Once the regions are selected, the area under each waveform for each region is determined. The area of the first region is calculated without using the first positive peak. This is due to the fact that the first positive peak is always smaller than subsequent peaks, and so removing this naturally low peak allows easier comparison to the other areas. These areas are then normalized to 100% free pipe and color-coded to allow easier viewing. This is somewhat similar to using the amplitude of waveforms to determine bonding, but multiple peaks are used instead of using a single cycle.

The circumferential acoustic scanning tool 212 may obtain ultrasonic measurements of the annular material 206 by using a rotating transducer to emit high-frequency acoustic pulses that are reflected from fluid in the wellbore 104, the casing 108, the cement 204, and the formation 106. The transducer senses the reflected pulses, and an associated logging system measures and records reflected pulse amplitude and two-way travel time. These data can be processed to produce detailed visual images of casing 108, the cement 204, and beyond. Suitable tools that may be used as the circumferential acoustic scanning tool 212 include, but are not limited to, the line of circumferential acoustic scanning tools (CAST) available from Halliburton Energy Services of Houston, Texas (e.g., CAST-I™, CAST-V™, CAST-M™, CAST-XR™, FASTCAST™, etc.).

The spectral density logging tool 214 may comprise a type of nuclear logging tool. In some embodiments, as illustrated, the spectral density logging tool 214 may include one or more actuatable arms 224 that may be selectively extended to move associated measurement sensors or detectors from a closed pad position to varying eccentric positions within the wellbore 104. As will be appreciated, this allows multiple depths of radial measurement within the wellbore 104, which is especially beneficial in evaluating wells that contain multiple concentric strings of casing 108. It is also easy to configure individual sensors in eccentric or decentralized configurations for specific geometries or customized situations. In the illustrated embodiment, the actuatable arm(s) 224 are extended to place the sensors or detectors of the spectral density logging tool 214 in direct engagement with the inner wall of the casing 108, or retracted when the density tool is in the “pad-closed” position. Additionally, dual spaced neutron tool 216 may be configured to acquire a neutron log of wellbore 104. In addition, dual spaced neutron tool 216 may comprise or more centralizers 208.

FIG. 3 illustrates a traditional example of cement bond logging tool 210. In examples, transmitter 302 may emit acoustic wave 222 into casing 108. Then, refracted waveform 223 may be observed with receiver array 304. In examples, the spacing for the traditional cement bond log (CBL) tools may be three feet between the nearest receiver in receiver array 304 and transmitter 302. In addition, receiver array 304 and transmitter 302 may be in line (along the same axial axis) with another. FIG. 4 illustrates a new example of cement bond logging tool 210 comprising standard orientation and spacing for receiver array 304 and transmitters 302. In addition, every receiver in receiver array 304 may be spaced 0.5 ft away. Cement bond logging tool 210 may also comprise far monopole 306, dipole X 308, dipole Y 310, and/or upper far monopole 312.

FIG. 5 illustrates cement bond logging tool 210 with two transmitters 302 of an upper-near monopole and lower-near monopole and receiver array 304 as R1-R13. The spacing between transmitter 302 for the upper-near monopole and the nearest receiver from receiver array 304 may be 1 foot. Similarly, spacing between transmitter 302 for the lower-near monopole and the nearest receiver from receiver array 304 may be 1 foot. Herein, the spacing illustrated may be defined as along the dimension of the axial length of the tool. In addition, spacings depicted from the center of the component of the tool to the next center component of the tool. In addition, far monopole 306 may be 7.5 feet from R1 or 13.5 feet from R13. Dipole X 308 may be 9 feet from R1 and 15 feet from R13. Dipole Y 310 may be 10 feet from R1 and 16 feet from R16. Upper far monopole 312 may be 14 feet from R1 and 20 feet from R13.

