Oil pools in Zhongyuan Oilfields are typical high temperature and high salinity (temperature:60℃～130℃;brine salinity 6×10

4

～32×10

4

mg/L)pools.41 bacterial populations were selected from 140 formation water samples by using HUNGATE technique.Most of the bacteria are bacilli form

some of them have gemmae.The most favourable temperature for the cultured bacteria is within 60℃～80℃

the abundance of the bacteria decreases with the increasing of salinity.The main metabolic products are organic acid and alcoho which could increase reservoir permeability

improve oil water boundary and considerably increase recovery percent.The result of laboratory test of Wen-15 block in Zhongyuan Oilfields indicates that the oil recovery factor could be increased by 6% or more.The test made in well site had also got fine result

input ouput ratio is 1:4.1.