Expansion and contraction compensation to account for temperature and pressure

The slip joint is an expansion- and contraction-compensation tool. It accommodates any changes in string length caused by temperature and pressure during a downhole test.

The joint has two parts: an outer housing and a moving inner mandrel in three sections. The splined moving mandrel at the top enables transmitting torque through the tool. The two pressure chambers below have one open to tubing pressure and the other open to annulus pressure. This hydraulically balances the joint to make it insensitive to applied tubing pressures.

Each slip joint has a stroke of 5 ft and the total number of joints required in a string depends on well conditons and the type of operation.

Slip joints are not required when the CERTIS high-integrity reservoir test isolation system is used.