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

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

• a well including a wellbore and an upper wellbore termination means;
• a first barrier provided in the wellbore, the first barrier having an upstream side below the first barrier and a downstream side above the first barrier;
• a second barrier positioned in the well below the first barrier that is to be tested, wherein the first barrier and the second barrier prevent flow into and out of an isolated volume created therebetween;
• a tracer;
• a storage means for storing said tracer, the storage means being provided at least below the first barrier in the well;
• a release mechanism for releasing the tracer from the storage means, wherein the system is configured to establish a pressure differential across the first barrier by increasing a pressure in the isolated volume by operating the release mechanism and/or operating a pump, wherein the pressure gradient is established such that a pressure within the isolated volume is greater than a pressure above the first barrier, and wherein the pressure differential is established for driving tracer from the upstream side to the downstream side of the first barrier;
• and
• a detector for detecting the tracer that has leaked through the first barrier, the detector being provided in the wellbore downstream of the first barrier.

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

• a well including a wellbore and an upper wellbore termination means;
• a first barrier provided in the wellbore, the first barrier having an upstream side below the first barrier and a downstream side above the first barrier;
• a tracer;
• a storage means for storing said tracer, the storage means being provided below the first barrier in the well;
• a release mechanism for releasing the tracer from the storage means;
• and
• a detector for detecting the tracer that has leaked through the first barrier, the detector being provided in the wellbore between the first barrier and the upper wellbore termination means, the method comprising the steps of:
• lowering the detector into the well;
• releasing the tracer from below the first barrier;
• establishing a pressure gradient across the first barrier by reducing a pressure above the first barrier, and/or providing a second barrier in the wellbore below the first barrier and increasing a pressure in an isolated volume between the first barrier and the second barrier, wherein the pressure gradient is established for driving the tracer from the upstream side to the downstream side of the first barrier;
• and
• monitoring a concentration of the tracer by the detector.