Casing patch method and apparatus

Abstract

The present invention relates to a method and an apparatus for making a casing patch while the casing is held under tension. The method includes the steps of lowering a casing patch tool to position the annular member to which the upper end of the casing is to be connected and a casing protection collar both in surrounding relationship to the upper end of the casing and with the cold forging tool and the tensioning spear within the casing, setting the spear within the casing at a level surrounded by the casing protection collar, pulling on the spear to tension the casing, and cold forging the casing into tight gripping and sealing engagement with the annular member. The apparatus includes the annular member to which the casing is to be connected, a guide sleeve on the lower end of the annular member sized to be lowered in the well bore and into surrounding relation to the upper end of the casing, a cold forging tool, a spear and a protection collar positioned wihtin said annular member at the level of the spear so that it surrounds the casing to prevent excessive deformation on setting and tensioning by the spear. It is also a part of this invention to provide an improved method and apparatus for tensioning the casing and protecting it from excessive deformation as a result of the setting and tensioning of the spear by surrounding its exterior in the area of spear engagement with a protection collar which has sufficient strength and is sufficiently close around the casing to provide such protection.