Download - Stogit Advanced Monitoring Approach
Stogit Tecnomare Snamprogetti
IGU Working Committee 2 Workshop on “Safety on UGS”
Rome, 2-4 October 2007
Stogit Advanced Monitoring Approach
Vanni Damiani, Daniele Marzorati (Stogit) Francesco Gasparoni (Tecnomare) Gianluca Patrignani (Snamprogetti)
Stogit Tecnomare Snamprogetti
•Stogit manages 8 of the 10 Italian gas storage facilities
•Location: 7 in the Po alluvial Plain (Northern Italy), 1 in the Apennines (Central Italy)
•All are located in depleted gas production reservoirs at average depths of between 1000 to 1500 m
Introduction
Stogit Tecnomare Snamprogetti
Background
•Stogit activities are based on experience acquired within the Eni Group in 40 years of operations
• first gas storage activities: 1964 (Cortemaggiore) • storage pressure initially maintained <=Pi
• in August 2002, with the authorisation of the Ministry of Trade and Industry, Stogit for the first time in Italy experiments storage in a reservoir (Settala) at pressures above the original reservoir pressure (P>Pi)
•as integral part of a plan aimed at increasing storage capability, Stogit has defined a new monitoring strategy (“Advanced Monitoring Approach”) to support correct and safe operation at high overpressure conditions
Stogit Tecnomare Snamprogetti
Geodesy Geophysics Geochemistry Process
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SURFACE -
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SOIL -
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-2000 m -
SAR topography
monitoring
Basic monitoring
RST logs
Wellhead
pressure
Bottom pressure
Stogit Tecnomare Snamprogetti
Geodesy Geophysics Geochemistry
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AIR -
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SURFACE -
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SOIL -
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GasFinder
remote sensing
Mobile geochemical
surveys
Advanced monitoring
4D microgravity &
gravity gradient
Deep borehole
geodesy
Geochemical
stations network Microseismic
stations network
Deep borehole
microseismics
Annular pressure
Stogit Tecnomare Snamprogetti
Geodesy Geophysics Geochemistry
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AIR -
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SURFACE -
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SOIL -
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Experimental activities (R&D)
Geomechanical monitoring
Fingerprint
techniques
Pore pressure Compactation Leak-off pressure
Stogit Tecnomare Snamprogetti
Advanced Monitoring Approach: why?
• to ensure continuous, real-time, permanent monitoring of the stability and integrity of reservoirs with geological and structural conditions operated in overpressure
• to safeguard the surrounding environment
• to give early warning of potentially hazardous situations (such as leakages, fracturation etc.)
• to give demonstration to the stakeholders of the correct and safe management of the reservoir
• to increase the knowledge base so that behaviour of the site can be understood and simulated
• to collect data useful for the study and evaluation of future development scenarios
Stogit Tecnomare Snamprogetti
Surface microseismic network
Purpose: detection of micro-earthquakes around the field area
Working principle: a network of automatic seismological stations recording H24 ground motions and transmitting data to a remote data management centre
Results:
• catalogue of seismic events
•3D seismicity pattern
• characterisation of seismogenic geological structures
Stogit Tecnomare Snamprogetti
Surface microseismic network - technical details
• includes 10 to 20 seismometric stations spaced approx. 5 km and equipped with:
– 3D, 1-80 Hz seismometers
– 24 bit digitiser
– GPS time reference
• continuous 100 Hz data acquisition (1-40 Hz useful band) and real-time wireless data transmission
• allows high-precision detection of local earthquakes with magnitude 1 to 4 at depth range 1 to 5 km
Stogit Tecnomare Snamprogetti
Purpose: detection of fracture occurrence and fault formation/reactivation Working principle: borehole observatory installed in a dedicated well (1200-1500 m), connected via umbilical cable to a Surface Station managing data acquisition, processing and networking Results: maps of seismic events
Deep borehole microseismic observatory
Stogit Tecnomare Snamprogetti
Deep borehole microseismics - technical details
• instrumented string including 5 modules spaced approx. 50 m
• based on
– 3C borehole geophones (10-500 Hz)
– 1000 Hz sampling rate
– 24 bit digitisers
– GPS time reference
– continuous acquisition
– real-time event detection (LTA/STA algorithm) and transmission
– local storage of all data
• allows detection of micro earthquakes with magnitude -3 to 2 within 500 m from borehole
Stogit Tecnomare Snamprogetti
Purpose: monitoring of formation
movements/settlement, determine fracture orientation, understand fracturing process Working principle: precision tiltmeters integrated in the borehole observatory
Deep borehole geodesy
Technical data •Self levelling sensors (within +/- 10°)
•Range +/- 300 µrad •Resolution <5 nanorad •1 measure/minute
Stogit Tecnomare Snamprogetti
Geochemical Monitoring Network
Purpose Continuous, “real-time" detection of anomalous CH4 contents pattern in free air, surface soil, shallow water tables Working principle • a network of stations placed
in selected points over the gas storage field
