Value of oil royalty before production

Where do I go to find the value of oil royalty when it was inherited and before production began?

The value of minerals are dependent upon location, location, location and what activity is going on at the time. You may get a better answer if you post this question in the state and county where you have the interests. Then knowledgeable folks can direct you to a licensed engineer or geologist who can help you for that area. If you are far out in wildcat territory with no drilling, it might be something like $.50 or $1.00 per acre. If you are in an active area, but just no drilling on your acreage at the time of inheritance, the values may be determined by activity close by and estimated at a higher value. You have to go local to find out.