Criterios exploratorios para el almacenamiento de gas

Underground storage experts

Jornada del almacenamiento
subterraneo

criterios exploratorios
Carlos GOMEZ MONTALVO

Madrid, 27 de Octubre 2008
1

Maj 09/07
The Géostock Group

25%

Geostock Holding s.a.
50%

25%

60%
100% 100%

Untergrundspeicher-
und Geotechnologie-
40%
Systeme GmbH
50%

40%

Verbundnetz Gas AG

40% 20%
GIE géométhane

IFP BRGM
50%

Gaz de France

Madrid, 27 de Octubre 2008 2

Underground Storage Techniques

AQUIFERS
LEACHED SALT
DEPLETED
CAVERNS
FIELDS

MINED CAVERNS


INVESTIGATION OBJECTIVES
Detection of the future storage potential weaknesses
– The structure
– The cap-rock
– The reservoir
– Salt extension or thickness
– The quality of the salt

For every weakness, doubt can be removed by a suitable investigation
method
– 3D seismic
– drilling
– sampling (cores, cuttings, etc.), hydraulic testing, etc.

The target is « fatal flaw »


MAIN STAGES OF THE INVESTIGATION
Stages Objectives Methods Results
• to check the existence of a
Detection • records studies • selection of the structure
geological formation with a
convenient structure,
Selection • new treatment of former • rough mapping
presumed during former
of potential seismic acquisition
investigation.
areas
• to precise contours and location
Positive
Investigation
Negative results
results abandonment

Prequalification • to determine depth, thickness • first investigation well(s) • confirmation of contours
and nature of main geological seismic cross-lines • reservoir and cap-rock
Capacity for formations • regular works notification characterization + samples
qualification

Positive Investigation
Negative results
results abandonment

Qualification • knowledge of these geological • drilling • samples
Capacity for formations for natural gas storage • seismic • hydraulic characteristics
storage • hydraulic tests
• investigation authorisation


First step : desk (basin) studies

Geological maps
Exploration records
Production records


Exploration


Improvements of exploration technology


Leached salt caverns: leaching process

WATER BRINE


Leached salt caverns operating
(liquid hydrocarbons)

BRINE
PRODUCT

1m3 of dissolved salt requires 8 m3 of water


First step : desk (basin) studies

Geological maps
Exploration records
Salt production
Water well records
……
What you have!


Isobath maps of top of the salt from seismic
and wells

extension : a few km2


Exploration : logging

Right depth >500 m
Right thickness ( >100m)
With not much of
insolubles (maxi 20%)


•ELAN Analysis (Halite-Anhydrite-Dolomite-Illite-Montmorillonite):
RHOB NPHI DT U GR plugs mineralogical
analysis

volume d’insolubles
=
anhydrite V
+
dolomite V
+
illite V
+
montmorillonite V

dolomite
anhydrite
halite
Bound water
illite
montmorillonite


Correlation between wells


Salt from dome


SALT FROM LAYER


SALT FROM ANTICLINAL


CREEP TESTING ON CORE SAMPLES


EXAMPLE OF A CREEP CURVE

16
T = 60 °C (140 °F)

14

12

Axial creep strain (%)
10

Test data from W hiting et al.
8
Fit curve

6

4
T = 22 °C (72 °F)

2

0
0 5 10 15 20 25 30
Time (days)


GEOTECHNICAL MODELISATION


Geomechanical modeling

Max. value = 0.55 %


DATA TO BE INCORPORATED IN THE GEOLOGICAL
MODEL

Old maps & Literature

Geophysics (seismic, gravity,
VSP, Salt Prox., etc.)

Well log data

Core data

Rock mechanics data

Historical records

Operational/Production Data

Brine Disposal studies

Leaching Plant
Brine Disposal Area
Settling Tanks
Brine Disposal
Plant
Brine Conditioning
Fresh Water
Brine Filtration
Supply Pumping Station Brine Disposal
Brine Transportation Pumps
for Leaching Well

Cavern in Leaching


Geological requirements - Cavern storage
site Kraak

sewage treatment
⎢ Two separated areas for: plant Schwerin
Schwerin 2/87
- cavern storage 0
120
- and brine disposal Schwerin 5A/96
0
140

⎢ location of salt dome 0
1 60
250 km²
1800

⎢ cavern location Schwerin 1/86
2 0 0 0 Schwerin 3/87

2200
⎢ disposal area with a 0
230

surface of about 250 km²
and dimensions of
approx. 22 x 12 km

⎢ brine pipeline
7 x 4.5 km

⎢ fresh water supply


Solution mining plan

Due to the different leaching
behaviour
of the various salt layers, creating a
favourable, stable cavern contour is
quite difficult.
Axis of the folded Leine rock salt;
one can see that all salt layers are mirrored
at this axis.
Compact or broken
anhydrite layers with bad solubility

