university of split, croatia royal institute of technology, stockholm, sweden

Risk Conference 2008, CephaloniRisk Conference 2008, Cephalonia, Greece, 5-7 Maya, Greece, 5-7 May

11

University of Split, CroatiaUniversity of Split, Croatia

Royal Institute of Technology, Stockholm, Royal Institute of Technology, Stockholm, SwedenSweden

Hrvoje Gotovac, PhD studentHrvoje Gotovac, PhD student

RISK ASSESSMENT RISK ASSESSMENT FROMFROM THE THE OIL WASTE DISPOSAL IN DEEP OIL WASTE DISPOSAL IN DEEP

WELLSWELLS

by R. Andricevic, H. Gotovac, M. Loncar and by R. Andricevic, H. Gotovac, M. Loncar and

V. SrzicV. Srzic


22

PRESENTATIONPRESENTATION

IntroductionIntroduction Computational setupComputational setup Flow and transport analysis of the Flow and transport analysis of the

injected oil waste in deep wellsinjected oil waste in deep wells Risk assessmentRisk assessment of the oil waste of the oil waste

disposal methodology (disposal methodology (exceeding riskexceeding risk)) ConclusionsConclusions


33

1. Introduction1. Introduction


44

Krovina

Podina

Kontroliranoinjektiranje

smjese

Pružanjefrakture nastale

injektiranjem

Waste injection

Impermeable

cap rock

Waste spreading

Impermeablebed rock

Suitable geological formation prevent wasteSuitable geological formation prevent waste propagationpropagation to the surfaceto the surface with negligiblewith negligible

risk of polluting shallow aquifers

waste disposal in a safe waste disposal in a safe and efficiant mannerand efficiant manner


55

Oil waste injection in deep Oil waste injection in deep wellswells


66

DEEP WELL INJECTION


77


88

Construction of deepConstruction of deep well well

Pi=95 bar

Q=250-300 l/min

Ph=145 bar

Fracture gradient=1,74 bar/10 m

Injected up to date

150,000 m3

Marl

Sandstone


99

2. Computational 2. Computational setupsetup


1010

Map of the oil field Žutica Map of the oil field Žutica (Croatia)(Croatia)


1111

Selection of appropriate Selection of appropriate geologic formations for oil geologic formations for oil waste injection in oil field waste injection in oil field

Žutica (Croatia)Žutica (Croatia) 0-500 m (sand and clay layers)0-500 m (sand and clay layers) 500 – 1000 m (sandstone and clay layers)500 – 1000 m (sandstone and clay layers) 1000 – 2500 m (sandstone and marl layers)1000 – 2500 m (sandstone and marl layers) Injection zone is located at depth around Injection zone is located at depth around

2000 (m) and consists of sandstone and 2000 (m) and consists of sandstone and marl layersmarl layers


1212

Selection of appropriate deep Selection of appropriate deep well for oil waste disposalwell for oil waste disposal

Deep well Žutica – 273 Deep well Žutica – 273 Open holes at 1976-1985 (m), 1994-Open holes at 1976-1985 (m), 1994-

2021 (m) and 2038-2055 (m) 2021 (m) and 2038-2055 (m) Injection fluid density is 1006 – 1020 Injection fluid density is 1006 – 1020

kg/mkg/m33, injection time period is 20 , injection time period is 20 yearyearss and injection capacity is and injection capacity is 30 30 mm33/day/day


1313

y = 0.7648x - 1.0071

R2 = 0.7492

0

50

100

150

200

250

0 20 40 60 80 100 120 140 160 180 200

kx

ky

Regression between core Regression between core horizontal and vertical horizontal and vertical

permeabilitypermeability


1414

SSpontaneouspontaneous potential potential

Depthi (m)

Sp

on

tan

ip

ote

nc

ijal

(mV

)

1850 1900 1950 2000 2050 2100 2150-90

-75

-60

-45

-30

-15

0

15


1515

Injectivity testInjectivity test

260

262

264

266

268

270

272

274

276

278

280

0 100 200 300 400 500 600 700 800 900 1000

Q_injection m^3/day

pre

ss

ure

, b

ar


1616

3. Flow and 3. Flow and transport transport analysisanalysis


1717

Stochastic approachStochastic approach Natural variability of the geological Natural variability of the geological

formations as well as lack of the formations as well as lack of the measurementsmeasurements

Results are given in the form of two first Results are given in the form of two first statistical moments: mean and variancestatistical moments: mean and variance

Spectral method, small perturbation Spectral method, small perturbation and Monte-Carlo method and Monte-Carlo method

For highly heterogeneous formations For highly heterogeneous formations and oil waste disposal Monte-Carlo is and oil waste disposal Monte-Carlo is the most powerful and robust method the most powerful and robust method


1818


1919

Monte-Carlo method for Monte-Carlo method for analysis of oil waste disposal in analysis of oil waste disposal in

the deep wells the deep wells Measurements (geological, laboratory, core tests, Measurements (geological, laboratory, core tests,

slug tests, surface and deep seismic, slug tests, surface and deep seismic, spontaneous potential, resistance, temperature, spontaneous potential, resistance, temperature, sound, tracer injection,…)sound, tracer injection,…)

Geostatistical analysis of conductivity field and Geostatistical analysis of conductivity field and generation of large number of conditional generation of large number of conditional realizationsrealizations

Flow solution using the conventional finite Flow solution using the conventional finite difference method in the each realization difference method in the each realization (MODFLOW)(MODFLOW)


2020

Transport solution in the each Transport solution in the each realization (PTRACK)realization (PTRACK)

Tracking large number of particles (200 Tracking large number of particles (200 000)000)