FIG. 6 illustrates an orientation of receiver array 304 spaced along cement bond logging tool 210. In examples, receiver array 304 may be spaced out 45 degrees and every 6 inches from the 3-foot station to the 9-foot station. Herein, receiver array 304 may be hydrophones or any other device configured to receive acoustic waves. When receiver array 304 are hydrophones, they may be disposed on the outer radius of cement bond logging tool 210. Further, receiver array 304 may be defined as a helical array. In examples, the nearest monopole transmitter to the nearest hydrophone receiver station is spaced at 1 foot. The receiver stations extend away at 6-inch increments for a total of 13 individual stations having 8 sensors at each station to a distance 7 feet from the nearest monopole transmitter. By using multiple monopole transmitters, a measured receiver signal is taken from 1 foot to 20 feet distances every 6 inches between monopole transmission to reception. Likewise, dipole measurements are achieved from 9 feet to 16 feet every 6 inches between dipole transmission and reception. the same axial relative location the receivers are evaluated for comparison between offset receivers in the next array moving spirally in 45-degree increments. The method provides sampling and evaluation at selectable receiver station levels spaced as desired through the hydrophone receiver array.

For example, sampling and using methods similar to the established PACERS can be applied to compare signals detected at all 8 sensors of the 3 foot spacing (transmitter-receiver) and compare signal character of the 4 foot receiver station for relative amplitude attenuation on the in-line axis 3 foot to 4 foot sensors as well as the 3 foot station sensor compared to the 45 degree offset sensors of the 4 foot station. Likewise, comparison of signal character of the 5-foot receiver station for relative amplitude attenuation on the in-line axis 3 foot to 5 foot sensors as well as the 3 foot station sensor compared to the 45 degree offset sensors of the 5 foot station.

Similarly, the comparison of signal character of the 5-foot receiver station for relative amplitude attenuation on the in-line axis 4 foot to 5 foot sensors as well as the 4 foot station sensor compared to the 45 degree offset sensors of the 5 foot station. Through similar logic the method can evaluate signal character between any desired receiver of the tool array and develop a volume or shell evaluation of acoustic energy transmission surrounding the tool. From this an interpretation based on signal laboratory and mathematically modeled response can derive an interpretation of annular contents in first annulus and beyond into multiple concentric annular regions in wellbore 104.

FIG. 7A illustrates channels A₅-C₇in receiver array 304 (e.g., referring to FIG. 6) as illustrated in FIG. 6. In addition, FIG. 7A illustrates spectral density log 702 and neutron log 704. FIG. 7B illustrates channels D₈-H₁₂in receiver array 304 (e.g., referring to FIG. 6) as illustrated in FIG. 6. A fast Fourier transform (FFT) may process each channel into cement bond property log. For example, multichannel multimode dispersion analysis (Matrix Pencil, Prony, or Modified DPFS) may be performed to extract all dispersion from every channel for each receiver of receiver array 304. With the dispersions, an FFT may be applied for every channel to yield a cement bond property log. In examples, cement bond property log may be fully bonded, partially bonded (and to what extent), or free pipe. In addition, one or more filters may be applied to enhance the measurements. Processing may be performed on information handling system 126 (e.g., referring to FIG. 1). In addition, spectral density log 702 and neutron log 704 may also be utilized. Further, baseline measurements may be utilized to enhance the processing for the cement bond property log. Herein, baseline measurements may correspond to measurements obtained during the calibration phase of the tool, in a controlled environment, in a known fluid, with a known distance between the transmitters and the 1st interface being measured (internal wall of a test casing, or a test jig during calibration). Measurements obtained during logging in a downhole environment are then compared to the baseline measurement to ensure accuracy and repeatability.

Well interventions may be performed based on the cement bond property log. Well intervention decisions may be operations to repair casing, remove casing, patch defects, and/or remove defects within the casing. In expels, repairing casing and/or defects may be performed by any suitable means, for example, inserting repair sleeves, adding concrete, and/or the like.

