Enhanced Oil Recovery (EOR) – Chemical Injection – Chemical Flooding – Polymer Flooding
Chemical flooding is one of the major techniques for Enhanced Oil Recovery (EOR), especially for reservoirs where thermal techniques are not feasible.
The most widely used chemical method is polymer flooding.
Polymer increases the viscosity of the injected water and reduces permeability of the porous media, allowing for an increase in the vertical and areal sweep efficiencies, and consequently, higher oil recovery.
The main objective of polymer injection is for mobility control, by reducing the mobility ratio between water and oil.
The reduction of the mobility ratio is achieved by increasing the viscosity of the aqueous phase.
Viscoelasticity of polymer solution flow was the main cause of the increase in oil displacement efficiency.
Different polymer fluids have quite different elastic properties.
Basically, two types of polymers, polyacrylamide and polysaccharide, are commonly used in EOR.
Polyacrylamides used in polymer EOR processes, normally are PHPAs.
The most used polysaccharide is xanthan gum, which is a bacterial polysaccharide. Compared to PHPA, xanthan gum has a more rigid structure and relatively non-ionic.
These properties make it relatively insensitive to salinity and hardness. However, it is susceptible to bacterial degradation after it has been injected into the field.
Actually, the Alkali-surfactant-polymer (ASP) enhanced recovery solution, is considered as the most promising chemical method in Enhanced Oil Recovery because it integrates the advantages of alkali, surfactant and polymer.
In the ASP process, a very low concentration of the surfactant is used to achieve ultra low oil/water interfacial tension (IFT) between the trapped oil and the injection fluid/formation water.
The alkali also simultaneously reacts with the acidic components in the crude oil to form additional surfactant in situ, thus, continuously providing ultra low IFT and freeing the trapped oil.
In the ASP process, polymer is used to increase the viscosity of the injection fluid, to minimize channelling, and provide mobility control.
However, even with these advantages and the success of many ASP projects, the process is not without problems.
One of the major problems in ASP process is the scale formation caused by the reaction between the alkali and concomitant divalent metals cations.
The presence of these cations such as calcium and magnesium ions, results in excessive alkali consumption and surfactant precipitation.
Our Green Solution
Our green and environmentally friendly solution, ALOERECOVER™ is a new developed green polymer that offers the viscoelastic properties required by the process, while offering a solution to the scale formation issue, since our formulation inhibits scale formation and also inhibits corrosion.
ALOERECOVER™ is not susceptible of bacterial degradation as xantahan gum, since aloe has many antibacterial and antifungal properties.
It is accepted that viscoelasticity of polymer solution flow is the main cause of the increase in oil displacement efficiency. Therefore,
ALOERECOVER™ is a perfect solution to increase viscoelasticity, providing antibacterial action and inhibiting scale formation, thus achieving excellent results in the EOR process using the ASP procedure.
The injection of ALOERECOVER™ as a polymer solution increases the viscosity of displacing fluid and reduces the effective permeability to water.
Microscopic displacement efficiency can be improved by injection of alkali and surfactant by several mechanism viz., reduction of the IFT, emulsification of oil and water, solubilization of interfacial films, wettability reversal, etc.
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