• automatic sampling and chemical analyses of CH4 contents in air, soils ad water tables
• Infrared and Flame Ionization techniques
Stogit Tecnomare Snamprogetti
Geochemical Monitoring Network – technical details
Results • time trend anomalies detection for CH4 contents
• location of zones with anomalous CH4 content trend
Technical data •Coverage: 1 station/5-10 km2 •Precision: ≥ 1 ppm CH4 in air, soil and water
•Sampling rate: 12 meas./day
Stogit Tecnomare Snamprogetti
Annular pressure monitoring
Purpose: continuous, real-time monitoring of gas leakages through defective wells Working principle: Pressure gauges applied to well casing valves Results: Pressure time series analysis in correlation with reservoir charge / discharge activities. Search for anomalous responses of gas pressure over the field Technical data
• Coverage: 1 well each 5-10 km2 • Precision: <1 bar
Stogit Tecnomare Snamprogetti
Purpose: determine the variations of fluids subject to storage / injection / production cycles inside a reservoir Working principle Time-lapse (4D) methods, based on microgravity measurements and relevant gradient (innovative technology developed by Eni method; submitted for international patent)
Time-Lapse Micro-Gravity & Micro-Gravity Gradient
Stogit Tecnomare Snamprogetti
A typical survey includes up to 1000 stations. Duration 10 working days (6 persons organised in 3 shifts) Main advantages of the method
• capability to detect possible reservoir compartmentalisations
• applicable both in onshore & offshore scenarios
• easy integration with seismic • cost effective technology • no environmental impact
Time-Lapse Micro-Gravity & Micro-Gravity Gradient
Stogit Tecnomare Snamprogetti
Gas leakage remote sensing
Purpose: Detection of CH4 pattern in free air over the entire area of a gas storage field Working principle: airborne methane laser sensor (GasFinder) mounted on an helicopter flying 10-50 m over the area Results: Location of zones with anomalous CH4 content trend Technical data
• Coverage: 1-5 measures / 1000 m2 over a XY grid
• Precision: ≥ 10 ppm CH4 • Timing: 100 km2/day
Stogit Tecnomare Snamprogetti
Geochemical Surveys
Purpose: Detection of anomalous CH4 content in free air, surface soil, shallow water tables Working principle: Field surveys using gas samplers and portable high-sensitivity FID CH4 detectors; laboratory analysis of samples collected Results: Maps, pattern recognition, time trend anomalies detection for CH4 contents Technical data: • Coverage: 1-3 samples / km2 • Precision: ≥ 1 ppm CH4 (in air, soil,
water) • Timing: 10 km2 / day
Stogit Tecnomare Snamprogetti
SAR topography
Purpose: Monitoring of the surface elevations micro-change during time (subsidence / uplift phenomena) Working principle: Satellite radar images processed with Differential Interferometry (DInSAR) methods to obtain micro-displacement trends of a series of "scatter points" mapped over the area of interest Results: Maps of topography elevations change Technical data
• Coverage: 10-1000 km2 • Precision: 1 mm elevation • Timing: 1 map/year
Stogit Tecnomare Snamprogetti
Data management infrastructure
• All data are collected in an integrated geographical database management system
• The system supports GIS applications and dedicated analysis, studies and modelling
• A multidisciplinary pool of experts read and analyse data to watch the status of reservoirs during storage activities
Stogit Tecnomare Snamprogetti
Experimental (R&D) activities
• advanced geochemical techniques (like isotopic techniques and fingerprint analysis) to recognise the origin and source of CH4 detected in air, soils and water
• downhole permanent monitoring of geomechanics parameters of the reservoir (like pore pressure, compactation, and horizontal stress)
• an integrated geomechanical model of the reservoir capable to analyse integrity of the sealing and predict possible occurrence of fracturation phenomena
• advanced leak detection technologies (infrared hyperspectral imaging systems), to enable quick and cost effective detection and quantification of fugitive methane leaks
Stogit Tecnomare Snamprogetti
Conclusions
• Stogit has launched a monitoring program aimed at supporting a safe and efficient management of gas storage reservoirs operated at P>Pi
• Stogit approach
– combines traditional and innovative techniques
– combines periodic surveys with continuous, in-situ observation
– is multidisciplinary (combines geophysics, geochemistry, geodesy, environmental monitoring tasks)
– focus on a permanent infrastructure, ensuring operativity 24/7/365
• This approach is tailored to the specific conditions and risks at each storage site
– dimensions and time scale of the application
– storage pressure
– reservoir characteristics
– sensitivity of the area
Stogit Tecnomare Snamprogetti
Program status
• First objectives (4 year project started 2006), are
– to set-up a network of 5 gas storage reservoirs fully instrumented, including relevant communication infrastructures
– to develop the data management infrastructure (SismoGIS)
• Within mid 2008 the start-up of the first fully instrumented node of the network (Fiume Treste) is scheduled
• Completed and ongoing activities
– 4D microgravity & gravity gradient surveys in one field
– Detailed design and development of surface and deep borehole microseismic and geodetic network
– Detailed design of the geochemical stations networks
– First (blank test) mobile geochemical survey