Selective frequency excitation for simultaneous cement evaluation and wellbore geometry measurement

Abstract

Systems (200; 800) and methods (700) herein are for use with a tool of a downhole environment having at least one processor (804A) and memory (804B). The memory includes instructions to allow a signal generator to generate (702) an acoustic waveform which includes a frequency-selective waveform that excites desired modes of frequency bands and avoids undesired modes, such as pertaining to regions of the frequency bands that are parasitic to an acoustic measurement to be performed. A transmitter (202) and one or more receivers (204) may perform (704) acoustic scanning within the downhole environment using the acoustic waveform. The processor may perform (706) qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement, as part of the acoustic measurement, using received waveforms from the acoustic waveform.

Description

PATENT 751777.51 1055PCT 68WLI-511055-WO-2SELECTIVE FREQUENCY EXCITATION FOR SIMULTANEOUS CEMENT EVALUATION AND WELLBORE GEOMETRY MEASUREMENTCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This is a Patent Cooperation Treaty (PCT) application that is related to and that claims the benefit of priority from U.S. provisional patent application Ser. No. 63 / 736,433, filed December 19, 2024, and entitled “SELECTIVE FREQUENCY EXCITATION FOR SIMULTANEOUS CEMENT EVALUATION AND WELLBORE GEOMETRY MEASUREMENT,” the entire contents of which is incorporated by reference herein and form a part of this specification for all intents and purposes.BACKGROUND1. Fi el d of Inventi on

[0002] This disclosure is related to downhole logging in oil and gas wells and specifically to cement evaluation and wellbore geometry measurement in oil and gas applications.2. Description of the Prior Art

[0003] A well or any completion installation may include logging requirements in support of hydrocarbon production and other features associated therewith. Aspects of the onshore well, a subsea well, or a completion installation may include an assembly of casings and tubings. There may be interference and focusing issues with respect to transmitted energy on frequency bands of interest used during downhole logging. Each of the frequency bands of interest may correspond with a specific property of interest with the downhole environment. In one example, frequency excitation may use basic square pulse shapes. The frequency excitation from such a square pulsemay include a sine (i.e., z«(x) / x)-like) profile that has a main lobe over the desired center frequency and may have unwanted sidebands in addition to zero crossings. This may eliminate sensitivity where it may be desired. Square pulses may cause interference and may not allow more degrees of freedom for precise bandwidth control.SUMMARY

[0004] In one example, selective frequency excitation herein may be performed for simultaneous cement evaluation and wellbore geometry measurement. Excitation pulses may be designed to have optimal and well-controlled single-or multiple-bands in a frequency domain and may be optimally determined using a Fourier transform of an acoustic waveform in time. This may be applied to a transmitter. By using acoustic pulse shaping based on the Fourier transform or a predetermined frequency domain analysis, a design of time-based pulse shapes may optimize efficiency of signal excitation in any number of precise frequency bands as possible. Any unwanted excitation modes may be avoided to simplify analysis of received acoustic waveforms. This may reduce interference and may allow for precise focusing of transmitted energy on particular frequency bands of interest, where each may correspond with different properties of interest of the downhole environment.

[0005] In at least one example, a system for a downhole environment may include at least one processor and memory having instructions to allow a signal generator to generate an acoustic waveform characterized by at least one frequency-selective waveform which avoids regions that are parasitic to an acoustic measurement to be performed. The at least one frequency-selective waveform may include a sine function, a cosine function, and a windowing function. For example, the waveform may include a product of a sine function, a cosine function, and the windowing function. The system may include a transmitter and one or more receivers to perform acousticscanning within the downhole environment using the acoustic waveform. The system may include the at least one processor to perform qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement, as part of the acoustic measurement, using received waveforms from the acoustic waveform.

[0006] In some examples, at least one processor may be used to perform qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement using received acoustic waveforms. The acoustic waveform may include at least one frequency-selective waveform which avoids regions that are parasitic to an acoustic measurement to be performed. The at least one frequency-selective waveform may include a sine function, a cosine function, and a windowing function. The acoustic waveform may be used in an acoustic scanning, for the acoustic measurement, performed within a downhole environment.

