Polymer Injectivity: Investigation of Mechanical Degradation of EOR Polymers Using In-Situ Rheology

Water soluble polymers have gained an increasing interest in enhanced oil recovery (EOR) processes, especially as polymer flooding. Despite the fact that the flow of polymer in porous medium has been a research subject for many decades with numerous publications, there are still some research areas that need progress. The prediction of polymer injectivity remains elusive. Polymers with similar shear viscosity might have different in-situ rheological behaviors and may be exposed to different extent of mechanical degradation. Hence, determining polymer in-situ rheological behavior is of great significance for defining its utility. In this study, an investigation of rheological properties and mechanical degradation of different HPAM (partially hydrolyzed polyacrylamide) polymers was performed using Bentheimer sandstone outcrop cores. Results show that, HPAM in-situ rheology is different from bulk rheology measured in rheometer. Specifically, shear thickening behavior occurs at high rates, and near-Newtonian behavior is measured at low rates in porous media. This deviates strongly from measurements in the rheometer. Polymer molecular weight and concentration influence its viscoelasticity and subsequently its flow characteristics in porous media. Exposure to mechanical degradation by flow at high rate through porous media leads to significant reduction in shear thickening and thereby improved injectivity. More importantly, the degraded polymer maintained in-situ viscosity at low flow rates indicating that improved injectivity can be achieved without compromising viscosity at reservoir flow rates. This is explained by reduction in viscoelasticity. Mechanical degradation also leads to reduced residual resistance factor (RRF), especially for high polymer concentrations. For some of the polymer injections, successive degradation (increased degradation with transport length in porous media) was observed. The results presented here may be used to optimize polymer injectivity.

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Polymer Injectivity: Investigation of Mechanical Degradation of Enhanced Oil Recovery Polymers Using In-Situ Rheology

Energies ◽

10.3390/en12010049 ◽

2018 ◽

Vol 12 (1) ◽

pp. 49 ◽

Cited By ~ 15

Author(s):

Badar Al-Shakry ◽

Tormod Skauge ◽

Behruz Shaker Shiran ◽

Arne Skauge

Keyword(s):

Porous Media ◽

Enhanced Oil Recovery ◽

Oil Recovery ◽

Shear Thickening ◽

Water Soluble ◽

High Rate ◽

Low Flow ◽

Mechanical Degradation ◽

Flow Rates

Water soluble polymers have attracted increasing interest in enhanced oil recovery (EOR) processes, especially polymer flooding. Despite the fact that the flow of polymer in porous medium has been a research subject for many decades with numerous publications, there are still some research areas that need progress. The prediction of polymer injectivity remains elusive. Polymers with similar shear viscosity might have different in-situ rheological behaviors and may be exposed to different degrees of mechanical degradation. Hence, determining polymer in-situ rheological behavior is of great significance for defining its utility. In this study, an investigation of rheological properties and mechanical degradation of different partially hydrolyzed polyacrylamide (HPAM) polymers was performed using Bentheimer sandstone outcrop cores. The results show that HPAM in-situ rheology is different from bulk rheology measured by a rheometer. Specifically, shear thickening behavior occurs at high rates, and near-Newtonian behavior is measured at low rates in porous media. This deviates strongly from the rheometer measurements. Polymer molecular weight and concentration influence its viscoelasticity and subsequently its flow characteristics in porous media. Exposure to mechanical degradation by flow at high rate through porous media leads to significant reduction in shear thickening and thereby improved injectivity. More importantly, the degraded polymer maintained in-situ viscosity at low flow rates indicating that improved injectivity can be achieved without compromising viscosity at reservoir flow rates. This is explained by a reduction in viscoelasticity. Mechanical degradation also leads to reduced residual resistance factor (RRF), especially for high polymer concentrations. For some of the polymer injections, successive degradation (increased degradation with transport length in porous media) was observed. The results presented here may be used to optimize polymer injectivity.

