Microseismic: examples and new technology developments

Monday, 10 November 2008 Read 6202 times
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Microseismicity is a pressure induced dynamic effect associated with cracks, fractures & faults. The monitoring reservoirs using the passive microseismic approach is now a mature technique which makes possible to get reliable data for field development.

Microseismic: examples and new technology developments

Christophe Maisons

Magnitude

Abstract:

Microseismicity is a pressure induced dynamic effect associated to cracks, fractures and faults. The monitoring of a reservoir using the passive microseismic approach is now a mature technique which makes it possible to obtain reliable information for oil and gas field development.

The approach: deploy three component sensors and record in continuous mode the transmitted seismic waves triggered by an unknown source. This source is actually what we will attempt to characterize, using the acoustic events taking place inside the reservoir. Such events are ascribed to rock pore pressure variations which generate instabilities by creating a slide along small fractures, which results in seismic wave emissions. These production induced micro-earthquakes will be located and mapped, along with their occurrence time. Indeed, here we deal with intrinsic 4D data: the unknowns are X, Y, Z, the microseisms coordinates, and T0, their origin time. 

From the event record, the processing consists in moving backwards, attempting to locate the micro-fractures or the faults which generated the event, in order to find the original wave source. This fundamentally dynamic approach focuses on production. Thus, the gathered data will be interpreted essentially as either fluid migration indicators or as indicators of reservoir active elements, such as mobile faults and spreading fractures. 

In any given situation, the passive seismic method is adaptable to spatial and/or time factors, depending on the problems to be solved.

- Spatially, it is possible to work on the scale of one well, several wells (injection and assisted retrieval) or on the scale of an entire field (large structural accidents, depletion).

- Temporally, it is possible to work from one day to a whole week (hydraulic fracturing), from one week to one month (observation of phenomena between wells) and over several months or several years for observations relative to the whole field.  

 

The passive seismic method is applicable throughout the lifespan of a field. Some examples of its uses:

• Very poor permeable reservoirs, which requires the use of hydraulic fracturing to generate fluid corridors.

• Fluid injection monitoring, which enables the detection of anomalies relative to fluid propagation (such as privileged fracturing corridors and permeability barriers, which accumulate constraints before breaking and generating waves).

• Highly depleted mature fields. These fields are the seat of compaction readjustments because of pressure variations. Such motions induce a microseismicity which provides clues for risk assessment, such as casing ruptures, and considerable permeability changes. 

 The work, methodology and equipment must be adapted in each case to the considered monitoring conditions. Both the tools and technology of this innovative seismic method exist and the market is expanding. Case studies show that the application of the passive seismic method has provided information likely to make substantial savings in reservoir follow-up and management.

 

Biography: 

Christophe Maisons is the founder, the managing director and the president of Magnitude SAS.  He has over 25 years experience in seismology and over a decade of entrepreneurial experience.  He has driven Magnitude toward technology development, consultancy and services.  He has positioned Magnitude as a leader in Microseismic Monitoring Services with a unique threefold focus on Fracture Mapping, Reservoir Monitoring and Underground Storage Surveillance.

Prior to joining Magnitude, Christophe Maisons held a project manager and team leader position with Geostock, an engineering company providing Underground Gas Storage solution (during 10 years).  Christophe Maisons also worked in the field of research seismology at CNRS-IPG/TAAF in France as geophysicist in charge of various French Sub-Antarctic geophysical-observatories (during 5 years). Christophe Maisons holds a degree in geophysics from EOST, Strasbourg, France.

Magnitude is a French company founded in 1999.  Magnitude started with an award for its R&D involvement in an innovative new business. Magnitude is a VSFusion company (BAKER HUGHES - CGGVeritas joint-venture) since June 2006.

 

Congress Center of RF CCI. Start at 7 p.m.:

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