Novel Insight into Polymer Injectivity for Polymer Flooding

Abstract

A considerable portion of world reserves are located in mature and viscous oil reservoirs having thickness less than 15 m. Polymer flooding is a mature technology and is the most important EOR method based on full field case histories. Accurate assessment of injectibility of viscous polymer solutions into these reservoirs without induced fractures is a major challenge. Therefore, the objective of this study is to experimentally investigate and model polymer injectivity in porous media using unfiltered partially hydrolyzed polyacrylamide (HPAM) solutions for wide range of polymer concentrations (125-5000 ppm) and salinities (5-20 g/L) in high permeability sandstones. Data from rheological measurements and single phase linear core flood studies carried out as a part of this study were utilized for understanding the key microscopic (pore level) mechanisms and for quantifying the injectivity.Based on the experimental analyses, it was found that viscous nature of polymer solutions and their retention in porous media were the main mechanisms for loss in injectivity. Data obtained from the experiments were used to validate and fine tune the model. Subsequently, with the help of the Langmuir adsorption isotherm, filtration theory, permeability reduction model, Non-Newtonian viscosity and Darcy laws numerical modeling was performed for predicting the injectivity losses during polymer injection. A good quality match was obtained with experimental data. Finally, sensitivity of polymer concentration and salinity on injectivity was studied. Further, the results from this study, will serve as an auxiliary input for field scale simulations, will help operators in the selection, design and execution of the field projects and will stand as guidelines for extending the polymer flooding technology for heavy oil reservoirs.

Analytical validation of a second-generation immunoassay for the quantification of N-terminal pro–B-type natriuretic peptide in canine blood

“…13 The second-generation assay utilizes 2 unique anti-canine NT-proBNP antibodies that are specific to distinct epitopes of canine NT-proBNP. These antibodies recognize different epitopes in a more stable region 18 of the NT-proBNP molecule compared with the antibody pair used in the first-generation assay. The change in epitope recognition eliminates the need for the protease inhibitor tube.…”

Assessment of Polyacrylamide Based Co-Polymers Enhanced by Functional Group Modifications with Regards to Salinity and Hardness

“…After preparing a brine solution with either NaCl or CaCl 2 -NaCl, it was placed under a propeller stirrer, and rotation at 700 rpm started just before adding polymer powder. This high-speed rotation at the time of polymer addition and the process of slowly adding polymer into the solvent was required to avoid agglomeration of polymer particles, which may be formed if the powder does not become wetted evenly [22,29]. Aluminum foils were used to cover the sample beakers so as to minimize solution contact with air.…”

Pressure Behavior and Fracture Development During Polymer Injection in a Heavy Oil Saturated Unconsolidated Sand

“…The reason is that the presence of a very viscous oil decreases the effective porosity and permeability for the polymer. It is known from earlier work (Yerramilli et al, 2013;Zitha et al, 1995Zitha et al, , 2001Zitha and Botermans, 1998) that the rate of increase of the injection pressure due bridging adsorption is much faster at lower permeabilities. Therefore, as explained above, injection pressure increases rapidly reaching the critical values for the failure of the near-wellbore.…”