Downhole Tapper for Nonlinear Acoustic Cement Bond Logging
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Solution Overview
Problem
Existing downhole inspection methods struggle to effectively measure the interface between casing and cement, and between cement and the formation, particularly in gas wells and highly attenuated wells, due to limitations in sonic wave propagation and interference issues with linear acoustic waves.
Innovation Solution
A downhole inspection device equipped with a tapper that generates nonlinear acoustic waves, which are recorded and analyzed to determine properties of tubing, cement, and adhesion between casing and cement, eliminating the need for a transmitter and reducing tool length and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sonic transmitter is installed on the same axis as the device to emit azimuthal sonic waves, then the wave can be reflected by the casing and received by hydrophones, but the wave may not reach the surface of the casing due to absence of propagation medium (gas well) or high attenuation (muddy wells)
Solution Approach 1:
The patent replaces the electromagnetic/acoustic transmitter system with a mechanical tapper system. The tapper mechanically contacts the casing and generates elastic waves through direct mechanical impact, eliminating the need for electromagnetic wave propagation through the well medium. This mechanical approach works reliably in gas wells, muddy wells, and highly attenuated wells where electromagnetic or acoustic waves fail to propagate effectively.
Solution Approach 2:
The patent introduces a mechanical intermediary (the tapper device with contact elements) that physically touches the casing to generate waves. This intermediary transfers energy directly from the device to the casing through mechanical contact, bypassing the need for wave propagation through the problematic well medium (gas, mud, or highly attenuated formations).
2Measurement precision
If a sonic transmitter is used to generate waves, then wave reflection can be detected, but interference between the emitted wave and received wave occurs, requiring complex signal treatment
Solution Approach 1:
The patent extracts and removes the wave emission function from the device. Instead of having a transmitter that emits waves, the device uses a passive mechanical tapper that only generates waves through impact. The receiver system then detects reflections without any emitted wave interference, as there is no continuous or pulsed electromagnetic/acoustic wave being transmitted. This separation of emission and detection functions eliminates the interference problem and simplifies signal processing.
Solution Approach 2:
The patent inverts the conventional approach by using a mechanical impactor instead of an electromagnetic transmitter. Rather than emitting waves and detecting their reflections, the system mechanically taps the casing to generate elastic waves that propagate through the casing and cement, then detects these mechanically-generated waves and their reflections. This inversion of the wave generation mechanism eliminates the emitted wave interference that plagues traditional sonic logging.
3Power
If a transmitter is used for sonic wave generation, then wave emission is achieved, but the tool length increases and power consumption increases
Solution Approach 1:
The patent replaces the power-intensive electromagnetic transmitter system with a simple mechanical tapper system. The mechanical impactor uses minimal power to generate waves through direct physical contact, eliminating the need for high-power electromagnetic transmission. This substitution dramatically reduces both power consumption and the physical space required for wave generation components, thereby shortening the overall tool length.
Solution Approach 2:
The patent employs a simple, inexpensive mechanical tapper that can be actuated briefly to generate the necessary waves. Unlike a transmitter that requires sustained power output and complex electronics, the mechanical impactor is a simple, robust component that delivers its function through brief mechanical action, reducing both power requirements and component size.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device accurately detects aberrations and properties of cement and adhesion, including inadequate adhesion and cracks, in gas wells and highly attenuated wells, providing detailed analysis of cement and formation interfaces without interference issues.
Implementation Method 1
generate a reflected sonic wave on the casing through a mechanical excitation
Implementation Method 2
actuating the tapper, wherein the tapper produces a nonlinear wave
Implementation Method 3
recording reflections of acoustic waves off a tubing or a casing
Implementation Method 4
recorded nonlinear acoustic waves generated by a tapper
Data Source
AI summary
A method and system for inspecting cement downhole. The method may comprise inserting an inspection device inside a tube. The inspection device may comprise a centralizing module as well as a tapper attached to the centralizing module. The inspection device may further comprise a receiver, a micro controller unit, and a telemetry module. The method may further comprise actuating the tapper, wherein the tapper produces a nonlinear wave, recording reflections of acoustic waves off a tubing or a casing, and creating a graph with an information handling system for analysis. An inspection device may comprise a centralizing module and a tapper attached to the centralizing module. The inspection device may further comprise a receiver, an information handling system, and a memory module.