Is an Awakened land an OK target for Ruins of Oran-Rief?
Yes, you can use Ruins of Oran-Rief on that Awakened land - as long as, like you're describing, you played that land in the same turn.

The ability in question is this one, I presume:


  {T}: Put a +1/+1 counter on target colorless creature that entered the battlefield this turn.


After your land's awakened, it's a colorless creature (as well as a land). That colorless creature did also enter the battlefield this turn. So, yes, at this point it meets all the prerequisites for targeting with this ability: it's a colorless creature that entered the battlefield this turn.

This is confirmed in a ruling on Ruins of Oran-Rief's gatherer page:


  1/22/2016 - The target of the last ability didn’t necessarily have to be a colorless creature as it entered the battlefield, provided it entered the battlefield during that turn. However, it does have to be a colorless creature to be a legal target of the ability.