Plug, system and method for testing the integrity of a well barrier

A method for testing for leaking past a barrier in a well, by means of a system comprising:

• a well having a wellbore and a upper wellbore termination means;
• at least one of a mud circulation system and a mud conditioning system operably coupled to the well for transporting, cleaning or storing mud outside said wellbore;
• a barrier provided in the wellbore, the barrier having an upstream side below the barrier and a downstream side above the barrier;
• a tracer;
• a storage means for storing said tracer, the storage means being provided in at least one of a lower part of the barrier and below the barrier in the well;
• a release mechanism for releasing the tracer from the storage means;
• and
• a detector arranged above the wellbore in at least one of the mud circulation system and the mud conditioning system, wherein the detector is configured to detect the tracer that has leaked past the barrier and into said mud by virtue of the at least one of the mud circulation system and the mud conditioning system operating;
• the method comprising:
• operating the at least one of the mud circulation system and the mud conditioning system;
• releasing the tracer from below the barrier,
• establishing a pressure gradient across the barrier;
• and
• monitoring a concentration of the tracer in the mud by the detector arranged in the at least one of the mud circulation system and the mud conditioning system to thereby test for leaking past the barrier.

A system for testing for leaking past a barrier in a well, the system comprising:

• a well having a wellbore and a upper wellbore termination means;
• at least one of a mud circulation system and a mud conditioning system comprising means for transporting, cleaning or storing mud outside said wellbore;
• a barrier provided in the wellbore, the barrier having an upstream side below the barrier and a downstream side above the barrier;
• a tracer;
• a storage means for storing said tracer, the storage means being provided in at least one of a lower part of the barrier and below the barrier;
• a release mechanism for releasing the tracer from the storage means;
• a pump operable to reduce a pressure on the downstream side above the barrier to thereby establish a pressure differential across the barrier such that the pressure on the downstream side of the barrier is less than a pressure on the upstream side of the barrier to thereby drive the tracer from the upstream side to the downstream side of the barrier;
• and
• a detector arranged above the barrier and configured to detect the tracer driven to the downstream side of the barrier via the pressure differential established across the barrier by the pump to thereby test for leaking past the barrier.