[0007] In some examples, a method used with a downhole environment, such as by acoustic scanning in the downhole environment, may include using a signal generator, generation of an acoustic waveform characterized by at least one frequency-selective waveform which avoids regions that are parasitic to an acoustic measurement to be performed. The at least one frequency- selective waveform may include a sine function, cosine function, and a windowing function. For example, the acoustic waveform may be a product of the sine function, the cosine function, and the windowing function. The method may include a step to perform, using a transmitter and one or more receivers, acoustic scanning for the acoustic measurement within the downhole environment using the acoustic waveform. The method may include a further step to perform, using at least one processor executing instructions from a memory, qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement using received waveforms from the acoustic waveform.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various examples in accordance with the present disclosure will be described with reference to the drawings, in which:

[0009] FIGURE 1 illustrates an example environment subject to improvements described herein.

[0010] FIGURE 2 illustrates a tool configured for acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein.

[0011] FIGURE 3 A illustrates physical details an example environment and downhole geometric completion and cement flaws / anomalies determined by acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein.

[0012] FIGURE 3B illustrates further physical details of an example environment and downhole geometric and cement flaws / anomalies determined by acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein.

[0013] FIGURE 3C illustrates still further physical details of an example environment and downhole geometric and cement flaws / anomalies determined by acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein

[0014] FIGURE 4A illustrates a graphical workflow from pulse echo measurements of an example environment with acoustic pulse shaping using Fourier transform and simultaneous broadband excitation of low and high ranges of frequency bands, according to at least one exampleherein.

[0015] FIGURE 4B illustrates casing thickness aspects from pulse echo measurements of an example environment with acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein

[0016] FIGURE 5A illustrates acoustic pulse shaping for frequency bands used in cement evaluation and wellbore geometry measurement herein, according to at least one pitch-catch measurement example herein.

[0017] FIGURE 5B illustrates acoustic pulse shaping using Fourier transform for frequency bands used in a wellbore geometry pulse echo measurement herein, according to at least one example herein.

[0018] FIGURE 5C illustrates undesirable frequency variations resulting from square pulse waveforms for cement evaluation and wellbore geometry measurement herein, according to at least one example herein.

[0019] FIGURE 5D illustrates a dual band pulse used in acoustic pulse shaping for simultaneous cement evaluation using a lower frequency band and wellbore geometry measurement using a higher frequency band herein, according to at least one example herein.

[0020] FIGURE 6 illustrates ranges of casing thickness estimation from broadband-shaped pulse -echo pulse, in accordance with at least one example.

[0021] FIGURE 7 illustrates a process flow or method for an example system, as described with respect to one or more of FIGURES 1-6, in accordance with at least one example.

[0022] FIGURE 8 illustrates computer and network aspects, associated with a system describedin connection with one or more of FIGURES 1-6, in accordance with at least one example.DETAILED DESCRIPTION

[0023] In the following description, various examples will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the examples. However, it will also be apparent to one skilled in the art that the examples may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the example being described.

[0024] Sonic and / or ultrasonic downhole logging tools may operate on a wide range of frequencies, which may each be uniquely sensitive to physical parameters of a well or downhole environment. In one example, low frequencies may be used for deeper investigation (such as using formation signals). Higher frequencies may be used for proximal high-resolution imaging or casing thickness applications. Examples of the low frequencies and the higher frequencies, relative to the low frequences, are provided and described in connection with FIGS. 5A-6 herein. These examples are non-limiting and make apparent other ranges available for low and high frequencies in at least one application of the deeper investigation facilitated in the system and method herein, but also in other applications when the remaining aspects of the sonic and / or ultrasonic downhole logging tools are used as described herein. Instead of two separate excitations in time which may incorporate inherent sacrifices, logging speed, logging resolution, and spatial resolution may be maintained by simultaneously exciting both ranges of frequency bands (which may be desired modes), while avoiding interference due to unwanted parasitic frequency excitation (which may be undesired modes).

