Does Polymer's Viscoelasticity Influence Heavy Oil Sweep Efficiency and Injectivity at 1ft/Day? (original) (raw)
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Does Polymer's Viscoelasticity Influence Heavy-Oil Sweep Efficiency and Injectivity at 1 ft/D?
SPE reservoir evaluation & engineering, 2019
For heavy-oil-recovery applications, mobility control is more important than interfacial-tension reduction, and therefore importance should be given to the recovery of remaining mobile oil by enhanced sweep efficiency. Although the relative roles of polymer viscosity and elasticity in capillary-trapped residual light-oil recovery have been studied extensively, their roles in sweeping mobile viscous oil have not been explored. Injectivity is vital for heavy-oil-recovery applications, and polymer selection is performed solely using criteria that is based on shear rheology. In this paper, the influence of viscous (shear) resistance and elastic (extensional) resistance of viscoelastic polymer on mobile-heavy-oil recovery and injectivity is investigated through the combination of bulk shear/extensional rheology and single-phase and multiphase coreflood experiments at a typical reservoir-flooding rate of 1 ft/D. Two polymer solutions with different concentrations and salinities are selected such that a polymer with low molecular weight (MW) [hydrolyzed polyacrylamide (HPAM) 3130] provides higher shear resistance than a high-MW polymer (HPAM 3630). Extensional characterization of these two polymer solutions performed using a capillary breakup extensional rheometer revealed that HPAM 3630 provided higher extensional viscosity than HPAM 3130. The results show that the behaviors of polymers in extension and shear are completely different. Two multiphase and two single-phase experiments are conducted at low flux rate to investigate the roles of extensional viscosity on mobile-heavy-oil recovery and high flux rates on injectivity. After 1 pore volume (PV) of polymer injections, higherconcentration and lower-MW HPAM 3130 contributes to approximately 17% higher incremental recovery factor vs. lower-concentration and higher-MW HPAM 3630. The core-scale pressure drop generated by HPAM 3130 is more than twice the pressure drop generated by HPAM 3630. Under low-flux-rate conditions at the core scale, shear forces dominate, and displacing fluid with higher shear viscosity contributes to better sweep. HPAM 3630 exhibits a shear-thickening phenomenon and possesses the apparent viscosity of approximately 90 cp at the flux rate of approximately 90 ft/D. In contrast, HPAM 3130 continued showing shear thinning and has the apparent viscosity of approximately 70 cp at approximately 90 ft/D. This signifies the role of extension rheology on the injectivity at higher flux rates. Results revealed that while the extensional rheological role toward sweeping the mobile heavy-oil recovery at low flux is lesser compared with the shear role, its negative role on the polymer injectivity is very significant. Polymer-selection criteria for heavy-oilrecovery applications should incorporate extensional rheological parameters.
An optimal viscosity profile in enhanced oil recovery by polymer flooding
International Journal of Engineering Science, 2004
Forced displacement of oil by polymer flooding in oil reservoir is one of the effective methods of enhanced (tertiary) oil recovery. A classical model of this process within Hele-Shaw approximation involves three-layer fluid in a Hele-Shaw cell having a variable viscosity fluid in the intermediate layer between oil and water. The goal here is to find an optimal viscosity profile of the intermediate layer that almost eliminates the growth of the interfacial disturbances induced by mild perturbation of the permeability field. We derive the dispersion relation and sharp bounds on the growth rate of the interfacial disturbances for an optimal viscosity profile of the intermediate layer. We also discuss how and why an appropriate choice of variable viscous profile in the intermediate layer can mitigate not only the Saffman-Taylor instability but also the tendency of preferential channeling of flow through high permeable region in the heterogeneous case.
Spe Journal, 2018
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Journal of Non-Newtonian Fluid Mechanics, 2020
Oil recovery processes depend on many factors that can be altered in order to maximize the sweeping efficiency in porous media, and one of these is the rheology behavior of the displacing agent. Furthermore, scales in the recovery process should also be considered: from the macro-to microscale systems, in which capillary forces become predominant. It is also well-known the non-Newtonian behavior of polymer solutions used in Enhanced Oil Recovery (EOR) processes. This has been considered before, explaining how the polymer's viscosifying properties enhance the displacing process. Recently, another property exhibit by polymer solutions started being considered: the viscoelasticity. The interaction between the (macro)molecules in the displacing phase generates a complex stress field which cannot be simply addressed by an increment in the shear viscosity. We present a 2D, multiphase simulation at macro-and microscale of a recovery process with different fluid models, showing that viscoelastic fluids increase the recovery performance due to the extra stresses generated by the polymer molecules, up to a 15.4% when compared to traditional waterflooding techniques. The viscosity of the displacing phase affects indeed the recovery efficiency, and moreover, the results also evidenced that not only the bulk viscoelasticity, but also the interfacial forces play a vital role in the microscopic sweeping efficiency in polymer EOR flooding processes. This can be used when determining the properties of future EOR agents to be synthesized.
The goal of enhanced oil recovery is to improve sweep efficiency in the reservoir by the injection of artificial materials in order to reduce the trapped oil saturation. In this study, the application of an anionic polyacrylamide polymer was investigated for heavy oil recovery based on the results of rheological measurements and oil recovery experiments. The properties of the polymer solution were interpreted by the use of well-known rheological models and oil recovery experiments were performed using a heterogeneous two-dimensional glass micromodel saturated with heavy oil of 270 cP. To provide a better understanding of the microscopic efficiency of the process, analysis of continuously provided pictures during the experiments by the use of image processing technique was performed. Rheological results combined with microscopic observations revealed that the non-Newtonian behavior of the solution enhances the sweep efficiency of the both pore throats and pore bodies. Macroscopic observations showed the ultimate oil recovery of 56% and dramatic improvement in breakthrough time during polymer flood in comparison to water flood. In addition, the microscopic pictures disclosed that the pulling effect and stripping mechanisms are responsible mechanisms for the high microscopic sweep efficiency during polymer flooding.
