According to the current standard used in China

the geological reserves can be divided into three categories: proved reserves

controlled reserves and prognostic reserves Seemingly

these reserves can be approximately correlated with the proved

probable and possible reserves commonly used in the world However there are remarkable differences in actual operation The essential difference is that economic factors has scarcely or seldom been considered For the sake of being coincide with those practiced in the world

it may be imperative to list commercial recoverable reserves in our reserves report Except applying the successive subtraction method to production prediction while evaluating the commercial recoverable reserves

various parameters should also be considered

such as operational cost and expenditure

expenses of taxation associated with production

development investment

prices of oil products

discount rate

and etc This method has been used to analyze and predict the commercial recoverable reserves in Dongxin oilfield The result shows that the magnitude of remaining commercial recoverable reserves has been affected by the regular pattern of production decline

but it has most obviously been affected by oil prices

especially when the oil price is lower than 20 (US)/bbl.