[0025] Frequency excitation may involve basic square pulse shapes. Frequency excitation withbasic square pulse shapes in the time domain may include frequency band of excitation that may be a .sv / otype profde (such as a function sin(x) / x) in a frequency domain. This type of profile may have a main lobe, over a desired center frequency (as part of a desired mode) and may have unwanted sidebands (as part of undesired modes), in addition to zero crossings that eliminate sensitivity where it may be desired. To address this elimination of sensitivity, excitation pulses may be designed to have optimal and well-controlled single-bands or multiple-bands in the frequency domain. These may be optimally determined through a Fourier transform performed in the frequency domain and applied as a time waveform which may be amplified for a transmitting transducer. This may be in addition to the simultaneous excitation of both ranges of frequency bands.

[0026] Acoustic pulse shaping may be used with the downhole logging tools herein and may be based at least in part on Fourier transform. In an advantage, different than the square pulse shapes which may cause interference and may not allow more degrees of freedom for precise bandwidth control, acoustic pulse shaping makes it possible to design time-based pulse shapes to optimize efficiency of signal excitation in any number of precise frequency bands. In doing so, unwanted excitation modes can be avoided to simplify an analysis performed on received acoustic waveforms from downhole logging tools. While chirped-type pulses may allow controlled or broadband frequency excitation, these may not include efficiencies incorporated in the acoustic pulse shaping at least because of the use of theoretical Fourier transform with analytic equations readily used to implement time-domain pulses with the desired precise frequency domain coverage.

[0027] FIGURE 1 illustrates an example environment 100 subject to improvements described herein. A system, such as for acoustic pulse shaping using theoretical Fourier transform and withsimultaneous excitation of low and high ranges of frequency bands, may be supported by other subsystems, including by one or more downhole and / or platform-based tools 102. The system may include a platform -based tool that may be above terrain surface 108 (of terrain 106) or above water surface. A downhole and / or platform-based tool 102 may be part of a string 112 of tools, which may include other components utilized for wellbore operations.

[0028] In an example, a string 112 may include other tools 114A-114C and components or all or part of a tool 820 (or the system generally in FIGURE 8) for performing acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, which is altogether referenced herein as selective frequency excitation. The string 112 may include at least the tool 200 for performing acoustic pulse shaping using Fourier transform and simultaneous excitation. In some examples, other than Fourier transform, a predetermined frequency domain analysis may be used as readily apparent using the descriptions herein for acoustic pulse shaping to include at least one frequency-selective waveform which avoids regions, which may be low sensitivity regions, that are parasitic to undesired modes, including to a pulse waveform in some examples.

[0029] In some examples, the frequency-selective waveform may include a combination of a sine function a cosine function, and a windowing function to excite desired modes corresponding to predetermined frequency ranges of waveforms and may be to avoid excitation of undesired modes corresponding to other frequency ranges of waveforms that are parasitic to the acoustic measurement. For example, the other frequency ranges of waveforms may be frequency variations resulting from square pulse waveforms. As such, the system and method herein facilitate selective frequency excitation (referred to as the frequency-selective waveform) for simultaneous cement evaluation and wellbore geometry measurement.

[0030] The tool 820 (or the system generally in FIGURE 8) may be able to use the selective- frequency waveform as an excitation for simultaneous cement evaluation and wellbore geometry measurement. The tools 114A-114C, 200 herein may be part of sensors, measurement devices, communication devices, and the like. Further, a string 112 may include one or more tools 114A- 114C, 200 to enable at least one of a logging operation (such as wireline logging), a perforating operation, a pressure testing, a reservoir fluid sampling, or a well intervention. In at least one embodiment, nuclear logging tools, fluid sampling tools, and core sampling devices may also be used in a string 112. The one or more tools may include part of or a complete subsystem to perform functions described herein.

[0031] In at least one embodiment, perforating operations may include ballistic devices being lowered into a wellbore 104 to perforate the casing or formation. In at least one embodiment, well interventions may include operations relating to analysis of one or more features of a wellbore 104, followed by performing one or more tasks in response to at least one feature. One or more of such features may include data acquisition, cutting, and cleaning. As such, in at least one embodiment, a string 112 may refer to a combination of one or more tools lowered into a wellbore 104. In addition, passive devices may also be included, such as centralizers or stabilizers, and tractors may be provided to facilitate movement of a string 112.

