Corrosion Assessment

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Assessment of corrosion and metal loss to evaluate well conditions, performance, MAASP and other operating parameters is a constant activity during the life cycle of a well. For operating companies, the ability to perform precise diagnostics rigless is a significant advantage as well as a cost-saving solution.

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Problem:

The Customer was preparing to launch a well integrity logging campaign including corrosion and metal loss diagnostics. Prior to it, they decided to evaluate through-tubing electromagnetic technologies from different providers available in the market to assess their accuracy.

Diagnosis:

TGT, among four major companies, was requested to conduct a blind yard test. The Customer made, through a third-party company, a number of random defects to assess tool accuracy and sensitivity. The following three scenarios were used in a set of tests:

A: 4-1/2” tubing inside 9-5/8” casing (centralised, tilted and laid down)

B: 3-1/2” tubing inside 9-5/8” casing

C: 5-1/2” tubing inside 9-5/8” casing

Findings:

The attached log shows the results of Scenario A.

– TGT’s EmPulse® was able to measure the individual thicknesses of three different strings and detect corrosion in them, and was ranked first among all competitors

– TGT’s first-string evaluation produced better results, even compared with multi-finger calipers

– All defects were detected in both tubing and casing, confirming the specifications and accuracy of the tool as well as a significant advantage over competitors

– When the tubing was tilted or decentralised, the sensitivity of the tool was less affected than that of the competitors’ tools

– Logging speed had a minor effect on the tool sensitivity compared with other assessed technologies

– With over 180 channels, TGT’s EmPulse® was superior in terms of both data acquisition and processing

Actions:

The Customer chose TGT as the best technology provider in the market to independently assess multiple strings for thickness and corrosion, and assigned the above-mentioned scope of work to the company.
July, 2016