Optimization of polymer performance for Enhanced Oil Recovery (EOR) at elevated temperatures and high salinity using polymers integrated technique

  • Kingsley Uranta

    Student thesis: Doctoral Thesis

    Abstract

    The most common synthetic polymers used for enhanced oil recovery (EOR) are polyacrylamide (PAM) and partially hydrolysed polyacrylamide (HPAM). Improving the performance of these water-soluble polymers would involve satisfying various specifications, including good solubility in water, good injectivity, and the polymer solution’s ability to maintain relatively optimum viscosity under the influence of challenging reservoir conditions such as high temperature, shearing and high water salinity during EOR polymer flooding applications.
    The mechanisms of PAM performance and stability under reservoir conditions are not clearly understood. In addition, a satisfactory technique for laboratory to evaluate, optimise and enhance the polymer performance before EOR applications integrated from laboratory is still not available.
    In recent times, the oil industry has shown increasing awareness towards maintaining optimum polymer selection and stability under reservoir conditions for the EOR applications through cost effective and better polymer design.
    This thesis presents a new synthetic approach called the polymer integrated technique (PIT) which can predict impact of environment and operational conditions on polymer performance and improve stability of PAM from extensive laboratory measurements carried out on formation water and polymers.
    In this study, the results of in-depth experimental research into polymer stability at elevated temperature, moderate and high salinity, different shear rates and ageing time and the relationships between them are presented. Correlation analysis was first conducted to determine the safe maximum temperature point (SMTP) for PAM in saline solution. It was found that different saline solutions like NaCl, CaCl2 and NaHCO3 possess different SMTPs. The proposed correlations provide a means of predicting the stability of PAM for reservoirs with different temperature, salinity and shear rates conditions. The effectiveness of the application of PAM in hydrocarbon reservoirs at different operational conditions was then investigated.
    Polyvinylpyrrolidone (PVP) and 2-acrylamido-2- methylpropanesulphonic acid (AMPS) was incorporated at different stages into the optimized polymer solution to stabilize and improve performance of PAM solutions at high temperature and extremely high water salinity. The Fourier transform infrared (FTIR) and Nuclear Magnetic Resonance (NMR) were utilised to determine the degree of hydrolysis of the integrated PAM, PVP and AMPS polymer solution. Fann model 35 Couette and a Cole Parmer, were utilized to measure solution viscosity at different shear rates.
    A number of results are presented to illustrate how the new PIT can be used to characterize and optimise best fit mixture composition selection, evaluate polymer performance and stability. The PIT is useful as a design and analysis technique for EOR applications in the lab and in the field. Recommendations are also made for further work on this fascinating field of study based on polymer integrated technique developed in this research.
    Date of Award1 Sep 2019
    Original languageEnglish
    Awarding Institution
    • Teesside University
    SupervisorSina Rezaei Gomari (Supervisor), Faik Hamad (Supervisor) & Paul Russell (Supervisor)

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