[0032] In at least one embodiment, power and / or data conducting tools may be used to send and receive signals and / or electrical power. Sensors may be incorporated into various components of a string 112 and may be enabled to communicate with a surface (platform) or with other string components. In an example, such communication may be via a cable 110, via mud pulse telemetry, via wireless communications, and via wired drill pipe, in a non-limiting manner. In at least one embodiment, it should be appreciated that while embodiments may include a wireline system, arigid drill pipe, coiled tubing, or any other downhole exploration and production methods may be utilized with at least one embodiment herein.

[0033] In at least one embodiment, an environment 100 includes a wellhead assembly 116 shown at an opening of a wellbore 104 to provide pressure control of a wellbore and to allow for passage of equipment into a wellbore 104. The equipment may include a cable 110 and a string 112 of tools. A cable 110 is or may include a wireline that is spooled from a service truck 118. The cable 110 may extend to an end of a string 112. Further, during operation, a cable 110 may be provided with some slack as a string 112 is lowered into a wellbore 104 to a predetermined depth.

[0034] In at least one embodiment, fluid may be delivered into a wellbore 104 to drive or assist in movement of a string 112. This may be a case where gravity may not be sufficient to assist, such as in a deviated wellbore. A fluid pumping system may be provided at a surface 108 to pump fluid from a source into a wellbore 104 via a supply line or conduit. Further, control of a rate of travel of a downhole assembly and / or control of tension on a cable 110 may be provided by a winch on a surface 108. The winch system may be part of a service tuck 118. In addition, a combination of fluid flow rate and tension on a cable 110 can contribute to a travel rate or rate of penetration of a string 112 into a wellbore 104.

[0035] In at least one embodiment, a provided cable 110 may be an armored cable that includes conductors for supplying electrical energy (power) to downhole devices and communication links for providing two-way communication between a downhole tool and surface devices. Further, tools, such as tractors, may be disposed along a string 112 to facilitate movement of such a string 112 into a wellbore 104. A string 112 may be retrieved from a wellbore 104 by reeling a provided cable 110 upwards using such a service truck 118. In at least one embodiment, logging operations may be performed as a string 112 is brought to a surface 108.

[0036] FIGURE 2 illustrates a tool 200 configured for acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein. The tool 200 may include a transmitter 202 and one or more receivers 204. There may be motors, directional hinges, blades, material collection, and other features within the tool 200. The tool 200 may include integrated preamplifiers that substantially reduce noise within one or more of the transmitter 202 or the one or more receivers 204. The tool 200 may include support structures due to additional weight added by the features herein. The tool 200 may include an upgraded motor and position encoders to support the acoustic pulse shaping using Fourier transform and simultaneous excitation described herein. The tool 200 may be a full vertical tool, used in the downhole direction 206 illustrated, with azimuthal scanning for at least two azimuthal rotations.

[0037] FIGURE 3A illustrates physical details 300 an example environment and downhole geometric and cement flaws / anomalies determined by acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein. The physical details 300 illustrates that the tool 200 is able to perform cement evaluation and wellbore geometry measurement for casings of 9-5 / 8” dimensions (310A) or of 7” top of cement (TOC) dimensions (310B, illustrated side-by-side). The cement evaluation and wellbore geometry measurement may be able to target a width of the casing 302 and is able to distinguish formation 304, water 306, and cement 308, with respect to the casing 302. FIGURE 3A also illustrates that the casings may have a different top 300A composition relative to a bottom 300B composition and that the tool 200 may be used to generate a profile for a top and / or for a bottom composition.

