1. gas shows in the mud2. drilling break3. cuttings that show...

1. gas shows in the mud
2. drilling break
3. cuttings that show hydrocarbons and give hints for a good poro/perm
4. logging while drilling (LWD): shows good gas, oil saturation, thickness, porosity
5. drill some cores perhaps
6. wireline logging: confirm LWD and get more data with a better resolution
7. try to get hydrocarbon samples with wireline formation tester tool, perhaps some side wall cores
After drilling: the well is cased with cemented casing and drilling is finished
8. completion
9. perforate based on results from logging and plan a production test
10. use this first exploration well as first production well

If there is no gas/oil the well will be plugged and abandoned after drilling and we will see no point 8.)