Design of Shape Memory Alloy Expanding and Contracting Guide

Photo of Emil Bitar, Jose Navar, Felipe Pereira, Eddie Wong Students: Emil Bitar, Jose Navar, Felipe Pereira, Eddie Wong

Sponsor: Baker-Hughes, Inc.

Date: Fall 2012

Requirements:
The guide needs to expand and contract to the inner diameters of the wellbore. The guide needs to stabilize the bottom hole assembly and guide it down to the fish in the wellbore. It must scoop the fish from the wall of the wellbore and allow the fishing tool to retrieve it. The guide will be used in a wellbore with inner diameters of 6.456" and 8.535". The guide will need to expand to the larger inner diameter of the casing. The shape memory alloy will allow the guide to expand and contract, while limiting the number of moving parts. The temperature range the guide will experience will be between ambient temperatures above-ground and 350°F. The guide must withstand high temperatures and pressures in the wellbore, and must be usable multiple times without failure.

Problem:
During drilling, items can break and be left in the wellbore. The items, called fish, must be retrieved before drilling can continue, a process called fishing. A guide on a fishing tool aligns the tool to the wellbore casing and allows the tool to catch the fish. There are mechanically expanding guides that can align the tool when the wellbore transitions to a larger diameter. The mechanical guides have independently moving parts though that may be prone to failure, and contain small pieces that may break and fall into the wellbore as well. The team was given a task to prototype an expanding and contracting guide for the bottom end of a bottom hole assembly that is actuated by a shape memory alloy.

Solution:
A proof-of-concept prototype was created using 0.157" Nitinol rods and a base and fins made from aluminum. The components were attached using an epoxy adhesive. The guide has a 6" diameter and when the Nitinol rods are heated, the guide expands to 8.535". The actual guide should be made of 4130 steel and Nitinol rods of a larger diameter and a higher actuation temperature.

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