Evaluation of development effect of clean water flooding into extremely deep heavy oil at normal temperature

Because of the deep burial depth of oil pay(2300 3700m)and large viscosity of crude oil(up to 9 569～25 570 mPa·s at 50℃at the surface and 154～526 mPa·s under the ground),it is hard to exploit.Partial wells were tested for production at the initial stage;partial blocks were put in- to extraction in 2000.On the base of evaluating and sieving displacement efficieneies of water,steam,chemical agent section plug,carbon dioxide section plug,natural gas section plug and flue gas section plug in laboratory physical analog in 2003,it is demonstrated that the waterflood development is viable in economic and technological conditions;and the opti- mal development mode is water flooding after one-year de- pletion exploitation,while other exploitation modes are rela- tively high in cost and maybe put into practice after argument and test.After the completion of water flooding demonstra- tion,Block Lu 2 was under injection test and the water flooding took effect after half a year.Since 2005,the yield of the block has been stable in after consecutive 3 years,thus obtaining a superior development effect.