The process of seismic exploration consists of three stages: seismic data acquisition, data processing and seismic data interpretation.
In the field observation, many geophones are usually arranged at equal intervals along the seismic line to receive the seismic wave signal. The survey line shall be arranged in a direction perpendicular to the strike of geological structure. According to different observation instruments, the number of geophones or geophone groups is 24, 48, 96, 120, 240 or even 1000. Each geophone group is equivalent to a single geophone at the center of the group. The signal received by each geophone group is recorded by an amplifier and a recorder, which is called a trace.
In order to meet different requirements of seismic exploration, there are different arrangements among geophone groups, such as the middle shooting arrangement, the end shooting arrangement, etc. The recorder will separate and sample the amplified electrical signal for a certain period of time and record it on the tape in digital form. The original data on the tape can be played back and displayed as a graph.
Conventional observation is carried out along a straight line, and the data obtained reflect the seismic information in the two-dimensional plane below the line. This kind of two-dimensional data form is difficult to determine the existence of lateral reflection and the direction of fault strike and other problems. In order to investigate the formation situation in detail and use the seismic data to describe the reservoir, sometimes several survey lines are arranged in a certain area of the ground to obtain a three-dimensional data body of sufficient density. This work method is called three-dimensional seismic exploration.
There are different forms of line distribution in 3D seismic exploration, but the fact that the reflection point is directly below the midpoint of source and receiver is generally used to design the location of source and receiver point, so that the midpoint is distributed in a certain area.