A more thorough explanation:

Definition: Gas sold refers to the natural gas that is actually sold, but not necessarily all that a well produces. This term is commonly used in natural gas leases.

Example: A natural gas well produces 1000 cubic feet of gas per day, but the owner only sells 500 cubic feet of gas to a buyer. In this case, the gas sold would be 500 cubic feet.

Explanation: The example illustrates that not all the gas produced by a well is necessarily sold. The gas sold refers only to the amount of gas that is actually sold to a buyer.

Definition: Gas used refers to the natural gas that is consumed while a well is in operation, but not necessarily sold.

Example: A natural gas well produces 1000 cubic feet of gas per day, but the owner uses 200 cubic feet of gas to power the equipment used to extract the gas. In this case, the gas used would be 200 cubic feet.

Explanation: The example illustrates that some of the gas produced by a well is consumed while the well is in operation. This gas is not sold, but rather used to power the equipment used to extract the gas.