A compact ocean bottom electromagnetic receiver and seismometer
<p>Joint marine electromagnetic (EM) and seismic interpretations are widely used for offshore gas hydrate and petroleum exploration to produce improved estimates of lithology and fluids and to decrease the risk of low gas saturation. However, joint data acquisition is not commonly employed. Cu...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-05-01
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| Series: | Geoscientific Instrumentation, Methods and Data Systems |
| Online Access: | https://www.geosci-instrum-method-data-syst.net/9/213/2020/gi-9-213-2020.pdf |
| Summary: | <p>Joint marine electromagnetic (EM) and seismic interpretations are
widely used for offshore gas hydrate and petroleum exploration to produce
improved estimates of lithology and fluids and to decrease the risk of low gas
saturation. However, joint data acquisition is not commonly employed.
Current marine EM data acquisition depends on an ocean bottom
electromagnetic receiver (OBEM), and current seismic exploration methods use
seismometers. Joint simultaneous data acquisition can decrease costs and
improve efficiency, but conventional independent data receivers have several
drawbacks, including a large size, high costs, position errors, and low
operational efficiencies. To address these limitations, we developed a
compact ocean bottom electromagnetic receiver and seismometer (OBEMS). Based
on existing ocean bottom <span class="inline-formula"><i>E</i></span>-field receiver (OBE) specifications, including
low noise levels, low power consumption, and low time drift errors, we
integrated two induction coils for the magnetic sensor and a three-axis
omnidirectional geophone for the seismic sensor to assemble an ultra-short
baseline (USBL) transponder as the position sensor, which improved position
accuracy and operational efficiency while reducing field data acquisition
costs. The resulting OBEMS has a noise level of 0.1 nV m<span class="inline-formula"><sup>−1</sup></span> rt<span class="inline-formula"><sup>−1</sup></span> (Hz) at 1 Hz in
the <span class="inline-formula"><i>E</i></span>-field, 0.1 pT rt<span class="inline-formula"><sup>−1</sup></span> (Hz) at 1 Hz in the <span class="inline-formula"><i>B</i></span>-field, and a 30 d battery
lifetime. This device also supports a Wi-Fi interface for the configuration
of data acquisition parameters and data download. Offshore acquisition was
performed to evaluate the system's field performance during offshore gas
hydrate exploration. The OBEMS operated effectively throughout the operation
and field testing. Therefore, the OBEMS can function as a low-cost, compact,
and highly efficient joint data acquisition method.</p> |
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| ISSN: | 2193-0856 2193-0864 |