It is important for the fractured and caved carbonate oil and gas reservoirs during the middle -late development period to study fracture-cave units in detail. Such blind deployment as infilling wells will be likely to lead to defeat because of having used the petroleum reserves in fracture-cave units. A method of multi-subject integrated division of fracture -cave units is proposed to determine the boundaries of fracture -cave units for the carbonate reservoirs in well areas and no well areas. This method is applied in Well LG 11 area of Lungu Oil Field where 80 fracture-cave units are divided, among which 55 units are reserves -unused (potential units). Some infill wells are deployed in this area, in which the drilled Well WX-1 is succeeded and yields 95t of oil per day, without water.