高溫高鹽疏水締合型聚丙烯酰胺研究現(xiàn)狀

1、Research status in Hydrophobically Research status in Hydrophobically Associating Hydrolyzed PolyacrylamideAssociating Hydrolyzed PolyacrylamideR Reportereporter:Xubngyue:XubngyueAbstractAbstractWater-soluble polymers are known to be used in chemically enhanced oil recovery (EOR) processes, but thei

2、r applications are limited in high-temperature and high-salinity oil reservoirs because of their inherent poor salt tolerance and weak thermal stability.Hydrophobic association of partially hydrolyzed polyacryamide (HAHPAM) complexed with silica nanoparticles to prepare nano-hybrids is reported in t

3、his work.The rheological and enhanced oil recovery (EOR) properties of such hybrids were studied in comparison with HAHPAM under simulated high-temperature and high-salinity oil reservoir conditions(T: 85 C; total dissolved solids: 32,868 mgL1; Ca2+ + Mg2+:873 mgL1).It was found that the apparent vi

4、scosity and elastic modulus of HAHPAM solutions increased with addition of silica nanoparticles, and HAHPAM/silica hybrids exhibit better shear resistance and long-term thermal stability than HAHPAM in synthetic brine.1 1、MMajor limitationajor limitations s of HPAM of HPAM Major limitations of HPAM1

5、）The main problem of HPAM in the oilfield application is its poor heat tolerance and salt resistance performance, which limit its applications in the high-temperature and high-salinity oil reservoirs.2）In addition the interaction of metal ions such as Na+ and K+ in the oilfield brines largely shield

6、s the mutual repulsion from the carboxylic groups along the HPAM skeleton,leading to the polymer coils to collapse and the hydrodynamic volume to decrease, ultimately lowering the solution viscosity.3）Another major limitation of HPAM is its flow-induced mechanical degradation because of its shear-th

7、inning behavior.2 2、RecentlyRecently1)To obviate the limitations of HPAM, many laboratories have been active in developing HPAM with improved thermal stability, shear stability and salinity tolerance. Hydrophobically associating polymers containing a small proportion of hydrophobic groups in the for

8、m of pendent side chains or terminal groups has been of increasing interest in improved oil recovery.2)hydrophobically associating partially hydrolyzed polyacryamide (HAHPAM) by copolymerization of acrylamide (AM), sodium acrylate (NaAA) with N-(4-benzoyloxy)-acrylamide and dimethylamino-ethyl metha

9、crylate (DMAEMA). N-(4-Benzoyloxy)-acrylamide acts as the rigid chain in the copolymer and dimethylamino-ethyl methacrylate (DMAEMA). N-(4-Benzoyloxy)-acrylamide acts as the rigid chain in the copolymer and apparently restricts the level of mechanical degradation to some extent, exhibiting better sh

10、ear stability than HPAM.Figure 1. (A) Apparent viscosity plotted as a function of shear rate for various concentrations of HAHPAM and (B) zero-shear Figure 1. (A) Apparent viscosity plotted as a function of shear rate for various concentrations of HAHPAM and (B) zero-shear viscosity (0) plotted as a

11、 function of polymer concentration for HAHPAM in brine (TDS = 32,868 mgL1, Ca2+ + Mg2+ = 873 viscosity (0) plotted as a function of polymer concentration for HAHPAM in brine (TDS = 32,868 mgL1, Ca2+ + Mg2+ = 873 mgL1, T = 85 mgL1, T = 85 C).C).3)The addition of nanoparticles can be used to manipulat

12、e the optical, thermal, magnetic, and electric properties of polymers. Compared with pure polymers, the polymer composite materials containing silica nanoparticles may exhibit more satisfactory thermal stability, toughness and strength owing to the effect of physical adsorption such as hydrogen bond

13、 formationFigure 1A shows the concentration-dependent flow curves of HAHPAM brine solutions between 0.05 wt% and 1.0 wt% at 85 C. When the polymer concentration (Cp) is lower than 0.4 wt%, the HAHPAM brine solutions behave as Newtonian fluids, that is, their viscosity is independent of shear rate, w

14、hile at higher polymer concentrations, the flow curves are composed of two parts: Newtonian behavior at low shear rates and shear-thinning response with increasing shear rates. In the Newtonian fluid region, the zero-shear or plateau viscosity (0) can be obtained by extrapolating the shear rate to z

15、ero. The variation of 0 as a function of polymer concentration at 85 C is plotted in Figure 1B, where the two parts can be separated at around 0.73 wt%. Below this concentration, 0 increases linearly with increasing polymer concentration; above 0.73 wt%, 0 increases drastically. This suggests that 0

16、.73 wt% is the CAC of HAHPAM brine solution, above which intermolecular hydrophobic associations play a major role in the solution.Figure 2. Dependence of apparent viscosity on silica nanoparticle concentration forFigure 2. Dependence of apparent viscosity on silica nanoparticle concentration for HA

17、HPAM/silica hybrids in brine and silica HAHPAM/silica hybrids in brine and silica suspensionsuspensionPresented in Figure 2 is the dependence of silica concentration on the brine solution viscosity of HAHPAM/silica hybrids at 85 C. It is apparent that the viscosity of hybrid systems is enhanced grad

18、ually with increasing silica concentration under high-temperature and high-salinity conditions.Figure Figure 3 3. Dependence of apparent viscosity on silica nanoparticle concentration for. Dependence of apparent viscosity on silica nanoparticle concentration for HAHPAM/silica hybrids in brine and si

19、lica suspension HAHPAM/silica hybrids in brine and silica suspension (TDS = 32,868 mgL1,Ca2+ + Mg2+ = 873 mgL1, T = 85 (TDS = 32,868 mgL1,Ca2+ + Mg2+ = 873 mgL1, T = 85 C, C, = 10 s1, Cp = 0.5 wt%). = 10 s1, Cp = 0.5 wt%).Compared in Figure 3 are the flow curves of pure HAHPAM brine solution and HAH

20、PAM/silica hybrids with different silica concentrations at 85 C. It is found that the samples revealed non-Newtonian shear-thinning behavior. With the increase of the shear rate (from 2.0 s1 to 550 s1),the viscosity of HAHPAM/silica hybrids obviously dropped.FigureFigure 4 4 Long-term thermal stabil

21、ity of 0.5% HAHPAM/0.5% silica hybrid in comparisonLong-term thermal stability of 0.5% HAHPAM/0.5% silica hybrid in comparison with 0.5% HAHPAM and 0.5% silica with 0.5% HAHPAM and 0.5% silica (TDS = 32,868 mgL1, Ca2+ + Mg2+ = 873 mgL1,= 10 s1). Both the aging and measuring temperature is 85 (TDS =

22、32,868 mgL1, Ca2+ + Mg2+ = 873 mgL1,= 10 s1). Both the aging and measuring temperature is 85 C.C.Figure 4 shows the variation of app as a function of aging time for the HAHPAM/silica hybrid and HAHPAM brine solution after aging at 85 C. app of 0.5 wt% silica suspension remains around 0.9 mPas, independent of the aging time.Fi