They are hiring H1B Visas.

This from the Congressional petition site November 27, 2016

Anon Y. from Anchorage, AK writes:
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There are many H1B visas being used in the oilfield also. Many Americans have been laid off while the oilfield service companies have kept their H1B visa holders working. The H1B do not have any special skills or abilities that were not the same as the Americans had. The companies keep the H1B workers because they feel indebted to the company and would have to go back to their home country if they say anything the management does not agree with.
https://www.petition2congress.com/7637/abolish-h1b-visa-program/comments/page/94


They always use the same excuse, 'we can't find workers'

No, they can't find workers who will work for less wages that they can control by threat of deportation.