PUYG stands for Potential Ultimate Yield of gas. It is the amount in cubic meters of gas that is expelled from a SR when it has gone to complete maturity for gas, i.e. completely overmature. It is expressed as M³ per %TOC per M³ of net SR.
PUYO stands for Potential Ultimate Yield of Oil. It is the amount in liters of oil that is expelled when a SR has gone through the oil window and expressed per percent of TOC and per cubic meter of net SR.