Statistical ensemble averaging over the Statistical ensemble averaging over the whole collection of realizations (100)whole collection of realizations (100)

Results are total mass through top side Results are total mass through top side of the injection zone, displacement and of the injection zone, displacement and concentration field concentration field


2121

2000

2200

5.056E+06

5.0565E+06

5.057E+06

5.0575E+06

5.058E+06

6.3775E+06

6.378E+06

6.3785E+06

6.379E+06

6.3795E+06

XY

Z

lapor

pjescenjak

INDIKATOR

Geostatistical indicator Geostatistical indicator analysis of sandstone and marl analysis of sandstone and marl

zoneszones


2222

2000

2200

5.056E+06

5.0565E+06

5.057E+06

5.0575E+06

5.058E+06

6.3775E+06

6.378E+06

6.3785E+06

6.379E+06

6.3795E+06

XY

Z 9E-077E-075E-073E-071E-078E-086E-084E-082E-081.5E-08

K (m/s)

Geostatistical analysis of the Geostatistical analysis of the sandstonesandstone


2323

2000

2200

5.056E+06

5.0565E+06

5.057E+06

5.0575E+06

5.058E+06

6.3775E+06

6.378E+06

6.3785E+06

6.379E+06

6.3795E+06

XY

Z

6E-093E-091E-099E-107E-105E-103E-102.7E-10

K (m/s)

Geostatistical analysis of the Geostatistical analysis of the marlmarl


2424

2000

2200

5.056E+06

5.0565E+06

5.057E+06

5.0575E+06

5.058E+06

6.3775E+06

6.378E+06

6.3785E+06

6.379E+06

6.3795E+06

XY

Z9E-075E-071E-075E-081E-085E-091E-095E-102.7E-10

K (m/s)

Final geostatistical analysis of Final geostatistical analysis of the injection zonethe injection zone


2525

1850

1900

1950

2000

2050

2100

2150

2200

Z

5.0566E+065.0568E+06

5.057E+065.0572E+06

5.0574E+06

6.378E+06

6.3782E+06

6.3784E+06

6.3786E+06

6.3788E+06

X Y

Z

32823153.83025.62897.42769.226412512.82384.62256.42128.22000

ZU -273

TRECA REALIZACIJA

h (m)

Pressure fieldPressure field


2626

0

0

200002000

Y

Z

X

Frame 001 07 Feb 2007 VELOCITY FIELD IN HETEROGENEOUS POROUS MEDIAFrame 001 07 Feb 2007 VELOCITY FIELD IN HETEROGENEOUS POROUS MEDIA

Velocity field in the one chosen Velocity field in the one chosen realizationrealization


2727


2828

t (godine)

F(%

)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 1000

10

20

30

40

50

60

70

80

90

100

t (godine)

F(%

)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 1000

10

20

30

40

50

60

70

80

90

100

Z3 = 1850 (m)

Z1 = 1950 (m)

Z2 = 1900 (m)

Fraction of the total mass Fraction of the total mass through horizontal control through horizontal control

planesplanes


2929

t (godine)

F(%

)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 1000

10

20

30

40

50

60

70

80

90

100

t (godine)

F(%

)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 1000

10

20

30

40

50

60

70

80

90

100

d3 = 500 (m)

d1 = 100 (m)

d2 = 300 (m)

Fraction of the total mass Fraction of the total mass through vertical control planesthrough vertical control planes


3030

Long-term vertical transport Long-term vertical transport analysisanalysis


3131

4. Risk 4. Risk AssessmentAssessment


3232

Risk assessment (Risk assessment (exceeding exceeding riskrisk))

PProbability that load “L” on the robability that load “L” on the system exceeding the resistance system exceeding the resistance “R” of the system“R” of the system

)( RLPpr

drdllrfpr

r

l

r

LRr

2

1

2

),(,

drrgldlfp R

r

Lr )()(


3333

Risk assessment (exceeding Risk assessment (exceeding risk)risk)

L - vertical spreading of the injected L - vertical spreading of the injected oil waste oil waste

R - vertical position of aquifer for R - vertical position of aquifer for water supply water supply

Alternatively, exceeding risk for Alternatively, exceeding risk for some defined time period can be some defined time period can be calculated using the travel time pdfcalculated using the travel time pdf

L

ldlfp Lr

0

)()(


3434

Risk assessment (Risk assessment (exceeding exceeding riskrisk))

Short-term Short-term exceedingexceeding risk ( risk (pprr =10=10 -3-3 for periodfor period t=100 year t=100 year ; Z = 1850 m); Z = 1850 m)

Long-term Long-term exceedingexceeding risk ( risk (pprr =10=10 -47-47 for periodfor period t=10 t=10 000000 year year; Z = 500 ; Z = 500 mm ))


3535

5. Conclusions5. Conclusions

Using all hard and soft input data to reduce Using all hard and soft input data to reduce uncertainty of the flow and transport analysisuncertainty of the flow and transport analysis

Short-term (Short-term (pprr =10 =10 -3-3 for period for period t=100 year t=100 year ) ) and long-term exceeding risk (and long-term exceeding risk (pprr =10 =10 -47-47 for for periodperiod t=10 000 year t=10 000 year ) )

Safe and reliable Safe and reliable oil oil waste disposal waste disposal methodology also appropriate for other methodology also appropriate for other hazardous wasteshazardous wastes

Consideration of other real physical effects as Consideration of other real physical effects as unsteady velocity fields, sorption or pore-unsteady velocity fields, sorption or pore-scale dispersion which considerably reduce scale dispersion which considerably reduce exceeding risk exceeding risk

university of split, croatia royal institute of technology, stockholm, sweden

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