Patent ID: 8245785

Claim:
Apparatus for cutting a hole in a casing of a well, comprising: a casing drill unit including a motor having a rotatable output element, and variable length cutting apparatus connected to the output element for rotation therewith including a resiliently compressible biasing element and at least one flexible element extending to and carrying a casing cutter, the drill unit having a weight, and the cutting apparatus having a predetermined overall length absent exertion of the weight of the drill unit thereagainst and being compressible in length by exertion of all or a portion of the weight of the drill unit thereagainst to compress the biasing element, the drill unit including a tubular element supported by and extending downwardly from the motor, the tubular element containing the output element of the motor and an upper end of the cutting apparatus including the biasing element for rotation within and relative to the tubular element, the tubular element having a fixed length shorter than the predetermined overall length of the cutting apparatus such that a lower portion of the cutting apparatus extends downwardly below the tubular element; the drill unit being configured to be suspended in and lowered through an interior cavity of a casing of a well to move the casing cutter and the flexible element through a curved passage through a down hole unit disposed at a predetermined depth within the interior cavity such that the casing cutter extends laterally outwardly from a lateral opening of the passage and until a lower end of the tubular element engages the down hole unit to form a fixed length passage extending from the motor through the curved passage to the lateral opening, the predetermined overall length of the cutting apparatus being a predetermined amount greater than the fixed length passage such that the casing cutter will contact a side surface of the casing opposite the lateral opening prior to the engagement of the lower end of the tubular element with the down hole unit, to transfer a fraction of the weight of the drill unit to the cutting apparatus to compress the resiliently compressible biasing element for resiliently urging the cutter against the interior side surface of the casing to advance the cutter into the casing as the casing is cut.