Abstract: Oil's heaviness and reservoir's looseness are the two main characters of gas一cap sandstone heavy-oil reservoir, end the complex relationship of oilavater}air directly affects the develop-ment of oilfield. Through analyzing the geologic background of gascap sandstone heavyoil reservoir and sedimentary feature of the delta, combined with single-well production test in Block Cao. 31，this paper summed up the variations of oilfield area and gascap, studied the distributing traits of well pattern and spac-ing in Sha 3 Segment and further demonstrated the possibility of watetflood development. 1'he results show that after the applica-lion of various correlative sand control technologies and sand-car-tying cold recovery of screw pump, with the oil production and
reasonable oil recovery rate of single well controlled, the first oil recovery will be enhanced obviously.

Key words: gas-cap, sand oil reservoir, heavy oil field, development strategy