중질유 회수증진을 위한 폴리머의 유변학 및 주입특성

다국어 초록 (Multilingual Abstract)

Polymer flooding characteristics of xanthan gum solution in 3 wt% and 10 wt% salinity conditions were investigated for heavy oil recovery in glass-bead packs. The polymer flooding characteristics were compared with the HPAM injection flooding experiment in 3 wt% salinity condition.
Rheological experiments were conducted to investigate the change in viscosity when the polymer was applied to a variety of reservoir conditions. According to rheology tests, it was observed that the xanthan solution was less sensitive in viscosity by increasing temperatures and salinity than the HPAM solution. However, the HPAM with zero salinity represented higher viscosity than xanthan solution with zero salinity.
In flooding experiment, HPAM in a 1500 ppm in 3wt% salinity condition showed 68.1% heavy oil recovery, which was 22.9% higher than water flooding. The xanthan solution was injected under same conditions, which showed 7.2 % more heavy oil recovery than HPAM. The flooding tests conducted using xanthan solution with the increased salinity up to 10 wt% represented 67.4% heavy oil recovery, which did not show much difference from the one performed with 3 wt% salinity.
Accordingly, xanthan gum injection would be more effective in higher salinity reservoir conditions than HPAM.

국문 초록 (Abstract)

염도 3 wt%, 10 wt% 조건에서의 잔산검(xanthan gum)을 이용하여 주입실험을 통해 폴리머 주입공법의 특성에 대해 연구하였다. 부분적으로 가수분해된 폴리아크리라미드(HPAM)를 3 wt%의 염도 조건에서 주입하여 두 가지 폴리머의 특성을 비교하였다. 다양한 저류층 조건 내에 폴리머가 주입되었을 경우 점도 변화를 알아보기 위하여 유동학 실험이 수행되었다.
xanthan gum 수용액은 HPAM 수용액에 비해 온도와 염도가 높아지는 조건에서 점도에 덜 민감한 것으로 나타났다. 그러나 염도가 없는 경우에는 HPAM이 xanthan gum보다 점도가 높게 나타났다. 염도가 3 wt% 조건에서 농도가 1,500 ppm인 HPAM 용액을 주입하여 얻은 실험에서는 중질유 회수량이 61.9%로 나타나 물을 주입하여 회수한 결과인 39.0%보다 22.9% 높게 나타났다. 위와 같은 조건에서 xanthan gum용액을 주입하는 경우 오일 회수량이 69.1%로 나타났으며 이는 HPAM을 주입했을 때 보다 7.2% 높게 회수되는 것을 관찰할 수 있었다. xanthan gum이 HPAM보다 높은 염도 조건에서 높은 점도를 나타낸 유변학 실험을 토대로 10 wt%의 염도 조건에서 xanthan gum을 주입한 결과 오일 회수량이 67.4%로 3 wt%의 염도 조건에서 얻은 결과와 큰 차이를 보이지 않았다.
따라서 염도가 높은 조건에서 xanthan gum을 주입하는 것이 HPAM보다 더 효과적임을 관찰할 수 있었다.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Review of Literature 2
• 2.1. Oil recovery process 2
• 2.1.1. Primary recovery methods 2
• 2.1.2. Second recovery methods 2
• 2.1.3. Enhanced oil recovery 3
• 2.2. Field Description 4
• 2.3. Heavy oil properties 5
• 2.4. Polymers used in EOR 7
• 2.4.1. Xanthan gum 7
• 2.4.2. The structure of xanthan 8
• 2.4.3. Solution properties 9
• 2.4.4. Partially hydrolyzed polyacrylamide 11
• 2.5. Rheology 12
• 2.5.1. Shear stress and shear strain 13
• 2.5.2. Viscometry 4
• 2.5.3. Factors affecting viscosity 17
• 3. Experiment 19
• 3.1. Experimental equipment 19
• 3.1.1. Viscometer 19
• 3.1.2. Schematic diagram of flooding experiment 20
• 3.2. Experimental materials 20
• 3.2.1. Glass beads 20
• 3.2.2. Heavy oil properties 21
• 3.2.3. Polymer solutions 22
• 3.3. Method 23
• 3.3.1. Rheological characterization of polymer solutions 23
