not forming a hydraulic seal and rendering the valve inoperable. In this particular well, there was a history of sand production, and the completion was more than 40 years old, which are both cause for concern when running slickline across a SCSSSV nipple profile. It was decided during job design to install an isolation sleeve across the landing nipple to prevent damaging the sealing profile.