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Impact of Mechanical Degradation on Polymer Injectivity in Porous Media

10.20944/preprints201805.0291.v1 ◽

2018 ◽

Author(s):

Badar Al-Shakry ◽

Tormod Skauge ◽

Behruz Shaker Shiran ◽

Arne Skauge

Keyword(s):

Porous Media ◽

Oil Recovery ◽

Polymer Solutions ◽

Shear Thickening ◽

Economic Cost ◽

High Viscosity ◽

Polymer Flooding ◽

Mechanical Degradation ◽

Thickening Behavior

Polymer flooding is an established enhanced oil recovery (EOR) method, still many aspects of polymer flooding are not well understood. This study investigates the influence of mechanical degradation on flow properties of polymers in porous media. Mechanical degradation due to high shear forces may occur in the injection well and at the entrance to the porous media. The polymers that give high viscosity yields at a sustainable economic cost are typically large, MW > 10 MDa, and have wide molecular weight distributions. Both MW and the distributions are altered by mechanical degradation, leading to changes in the flow rheology of the polymer. The polymer solutions were subjected to different degrees of pre-shearing and pre-filtering before injected into Bentheimer outcrop sandstone cores. Rheology studies of injected and produced polymer solutions were performed and interpreted together with in-situ rheology data. The core floods showed a predominant shear thickening behavior at high flow velocities which is due to successive contraction/expansion flow in pores. When pre-sheared, shear thickening was reduced but with no significant reduction in in-situ viscosity at lower flow rates. This may be explained by reduction in the extensional viscosity. Furthermore, the results show that successive degradation occurred which suggests that the assumption of the highest point of shear which determines mechanical degradation in a porous media does not hold for all field relevant conditions.

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New Insights Into Polymer Rheology in Porous Media

SPE Journal ◽

10.2118/129200-pa ◽

2010 ◽

Vol 16 (01) ◽

pp. 35-42 ◽

Cited By ~ 68

Author(s):

R.S.. S. Seright ◽

Tianguang Fan ◽

Kathryn Wavrik ◽

Rosangela de Carvalho Balaban

Keyword(s):

Porous Media ◽

Oil Recovery ◽

Shear Thickening ◽

Shear Thinning ◽

Mechanical Degradation ◽

Polymer Rheology ◽

Resistance Factors ◽

Polymer Component ◽

Flow Through ◽

Hydrolyzed Polyacrylamide

Summary This paper clarifies the rheology of xanthan and partially hydrolyzed polyacrylamide (HPAM) solutions in porous media, especially at low velocities. Previous literature reported resistance factors (effective viscosities in porous media) and an apparent shear thinning at low fluxes that were noticeably greater than what is expected on the basis of viscosity measurements. The polymer component that causes the latter behavior is shown to propagate quite slowly and generally will not penetrate deep into a formation. Particularly for HPAM solutions, this behavior can be reduced or eliminated for solutions that experience mechanical degradation or flow through a few feet of porous rock. Under practical conditions where HPAM is used for enhanced oil recovery (EOR), the degree of shear thinning is slight or nonexistent, especially compared to the level of shear thickening that occurs at high fluxes.

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Effect of Tip Clearance on Suction Performance at Different Flow Rates in a Mixed Flow Pump

Volume 1B, Symposia: Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Flow Manipulation and Active Control: Theory, Experiments and Implementation; Multiscale Methods for Multiphase Flow; Noninvasive Measurements in Single and Multiphase Flows ◽

10.1115/fedsm2014-21207 ◽

2014 ◽

Author(s):

Yo Han Jung ◽

Young Uk Min ◽

Jin Young Kim

Keyword(s):

Performance Test ◽

Stokes Equations ◽

Flow Characteristics ◽

Tip Clearance ◽

Low Flow ◽

Tip Leakage Flow ◽

Mixed Flow ◽

Flow Rates ◽

Suction Performance ◽

Flow Pump

This paper presents a numerical investigation of the effect of tip clearance on the suction performance and flow characteristics at different flow rates in a vertical mixed-flow pump. Numerical analyses were carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations. Steady computations were performed for three different tip clearances under noncavitating and cavitating conditions at design and off-design conditions. The pump performance test was performed for the mixed-flow pump and numerical results were validated by comparing the experimental data for a system characterized by the original tip clearance. It was shown that for large tip clearance, the head breakdown occurred earlier at the design and high flow rates. However, the head breakdown was quite delayed at low flow rate. This resulted from the cavitation structure caused by the tip leakage flow at different flow rates.

