Patent ID: 7591175

Claim:
A method for monitoring well casing comprising: (a) providing a vessel having drilling fluid circulating therethrough, the drilling fluid entering the vessel including that returning from a well; (b) placing a magnetic separator in the drilling fluid in the vessel, the magnetic separator comprising a magnetic body and an exterior surface and placing includes connecting the separator to at least one hanger and suspending the separator within the vessel using the at least one hanger; (c) retaining the magnetic separator in the drilling fluid for a first selected period of time such that fragments from the drilling fluid become magnetically attached to the magnetic separator; (d) removing the magnetic separator from the vessel and removing the fragments from the exterior surface; (e) replacing the magnetic separator in the drilling fluid in the vessel; (f) retaining the magnetic separator in the drilling fluid for a second selected period of time having a duration similar to the first selected period of time such that a second amount of fragments from the drilling fluid become magnetically attached to the magnetic separator; (g) removing the magnetic separator from the vessel and removing the second amount of fragments from the exterior surface; and (h) comparing the fragments with the second amount of fragments to assess the well casing comparatively between the first period of time and the second period of time.