If you live inside the city limits of Shreveport or Bossier City, it is likely that you own your minerals (as most developers didn't reserve minerals in the past).
The tax assessor's office is a good place to start.
The Sonris site is a really good starting point. If you're located in an area with lots of production the land might have been HBP (held by production) for several decades. If there's no production in your section or hasn't been for the last ten years, chances are good that you do own the minerals.