Study On Preparation And Performance Of A New Drag-Reduction Agent In Brine

In recent years, the demand of brine resources is keeping increasing due to the growing of brine industries, especially the development and the rapid increase of capacity of fine chemical industry of chlorine and bromine. Due to years of unscientific exploration, the shallow underground brine reserves decline significantly. So, the mining and using of deep underground brine is getting more public’s attention. Compared with the shallow underground brine, the mining of deep underground brine has traits that high mining investment and high operating costs and huge energy costs. Therefore, it is particularly important to dwindle the energy consumption during the mining and transportation of deep underground brine. Looking for an effective water soluble drag-reduction agent to reduce energy consumption is a feasible way.As the most commonly used water soluble drag reduction agent at present, Polyacrylamide does well drag reduction effect in pure water. But the drag reduction effect falls obviously in brine, because the deep underground brine has the characteristics of high temperature and high salinity, and polyacrylamide molecule is sensitive to salt. When it is in brine system, molecular chain will curl to lead the decrease of the drag reduction effect. And when the temperature is higher, polyacrylamide molecular stability decreases, as a result, the drag reduction effect will also be affected. In order to improve the heat resistance and salt resistance of polyacrylamide, the modified binary copolymer is synthesized using the modified monomers such as 2-acrylamide-2-methyl propane sulfonic acid (AMPS) and octadecyl methyl-acrylate with hydrophobic groups, etc. Binary copolymer has fine drag reduction effect under certain temperature and certain salinity, however, the drag reduction effect is significantly lower as the temperature and salinity ascend. It is particularly important to enhance the heat resistance and salt resistance of the modified copolymer.The anionic and water-soluble sulfo group of AMPS molecules, which is not sensitive to the attack of positive ion, provides excellent salt resistance. Its large side group can improve the heat resistance performance.; The carboxyl of AA and IA can chelates calcium and magnesium ions, so that reducing attack on polymer molecules and improving salt resistance; The benzene ring of SSS, which can improve the rigidity of the chain, strengthen the heat-resistant performance of the polymer. And its sulfonic group can improve polymer salt resistance.In this paper, three kinds of ternary copolymer, using AM and AMPS as based monomer and introducing AA and IA and SSS as the third monomer respectively, were synthesized with initiator system in aqueous solution. The drag reduction performance in brine system was evaluated. Designing orthogonal experiment to make up the best parameters and the polymers are characterized. The molecular weight was tested by Multi-angle Laser Light Scattering instrument and viscosity method.The relationships between drag reduction rate and salinity and temperature were tested by the indoor test loop under certain conditions. The results of P P(AM/ AMPS/AA) and P(AM/AMPS/IA) and P(AM/AMPS/SSS) show that:1. The P(AM/AMPS/AA) can get a drag reduction rate of 41.2% when the temperature is 15℃ and the salinity is 150 g/L and the flow rate is 950 L/h and the usage of drag reduction agent is 20ppm. When the salinity increases to 250 g/L, drag reduction rate can be maintained at 30.3%. The drag reduction rate can also be left a number of 21.8% when temperature ascends to 60℃. It verifies that P(AM/AMPS/AA) has good heat resistance and good salt resistance.2. The P(AM /AMPS/IA) can get a drag reduction rate of 31.3% when the temperature is 22℃ and the salinity is 150 g/L and the flow rate is 900 L/h and the usage of drag reduction agent is 20ppm. When the salinity increases to 250 g/L, drag reduction rate can be maintained at 26.5%. The drag reduction rate can also be left a number of 16.4% when temperature ascends to 50℃. It verifies that the drag reduction performance of P(AM/AMPS/IA) is not very good as a whole but it has good heat resistance and magnificent salt resistance.3. The P(AM/AMPS/SSS) can get a drag reduction rate of 34.6% when the temperature is 15℃ and the salinity is 150 g/L and the flow rate is 800 L/h and the usage of drag reduction agent is 20ppm. When the salinity increases to 250 g/L, drag reduction rate can be maintained at 26.6%. The drag reduction rate can only be left a number of 11.5% when temperature ascends to 65 ℃. It verifies that the P(AM/AMPS/SSS)has excellent salt resistance but its temperature resistant is not outstanding.By studying the relationship between the drag reduction rate of polymers and the intrinsic viscosity number, we find that the drag reduction rate of polymers had clear correlation with its intrinsic viscosity number. Based on this, we infer that using the intrinsic viscosity number to evaluate the drag reduction performance of a new polymer is feasible and it can also avoid the disadvantages of indoor test loop that it wastes much time and energy.