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Unformatted text preview: time. • Marine sources: • Air gun: the common in offshore survey (first produced in 1960). This gun releases highly compressed air into water. It uses a compressed air at 2000‐ 5000PSI to produce an explosive blast of air. Several air guns with different sizes are fired to enhance their initial pulses & reduce their bubble effects. 3‐Seismic detectors: • Land detectors (Geophone): It is a device is used to detect the sound waves. It consists of coil of wire suspended from spring & surrounded by (W) shaped magnet. Upward energy from seismic source is recorded as electrical current generated by movement of coil. • Marine detectors (Hydrophone): It is a device used to detect the pressure waves. Upward energy is recorded as electrical current generated by piezoelectric device (which generates a voltage if acted with pressure). Hydrophone cable Geophone Air gun Weight drop Vibroseis 35 Geology & Geophysics in Oil Exploration Mahmoud Sroor Geology & Geophysics in Oil Exploration Seismic acquisition: It is the generation and recording of seismic data. Acquisition involves many different receiver configurations, including laying geophones or seismometers on the surface of the Earth or seafloor, towing hydrophones behind a marine seismic vessel to record the seismic signal. A source, such as a vibrator unit, dynamite shot, or an air gun, generates acoustic or elastic vibrations that travel into the Earth, pass through strata with different seismic responses and filtering effects, and return to the surface to be recorded as seismic data. Seismic Crew: A seismic crew is a team of people who conduct seismic tests to gather information about the geology of an area of interest. The biggest employer of seismic crews is the oil industry, which conducts extensive seismic research before drilling new wells for oil. • Party Chief: is the manager of the crew • Camp Boss: is responsible for camp services such as food & beverages. • Company Representive: is a person from the owner company to follow the acquisition s...
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- Spring '10