Possibly try making the circle a little smaller. We would also like to see what it looks like with the circle to the left of the text. Try to incorporate extraction of the oil from the sphere with a derrick or a pump jack. Overall good concept.
I still like your first design the best, and the pump jack on top doesn't work for me. #37 has a nice theme though, maybe try similar themes with rock hammer, derrick, earth science and compass themes. Keep up the great work!