摘要
By the end of 1990,Daqing,Oilfields had been produ-cing for 30 years with water flooding.The composite water cut was as high as 79%.In the general regularity of developing large scale sandstone reservoirs,the oilfields had been in their later stage of production,char-acterized by rapid decline of oil.output.It is very difficult to keep a steady oil production without any breakthrough in oilfield development techno-logies.
