Comparison Of Sonic Log Data For 4 Types Of Acoustic Tools

Four types of sonic log tools were tested in the same borehole drilled in a hard formation. One is the<br>suspension type P-S logging tool with a dipole source and two receivers. Second one is a conventional full<br>wave sonic tool with two monopole transmitters and three receivers. The third is a newly developed full<br>wave digital sonic tool with two monopole sources and two receivers, and the fourth is an array sonic tool<br>with two transmitters and twelve receivers. The former two tools transmit analog signals through the<br>cable and convert the data digitally in the surface equipment, whereas the latter two transmit digital data<br>converted using 12 bit A/D boards incorporated in the probe to the surface unit. All tools are available in<br>the slim hole with diameter from 66mm to 120mm. The result of field measurement showed the obtained<br>Vp profiles coincided well with each other, and careful discrimination of waveform taking account the<br>tool characteristics is important for the precise analysis. Obvious attenuation of the Stoneley wave was<br>observed at fracture zone recognized with a borehole video image tool.