By using the advanced search, you will make a search query using more than one keyword & search in different fields (Full Text, Author, Company/Institution, Publisher/Journal and Conference).
1. Click on the Advanced search link
2. Choose your search field by (eg: Full text).
3. Select your search mode to search using Exact phrase or without (eg: Exact phrase).
4. Type your search term in the search box (eg: drilling engineering).
5. Click Add.
6. your search query will appear above.
7. Enter another search term (eg: well logging).
8. Click Add.
9. your search query will appear above.
10. Choose another search field (eg: Publisher).
11. Scroll down to select a specific publisher (eg: World Petroleum Congress).
12. Press Add.
13. Click Search to apply your search query.
OnePetro has a help page. There is a link to this in the top right corner of the homepage.
It includes frequently asked questions on how to use OnePetro.