SPE Reserves Categorisation
Reserves are Like Fish Analogy
Proved Developed: The fish is in the boat. You have weighed it. You can smell it and you will eat it.
Proved Undeveloped: The fish is on your hook in the water by the boat and you are ready to net it. You can tell how big it looks (they always look bigger in the water).
Probable: There are fish in the lake. You may have caught some yesterday. You may even be able to see them, but you have not caught any today.
Possible: There is water in the lake. Someone may have told you there are fish in the lake. You have your boat on the trailer but you may go play golf instead.
However, these humouros definitions do not recognise the impact of the price of fish.