Both 48-hour and 24-hour strikes were held on seven Shell-operated platforms.
A "mutually agreeable proposal" was drawn up between unions and the Wood Group earlier this month. A ballot of RMT and Unite union members closes on Thursday afternoon.
The initial 24-hour strike in July was the first industrial action of its kind in the North Sea in nearly 30 years.
The platforms involved were the Curlew, Brent Alpha, Brent Bravo, Brent Charlie, Nelson, Gannet and Shearwater.
Aberdeen-based Wood Group provides maintenance and construction to Shell and signed a three-year extension to its contract earlier this year.
A ballot of offshore workers on a new proposal aimed at ending a dispute over pay and conditions is due to close.