merit function
9.According to the principle i. e. the investor obtains only the expected minimum benefit when NPV is zero, based on the analysis of various factors effecting the cash flow of gas investment, the parameters related with the reserves are expressed as the function of reserve scale, and the mathematical model is developed to determine the gas minimum economic resources taking the resources as a variable and given NPV is zero, which pro vides a decision making method for gas exploration invest merit.

