LB3D: Controlled Source Survey

Controlled-Source Reflection Survey

The active source reflection survey was conducted with 30 ton vibrators. On the major streets they were operated as a group of 4, running bumper to bumper as shown the figure. For the residential streets they operated as four independent vibrators in different parts of the survey area. The vibrators were restricted to operate only duing business hours on weekdays. The data from the controlled source part of the experiment is being processed by a contractor working for Signal Hill Petroleum.

The recorder is a self contained unit that contains a OYO CT32D geophone (velocity sensor) with a corner frequency of 10 Hz. The unit has sufficient battery life to last 10-14 days. It has a GPS clock to maintain time, and a 24-bit digitizer. The unit is deployed by burying it n a hole (dug with a post hole auger) and covered with approximately 6 inches of soil. The GPS clock maintains satellite sync beneath the soil layer. They are replaced every 10-14 days by deployment crews.

Most of the sensors are buried 6 inches below the surface in the grass median beside the roads. The GPS clock on the sensors performs well under 6 inches of soil.