Historically, internal coatings have been used primarily to successfully mitigate corrosion in drill strings. Advancements in technology have improved the performance of these materials leading to much longer life expectancies as well as the expansion of their use into other areas of the market. These newer systems are now finding their way into more aggressive completion operations where the use of coatings was largely not accepted due to fears of coating damage. With new abrasion resistant systems coming out on the market, successes are now being seen in cementing, the pumping of gravel packs, fracing, acidizing as well as other mechanical interventions. This paper will discuss several significant recent applications:

  1. 17 completions in which numerous acid treatments were performed in conjunction with multiple frac packs. The majority of this work was performed in wells with deviations from 23° to a maximum of 75°. Inspections performed on this string include electromagnetic inspection of the pipe body as well as a magnetic particle inspection on the tool joints. The results of these inspections indicated that not one single joint was downgraded due to internal corrosion or wall loss. These results are particularly impressive considering this pipe was made up and broken out a total of 150 times.

  2. A comparison in the performance of an internally bare string and then a string internally coated with a modified epoxy-phenolic coating being subjected to numerous cementing operations. Even though the pipe was used and pitted, prior to the initial coating, repeated uses did not cause adverse damage to the coating and did not allow further corrosion to take place on the ID surface.

Lastly, there are new coating materials being introduced into the market that improve upon existing technologies. These materials will provide even greater abrasion resistance, chemical resistance and possess greater flexibility and toughness allowing them to succeed in even the harshest of applications such as deepwater and extended reach completions.

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