Double-interface ultrasonic detection imaging method for cased well

Abstract

The invention relates to a double-interface ultrasonic detection imaging method for a cased well. In the method, a frequency-adjustable tone burst / electric pulse-excited broadband transducer is used; the control excitation frequency is the case thickness resonant frequency; under the excitation action of electric pulses, the transducer radiates narrowband ultrasonic pulses; the narrowband ultrasonic pulses perpendicularly enter the wall of the well and radially pass through each medium layer; simultaneously, each interface layer produces a reflection echo; the received echo is processed; the double-interface echo is separated to obtain double-interface bonding information; and when carrying out multi-point measurement and scanning on the wall of the case, the transducer can obtain double-interface bonding characteristic images. Compared with the prior art, the invention overcomes the disadvantage that the present ultrasonic pulse echo logging instrument and other logging instruments can not detect the double-interface bonding defects; and by separating the double-interface echo in the received signal, the invention can obtain the double-interface cement bonding quality images, andcan simultaneously obtain the detection result in the traditional pulse echo logging process.

Description

technical field [0001] The invention relates to an acoustic logging technology, in particular to an ultrasonic detection and imaging method for the two interfaces of a cased hole. Background technique [0002] Quality inspection and evaluation of cement bonding in cased wells is an important logging method and technology, which is of great significance for avoiding leakage between oil and water layers in oil wells. Cased hole cement bonding logging refers to the following inspection and evaluation through logging methods: checking the bonding status between the steel casing and cement (called the first interface), and the bonding between the cement and the formation rock (called the second interface). condition, and a partial absence of cement in the annulus between the steel pipe and the rock. [0003] Traditional acoustic amplitude logging (CBL) and variable density logging (VDL) are the most widely used detection methods with the longest history. The CBL method can only...

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Problems solved by technology

Because the ultrasonic energy transmitted through the steel casing by this method is only a very small part of the entire ultrasonic pulse, that is, only the component corresponding to the resonance frequency of the casing thickness can penetrate, so the signal of the two interfaces in the echo is very weak, and usually Submerged by the resonant wave signal in the casing wall, it is almost impossible to observe, so it is impossible to detect and evaluate the bonding status of the two interfaces

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