Experimental Investigation of the Rise Behavior of Live-Oil Droplets during Deep-Sea Oil Spills

Transcription

1 Marine Technology Society (MTS) / Gulf of Mexico Research Initiative (GoMRI) Advancing Oil Spill Research Part 2 Webinar, March 13, 2018 Experimental Investigation of the Rise Behavior of Live-Oil Droplets during Deep-Sea Oil Spills Simeon Pesch 1, Marc Maly 1, Philip Jaeger 2, Karen Malone 3, Dieter Krause 3, Michael Schlüter Institute of Multiphase Flows, Hamburg University of Technology, Hamburg, Germany 2 - EUROTECHNICA GmbH, Bargteheide, Germany 3 - Institute of Product Development and Mechanical Engineering Design, Hamburg University of Technology, Hamburg, Germany

2 MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 2

3 Pressure release during blowout and droplet ascent supersaturation Gas bubbles form and grow within the droplet Three complementary effects of degassing 1. Gas density decreases with decreasing pressure 2. Internal gas holdup increases overall density decreases as pressure decreases ρ ҧ = 1 ε gas ρ oil + ε gas ρ gas 3. Diameter of the droplet (assumed spherical) increases with decreasing pressure: Mathematical procedure Eo = g Δρ d p 2 σ H = 4 3 Eo M d p = 3 6 V p π, V p = V oil + V CH4, M = g μ c 4 Δρ ρ c 2 σ 3, Re = ρ c d p u p μ c μ c Pa s J = 0.94 H < H 59.3 ; J = 3.42 H H > 59.3 u p = Internal degassing μ c ρ c d p M J (M < 10 3, Eo < 40, Re > 0.1) initial diameter d p,0 = 1 mm [Clift, R.; Grace, J.R.; Weber, M.E. (1978): Bubbles, Drops, and Particles, Academic Press, University of California, ISBN: ] MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 3

4 Experimental setup I Experimental high-pressure facility with direct optical access for high-speed camera Presaturation of oil with methane for generating live oil Determination of droplet size/shape and rise velocity in counter-current flow Pressure is reduced according to decreasing water depth max. pressure saturation pressure 15 MPa up to 25 MPa temperature 4 35 C data acquisition pressure, temperature, mass flow, HD video [Pesch, S.; Jaeger, P.; Jaggi, A.; Malone, K.; Hoffmann, M.; Krause, D.; Oldenburg, T.B.P.; Schlüter, M. (in press): Rise Velocity of Live-Oil Droplets in Deep-Sea Oil Spills, Environ. Eng. Sci., doi: /ees ] MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 4

5 Experimental results I calculated curve experimental result Predicted behavior can be confirmed qualitatively, but: Shrinking due to dissolution Delayed droplet growth Gas bubble nucleation MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 5 LSC oil, Item ID: A010BB, 20 C [Pesch, S.; Jaeger, P.; Jaggi, A.; Malone, K.; Hoffmann, M.; Krause, D.; Oldenburg, T.B.P.; Schlüter, M. (in press): Rise Velocity of Live-Oil Droplets in Deep-Sea Oil Spills, Environ. Eng. Sci., doi: /ees ]

6 Reservoir conditions Crude oil is saturated with natural gas in the reservoir at high pressure Pressure decrease during blowout and droplet rise from bubble point curve into two-phase region: Potential bubble formation Pressure, MPa [Hickman, S.H.; Hsieh, P.A.; Mooney, W.D.; Enomoto, C.B.; Nelson, P.H.; Mayer, L.A.; Weber, T.C.; Moran, K.; Flemings, P.B.; McNutt, M.K. (2012): Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout, PNAS 109 (50), , doi: /pnas ] [Satter, A. & Iqbal, G.M. (2016): Reservoir Engineering, Gulf Professional Publishing, Waltham, MA, ISBN: ] MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 6

