Effect of produced water salinity on wax precipitation in oil

1. Effect of produced water salinity on wax precipitation in oil TPG 4520 - Specialization CourseCarolin GjengedalDepartment for Petroleum Engineering and Applied Geophysics June 10th, 2013

2. Outline • Part 1: Background Information • Part 2: Case Study • Discussion

3. Wax Napthenic Hydrocarbons General FormulaofParaffin Paraffin Wax Microcrystalline Wax (Source: G. A Monsoori)

4. Colloidal Dispersion Two-phase system consisting of particle/drops/bubbles of one phase dispersed in another continuous phase. Dispersed Phase Continuous Phase • Emulsions: Liqiud dispersed in liquid • W/O Emulsion • Suspensions: Solid dispersed in liquid • Wax (1 nm – 10 μm)

5. Van der Waals Forces Attractive forces between atoms, molecules or particles: Attractive interaction energy Between two spherical Particles of the same radii, Rs Rs Rs Separation between particles: d

6. The Electrical Double Layer • Variation in the ion density near a charged surface. • When a charged particle is present in an aqueous solution it is influenced by the ionic strengt in the solution. • Counter-Ion: Ion of opposite charge • Co-Ion: Ion of equal charge (Source: G. Øye)

7. Aggregation- ColloidalInstability Stable Suspension UnstableSuspension

8. Zeta PotentialDescribing Colloidal Stability Henry´s Equation: ζ: Zeta potential.u : Electrophoretic mobility. ε: Dielectric constant.η: Viscosity κ: Debye-Hückel parameter Rs: Particle radius ƒ(κRs) : Henry’sfunction. Used to calculate the Zeta Potential (ZetasizerNano Series )

9. Colloial Stability & DLVO Theory(Derjagin-Landau and Verwey-Overbeek) Interaction energy between dispersed particles Van der Vaals Attraction ΦTot= ΦR+ΦA Φ = Interaction energy R = Repulsive A = Attractive Electrostatic Repulsion

10. Colloidal Stability & DLVO Theory(Derjagin-Landau and Verwey-Overbeek) Total Ineraction Energy • Energy minimum : Coagulation – Instability • Energy barrier : Obstacle to Coagulation - Stable • Secondary minimum : Reversible Aggregation (Source: G. Øye)

11. Colloidal Stability & DLVO Theory(Derjagin-Landau and Verwey-Overbeek) • High zeta potential  Large repulsion between particles • Large Hamaker constant  Large attraction between particles

12. Water TDS = Total Dissolved Solids (Source: Gudmundsson, 2009)

13. Water (M. Abdou et al., 2011)

14. Paraffinic Hydrocarbons in Aqueous Suspensions (S. N. Srivastavaand D. A. Haydon, 1963) Aggregation of paraffin wax suspension depending on electrolyte concentration

15. Electro kinetic Properties of Paraffin Suspensions In Water & Electrolyte Solutions(E. Chibowski et al., 2005) PREPARATION • 100 mL of water or electrolyte solution was heated to 68-70 °C • 0,1 g of pharmaceutical paraffin wax was added. The paraffin melted at this temperature • The content was homogenized • The suspension of solid particles of paraffin was obtained by cooling • ELECTROLYTES • NaCl • LaCl3 • Natural pH of the suspension • In water: 6.6 (+- 0.2) • In NaCl: 6,8 • In LaCl3: 6,64-6,68

16. Electro kinetic Properties of Paraffin Suspensions In Water & Electrolyte Solutions(E. Chibowski et al., 2005) MEASUREMENT POINTS: • 40 min • 50 min • 60 min • 70 min • 80 min • 90 min • 120 min • 24 h • SOLUTIN pH: • pH = 4 • pH = Neutral • pH = 10

17. Electro kinetic Properties of Paraffin Suspensions In Water(E. Chibowski et al., 2005) Zeta potentialsofparaffinparticles in water at different pH and time. Bars = Standard errors.

18. Electro kinetic Properties of Paraffin Suspensions In Electrolyte Solutions(E. Chibowski et al., 2005 ) Zeta potensials ofparaffinparticles in 10-4 M NaCl at different pH and time Zeta potensials ofparaffinparticles in 10-4 M LaCl3 at different pH and time

19. Electro kinetic Properties of Paraffin Suspensions In Electrolyte Solutions(E. Chibowski et al., 2005 ) Zeta potensials ofparaffinparticles in 10-3M NaCl at different pH and time Zeta potensials ofparaffinparticles in 10-3M LaCl3 at different pH and time

20. Summarized • Ion concentration is affectingthe zeta potential, whichagain is reflecting a suspensionsstability • Higher ion concentrationwilldestabilize water-waxsuspensions

21. Discussion • Salt will have almost no influence on wax precipitation because the salt is sustained in the aqueous phase, and wax is sustained in the oil phase. • The wax will not be in contact with the salt in the water phase, and the salt will not be in contact with wax in the oil phase

22. Discussion • Wax precipitation depends almost entirely on the temperature and temperature gradients. (Kristofer Paso – Kjemi, NTNU)

23. References • Chibowski, Emil, Agneszka Ewa Wiacek, LucnaHolysz, og Konrad Terpilowski. «InvestigationoftheElectrokinetic Properties ofParaffinSuspension. 1. In InorganicElectrolyte Solutions .» Paper, Department ofPhysicalChemistry, FacultyofChemistry, Maria Curie-SklodowskaUniversity, 2005. • Guðmundsson, Jón Steinar. TPG 4135, Prosessering av Petroleum, Grunnleggende enhetsoperasjoner i produksjon av olje og gass. . Trondheim: Department of Petroleum Engineering and Applied Geophysics, 2009. • Hiemenz, Paul C, og RajRajagopalan. PrinciplesofColloid and SurfaceChemistry. 1997. • Mansoori, GA. «Thermodynamics Research Laboratory.» The Universityof Illinois at Chicago. http://tigger.uic.edu/~mansoori/TRL_html (funnet June 9, 2013). • Medhat, Abdou, et al. Finding Value in Formation Water. Report, Schumberger, OilfieldReview Spring, 2011. • Nelson, Jessica DeGroote, Drucker, Jarrett A, Andrew A Haefner, og Robert A Wiederhold. «Varyingelectro-kineticinteractions to achievepredictableremoval rates and smoothsurfacesonZnS .» 2009. • Ocean Health . Ocean Health. 9 June 2013. http://oceanplasma.org/documents/chemistry.html. • Sirvastava, S. N, og D. A Haydon. «EstimateoftheHamakerCOnstant For ParaffinicHydrocarbons in AqueousSuspensions.» Paper, Department ofColloidScience, Universityof Cambridge, 1963. • Gisle Øye, Lecture notes in TKP4115 Surface- and ColloidChemistry • ZetasizerNano Series. «Zeta Potentialtheory.» http://www.nbtc.cornell.edu/facilities/downloads/Zetasizer%20chapter%2016.pdf.