using locas software to predict the long-term behavior of salt caverns

USING LOCAS SOFTWARE
TO PREDICT
THE LONG-TERM BEHAVIOR
OF SALT CAVERNS
Technical Class
SMRI Fall Meeting – Leipzig, Germany
October 3, 2010
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OUTLINE
• Introduction – LOCAS main features
• Example of application: cavern abandonment
• Conclusions
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QUICK INTRODUCTION
WHAT IS LOCAS?
• A 2D axisymetrical Finite Element code
• Af fully coupled dThermo-Hydro-Mechanical h code
• A powerful —but user-friendly— Windows ® software
WHAT IS IT FOR?
• Study of liquid-filled or gas-filled salt caverns
• Short-term and long-term behavior of caverns
Examples of applications:
• Stability of cavern at min/max pressure, cycling
• Analysis of Mechanical Integrity Tests
• Abandonment of salt caverns
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EXAMPLE OF APPLICATION
CAVERN ABANDONMENT
Carresse SPR2 cavern test supported by SMRI
300 m
9000 m 3
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KEY POINTS IN THE ANALYSIS OF AN ABANDONMENT TEST
• PRELIMINARY TASKS
Task 1: Calculate cavern pressure evolution during the test
Task 2: Calculate long-term cavern temperature evolution
Task 3: Assess casing/casing shoe leaks during the test
• DETERMINATION OF SALT PARAMETERS
- Mechanical parameters
• elasticity
• secondary creep (Norton-Hoff)
- Hydraulical parameters: salt permeability at cavern scale
• LONG-TERM FEM COMPUTATIONS PREDICTIONS
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ANALYSIS OF A PRE-ABANDONMENT TEST
Wellhead measurements Sonar survey Cavern temperature measurement
Cavern pressure evolution Cavern mesh Cavern temperature evolution
Cavern fluid(s) properties
Rock salt properties
LONG-TERM COMPUTATIONS
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ANALYSIS OF A PRE-ABANDONMENT TEST
Wellhead measurements Sonar survey Cavern temperature measurement
Cavern pressure evolution Cavern mesh Cavern temperature evolution
Cavern fluid(s) properties
Rock salt properties
LONG-TERM COMPUTATIONS
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Task 1: Determination of cavern pressure evolution during the test
Pressures measured at well head
Cavern pressure
Well data
• columns composition
• temperature log
• fluids compressibilities
• possible leaks
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History of Wellhead Pressures
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History of Ground Temperature
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History of Atmospheric Pressure
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A FILTERING TOOL IS EMBEDDED
Wellhead pressure
Ground temperature
Atmospheric pressure
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Measured pressure
Corrected pressure
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Earth tides
Right-click on corrected pressure spectrum
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Task 1: Determination of cavern pressure evolution during the test
Corrected pressures at well head
Corrected cavern pressure
Well data
• columns composition
• temperature log
• fluids compressibilities
• possible leaks
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Well Data in LOCAS
Strings database
Fluids database
Rocks database
Layers database
Sections database
Stratigraphic cross-section view
Well architecture view
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LIQUIDS DATABASE
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PURE GASE DATABASE
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NATURAL GASES DATABASE
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SECTIONS DATABASE
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WELL ARCHITECTURE
Section #2
Section #3
Section #5
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INJECTIONS/WITHDRAWALS DATABASE
Data can be loaded from a flow measurement file
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COLUMNS DATABASE
It’s possible to have up to 4 different fluids in each column (3 interfaces)
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HISTORY OF CAVERN PRESSURE
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ANALYSIS OF A PRE-ABANDONMENT TEST
Wellhead measurements Sonar survey Cavern temperature measurement
Cavern pressure evolution Cavern mesh Cavern temperature evolution
Cavern fluid(s) properties
Rock salt properties
LONG-TERM COMPUTATIONS
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CAVERN GEOMETRY IN LOCAS
2D axisymetrical caverns
Simple shape (sphere, cylinder) or Real shape from sonar survey
Av. cavern radius as a function of depth
Embedded mesher
Meshing parameters
Cavern mesh
Meshes databases
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CAVERN PROFILE FROM SONAR SURVEY
Load file from sonar survey
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MESHING PARAMETERS
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MESH VIEW
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3D VIEW
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SPR2
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MESHES DATABASE
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ANALYSIS OF A PRE-ABANDONMENT TEST
Wellhead measurements Sonar survey Cavern temperature measurement
Cavern pressure evolution Cavern mesh Cavern temperature evolution
Cavern fluid(s) properties
Rock salt properties
LONG-TERM COMPUTATIONS
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Task 2: Determination of long-term cavern temperature evolution