7 Bubble nucleation Classical nucleation theory: J = J 0 exp 4 π σ R c 2 3 k T Critical nucleation radius: R c = 2 σ Δp c J: Rate of nucleation J 0 : Preexponential factor σ: Interfacial tension k: Boltzmann constant; J K T: Temperature Δp c : Critical pressure difference depressurization gas solubility decreases supersaturation accumulation of gas molecules cluster formation bubble formation diffusion into bubble, gas volume expands bubble grows Theory of preexisting bubbles: Preexisting (micro) bubbles, even under pressure Stabilization of bubbles by natural surfactants Pressure decrease leads to reactivation of bubbles Activation threshold radius: R c = 2 σ Δp c [Blander, M.; Katz, J.L. (1975): Bubble nucleation in liquids, AIChE Journal 21 (5), , doi: /aic ] [Taki, K. (2008): Experimental and numerical studies on the effects of pressure release rate on number density of bubbles and bubble growth in a polymeric foaming process Chem. Eng. Sci. 63 (14), , doi: /j.ces ] R c (Δp c ) [Bauget, F.; Lenormand, R. (2002): Mechanisms of Bubble Formation by Pressure Decline in Porous Media: a Critical Review, SPE 77457, doi: /77457-MS] MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 7

8 Experimental setup II evaluation of droplet size evolution by volume integration determination of Δp c Experimental high-pressure facility with direct optical access for video camera Presaturation of oil with methane for generating live oil Sessile oil droplet in artificial seawater Determination of droplet size over time Pressure is reduced according to decreasing reservoir pressure / water depth pressure saturation pressure pressure release rate ~ 25 0 MPa 25 MPa 0.5, 1.0 MPa/min temperature 10, 20 C data acquisition pressure, temperature, HD video LSC oil, Item ID: A010BE MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 8

9 Experimental results II methane-saturated oil droplet in artificial seawater, pressurized with methane different equilibration times, temperatures and pressure release rates Example series: equilibration time: > 20 h initial pressure: 23 ± 0.8 MPa Pressure release rate: 1.0 MPa/min T 0 / C V 0 / mm 3 Δp c / MPa 20.7 ± ± Δp c 12.3 MPa MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 9

10 Experimental setup III back pressure regulator for quick pressure release before experiment saturation pressure to experimental pressure Experimental high-pressure facility with direct optical access for high-speed camera Presaturation of oil with methane for generating live oil Determination of droplet size/shape and rise velocity in counter-current flow Pressure is reduced according to decreasing water depth max. pressure saturation pressure 15 MPa up to 25 MPa temperature 4 35 C data acquisition pressure, temperature, mass flow, HD video MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 10

11 Experimental results III 0 s 100 s 250 s 300 s 350 s 400 s No initial shrinking Less time delay Progressive droplet growth Nucleation barrier is overcome Experimental curve represents predicted behavior (qualitatively) well MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 11

12 Conclusion (Super)saturation of oil with gaseous components must beconsidered for modeling deep-sea oil well blowouts Influence on initial droplet size distribution Bubble formation inside rising droplets increases their buoyancy Dissolution of gas components into surrounding water phase High pressure and strong pressure decrease during blowout and droplet rise Gas bubble nucleation is crucial for investigated effects If critical pressure difference is overcome, bubbles form and grow R c = 2 σ Δp c Experimental results confirm predicted effects Critical pressure difference has been determined Supersaturation due to initial pressure release Droplet growth during droplet rise under deep-sea conditions MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 12

13 Acknowledgement Thank you for your attention! In close collaboration with This research was made possible by a grant from The Gulf of Mexico Research Initiative. Data are publicly available through the Gulf of Mexico Research Initiative Information & Data Cooperative (GRIIDC) at (doi: /N7F18X57, doi: /N79885GB). MTS / GoMRI Webinar Advancing Oil Spill Research Part 2 March 13, 2018 Simeon Pesch 13