Study On The Preparation Of Polymer Microspheres And The Effect Of Fluid Steering

Polymer flooding technology has become an important technical mean for oil development because of its relatively simple technology,less equipment investment and higher recovery rate.Polymer flooding technology uses polymer solutions to stay in porous media to increase the seepage resistance of high permeable layers,and then increase the injection pressure and increase the pressure difference between the middle and low permeable layers,In the end,the absorption of medium and low permeable layer is increased,that is,enlarging the volume effect of the medium and low permeable layer.With the polymer flooding process continuing,on the one hand,the increase of seepage resistance caused by polymer retention in medium and low permeability layer is much larger than that in high permeable layer,resulting in the increase of suction starting pressure in medium and low permeable layer.On the other hand,the injection pressure can not be improved without restriction because of the pressure of reservoir rock fracture and the pressure resistance of the equipment.Therefore,the medium and low permeability layer suction pressure gradient(injection pressure-starting pressure)will decrease gradually,and reduce the amount of suction gradually,which is called "profile reversal" phenomenon,which greatly limits the effect of increasing oil and decreasing water of polymer flooding,there are still about 50% of crude oil reserves are not produced after polymer flooding.In recent years,the research of polymer microspheres profile-control flooding technology has been paid much attention,and the field test has also obtained obvious effect of increasing oil and decreasing water.In addition,because polymer microspheres do not need ripening process,it has solved the technical problem of long-term application effect and scale of polymer flooding technology in offshore oilfield,and has become one of the important measures for profile control in offshore oilfield.But we must also see that compared with the scale of field test and the application effect of microspheres profile-control flooding mechanism research and understanding cannot meet the actual demand,the current performance evaluation of microspheres still uses the polymer solution approaches and technical indicators,such as viscosity,rheological property and viscoelasticity,which restricts the development of the theory and technology of microspheres profile-control flooding in a certain degree.According to the actual demand of the field,a new type of polymer microspheres profile-control flooding technology is selected as the alternative,taking the reservoir and fluid properties of the Bohai oilfield as the simulation object,the reservoir adaptability evaluation method and profile-control mechanism of the polymer microspheres are carried out to find the polymer materials and process methods suitable for large-scale application of offshore oil fields and it is of great significance for improving polymer microspheres profile-control flooding theory and profile-control flooding effect of fields.