On the Effect of Polymer Elasticity on Secondary and Tertiary Oil Recovery
Industrial & Engineering Chemistry Research, 2013
Typically, a polymer for enhanced oil recovery (EOR) is selected based on the viscosity range or average molecular weight, concentration, and brine composition, besides other reservoir properties. There is not much emphasis given on how the elasticity of polymers could enhance the oil recovery. In this study, in an effort to find a systematic approach for selecting the best polymer for water flooding, effect of molecular weight distribution (MWD), a direct measure of polymer's elasticity was studied on oil recovery performance. Individual effect of elasticity of polymers on oil recovery, breakthrough and overall recovery, and residual resistance factor (RRF) was determined by keeping the viscosity constant and varying the elasticity during secondary and tertiary recoveries experiments. Within two different groups of polymers each with similar average molecular weight studied here, nearly 10% higher recovery for highest elastic polymer was observed during secondary recovery; whereas for tertiary flood ~ 6% higher recovery with ~5 times higher RRF value was observed for highest elastic polymer solution studied here. Results have shown that average molecular weight by itself might not be the best criteria to select the optimum polymer fluid composition for polymer flooding operations. Polymer elasticity should be weighted more than the average molecular weight as it could correspond to higher sweep efficiency due to the stretching of polymer along the pores. Considering the polymer elasticity or MWD together with average molecular weight seems to be a better approach for achieving higher oil recovery performance at lower polymer concentrations.
Investigate Polymer Flooding for Enhanced Oil Recovery in a Mature Oil Field
International Journal of Petroleum and Petrochemical Engineering
Polymer flooding is the evolution of conventional water flooding technique. Instead of using just water to displace oil, polymer is used as an alternative to injection water. The polymer introduced to the injection water affects the viscosity of displaced fluid and hence decreases mobility ratio, improves stratification efficiencies and frontal saturations. The relative flow rates of water and oil are altered by the polymer solution, sweeping larger area of the reservoir and; therefore, more oil is in contact with the polymer solution and displaced to the production well. One of the principal purpose of this research is to examine the efficiency of polymer flooding in an oilfield by performing sensitivity analysis, which includes altering injection timing, polymer concentration, injection rate, injection layer, injection period and well configurations in a Western Australian oilfield. Also, water flooding is to be conducted as a base case to compare the efficiency of oil recovery for polymer flooding. A 7x7x6 box model was built and all the reservoir fluid data were analyzed using Computer Modeling Group (STARS). The results show that there is a slight increase in oil recovery (1.72%) after polymer is injected. However, by changing the well configurations, a significant increment of 12.46% of oil recovery is observed.
The Efficiency of Polymer Flooding for Oil Recovery
International Journal of Advance Research and Innovative Ideas in Education, 2019
The world keeps on depending intensely on oil for essential vitality. As the extraction of oil turns out to be additionally testing, new systems are set up to build the measure of oil removed. Polymers assume significant job in the Enhanced Oil Recovery; they help remove up to 30% of the first oil set up. Polymers help increment the thickness of the uprooting fluid (water) to drive the dislodged fluid (oil) to the generation well. An assortment of polymers is utilized in various oil fields relying upon working states of that field. Before the correct polymer is picked, a cautious investigation ought to be directed to guarantee that the polymer is powerful amid a broad timeframe. Warm and compound flooding are great choices to recuperate overwhelming oil. Polymer flooding technique is a standout amongst the most essential upgraded oil recuperation (EOR) systems which improve the portability proportion of water and oil. Polymers containing mixes of long chain, for example, polyacrylam...
Polymer Flooding for Improving Oil Recovery
Several methods to enhance oil recovery are encouraging in Indonesia as well as in the world today. In compliance with this, research in the area of enhanced oil recovery (EOR) is still carried out by many examiners. One of the research areas is exploitation of chemicals for seeking the enhancement of oil recovery. Some chemicals have been found for Enhanced Oil Recovery processes. However, in order to determine chemicals used in this experiment, some aspect have been set as follows: it is easily found in Indonesia, it can be produced inexpensively, it has high recoverability and it is not petroleum base. The goal of this research is to investigate the effect of polimer found in the market and developed in the laboratory such as Poly Vynil Alcohol (PVA) and Partially Hydrolyzed Polyacrylamide (HPAM) polymer on the oil recovery which can be used to optimize recovery and minimize residual oil in the reservoir by: lowering the oil / water interfacial tension and improving mobility ratio. The effectiveness of chemicals was tested through micro displacement using artificial reservoir as porous medium. The procedure of operation is as follows: initially the reservoir model was filled with brine until it was 100 % saturated. Then to represent oil migration, oil was injected into the medium until minimum water saturation (S wc) of about 30 % is reached. After this, the medium was flooded by the same brine until minimum oil saturation, S or, was reached, which was about 10 %. The oil remaining in the reservoir model after this water flood was then subjected to the injection of various chemicals for additional oil recovery. A set of mathematical model of oil displacement from porous media using water and polymer flooding has also been developed, based on fundamental theories of two phase flow. Since the model includes the material balance of the water and polymer, the concentration of the polymer at any position and time can be predicted. The oil displacement experiments show that as much as 20 % to 60 % of remaining oil can be recovered by flooding it with the chemical developed in the laboratory. The results also show the oil recovery depends on chemical, chemical concentration, pressure and temperature in the model reservoir, and crude oil. It turns that the mathematical models proposed were in a good agreement with the experimental data.