Multi-frequency Acoustic Method for Cement Bond Logging based on One-sided Excitation and Reception of Elastic Waves from the Top of a Well

摘要

A brief overview of the acoustic method and the description of the device for inspection the cementation of a well casing based on one-sided excitation and reception of elastic waves at 1 -20 kHz from the top of a well is given. A mathematical model of propagation of elastic waves in the system of a well casing and its cement ring containing defective and defect-free areas is considered. The influence of the reflection waves from the boundaries of the two solids and the dependence of the attenuation coefficient of elastic waves on the frequency and location of defective areas along the pipeline of a well are accounted for. The device operates under the computer control using the software made in the National Instruments LabVIEW environment. The test experiments on the real wells were performed. The comparison of the method with a usual acoustic method of logging is fulfilled. The results of the two acoustic methods agree with each other. The developed testing technology is sufficiently rapid, does not require lowering of the measurement instrument into the well body and is therefore less expensive in comparison with other well logging technologies. Unig the method in combination with other geophysical methods of well logging is suggested.