You asked

Please provide oil and gas industry wage estimates or average wage. I'd like to request this information for an ATEX inspector or CompEx inspector/electrical inspector engineer.

We said

We publish estimates of wages for both occupation and industry groupings, based on data collected in the Annual Survey of Hours and Earnings (ASHE). These estimates are published in this location

https://www.ons.gov.uk/employmentandlabourmarket/peopleinwork/earningsandworkinghours/bulletins/annualsurveyofhoursandearnings/2018/relateddata

Tables 14 and 15 contain estimates by detailed occupation groups, and table 16 contains estimates for detailed industry groups. In addition, tables 4 and 5 contain estimates for less detailed industry groups, for example 'Extraction of crude petroleum and natural gas'. You may wish to view the Guide to Tables to understand the content of all published data tables based on ASHE.