Design, build, develop and test a fieldworthy spiral tool and packer for casing repair

Abstract

A new method for sealing casing is under research and development by Nu-Bore Systems. The method involves internally lining a section of the wellbore with a multi-layer spiral wrapping of a high strength, corrosion resistant metal interleaved with a high bond strength, resilient epoxy. The high strength metal is preferably a copper based alloy hardened to a very high strength in order to resist the internal and external pressures of downhole environments. The epoxy adhesive formulation is one that forms a bond between the steel inner wall of the casing and copper alloy strip. The copper alloy strip spiral wraps are interleaved with epoxy, and the whole system provides a high level of outward directed spring force and, thus, resists both internal and externally directed forces. In this report, the cost savings to the nation's energy program was estimated to be in the range of hundreds of millions of dollars per year, and the method was judged technically feasible once certain well defined engineering obstacles are Overcome. The objective of this program is to develop a joint between packer segments that is easily assembled before lowering downhole and easily disassembled after the sealing job is done. In addition, this tool joint must expand uniformly as though it were a part of the rubber and must not fail under the relatively high pressure of the epoxy cure cycle. The overall goal of the work was to design, build, develop, and test a spiral tool and packer into a single universal tool that can repair casings with diameters varying from 4.5 to 7 inches.