AAPG/SEG International Conference & Exhibition

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Recent improvements for Quantitative 4-D Seismic

Abstract

Abstract

Born nearly thirty years ago, time lapse (4D) seismic technology is today a common tool for reservoir monitoring and is the only one that provides a spatial image of field production. Its ultimate aim is to quantitatively improve the predictive capability of reservoir models, and finally optimize the reservoir management.

For the last ten years, Total has recognised the importance of time lapse seismic and has therefore conducted 4D seismic monitoring studies in different geological environments and for different monitoring purposes. Key 4D innovations were developed to meet monitoring needs:

  • - Extending 4D full wave modelling for feasibility study in very complex structured area.
  • - Deliver 4D attributes suitable for fast 4D interpretation: The 4D warping® which is an inversion in reflectivity and time that delivers 4D volumetric attributes easy to use for interpretation and integration inside reservoir models.
  • - 4D well tie using a dedicated tool in order to go towards quantitative use of 4D inversion results.
  • - Develop 4D well tie between seismic observation and production data at the well.
  • - Develop 4D interpretation methodologies which go from 4D QC to 4D integration into reservoir models with in-house 4D Toolbox platform.
  • - Develop 4D links with geomechanics study to understand overburden reaction to production and to forecast cap rock integrity.
  • - Go towards 4D quantitative approaches by computing 4D injected and produced volumes which are used as History match indicators and for allocations controls.
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    Several 4D field examples are shown to illustrate the use of these main technologies.

    Thank to these recent improvements 4D becomes a mandatory tool to assess the monitoring of production phenomena in more difficult domains where 4D signal is weaker or where 4D noise is stronger as carbonates fields, onshore fields, subsalt fields. Positive results have been obtained on some offshore carbonates fields where 4D contributed to assess subsidence of carbonate platforms, water rises, depleted areas, facies quality, permeability barriers and fault behaviour. As well positive results have been obtained on overburden knowledge (compaction, HSE, well integrity) that fit with the results of geomechanical modeling and geological heterogeneities characterization.

    This discipline requires full geosciences integration between 4D seismic interpretation, Rock Physics, Sedimentology, Well monitoring data and Reservoir simulation.