to the controller 72 which in turn deactivates the motor 68 and therefore the pump 62 thus according to the embodiments of fig2 and 3 any set loss of the packer 16 exceeding a predetermined valve is immediately determined and compensated for to insure that the original set conditions of the packer 16 are maintained it is understood that although components of the system of the embodiments of fig2 and 3 are shown diagrammatically and therefore out of scale for the convenience of presentation they can be located downhole in the casing 12 or the wellbore it is understood that variations may be made in the foregoing without departing from the scope of the invention for example the casing 12 can be eliminated and the tool 10 can be inserted directly in the well also the anchoring slips 20 a and 20 b can extend upstream from the packer elements 16 a 16 b and 1 6 c further the controllers 32 and 72 can respond to increases or decreases in the compression of the packer 16 from a predetermined value and generate a corresponding output signal still further in the unlikely event that the compression of the packer 16 needs to be decreased fluid can be withdrawn from the cavity in the packer 16 and from the cylinder 54 as needed it is also understood that spatial references such as u201c downwardly u201d u201c downstream.