Numerical simulations of oil contaminant transport in sandy coastal aquifers

Presenter： Yi-Ming Wei

Adviser： Chuen-Fa Ni

Date： 2011/04/21

Outline

Motivation Objectives Methodology Test example Future work

Motivation

With the increasing developments of tourist and industrial

estates in coastal area, different sources of contaminants

can be discharged into the sea.

Marine pollution ： Oil spills happen when people make

mistakes or are careless and cause an oil tanker to leak

oil into the ocean.

彭薩科拉海灘 ( Pensacola)

Objectives

when a petroleum spill reaches the beaches, there may be

deeper penetration in the soil, which depends on sand grain

size, so causing serious damages to the ecosystem.

(1) how much and how deep oil is transported into the beaches.

(2) Whether oil polluted groundwater or not.

(3) Other factor of influence oil transportation ： tidal 、 wave 、

beach slope 、 pumping well 、 recharge water …

Methodology-HYDROGEOCHEM-2D

A coupled model of fluid flow, thermal transport, and

HYDROGEOCHEMical transport through saturated-

unsaturated media.

Deal with equilibrium and kinetic reaction in terms

of reaction networks.

Incorporate the effect of precipitation /dissolution

on the change of pore size, hydraulic conductivity,

and diffusion/dispersion.

Flow Equations

0 0 0

ee

00

s r

00

hF K ( h+ z) q

t

dSF n

n dh

gg

K k k k

1F is storage coefficient

L

1q is the source/sink

T

3

M is fluid density with dissolved chemical concentrations

L

0 3

M reference fluid density at zero chemical concentration

L

3

M is the density of the injected fluid

L

is effective moisture content1

is the modified compressibility of the soil matrixL

1

is modified compressibility of the liquidL

2sk is saturated permeability tensor L

rk is relative permeability or relative hydraulic conductivity

2 is degree of effective saturation of water LS

Reactive Chemical Transport Equations

ii f j j i

C( C V ) J r M

t

The rate of mass accumulation

The net rate of mass flux due to advection

The net mass flux due to dispersion and diffusion,

The rate of mass production and reduction due to chemical reactions and radioactive decay

The source/sink term corresponding to artificial injection and/or withdrawal

iC

t

i f( C V )

jJ

jr

iM

j i T L T mJ C a V (a a )VV / V aD

Test example

Pressure head= 85m

400 m

100 m

Pressure head= 84m

Impermeable bottom

Variable boundary condition

15 /K m day porosity of the aquifer = 0.35

Slope

Pressure head= 85m

400 m

100 m

Pressure head= 84m

Impermeable bottom

Beach slope = 0.2、 0.3

No rainfall

1.0 mole/liter ( C6H6)

x (m)

z(m)

0 100 200 300 4000

50

1008685.885.685.485.28584.884.684.484.2

0 100 200 300 4000

50

100

Beach slope = 0.2

Beach slope = 0.3

Total head

x (m)

z(m

)

0 100 200 300 4000

50

100 8685.885.685.485.28584.884.684.484.2

0 100 200 300 4000

50

100

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

Beach slope = 0.2

Beach slope = 0.3

12day

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

Beach slope = 0.2

Beach slope = 0.3

27day

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

Beach slope = 0.2

Beach slope = 0.3

46day

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

I = 0.01 m/day

Recharge

Pressure head= 85m

400 m

100 m

Impermeable bottom

Pressure head= 84m

Beach slope = 0.2

1.0 mole/liter ( C6H6)

x (m)

z(m)

0 100 200 300 4000

50

1008685.885.685.485.28584.884.684.484.2

0 100 200 300 4000

50

100

Total head

No rainfall

x (m)

z(m)

0 100 200 300 4000

50

1008685.885.685.485.28584.884.684.484.2

0 100 200 300 4000

50

100

I = 0.01 m/day

27day

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

No rainfall

I = 0.01 m/day

x (m)

z(m)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

Pumping well

Pressure head= 85m

400 m

100 m

Impermeable bottom

Beach slope = 0.2

No rainfall

1.0 mole/liter ( C6H6)

Pressure head= 84m

-20 m2/day(抽水 )

Total head

x (m)

z(m)

0 100 200 300 4000

50

1008685.885.685.485.28584.884.684.484.2

0 100 200 300 4000

50

100

no pumping well

pumping well

x (m)

z(m)

0 100 200 300 4000

50

100

8685.885.685.485.28584.884.684.484.28483.883.683.483.283

0 100 200 300 4000

50

100

27day

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

pumping well

no pumping well

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

46day

pumping well

no pumping well

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

x (m)

z(m

)

0 100 200 300 4000

50

100

0.950.90.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.05

Future work

Thanks for your attention