Investigation of the crude oil/brine interaction through interfacial viscoelasticity and microdispersion

Peyman Nazifi

Research output: ThesisMaster's Thesis

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Abstract

Smart waterflooding in hydrocarbon reservoirs has been a topic of profound conjecture. Several recovery mechanisms have been proposed for the process, including wettability alteration toward water-wetness. On the other hand, less attention has been given to the fluid-fluid interactions. The long-held hypothesis that the Low Salinity Effect (LSE) depends mainly on rock and fluid interactions has led to occasional failures that fluid-fluid interactions can explain. Therefore, improving our knowledge about the microscopic interactions in the crude oil/brine/rock systems appears to be vital. In this study, the emphasis is on the two fluid/fluid mechanisms proposed recently, namely the interfacial viscoelasticity and microdispersion. Hence, interface viscoelasticity and formation of water in oil microdispersions are investigated experimentally and analytically. The impact of the aqueous phase ionic strength and ionic composition are examined on the viscoelastic properties of the crude oil/brine interfacial film by conducting interfacial dilatational rheological measurements under controlled water chemistry. Interfacial viscoelasticity measurements were conducted on three Austrian crude oils. In general, the viscoelastic properties of the interface have a reverse relationship with the brine salinity reduced no matter what type of ions are present in the brine. However, the rate of elasticity build-up depends upon specific ions present in the solution as well as crude oil properties. The interface viscoelasticity for NaCl solutions and crude oil increased continuously as the salt concentration decreased. However, it increased non-monotonically until a maximum in viscoelasticity was observed, at 10,000 ppm for a pure solution NaCl with 2.5% Na2SO4. The interfacial film response depends on the combined characteristics of crude oil and water and the aging time between two fluids. A good correlation was developed for the oil property, namely, the acidic component and the oil viscosity and interfacial mechanical moduli. This correlation might indicate that the adsorption of polar materials onto the interface can be considered a diffusion-like process. The analytical investigation of the available microdispersion data from the literature revealed the importance of crude oil acidic components as the main contributing factor in the formation of water in oil microdispersions. Furthermore, the total brine salinity was determined as the main factor regarding the brine properties with a negative correlation factor. Thus, the outcomes of the statistical investigation of the microdispersion ratio were in agreement with the observations done in the literature, whereby the oil acidic components were detected as the main crude oil fractions contributing to the microdispersion formation.
Translated title of the contributionUntersuchung der Wechselwirkung zwischen Rohöl und Salzlösung durch Grenzflächenviskoelastizität und Mikrodispersion
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Kharrat, Riyaz, Supervisor (internal)
Award date25 Jun 2021
Publication statusPublished - 2021

Bibliographical note

embargoed until null

Keywords

  • Enhanced Oil Recovery
  • Low Salinity Water
  • Interfacial Viscoelasticity
  • Micro Dispersion Ratio

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