Study Of Polymer Solution Degradation Caused By The Process Of Making Up And Injecting Polymer Solution

Polymer flood is one technology of EOR that polymer solution replaces water asdisplacing fluid to displace crude oil. Polymer solution viscosity is a key parameter ofthe technology. The procedure of making up and injecting polymer solution causespolymer viscosity loss mostly. The study followed the order of making up and injectingpolymer solution. The paper researched on the mechanisms of the viscosity loss of eachpart and the present viscosity loss situation by the aid of the methods of theories, testsand spot trials, at last advices were put forward.The order of making up and injecting polymer solution is dispersal, maturation,filtering, pressure boost, mixture, transportation and injection. A stirrer is necessary tomake up polymer solution. It has to possess two functions, one is to help polymerdissolve and the other is to protect the viscosity. If the stirrer's vanes are made properlyand the velocity of vanes' tip is less than 1.75m/s, the viscosity loss is less than 0.9%,otherwise, 26.4%. Apparently, the vanes' structure and rotary speed are very importantto the viscosity loss. Filters are equipments to dispose of impurities of polymer solution,the viscosity loss of the two-grade-filters is 1.6%-6.1%. The study results indicate thatthe filters aren't indispensable for polymer flood on condition of spot trial, so peoplemay degrade the filters, even canceled it. Injecting polymer pumps are equipments toincrease polymer solution's pressure. In order to protect the solution' viscosity, thepumps have to have the properties that its valves hoist much highly, its channels aremore smooth, its pump frequency is less compared with injecting water pump. Theviscosity loss caused by it is less than 5% now. The Static mixer is an equipment todilute thick polymer solution rapidly. The viscosity loss caused by the mixer is2.5%-5% now. When the transportation line's length is longer than 100m, the mixedeffect is equal almost whether there installs the equipment or not, so the static mixermay be cancelled on this condition. Transportation lines are essential channels totransport polymer solution from one site to another. Different stuffs of the lines dodifferent harms to polymer solution. The present viscosity loss is 1.27%-3.7%/km, thestudy indicates that glass fiber is the best of them, the second is tube filmed withethoxyline, but carbon-steel isn't recommended to use. Shot hole is the last site forpolymer solution to enter oil layers, the viscosity loss caused by it is 28.8% now.Because the viscosity loss has relations to shot parameter and compacting thickness,people can lessened it by means of improving shot technologies. Flow distributors areused to allocate the polymer solutions. The equipments have two styles now, namelycoil pipe (the viscosity loss is 8%-17%) and Venturi tube (the viscosity loss is 3.45%),so the latter is applied generally now.The study concludes that every process of polymer flood does harm to polymersolution, the account of viscosity loss in the entire process is 50%-60%, among them,the main processes to cause the viscosity loss are stirrer, filter, injecting polymer pump,static mixer and shot hole. If we improve or innovate the present process and technology,the viscosity loss will decrease by 8-16%, thus, this will be beneficial to EOR, lowercost of polymer flood and enlarging the application scope of the technology very much.