- Determination of natural rock temperature T
- Fitting of a cavern temperature measurement
Accurate prediction of
brine temperature evolution
brine thermal expansion
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SPR2 Geothermal Temperature
SPR2 - Logs de température et calage gradients SPR3
Temperature (°C)
Température (°C)
13 14 15 16 17 18 19 20 21
0
50
100
ofondeur / sol (m)
Depth (m)
Pro
150
200
250
300
350
Top of salt
T
19.5 °C
12/06/2002 moyenne
20/08/2002 moyenne
08/10/2002 moyenne
1ères inclusions sel
Sabot Casing
Base Cheminée
Landing Nipple
SPR3 : 2,5 °C/100 m
SPR3 : 1,2 °C/100 m
400
450
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SPR2 TEMPERATURE MEASUREMENT IN 2002
reference
18.35°C – 058°C/year 0.58 37
Cavern Temperature
measurement
T
19.5 °C
Accurate prediction
actual
virtual
Time
July 2002
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SPR2 CAVERN TEMPERATURE FITTING
18.35 °C
+0.58 °C/year
Temperature
1 st June 2000
763 days
1 st July 2002
Time
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ANALYSIS OF A PRE-ABANDONMENT TEST
Wellhead measurements Sonar survey Cavern temperature measurement
Cavern pressure evolution Cavern mesh Cavern temperature evolution
Cavern fluid(s) properties
Rock salt properties
LONG-TERM COMPUTATIONS
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BRINE PROPERTIES
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SALT PROPERTIES
• Mechanical properties
• Elasticity
• Creep: stationnary + transient
4 implemented creep laws
Norton-Hoff
Lemaitre-Menzel-Schreiner
Munson-Dawson
Lubby2
+ possibility of reverse creep using a modified d Munson-Dawson law
• Thermal properties
• Hydraulical properties (micro-permeation)
• Chemical properties (dissolution/crystallization)
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Munson-Dawson Database
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Salt Micro-permeation Properties
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Calculation Steps
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Phenomena that can be taken into account:
• Salt creep
• Cavern fluid heating/cooling
• Cavern fluid micro-permeation
• Salt complementary dissolution/crystallization
• Cavern fluid adiabatic compression/release
Coupled through cavern compressibility
Cavern pressure/temperature and casing leaks
can be set or calculated
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Example of parameters
back-calculation
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Salt parameters to be determined
for long-term computations:
‣ Salt elastic parameters
E,
‣ Salt creep parameters
Stationnary creep: Norton-Hoff parameters
A, nQ , R
‣ Salt hydraulical parameters
hyd
K salt
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Back-calculation of Salt Elastic Parameters
Compressibility
test
V
3
3.97 m /MPa
0.25
assumed
Finite Elements computation
E 16,500 MPa
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STATIONNARY PARAMETERS FITTED FOR TWO PERIODS
Transient phase
2 nd fitting period
1 st fitting period
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Selection of Parameters to be Fitted
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Parameters to be Fitted
Search domain
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Selection of Fitted Periods
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Selection of the Optimization Method
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Fitting results can be emailed
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Worst
(hPa)
lt permeability
Sal
Pressure
computation
measure
Time
Best
Norton A parameter
5×10 -20 m²
4×10 -20 m²
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INVESTIGATION OF FITTING SENSIBILITY
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SPR2 - FITTING MAIN RESULTS
hyd
Salt permeability:
K 3 4
10 m
salt
20 2
Salt stationnary creep:
Q n
Aexp
RT
(Norton-Hoff law)
-n
A (/MPa -year)
n
Q R
(K)
2 possible sets
of parameters
Set #1 2.5 2.5 4100
Set #2 7.8 5 4100
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STATIONNARY PARAMETERS FITTED FOR TWO PERIODS
Average pressure difference < 10 hPa
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Long-term computation
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Norton-Hoff set #1
hyd
K salt
410 m
20 2
n 2.55
2.5
A 2.5 /MPa -year
Q R 4100 K
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SUBSIDENCE CALCULATION
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NO-TENSION CRITERIA, DILATION CRITERIA…
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EXAMPLE OF CONTOUR PLOTS
It’s also possible to create movies (.avi)
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CONCLUSIONS
• Many features have been implemented in a software called LOCAS
• LOCAS can be helpful for various kinds of studies, as for instance:
pressure/temperature prediction including transient behavior
simulation of fast cycling loading – Natural gas, CAES
long-term simulations (abandonment, subsidence)
mechanical integrity tests (MITs) analysis
short-term term stability (min./max. operating pressure)
mechanical/thermal/hydraulical parameters fitting from in situ tests
Prediction from data at cavern scale
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CONCLUSIONS
‣ LOCAS supports all 32-bits Windows versions, Windows Seven included.
‣ 3D & 64 bits versions under development.
‣ LOCAS is not yet available for sale.
Interested people, please contact Benoit Brouard:
contact@Brouard-Consulting.com
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