Molded Composite Mandrel for a Downhole Zonal Isolation Tool

Abstract

A composite mandrel includes a filament-wound composite tube, and composite material molded over the filament-wound composite tube. For example, the composite material includes chopped fibers and a matrix of thermoset resin. The chopped fibers are arranged in layers upon the filament-wound composite tube, and the chopped fibers in each of the layers are randomly oriented along first and second orthogonal directions in each of the layers. The composite material includes at least one sheet of the composite material wound over the filament-wound tube, and at least one strip of the composite material wound over the sheet of the composite material and forming a head on the composite mandrel. An internal cavity of the filament-wound composite tube may provide a lumen for the composite mandrel. The internal cavity may be threaded to receive a removable bridge plug.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a molded composite mandrel for a downhole zonal isolation tool.BACKGROUND OF THE INVENTION[0002]A downhole zonal isolation tool often is used for stimulation or service work upon a well. For example, the zonal isolation tool is a bridge plug, frac plug, or packer for bridging a hole or gap of a metal tubular such as a well casing.[0003]The zonal isolation tool typically has an internal elongated mandrel and a circular array of slips mounted on the mandrel at each end of the tool. Each slip has an outer surface adapted for engagement with the internal surface of the well casing. Each slip also has an inclined inner surface. Each array of slips is disposed next to a respective conical ring mounted on the mandrel for sliding under the inclined inner surfaces of the slips in the array. In the middle of the zonal isolation tool, rings of elastomeric sealing material are mounted on the mandrel between the conical rings. When a s...

AI Technical Summary

Benefits of technology

The invention provides a way to make a composite mandrel for a downhole zonal isolation tool that is cheaper and more efficient than previous methods. The composite mandrel is made by winding a filament-wound composite tube with a composite molding sheet material made of chopped fibers and thermoset resin. The chopped fibers are arranged in layers and randomly oriented along first and second directions. The composite molding sheet material is wound over the filament-wound tube and forms a head on the composite mandrel. The method involves winding the composite molding sheet material onto an elongated core and placing it in a mold to mold the composite mandrel.

Problems solved by technology

However, the zonal isolation tool is most economical to manufacture when it has been constructed to become permanently set in the well casing so that it must be drilled out destructively to unseal the well casing.

Such a composite mandrel was rather expensive due to the cost of the head plug and the cost of the two composite tubes, and the cost of grinding the inner composite tube.

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