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Haldorsen J.B.U.,READ AS | Brooks N.J.,READ U.S. | Milenkovic M.,READ AS
4th EAGE Passive Seismic Workshop | Year: 2013

We describe and illustrate a locating method based on full-waveform 3D migration of three-component data to reconstruct components of the elastic wave field at any point in 3D space. To be a viable micro-earthquake source at a location, the compressional (P) and shear (S) wave fields reconstructed at this location should have similar wave shapes and be simultaneous. These two conditions are assured by an imaging condition based on inverse-energy-weighted correlation between the reconstructed P and S signals. This weighted correlation process is the least-squares solution to the problem of maximizing the zero-phase bandwidth of the common signal while minimizing the noise. The process measures, at optimal resolution, both the similarity and the synchronicity of the two signals, while the adaptation to the signal and noise conditions of the data ensures numerical stability. The process does not require an absolute timing of the data as the floating time reference common to the reconstructed P and S signals is eliminated by the correlation process. Without explicit phase picking and event association, the new method is well suited for automated data processing, and is equally applicable to the analysis of three-component data, acquired either in boreholes or on the surface. Source

Buss J.,READ AS | Mallinckrodt C.,READ AS | Hilton T.,READ AS | Haldorsen J.B.U.,READ AS
2nd EAGE Workshop on Permanent Reservoir Monitoring: Current and Future Trends | Year: 2013

We have developed a cost-effective downhole PRM system. This system can be installed on production tubing and has a flexible interface, which allows integrating data from other sensors. The system uses electric geophones with electric (copper) communication with 100% redundancy between the sensor nodes, and high-capacity digital transmission of measurements to the surface. The high-bandwidth digital communication to the surface allows the deployment of up to 120 sensor nodes at 2 ms sampling. The digital transmission also allows the possibility of feeding through a wellhead in a sub-sea completion using electrical penetrators and temporary conversion to electric digital signal. The first pilot system has been delivered to Petrobras and is scheduled to be installed offshore Brazil, Q2, 2013. Source

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