Cross-borehole and surface-to-borehole electromagnetic induction for reservoir characterization
Audio-frequency cross-borehole and surface-to-borehole electromagnetics (EM) are interesting alternatives to existing techniques for petroleum reservoir characterization and monitoring. With these methods signals may be propagated several hundreds of meters through typical sand/shale reservoirs and data may be collected at high accuracy with a high sensitivity to the subsurface resistivity distribution. Field systems for cross-borehole and surface-to-borehole EM measurements have been designed and built by Lawrence Livermore and Lawrence Berkeley Laboratories for reservoir evaluation and monitoring. The cross-borehole system utilizes vertical axis induction coil antennas for transmission and detection of sinusoidal signals. Data are collected in profiles with the source coil moving continuously while its signal is detected by a stationary receiver coil located in a separate well. Subsequent profiles are collected using a different receiver depth and the same transmitter span until a suite of profiles is obtained that cover the desired interval in the borehole. The surface-to-borehole system uses a large diameter surface loop transmitter and a vertical axis borehole receiver. Due to its high signal strength this system operates using a sweep frequency transmitter waveform so that data may be simultaneously collected over several decades of frequency. Surface-to-borehole profiles are equally repeatable and although this data is less sensitive than cross-borehole EM, it can be fit to a resistivity section consistent with the borehole log. 8 refs., 14 figs.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5298486
- Report Number(s):
- DOE/BC-91002253; ON: DE91002253
- Country of Publication:
- United States
- Language:
- English
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