MICROSEISMICITY MONITORING IN ENI

2 Seisan Workshop Microseismicity monitoring in ENI Environmental Monitoring: local authorities often requires monitoring programs to control the impact of the production activities even in non seismic areas. Reservoir Passive Monitoring: the study of the microseismicity associated to reservoir behaviour before and during the production. The purpose is to improve the reservoir characterization and/or to check the hydraulic fracturing operations. Tools need to be installed in active or dedicated wells at the reservoir depth.

3 Seisan Workshop Eni (formerly Agip) is active in microseismic monitoring since 1978 First experience near Naples during geothermal explorations Total of 9 networks operated All networks operated in Italy At present time 5 networks are still active with a total of 29 remote stations In February 2004 installation of 2 offshore permanent stations with real time data transmission In August 2007 installation of a borehole microseismic string into live oil well. Continuous recording for 2 months A lot of feasibility studies for borehole passive seismic projects in Italy and abroad are ongoing History

4 Seisan Workshop Networks Lago di Patria ( ) 15 Geothermal field Sergnano ( ) 7 Gas storage Minerbio (1979 -> ) 3 Gas storage Cavone (1982 -> ) 4 Oil field Malossa ( ) 7 Oil field Metanopoli ( ) 5 Geothermal well Correggio (1991 -> ) 3 Gas field Val d’Agri (2001 -> ) 13 Oil field Crotone (2003 -> ) 6 Gas field

5 Seisan Workshop Val D’agri Network - Goals 24h seismological monitoring of the Val d’Agri reservoir, located in an active seismic region (area of about 1500 km 2 ) Identify seismic events and discriminate between natural and oil production induced seismic activity Monitor water and gas injection Provide Regione Basilicata with local seismological data 45 km 38 km

6 Seisan Workshop Val D’agri Network - Characteristics 11 completely autonomous stations + 2 connected to lines GSM system for data transmissions to Milan office Solar panels supply

7 Seisan Workshop Crotone Network - Goals 24h seismological monitoring of the Luna – Hera Lacinia offshore gas field Seismological monitoring of the Crotone region Monitoring of the human and natural activities in the archaeological area of Capo Colonna 12 km 21 km

8 Seisan Workshop Crotone Network - Characteristics 6 stations: 4 onshore and 2 offshore GSM data transmissions to Milan office Use of the land seismological equipment for easy integration with existing networks Full remote control of sensor levelling and heading No need for tool recovery to download data or to change batteries Applicable to water depths greater than 100 m

9 Seisan Workshop Network feasibility study Network design Network installation & maintenance Data acquisition Data processing Data Interpretation Studies on seismological items Vibrometric measurements What We Do

10 Seisan Workshop Alarm Procedure Defines critical conditions Defines actions to be undertaken Defines people to be alarmed

11 Seisan Workshop Lennartz Le-3D: 3 components geophone 1-80 Hz band Lennartz Le-3D/5s: 3 components geophone Hz band Lennartz Mars-88: 20 bit recording system with 4 MB RAM memory (3 h continuous recording) Lennartz M24: 24 bit recording system with 50 GBmemory (6 months continuous recording) Sampling frequency: 62.5 Hz (16 ms) typical Frequency band: 1-25 Hz useful for a local network Data retrieval every 2 hrs, shorter on contingent Data transmission to Milano via analogic or GSM modem 11 stations with solar panels, 18 stations with electric line supply Equipment

12 Seisan Workshop Equipment Mars-88 Geophone Battery GSM modem

13 Seisan Workshop Processing Data are checked and events retrieved by using Lennartz m88select Data are processed for location, magnitude by using Giant and Pitsa software only when identified as Local (d<=10 km). To locate the Regional ones (100km 10 km) we have to wait for INGV (National Erathquakes Survey) data. When ML is over 2.0, distance <10 km and depth near to the reservoir one, an alarm is delivered. At the end of the month a bulletin for each network is delivered.

14 Seisan Workshop Seisan to locate a local event recorded by Emilia network

15 Seisan Workshop 2007 Emilia Locations on Google map

16 Seisan Workshop EMILIA SEISMICITY FROM 1982 to 2002

17 Seisan Workshop BOREHOLE PASSIVE SEISMIC Case History Events located using surface network: 57 Events located using downhole network:15000 Statistical redundancy to study the reservoir Improved events location (from ABB Resevoir Geoscience Group : Microseismic Monitoring)

18 Seisan Workshop More than 2000 recorded events BOREHOLE PASSIVE SEISMIC Case History

19 Seisan Workshop BOREHOLE PASSIVE SEISMIC Case History

20 Seisan Workshop Many thanks to Jens and Lars for the fruitful First Seisan Workshop, the many coffee breaks and ice- breakings, the walk under the rain and the social dinner. I’m looking forward to the next one!