Monitoring and modelling 3-D ground movements induced by seasonal gas storage in deep reservoirs P....
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Transcript of Monitoring and modelling 3-D ground movements induced by seasonal gas storage in deep reservoirs P....
Monitoring and modelling 3-D ground movements induced by seasonal gas storage in deep reservoirs
P. Teatini, G. Gambolati, N. Castelletto, M. Ferronato, C. Janna – Uni. Padova, Italy
E. Cairo, D. Marzorati – Stogit S.p.A., Crema, Italy
D. Colombo, A. Ferretti, F. Rocca – T.R.E. S.r.l., Milan, Italy
A. Bagliani, F. Bottazzi – Eni E&P, Milan, Italy
DMMMSADepartment of Mathematical
Methods and Models for Scientific Applications
Outline
Introduction
The Lombardia field: history, location, and geology
Analysis and management tools: fluid-dynamic and geomechanical
modelling, PSInSAR monitoring
UGS activity in the Lombardia field: geomechanical response
Future UGS scenarios: land displacement prediction
Summary and conclusions
Introduction
Underground Gas Storage projects are increasingly popular worldwide:
about 600 UGS plants currently active with an overall working gas
volume of about 350 billions of Sm3
Hazards: safety related to public perception, economic risk and
environmental impact
Geomechanical issues:
Need for a comprehensive modelling and monitoring effort
• subsurface: sealing caprock integrity
• surface: land displacements
The Lombardia fieldLocation and geological setting
Northern Italy, Po River plain: normally consolidated and pressurized basin
Three gas-bearing pools between 1050 and 1350 m below m.s.l.
The reservoir is of stratigraphic type and consists of Pliocene sandy sediments
The Lombardia fieldProduction life and UGS program
Primary production started from pool C in 1981 with 2.7 GSm3 withdrawn
until 1986 and 35 bar of pore pressure decline
UGS started soon after superposing to the natural pressure recovery
From 2002, UGS program
has pushed the maximum
pressure up to 103% pi
with 30-35 bar cycles and
1.2 GSm3 of working gas
Objective: pushing the
maximum pressure up to
107% and 120% pi
Analysis and management toolsPSInSAR data over the Lombardia field
PSInSAR is a methodology for monitoring the land displacements through the analysis of Synthetic Aperture Radar (SAR) scenes acquired from satellites over a number of benchmark points known as Permanent Scatterers (PS)
Seasonal behavior of two PS compared to the stored gas volume: phase accordance
The ground surface “breathes” as the gas is pumped in and out
Analysis and management toolsPSInSAR data over the Lombardia field
PSInSAR analysis of data acquired from:
November 2005 to
April 2006 (left)
April 2006 to
November 2007
(right)
Seasonal movements of 8-10 mm (vertically) and
6-8 mm (horizontally)
Analysis and management toolsFluid-dynamic and geomechanical computational models
Water dynamics in the connected aquifer is predicted by coupling a 3D FE groundwater flow simulator calibrated over the primary production period 1981-1986
Gas/water dynamics in the reservoir is predicted by the multi-phase flow simulator Eclipse calibrated over the 1981-2007 period
Analysis and management toolsFluid-dynamic and geomechanical computational models
Geomechanics is
predicted with the aid of
the FE code GEPS3D
developed by UniPD
Non-linear hysteretic
hypo-plastic law for the
soil compressibility
Anisotropic constitutive model: calibrated using both vertical and horizontal
PSInSAR displacements
Five independent parameters: =Eh/Ev, =Gh/Gv, h, v and s=cM,I/cM,II
UGS activity in the Lombardia fieldGeomechanical response
Calibration of the anisotropic model using the 2003-2007 PSInSAR measurements
Selected parameters:
Very good match between measures
and computation
The parameters are consistent with
literature data in the same basin
• = 3.0 and = 1.0
• h = 0.15 and v = 0.25
• s = 4.0
UGS activity in the Lombardia fieldGeomechanical response
Measured (from PSInSAR) and simulated vertical and horizontal displacements from April 2006 to November 2006
Maximum vertical displacement simulated over the reservoir
Future UGS scenariosPore pressure prediction
Two future UGS scenarios: 107% pi and 120% pi
Increase of the stored gas volume by 65% and 180% relative to the current
maximum storage
Pore pressure variation in a cycle
and its propagation in the connected
aquifer: 50 bar and 70 bar
No problems are expected for the
caprock integrity
Future UGS scenariosLand displacement prediction
Absolute value of the expected vertical displacement (mm) during a seasonal
injection/extraction cycle
From the current 10 mm at 103% pi to 17
mm at 107% pi and 27 mm to 120% pi
No problems are expected for the
stability and integrity of surface
structures because of the small
differential displacements (< 10-5 m/m)
Summary and conclusions
Major points:
UGS at the Lombardia field is responsible for a 10-mm excursion over the
last five years which can increase to about 15 mm and 25 mm at 107%
and 120% pi with no expected consequences on surface structures
The model calibration provides geomechanical parameters consistent
with available studies on the same basin in the framework of a
transversally isotropic constitutive model
This study can be viewed as a prototype application of a promising
interdisciplinary approach integrating petroleum engineering, remote
sensing and computer modeling for a complete geomechanical
characterization and management of a UGS program
DMMMSADepartment of Mathematical
Methods and Models for Scientific Applications
Thank you for your attention