GRAN TIERRA ENERGY INC.

A target is an oil or gas accumulation GRAN TIERRA ENERGY INC. has published an estimate for. All of them count to start with, largest first - untick any you don't believe in.

A discovery has already been drilled and found oil or gas. A prospect has not been drilled yet, so it carries extra risk that nothing is there. Reserves are already being produced or approved.

Companies give a low, best and high case. Pick one - the badges show how much the targets you picked hold in that case.

The low case has a 90% chance of being matched or beaten, the best case 50%, the high case only 10%. Gas is in billions of cubic feet, oil and condensate in millions of barrels.

Two chances multiply together: that the oil or gas is really there, and that it actually gets produced.

Being there only matters for an undrilled prospect - a discovery has already proved it. Getting produced needs funding, approvals, buyers and costs to line up. Reserves carry neither.

Oil or gas still underground is worth far less than at the market - someone still has to pay to drill, build and produce it.

These defaults are a common rule of thumb for in-ground value. Takeover prices and broker reports help if you want your own figure.

GRAN TIERRA ENERGY INC.'s own stated next steps, from its announcements.

The further away a result is, the longer your money waits - and the more chance of delays or new shares being issued to fund it.