It's never been rocket science what investors want to see from their oil and gas companies: oil and gas production. That means fresh barrels and Btus, quarter in, quarter out. It means gathering reserves -- finding new resources to show they can keep it up for years or decades. Should a company stumble on this mission, markets can be merciless, dashing its stock price and possibly giving competitors a boost. It's gotten the oil and gas business this far. But the investment community is now hearing a distant voice wondering, "How much further can this go?"