
{"publication_number": "US-6202748-B1", "abstract": "a thermal compensating apparatus and method for maintaining a substantially constant fluid pressure within a subterranean well tool of the type that includes a bladder that is selectively expandable upon the introduction of pressurized actuation fluid for actuating said tool at a location in a well . a multi - stage piston is movable in a housing . the piston includes a first surface in contact with the actuating fluid and a plurality of second surfaces in contact with well fluid surrounding the apparatus . the combined surface areas of the second surfaces are greater than the surface area of the first surface , so that expansion or contraction changes in the volume of the actuating fluid caused by temperature changes in the vicinity of the tool will result in movement of the piston for maintaining the actuating fluid at a relatively constant pressure .", "application_number": "US-29252999-A", "description": "the multi - stage thermal compensating apparatus of the present invention is an improvement over the single - stage apparatus described in pct application wo98 / 36152 , the drawings and description of which are incorporated herein by reference as though fully set forth . the improved apparatus has particular applicability for service conditions where the diameter of the inflatable tool is less than about 50 % of the diameter of the set inflatable tool and the intensification ratio is greater then 1 . 4 : 1 and the temperature of the inflatable tool is expected to cycle or significantly depart from its initial temperature at the end of the setting operation , for example the invention is ideally suited for a 1 { fraction ( 11 / 16 )