Since 1991, IFP and GDF have been improving microseismic monitoring for reservoir characterization.
Using permanent downhole geophones, the location of small microseisms has been performed on two underground gas storage facilities. These experiments make it possible to learn about Passive Seismic Monitoring especially for long term applications.
Instrumentation and implementation of a permanent monitoring are discussed. Considering production and microseismic data together, reservoir pressure effects are highlighted: relationships between microseisms and production data being identified. Variations over time have also been observed.
The approach developed to process microseismic data on an exploitation site, during a long term microseismic monitoring experiment, is described. This approach, consisting in an evolving platform software, makes the integration of the acquired experience possible. Results obtained suggest the development of a pseudo-real-time monitoring methodology to be applied to production and fluid reinjection or storage.
Our topic is to present some results of a ten-year research program on Passive Seismic Monitoring (PSM hereafter) associated with gas storage. This program was based on a partnership between Institut Français du Pétrole (IFP) and Gaz de France (GDF). Measurements have been performed on two underground gas storage facilities belonging to GDF. The program benefits from the development of well instrumentation - especially the permanent downhole geophones- initially developed for repetitive well seismic applications.
The first part of the paper briefly defines the context of PSM. It also gives some elements of the following challenges: the permanent measurement and the interpretation of microseismicity associated with reservoir exploitation.
The second part briefly presents the two field experiments in terms of instrumentation and main results.
The third part reports on instrumentation and presents how we benefit from this experience.
Potentialities of new developments are highlighted.
The fourth part deals with the processing and the interpretation of microseismic data related to reservoir exploitation. It defines the requirements for a real-time application of PSM and presents the approach finally adopted to integrate our field experience and to take into account the exploitation data in both the processing and the interpretation of measurements.
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The last part gives some conclusions and makes some recommendations for the setting up and use of this technique to characterize the reservoir mechanics.
Although our experience mainly concerns gas storage, it is important to mention that the results, tools and methodology are suitable for oil