Abstract: New oil-bearing fault block in a complex fault block oilfield needs more detailed prospecting wells to prove its reserves for development. For a given oil-bearing fault block with homogeneous reservoir rocks, its oil-bearing area and reservoir depth are the key factors for deciding results from investment. Under given reservoir depth, ground communication and hydroelectricity conditions, this paper presents the economic limit oil-bearing area model based on discounted cash flow method, using available data from discovery wells in the fault block integrated with characteristics of complex fault block oilfields. The comparison of prospective oil-bearing area with economic limit oil-bearing area could quickly eliminate the investment projects to be obviously unfeasible, so as to shun related risk and increase decision-making efficiency.

Key words: complex-fault-block oilfield, investment strategy, economic limit reserves, economic limit oil-bearing area