FIG. 8 illustrates an example information handling system 126 which may be employed to perform various steps, methods, and techniques disclosed herein. Persons of ordinary skill in the art will readily appreciate that other system examples are possible. As illustrated, information handling system 126 includes a processing unit (CPU or processor) 802 and a system bus 804 that couples various system components including system memory 806 such as read only memory (ROM) 808 and random-access memory (RAM) 810 to processor 802. Processors disclosed herein may all be forms of this processor 802. Information handling system 126 may include a cache 812 of high-speed memory connected directly with, in close proximity to, or integrated as part of processor 802. Information handling system 126 copies data from memory 806 and/or storage device 814 to cache 812 for quick access by processor 802. In this way, cache 812 provides a performance boost that avoids processor 802 delays while waiting for data. These and other modules may control or be configured to control processor 802 to perform various operations or actions. Another system memory 806 may be available for use as well. Memory 806 may include multiple different types of memory with different performance characteristics. It may be appreciated that the disclosure may operate on information handling system 126 with more than one processor 802 or on a group or cluster of computing devices networked together to provide greater processing capability. Processor 802 may include any general-purpose processor and a hardware module or software module, such as first module 818, second module 816, and third module 820 stored in storage device 814, configured to control processor 802 as well as a special-purpose processor where software instructions are incorporated into processor 802. Processor 802 may be a self-contained computing system, containing multiple cores or processors, a bus, memory controller, cache, etc. A multi-core processor may be symmetric or asymmetric. Processor 802 may include multiple processors, such as a system having multiple, physically separate processors in different sockets, or a system having multiple processor cores on a single physical chip. Similarly, processor 802 may include multiple distributed processors located in multiple separate computing devices but working together such as via a communications network. Multiple processors or processor cores may share resources such as memory 806 or cache 812 or may operate using independent resources. Processor 802 may include one or more state machines, an application specific integrated circuit (ASIC), or a programmable gate array (PGA) including a field PGA (FPGA).

Each individual component discussed above may be coupled to system bus 804, which may connect each and every individual component to each other. System bus 804 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. A basic input/output (BIOS) stored in ROM 808 or the like, may provide the basic routine that helps to transfer information between elements within information handling system 126, such as during start-up. Information handling system 126 further includes storage devices 814 or computer-readable storage media such as a hard disk drive, a magnetic disk drive, an optical disk drive, tape drive, solid-state drive, RAM drive, removable storage devices, a redundant array of inexpensive disks (RAID), hybrid storage device, or the like.

Storage device 814 may include software modules of second, first, and third software modules 816, 818, and 820 for controlling processor 802. Information handling system 126 may include other hardware or software modules. Storage device 814 is connected to the system bus 804 by a drive interface. The drives and the associated computer-readable storage devices provide nonvolatile storage of computer-readable instructions, data structures, program modules and other data for information handling system 126. In one aspect, a hardware module that performs a particular function includes the software component stored in a tangible computer-readable storage device in connection with the necessary hardware components, such as processor 802, system bus 804, and so forth, to carry out a particular function. In another aspect, the system may use a processor and computer-readable storage device to store instructions which, when executed by the processor, cause the processor to perform operations, a method or other specific actions. The basic components and appropriate variations may be modified depending on the type of device, such as whether information handling system 126 is a small, handheld computing device, a desktop computer, or a computer server. When processor 802 executes instructions to perform “operations”, processor 802 may perform the operations directly and/or facilitate, direct, or cooperate with another device or component to perform the operations.

As illustrated, information handling system 126 employs storage device 814, which may be a hard disk or other types of computer-readable storage devices which may store data that are accessible by a computer, such as magnetic cassettes, flash memory cards, digital versatile disks (DVDs), cartridges, random access memories (RAMs) 810, read only memory (ROM) 808, a cable containing a bit stream and the like, may also be used in the exemplary operating environment. Tangible computer-readable storage media, computer-readable storage devices, or computer-readable memory devices, expressly exclude media such as transitory waves, energy, carrier signals, electromagnetic waves, and signals per se.

To enable user interaction with information handling system 126, an input device 822 represents any number of input mechanisms, such as a microphone for speech, a touch-sensitive screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. Additionally, input device 822 may take in data from measurement assembly 134, discussed above. An output device 824 may also be one or more of a number of output mechanisms known to those of skill in the art. In some instances, multimodal systems enable a user to provide multiple types of input to communicate with information handling system 126. Communications interface 826 generally governs and manages the user input and system output. There is no restriction on operating on any particular hardware arrangement and therefore the basic hardware depicted may easily be substituted for improved hardware or firmware arrangements as they are developed.

