Micro-logging is based on one or more wells passing through the low and deceleration zones. Transmission waves are recorded by means of well excitation (or reception), ground reception (or excitation) , according to the transmission wave. A method of studying near-surface structures at the first arrival time.
The borehole seismic PS logging adopts the method of well excitation and ground receiving. The depth of the experimental well is 15 m, of which the excitation interval of 0.5~12.5 m is 0.5 m, and the excitation interval of 13~15 m is 1 m. 1 Detonator excitation, while ensuring that the detonator is excited in water.
Adopts WZG-24 engineering seismograph, the preamplifier gain is 12 dB, the sampling interval is 0.2 ms, the recording length is 500 ms; the PS-38 single detector is 12 channels in total, and the 1-5 well spacing is 1 m, 6 The 12-well well spacing is 2 m, as shown in below.
The shot collection of the micro-well logging in the well is easy to read at the beginning and the start. The interpretation results are shown in Figure 11: the low velocity layer has a thickness of 2.66 m and the velocity is 431 m/s; the deceleration layer has a thickness of 4.32 m and a velocity of 989 m/s; the high velocity layer 1 has a thickness of 4.68 m and a velocity of 2 804 m. /s; High speed layer 2 speed is 4 137 m/s.