Feature simulating a blanket trap
Thin but compact anhydrite layers
Potassium salt layers with very aniso-
tropic leaching behaviour
Staßfurt rock salt


Well design


06/98$$$00
Depleted fields / Aquifers

Consist in:
– A porous and permeable
formation (the reservoir)
structured so as to ensure
lateral containment (e.g. Dome
Shape)
– An overlaying impermeable
formation (the cap rock) which
ensures vertical containment
– 1916: first depleted field
conversion in New York State
(USA)
– 1946: first aquifer storage in
Kentucky (USA)


QUALIFICATION CRITERIONS
1 - Existence of a convenient structure
Search of a « trap »

• Closure
• Spill point

2 - Cap-rock tightness
Definition of the Authorized Maximum Pressure

3 - Reservoir characteristics
Porosity
Permeability

4 - Environnement of the site and of the reservoir


1st QUALIFICATION CRITERION

EXISTENCE OF A CONVENIENT STRUCTURE


SOME KINDS OF TRAPS


POTENTIAL WEAKNESSES OF THE STRUCTURE

No closure Spill point Too small volume


DEFINITION OF CLOSURE AND SPILL POINT
Closure level

C
C
Top Spill point = Leakage
Spill point = Leakage Top
B B
FAULT FAULT
OK
Closure on fault
A
A

1st Hypothesis : no closure on the fault 2nd Hypothesis : closure on the fault
A B C A B C
Top Top

FAULT FAULT
Spill point = Leakage Spill point = Leakage
Closure
Closure

Reservoir filled with gas
CRITICAL AREA
Aquifer


2nd QUALIFICATION CRITERION

CAP-ROCK TIGHTNESS


CAP-ROCK TIGHTNESS

PERMEABLE FAULT
NOT CONTINUOUS CAP-ROCK


CAP-ROCK INVESTIGATION
• Continuous coring
displacement pressure, plasticity, etc.

• DST (Drill Stem Test)
detection of any permeable or cracked layer in the cap-rock

• Fault detection
tightness

• Side continuity or facies boundaries
sedimentology
sequential stratigraphy

• Permanent monitoring of the upper aquifers
monitoring of the direct « control » upper aquifer
monitoring of all aquifers already used


3rd QUALIFICATION CRITERION

RESERVOIR CHARACTERISTICS


RESERVOIR STUDIES
• Characteristics to be asked for
high porosity and permeability

side continuity or homogeneity of the reservoir facies

knowledge of the aquifer characteristics

• Investigation methods
lab petrophysical measurement on cores

numerous and various electrical logging

numerous and various hydraulic tests :
• Drill Stem Test
• long duration production test
• long duration injection test
• interference test

geological modelization

CORES


PETROPHYSICAL MEASURES
Vvoid
φ=
• Pay porosity : Vvoid + Vsolid

maximal storage capacity
Vwater
Sw =
• Saturation : Vvoid ( open pore )

µQ ∆x
k=− productivity
• Specific permeability (darcy) : S ∆P
k real of fluid
k rw and k rg =
• Relative permeability : k

• Capillarity and hysteresis :
1 dVF
cF = −
• Compressibility : VF dP


DRILLING AND LOGGING


Electrical logging
TOOL PHYSICAL PARAMETERS FORMATION PARAMETERS

Spontaneous Potential difference Clay content
polarization

Laterolog Formation resistivity in (Water salinity)
Microlaterolog different directions and at (Porosity)
Microlog different distances from Saturation in gas
Dipmeter the well Dip and/or stratification

Gamma Ray Natural radioactivity Clay content

Porosity
Neutron Hydrogen atom
Saturation in gas

Density Gamma ray absorption Density

Sonic Sound velocity Porosity


Principle of the hydraulic tests

Well or wells
Water Pressure
behaviour
production variation

Q P

t t
Unknown
Measured Measured
permeability?
flowrate pressure


Example of one kind of hydraulic test
at constant flowrate
Vanne
Compteur de volume

Pw

1 2

FA
ILL
E
Pompe

Ecoulement Ecoulement
radial hémi-radial
Faille étanche atteinte

1 2
Descente du capteur Mise en débit -
puis attente de la stabilisation Drawdown


Result of one kind of hydraulic test

• Information on the well
capacity of the well
skin effect
productivity factor

• Informations on the reservoir
transmissivity and permeability
homogeneous infinite
double porosity or radial circular
multilayer