As illustrated, each individual component described above is depicted and disclosed as individual functional blocks. The functions these blocks represent may be provided through the use of either shared or dedicated hardware, including, but not limited to, hardware capable of executing software and hardware, such as a processor 802, that is purpose-built to operate as an equivalent to software executing on a general-purpose processor. For example, the functions of one or more processors presented in FIG. 8 may be provided by a single shared processor or multiple processors. (Use of the term “processor” should not be construed to refer exclusively to hardware capable of executing software.) Illustrative embodiments may include microprocessor and/or digital signal processor (DSP) hardware, read-only memory (ROM) 808 for storing software performing the operations described below, and random-access memory (RAM) 810 for storing results. Very large-scale integration (VLSI) hardware embodiments, as well as custom VLSI circuitry in combination with a general-purpose DSP circuit, may also be provided.

The logical operations of the various methods, described below, are implemented as: (1) a sequence of computer implemented steps, operations, or procedures running on a programmable circuit within a general use computer, (2) a sequence of computer implemented steps, operations, or procedures running on a specific-use programmable circuit; and/or (3) interconnected machine modules or program engines within the programmable circuits. Information handling system 126 may practice all or part of the recited methods, may be a part of the recited systems, and/or may operate according to instructions in the recited tangible computer-readable storage devices. Such logical operations may be implemented as modules configured to control processor 802 to perform particular functions according to the programming of software modules 816, 818, and 820.

In examples, one or more parts of the example information handling system 126, up to and including the entire information handling system 126, may be virtualized. For example, a virtual processor may be a software object that executes according to a particular instruction set, even when a physical processor of the same type as the virtual processor is unavailable. A virtualization layer or a virtual “host” may enable virtualized components of one or more different computing devices or device types by translating virtualized operations to actual operations. Ultimately however, virtualized hardware of every type is implemented or executed by some underlying physical hardware. Thus, a virtualization computer layer may operate on top of a physical computer layer. The virtualization computer layer may include one or more virtual machines, an overlay network, a hypervisor, virtual switching, and any other virtualization application.

FIG. 9 illustrates an example information handling system 126 having a chipset architecture that may be used in executing the described method and generating and displaying a graphical user interface (GUI). Information handling system 126 is an example of computer hardware, software, and firmware that may be used to implement the disclosed technology. Information handling system 126 may include a processor 802, representative of any number of physically and/or logically distinct resources capable of executing software, firmware, and hardware configured to perform identified computations. Processor 802 may communicate with a chipset 900 that may control input to and output from processor 802. In this example, chipset 900 outputs information to output device 824, such as a display, and may read and write information to storage device 814, which may include, for example, magnetic media, and solid-state media. Chipset 900 may also read data from and write data to RAM 810. Bridge 902 for interfacing with a variety of user interface components 904 may be provided for interfacing with chipset 900. User interface components 904 may include a keyboard, a microphone, touch detection and processing circuitry, a pointing device, such as a mouse, and so on. In general, inputs to information handling system 126 may come from any of a variety of sources, machine generated and/or human generated.

Chipset 900 may also interface with one or more communication interfaces 826 that may have different physical interfaces. Such communication interfaces may include interfaces for wired and wireless local area networks, for broadband wireless networks, as well as personal area networks. Some applications of the methods for generating, displaying, and using the GUI disclosed herein may include receiving ordered datasets over the physical interface or be generated by the machine itself by processor 802 analyzing data stored in storage device 814 or RAM 810.

Further, information handling system 126 receives inputs from a user via user interface components 904 and executes appropriate functions, such as browsing functions by interpreting these inputs using processor 802.

In examples, information handling system 126 may also include tangible and/or non-transitory computer-readable storage devices for carrying or having computer-executable instructions or data structures stored thereon. Such tangible computer-readable storage devices may be any available device that may be accessed by a general purpose or special purpose computer, including the functional design of any special purpose processor as described above. By way of example, and not limitation, such tangible computer-readable devices may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other device which may be used to carry or store desired program code in the form of computer-executable instructions, data structures, or processor chip design. When information or instructions are provided via a network, or another communications connection (either hardwired, wireless, or combination thereof), to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of the computer-readable storage devices.