Technology Of Bio-enzyme Flooding For The Ultra-low-permeability Formation Of Oil Field

After 20 years development,Chaoyanggou Oilfield,a typical ultra-low-permeability oilfield,appears many problems that restrict its sustainable development.These problems include:the former well patterns of some blocks turn to poor adaptability;effective driving system could not be set up;pressure of oil-well restore slowly,the present formation pressure is lower than original pressure and even lower than saturation pressure;the recovery of water-flooding is low and has insufficient stimulation methods.We deployed enzyme-technique experiment in order to make up for the limitation of water-flooding technique,propose the non-water-flooding techniques suitable to the increase of ultimate recovery of low-permeability oilfields,and achieve the effective performance.According to the geological features and developmental characteristics of Chaoyanggou Oilfield,we formulated the bio-enzyme technology appropriate to the development of low-permeability oilfields. This paper is about the characteristics and functions of bio-enzyme and its mechanisms of bio-chemical reaction and driving-oil,and relates the details of laboratory and performance of in situ driving-oil tests.Laboratory test shows that enzyme has unique oil displacement mechanism.Enzyme could eliminate the bound layer,alter the wettability of reservoir rocks from oil wettability to water wettability,decrease the angle of wettability,and reduce the interfacial tension.So the flowing resistance of oil within formation is lowered and petroleum being released from both rock surface.Thus achieve the goals of removing blockage,driving oil through dialysis function.The experiments of enzyme puff-and huff and enzyme-flooding have obviously increased the oil production,meet the desired goal.So this technique has become effective mean to improve the development performance of the ultra-low formation in Chaoyanggou Oilfield.