The Weatherford Model A slip joint compensates for expansion and contraction of the test string during downhole testing or stimulation operations, which prevents string buckling or packer unseating. This capability is essential when the string is fixed at surface within the blowout preventer.
The number of slip joints required in a test string depends on the test program and well conditions. The slip joints are positioned in the test string at the top of the test tool bottomhole assembly, creating a free point. Therefore, sufficient collar weight is required below the slip joints for packer setting operations. The slip joints are volume balanced as they reciprocate and are unaffected by changes in tubing pressure. In-situ reciprocation of the slip joint is affected by pressure, causing contraction and expansion depending on ballooning or reverse-ballooning and temperature changes in the string.
- Drillstem testing
- Production testing
- Perforating operations
Features, Advantages and Benefits
- Volume- and pressure-balanced areas within the slip joint make it insensitive to changes in internal pressure at the tool.
- As long as the function of the slip joint is not compromised, small corrections in spacing out tubing-conveyed-perforating (TCP) guns can be accommodated within the slip joints. This avoids tripping the subsea landing string to add or remove space-out tubing below.
- The fullbore ID of the slip joint facilitates unrestricted flow and access for well interventions.