• 3.3.2. Polymer flooding experiments procedures 23
• 4. Results and Discussion 24
• 4.1. Viscoelastic behavior of polymer solutions 24
• 4.1.1. The effect of two different types of polymer solutions concentration 24
• 4.1.2. The effect of NaCl into two types of polymer solutions 26
• 4.1.3. The effect of temperature on shear viscosity of polymer solutions unmixed salinity 30
• 4.2. Flooding tests 32
• 4.2.1. Petrophysical properties of glass-bead packs 32
• 4.2.2. Comparison of water flood and polymer flood 33
• 5. Conclusions 37
• List of Nomenclature 38
• References 39
• List of Tables
• Table 1. Reservoir properties 4
• Table 2. Uses of xanthan gum 11
• Table 3. Standard of Glass beads 21
• Table 4. Properties of Crude Oil (VGH from Australia) 22
• Table 5. Xanthan gum viscosity at different NaCl concentration 27
• Table 6. HPAM viscosity at different NaCl concentration 27
• Table 7. Viscosity of HPAM aqueous solutions (1500ppm, 3wt% NaCl) versus 11.7-1 shear rate 32
• Table 8. Viscosity of Xanthan gum aqueous solutions (1500ppm, 3wt% NaCl) versus 11.7-1 shear rate 32
• Table 9. Properties of injection experiments 32
• Table 10. Summary of flood tests 35
• Table 11. Summary of pressure on flood tests 35
• List of Figures
• Figure 1 Heavy oil viscosity of Alaska 6
• Figure 2 Global heavy oil distribution and resources 7
• Figure 3 The primary structure of xanthan 9
• Figure 4 A diagrammatic representation of the order to disorder transitions in xanthan gum under the influences of temperature and shear 9
• Figure 5 Hydrolyzed Polyacrylamide 12
• Figure 6 A diagrammatic representation of shear strain deformation 14
• Figure 7 Diagrammatic representations of the four principal types of continuous shear behaviour exhibited by fluids 16
• Figure 8 Physica Rheometer (Physica MCR 300, Anton Paar) 19
• Figure 9 Schematic diagram of flooding experiment 20
• Figure 10 Effect of concentration of xanthan gum (3wt% NaCl) on shear viscosity at 25C 25
• Figure 11 Effect of concentration of HPAM (12% hydrolysis, 3wt% NaCl) on shear viscosity at 25C. The solid line obtained from Carreau model 26
• Figure 12 Xanthan gum (1500ppm) viscosity at different NaCl concentration at 25C versus shear rate 28
• Figure 13 Xanthan gum (1500ppm) viscosity at high brine concentration at 25C versus shear rate 28
• Figure 14 Viscosity of HPAM aqueous solutions (1500ppm, 3wt% NaCl) at different temperatures 29
• Figure 15 HPAM (1500ppm) viscosity at high brine concentration
• at 25C versus shear rate 29
• Figure 16 Viscosity of Xanthan gum aqueous solutions (1500ppm, 3wt% NaCl) 31
• Figure 17 Viscosity of HPAM aqueous solutions (1500ppm, 3wt% NaCl) at different temperatures 31
• Figure 18 Comparison of oil recoveries in water and polymer flood tests 34
• Figure 19 Comparison of oil recoveries in Xanthan gum polymer flood tests at 3wt% and 10 wt% NaCl 34
• Figure 20 The shape of pressure drops in water flood and polymer flood (HPAM) 36
• Figure 21 The shape of pressure drops in Xanthan gum at 3wt% and 10wt% 36