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Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650917695672 ◽

2017 ◽

Vol 231 (4) ◽

pp. 290-302 ◽

Cited By ~ 4

Author(s):

Can Kang ◽

Ning Mao ◽

Chen Pan ◽

Yang Zhu ◽

Bing Li

Keyword(s):

Centrifugal Pump ◽

Flow Rate ◽

Pressure Fluctuations ◽

Flow Characteristics ◽

Low Flow ◽

Back Surface ◽

Flow Rates ◽

Pump Operation ◽

Low Specific Speed ◽

Specific Speed

A low-specific-speed centrifugal pump equipped with long and short blades is studied. Emphasis is placed on the pump performance and inner flow characteristics at low flow rates. Each short blade is intentionally shifted towards the back surface of the neighboring long blade, and the outlet parts of the short blades are uniformly shortened. Unsteady numerical simulation is conducted to disclose inner flow patterns associated with the modified design. Thereby, a comparison is enabled between the two schemes featured by different short blades. Both practical operation data and numerical results support that the deviation and cutting of the short blades can eliminate the positive slope of pump head curve at low flow rates. Therefore, the modification of short blades improves the pump operation stability. Due to the shortening of the outlet parts of the short blades, velocity distributions between impeller outlet and radial diffuser inlet exhibit explicitly altered circumferential flow periodicity. Pressure fluctuations in the radial diffuser are complex in terms of diversified periodicity and amplitudes. Flow rate influences pressure fluctuations in the radial diffuser considerably. As flow rate decreases, the regularity of the orbit of hydraulic loads exerted upon the impeller collapses while hydraulic loads exerted upon the short blades remain circumferentially periodic.

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Pore-Scale Transport Mechanisms and Macroscopic Displacement Effects of In-Situ Oil-in-Water Emulsions in Porous Media

Journal of Energy Resources Technology ◽

10.1115/1.4040200 ◽

2018 ◽

Vol 140 (10) ◽

Cited By ~ 8

Author(s):

Chuan Lu ◽

Wei Zhao ◽

Yongge Liu ◽

Xiaohu Dong

Keyword(s):

Porous Media ◽

Oil Recovery ◽

Heavy Oil ◽

Mobility Control ◽

Pore Scale ◽

Sweep Efficiency ◽

Emulsion Droplets ◽

Oil In Water ◽

Retention Volumes

Oil-in-water (O/W) emulsions are expected to be formed in the process of surfactant flooding for heavy oil reservoirs in order to strengthen the fluidity of heavy oil and enhance oil recovery. However, there is still a lack of detailed understanding of mechanisms and effects involved in the flow of O/W emulsions in porous media. In this study, a pore-scale transparent model packed with glass beads was first used to investigate the transport and retention mechanisms of in situ generated O/W emulsions. Then, a double-sandpack model with different permeabilities was used to further study the effect of in situ formed O/W emulsions on the improvement of sweep efficiency and oil recovery. The pore-scale visualization experiment presented an in situ emulsification process. The in situ formed O/W emulsions could absorb to the surface of pore-throats, and plug pore-throats through mechanisms of capture-plugging (by a single emulsion droplet) and superposition-plugging or annulus-plugging (by multiple emulsion droplets). The double-sandpack experiments proved that the in situ formed O/W emulsion droplets were beneficial for the mobility control in the high permeability sandpack and the oil recovery enhancement in the low permeability sandpack. The size distribution of the produced emulsions proved that larger pressures were capable to displace larger O/W emulsion droplets out of the pore-throat and reduce their retention volumes.

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