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Mansour A.M.,Sultan Qaboos University | Al-Maamari R.S.,Sultan Qaboos University | Al-Hashmi A.S.,Sultan Qaboos University | Zaitoun A.,Poweltec | Al-Sharji H.,Petroleum Development Oman
Journal of Petroleum Science and Engineering

A study of rheological behavior and mechanical degradation of hydrolyzed polyacrylamides (anionic) used in EOR/IOR applications under low-to-medium shear rates (γ<500s-1) has been carried out. Aqueous polymer solutions have been injected into a core sample. Polymer degradation rate was evaluated from the flow induced viscosity loss of the polymer solution. Polymer degradation and mobility reduction were evaluated at different shear rates, salinities and concentrations. The effects of polymer viscosity, brine salinity and re-circulation of polymer effluent on degradation were investigated. The experiments revealed that polymer degradation in cores is low (<20%) and no further degradation was observed above a critical shear rate. Degradation due to re-injection of polymer effluents into the core was found to be very small (3-5%). Degradation increases with salinity and viscosity. An apparent shear thinning behavior is observed at low shear rates until a critical shear rate above which shear thickening behavior takes place. © 2014 Elsevier B.V. Source

Al-Hashmi A.R.,Sultan Qaboos University | Luckham P.F.,Imperial College London | Al-Maamari R.S.,Sultan Qaboos University | Zaitoun A.,Poweltec | Al-Sharji H.H.,Petroleum Development Oman
Colloids and Surfaces A: Physicochemical and Engineering Aspects

This study investigates the effect of two alkali metal cations (Li+, K+) on the adsorption of high-molecular-weight, nonionic polyacrylamide on glass surfaces using a colloidal force probe. The effect of two different anions (Cl-, NO3 -) on polymer adsorption is also presented. There is a general consensus that hydrogen bonding is the main mechanism by which nonionic polyacrylamides adsorb to silica and glass surfaces. In the current study, the adsorption of the polymer is found to result in repulsion on approach as early as 20min of incubation in polymer solutions using both 0.27M lithium and potassium chlorides. On the other hand, adhesion on retraction occurs in both solutions but with higher magnitudes for the polymer solution prepared in potassium chloride. Adhesion on retraction in potassium chloride solutions occurs even after 24h of incubation, whilst the adhesion disappears in lithium chloride after 24h of incubation. The force at hard contact measured in the potassium chloride solution is generally one order of magnitude lower than those measured in lithium chloride. This indicates that the adsorbed polymer molecules in potassium chloride solutions attain flatter conformation than the ones in lithium chloride. This is attributed to the higher ability of the potassium cation to increase the adsorption energy of the polymer to the glass surface. This higher adsorption energy results in the adsorbed amount of the polymer in KCl being higher than in LiCl. Because of their lower hydration and larger size compared to lithium, potassium cations decrease the hydration of the glass surface and they have the ability to bind with the oxygen atoms in the polymer molecule to the negatively-charged sites on the glass surface. With potassium nitrate, the approach-retraction measurements indicate different adsorption kinetics of polyacrylamide compared to potassium chloride. The nitrate enhances the extension of the adsorbed polymer molecules away from the surface, reflected by the longer ranged steric repulsion in the approach measurements conducted during 24h of incubation. This is probably attributed to the large size of the nitrate anion, its lower hydration and different chemical structure, which allow it to form H-bonds with the polymer. Hence, the polymer is prohibited from forming H-bonds with the surface allowing it to extend away from the surface. This also negatively affects the adsorbed amount, which is found to be lower than in LiCl. © 2012 Elsevier B.V. Source

Al-Hashmi A.R.,Sultan Qaboos University | Luckham P.F.,Imperial College London | Heng J.Y.Y.,Imperial College London | Al-Maamari R.S.,Sultan Qaboos University | And 3 more authors.
Energy and Fuels

High-molecular-weight (HMW) polyacrylamide and its derivatives are widely used in oilfield applications ranging from drilling fluids, enhanced oil recovery (EOR), and treatment of oil sand tailings. In these applications the adsorption characteristics of these polymers are essential since it would affect their applicability and efficiency. In this study, adsorption of three high-molecular-weight polymers (nonionic (NPAM), partially hydrolyzed (HPAM), and sulfonated (SPAM) polyacrylamides on silica surfaces from 2% KCl) is characterized using a quartz crystal microbalance with dissipation monitoring (QCM-D) and an AFM-based colloidal probe apparatus. QCM-D measurements show that semiequilibrium for adsorption on silica surfaces is reached within 3 h. The adsorbed amount and adsorption rate are highest for NPAM and lowest for SPAM. AFM experiments revealed that after 20 min of incubation in solution, HPAM induced bridging attraction on approach (i.e., compression). On the other hand, only a weak attraction is observed in the NPAM solution. However, SPAM shows only steric repulsion on approach after 20 min of incubation commencing at a separation of around 250 nm. Significant adhesion on retraction was observed after 20 min of incubation in NPAM and HPAM. However, only slight adhesion was observed in SPAM in the same time frame. After incubation in polymer solutions for 20 h, all polymers induced steric repulsion on approach and the absence of adhesion on retraction at different separations, indicating full surface coverage and different effective hydrodynamic layer thickness (EHT). On the basis of the AFM measurements after 20 h of incubation, the EHT of the adsorbed layers in NPAM, HPAM, and SPAM is 125, 30, and 175 nm, respectively. We believe that the results in this study will lead to enhanced understanding of the polymers under investigation with respect to their use in EOR applications. Moreover, this study gives clues on the differences between the three polymers under consideration with respect to their flocculating power, which is employed in the oil sand tailings treatments. © 2013 American Chemical Society. Source

A process for the treatment of a rock formation or cavity, including the step of injecting, into the rock formation or cavity, a water solution of a water-soluble thermo-thickening polymer, the thermo-thickening polymer being able to form a gel at a threshold temperature (T

Poweltec | Date: 2013-06-12

Chemical products used in industry, science, agriculture, unprocessed artificial resins, unprocessed plastics; fire extinguishing compositions; catalysts, adsorbents, catalyst carriers, chemical additives and chemical reagents other than for medical or veterinary use, chemical products used for drilling, extraction, production, treatment of gas, petroleum, water and fluids. Building materials, not of metal; non-metallic rigid pipes for building; asphalt, pitch and bitumen; non-metallic transportable buildings; monuments, not of metal; buildings, not of metal; building glass; concrete; cement; sands; silicas. Construction; construction information; construction consultation; building construction supervision; installation, maintenance and repair of machines for drilling, extraction, production or treatment of gas, petroleum, water and fluids; shipbuilding; drilling works; drilling work supervision.

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