Carbonate palaeo-subterranean river reservoirs are fractured-vuggy reservoirs composed of deep main rivers

shallow branch and high-angle fractures

with large-scale karst caves as the storage space

belonging to the three main reservoir types in Tahe oilfield. Taking the knowledge of remaining oil and tapping potential in TK440 well area as an example

through the fine characterization of the fracture-cave structure

comprehensive analysis of production dynamics

and systematic analysis of water flooding characteristics

four patterns of remaining oil distribution and feasible potential tapping methods are summarized..The results show that: using large pump for the well drainage and changing the distribution of pressure field

can excavated the remaining oil in shallow underground river. Water flooding in reverse direction

with the advantage of the height difference

can effectively excavate the remaining oil in deep underground river. Based on the difference of oil and gas density

the vertical displacement of artificial gas cap formed of the principle of gravity differentiation can effectively recovery the attic oil around single well and the remaining oil in the blind side of underground rivers. Feasible means of potential tapping under different distribution patterns of remaining oil has been found

and good results have been achieved in the field implementation

which further validates the reliability of remaining oil distribution patterns and the effectiveness of tapping the potential of the reservoir

and provides technical support for the effectively potential tapping of remaining oil in the similar reservoir.