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- Application of polyacrylamide in the whole process of oil recovery
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PolyacrylamideasEOR flooding agent,, has been put into use in the Daqing Oilfield, Shengli Oilfield, Dagang Oilfield, Changqing Oilfield, Xinjiang Oilfield, Henan Oilfield. And Shengli Oilfield, which is currently the largest amount of polyacrylamide applications. Compared to other EOR technologies. Polyacrylamide is mature, low cost, input-output ratio is low, more suitable reservoir characteristics.
1, the mechanism of polymer flooding
The main mechanism of polymer flooding is the viscosity of molecular chain of water-soluble polyacrylamide to improve mobility ratio of displacing fluid , improving the displacement efficiency and sweep volume, so as to achieve the aim of improving oil recovery.
(1) Reduce the oil flow ratio, it can change the sub-flow curve. Polymer flooding frontier oil saturation and oil saturation were significantly higher than the breakthrough when water flooding, polymerThis shows that polymer flooding can reduce the moisture content of produced fluid, increase production rate, have better displacement effect.
(2) Polymer flooding by improving the flow of water flooding ratio, can improve water flooding in inhomogeneous plane viscous fingering phenomenon, improve plane sweep efficiency;In vertical heterogeneity of formation, polymer slug into high permeability layers first, Using high viscosity characteristics of "blocking" the high permeability layer,so thatthe subsequent water flooding into the low permeability layer turned Added absorption thickness, expanded vertical sweep efficiency. Stranded adsorption, mechanical traps and other effects
(3) Polymer in the through porous media adsorption, capture machinery, such as the role of stranded, changed the polymer in the pore permeability. By adsorption of polymer molecular chain toward the part of the fluid is hydrophilic, can reduce the permeability and not from the phase of the water phase relative permeability to oil, the water plugging is oil; polymer retention can be increased while the resistance coefficient and residual resistance coefficient increased flow resistance, causing the drive pressure increases, help drive the flow of oil had never improve reservoir swept volume.
(4) Polymer solution with viscoelastic effect improve the oil-water interface, make the oil or oil film is easy to draw texturing, more easily through the narrow throat, improve the effect of the micro displacement and improve oil recovery
2. Summary and Outlook
With oilfields have entered late-stage development, Rising water-bearing of produced liquid, Tertiary oil recovery for the country's energy security is more and more important, As a tertiary oil recovery are the main additives-Polyacrylamidedemand quantity is more and more big, at the same time, has higher requirement for the product performance indicators. To further improve product heat resistance salt resistance and improve the dissolution rate of products, especially in the dissolution rate of brine, meet the requirements of different reservoir conditions, is an important part of the polyacrylamide in the future development direction