• Informations on the reservoir boundaries
tight or permeable faults
limits at constant pressure
channel, closed reservoir


Hydrodynamical impact model
INVESTIGATION GATHERED RESULTS
WORKS DATA

• 2D or 3D seismic GEOLOGICAL
• Layers geometry
MODEL
• Wells
• Faults localisation
Detailed
• Cores
• Lithology description
• Electrical logging of aquifers
• Petrophysical
characteristics

• Hydraulival tests • Evolution of the DYNAMIC
piezometers MODEL
• Operation monitoring
Flows
• Produced and injected
• Piezometers monitoring
simulation
volumes
• Physical and chemical
• Boundaries conditions
monitoring


Geological modelization

Construction of a geological 3D model
with a geostatic interpolator


Numerical Modeling Process
Geological and Geophysical
Data Analysis and
Data processing
Interpretation
Database
Petrophysical Data Analysis and
GIS
Interpretation

Data Analysis
Facies Modeling
History Match Structural Modeling
Injection forecast &
Failure scenarios

Commercial Software
(Eclipse…)

PVT analysis,
EOS parameters
Multiphase Flows Modeling
tuning
Mass transport
Geochemical
Poro-Mechanical Modeling
Selection of Geostatiscal
Upscaling & Upgriding of
realization & Property
properties
Population
3D Geological Model

Source : Doc. Schlumberger Carbon Services


EXAMPLE OF MODEL


DEPLETED FIELDS CONVERSION CRITERIA

• Geographical location Ravenspurn South & North

• Depth and volume
Viking A
Indefatigable
•Structure and permeability
Closure, support from aquifer
•Fluids in place
Composition, viscosity, gas cap
•Status of the wells (production, exploration, abandoned)
Identification of all the wells Hewitt 1 & 2
Offshore UK
Status of cementation and corrosion Blue: depleted
Orange: depleted in 2015
• Status of the field (GOR) Pink: depleted beyond 2015


NON CONVERSION CRITERIA

Corrosive or toxic hydrocarbons
CO2, H2S

High viscosity fluids
Heavy oil

Complex geology
Heterogenous reservoirs

Enhanced recovery
Injection of water, vapor


ADVANTAGES

Existing infrastructure (topside and wells
Regulatory environment more favourable
Reservoir and caprock are already qualified
Exploration phase is reduced in time and budget

Cushion gas is there (or part of it)
Optimisation of schedule
Optimisation of cost is negociated

• Behaviour of the reservoir is known
Production history


Main scenarios for converting
depleted fields to UGS
Pressure

Initial

Working gas
Minimum

1
Ultimate
1 = Recoverable cushion gas

2 = Unrecoverable cushion gas
2

Time

AUTHORIZED MAXIMUM PRESSURE

• It is based on a safety gradient G

Pmax [barabs] = 1 + 0,0981.G.Depth Réservoir’s top [m]

• G varies between 1.2 and 1.5 depending on storage characteristics

Lithostatic
Hydrostatic Storage safety <
< gradient
gradient gradient


OVERPRESSURE OF DEPLETED FIELD MONITORING

ratio maximum operating pressure over original
pressure

200
175
180

number of occurences
160
140
120
100
80
60
42 41 41
40 25 21
14
20 11
7 7 4
3 3 3 2
1 0
0
0,30 0,40 0,50 0,60 0,70 0,80 0,90 1,00 1,10 1,20 1,30 1,40 1,50 1,60 1,70 1,80 1,90


Performance increase study

How many wells, existing or to be created, are needed to:
– produce X million cum per day
– during Y days
– with a volume Z of gas in place

Client
Field
Vtot=900MNm3, Wg=530 MNm3, DP=(PRES-FBHP)=10bar
16000 100%

90%
14000

80%
12000

Production Flow Rate 10^3Nm3/day
70%

%Produced Volume
10000
60%

8000 50%

40%
6000

30%
4000
20%

2000
10%

0 0%
01/12/98 21/12/98 10/01/99 30/01/99 19/02/99 11/03/99 31/03/99 20/04/99 10/05/99 30/05/99 19/06/99
date

Flow rate Pot. 1- THP 70 Pot. 2-THP 70 Pot. 3 THP 70 Pot. 4 - THP 70
Pot. 4 THP 80 Pot. 4 THP 85 Pot. 4 THP 75 %Produce d V olum e


Simulation of increased productivity
with horizontal drains in existing wells

Source Enagas
Source Enagas

Source Baker Hughes
Source Baker Hughes


Offshore Platform
Onshore Facilities

Umbilical Line

Export Pipeline X-mas Tree
subsea
P4
P2 P1 P3
subsurface


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