53 2. Well seismic surveying 2.2 Well seismic data acquisition Typically, well seismic profiling is carried out with a seismic source at the surface and a receiver system in the well. In this paragraph, we present: • the necessary resources for data acquisition; • implementation in the field. 2.2.1 Necessary resources for data acquisition We present here a list of the necessary resources, in terms of: equipment, vehicles and personnel. • Equipment 1. logging unit, which includes: a receiver system composed of one or more well sensors (geophones and/ or hydrophones), a winch with several hundred meters of cable, that is connected to the well sensor, a recording and digitization unit (digitization can be done at the sensor level), a system for the visualization and printing of the field recordings, and a depth measurement system; 2. one or more surface sensors for source calibration; 3. a seismic source (explosive, hammer, weight drop); 4. a lifting system with pulleys to lower the receiving system; 5. equipment should be checked (maintenance, calibration) periodically. • Vehicles 1. either: 1 or 2 vehicles (preferably all-terrain/off-road), enabling the transport of personnel and equipment 2. or: one logging unit and one vehicle to transport personnel and the source. • Personnel and expertise 1. two operators qualified for the implementation (source, winch, acquisition); 2. one geophysicist (Head of Mission) qualified for data quality control at acquisition and who can also be an operator. 2.2.2 Implementation in the field In this section, we describe: 2.2.2.1 Description of classical VSP operation in a vertical well The well receiver or probe is lowered to a certain depth. The source is positioned on the ground surface at a short distance (<5 m) from the wellhead. A reference
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