Hubbert's Peak was originally used to calculate the taper affect of single wells as well as regional wells. His formula has been used longer than you have been on the earth to predict the outputs of wells locally and regionally. It is a fundamental tool for geophysicists. It's like Ohm's Law, it;s the metric that allows tem to make money and stay profitable.
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"Gentlemen, you can't fight in here, this is the War Room!"
President Merkin Muffley