[0038] FIGURE 3B illustrates further physical details 330 of an example environment anddownhole geometric completion and cement flaws / anomalies determined by acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein. The example environment may include 9-5 / 8” casings 334A that are normal or expected and may include other 9-5 / 8” casings 334B that may include downhole geometric and cement flaws / anomalies, illustrated at a top 330A composition and a bottom 330B composition. The further physical details 330 illustrate that the acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands may detect downhole geometric and cement flaws / anomalies such as flaws 332 in at least the casing 302 or the cement 308. The flaws 332 may include channels that have water 306 filled therein or that may be empty, which may not be in the casings 334A that are normal or expected.

[0039] FIGURE 3C illustrates still further physical details 360 of an example environment and downhole geometric and cement flaws / anomalies determined by acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands, according to at least one example herein. The downhole geometric and cement flaws / anomalies are illustrated at a top 360 A composition and a bottom 3602B composition of the 9-5 / 8” casings 362A, 362B. FIGURE 3C illustrates that the downhole geometric and cement flaws / anomalies may include flaws 332, including channels with different angles, sizes, and fillings. For instance, the channels may include unreplaced mud, channels may be empty or without sealing, may include developed cracks causing vertical and horizontal pathways, may be empty around the casing 302, may include microchannels from pressure or temperature changes, may include increased permeability, or may include increased or evidence of gas inclusions. FIGURES 3A-3C may also include separate metal flaws and cement flaws, with each corresponding to a different frequency range in the acoustic scanning performed herein, in some examples.

[0040] FIGURE 4A illustrates a graphical workflow 400 from pulse echo measurements of an example environment with a single excitation and having simultaneous high and low broadband excitations, according to at least one example herein. The graphical workflow 400 may be an automated workflow. In one example, the graphical workflow 400 may be for determination of first tubular geometry using data 410 from the receivers of the tool 200. Specifically, travel times (tl, t2) of applied and received waves may be reflected in a first graphical interpretation of the data, at different depths of the tool 200 in the downhole direction 206. The y-axis provides data from different azimuthal positions of the tool 200.

[0041] A lack of sensitivity 404 over different frequencies may be overcome to identify a resonance frequency (illustrated as the identified resonance freq. 408). The different frequencies may include a first frequency of about 200 Kilohertz (KHz) and a second frequency of about 300 KHz. In some examples, a background estimation 406 may be performed to remove any noise that may be within the data. The background estimation 406 may be used with the lack of sensitivity 404 plot or data determination to filter for the possible resonant frequencies and to identify a specific resonant frequency (freq.) or range 408.

[0042] FIGURE 4B illustrates casing thickness aspects 450 from pulse echo measurements of an example environment with a single excitation and having simultaneous high and low excitations, according to at least one example herein. The casing thickness aspects 450 indicate that there may be flaws 332 in at least the casing 302 from the data analyzed in FIGURE 4A for the casing 302. FIGURE 4B also illustrates an overlaid model 454 that may formalize flaws 332 according to a type, including a channel and any filing or lack thereof.

[0043] In some examples, the desired modes may be based in part on the time-based pulse shapes provided for excitation and the undesired modes may be to avoid excitation of undesired modesthat are parasitic to the acoustic measurement To achieve accurate acoustic measurements, the focus on desired modes herein may be with reference to specific the time-based pulse shapes which may be intend for acoustic measurements. As such, the system and method herein may eliminate or minimize the undesired modes which may be parasitic, which may appear as peaks and dips in the frequency response, and which may distort the acoustic measurement.

[0044] FIGURE 5A illustrates acoustic pulse shaping 500 for frequency bands used in cement evaluation and wellbore geometry measurement herein, according to at least one pitch-catch measurement example herein. For instance, as particularly illustrated, a flat profile 502 may be achieved over the range of pitch-catch frequencies 504 of interest using acoustic pulse shaping using Fourier transform.

[0045] FIGURE 5B illustrates acoustic pulse shaping using Fourier transform 530 for frequency bands used in a wellbore geometry pulse echo measurement herein, according to at least one example herein. While cement evaluation may use a lower frequency range than illustrated in FIGURE 5B, this FIGURE is exemplary for mostly a geometry estimation usable with the system and method herein. In some examples, the illustrated frequencies may be used for cement evaluation. In some examples, as particularly illustrated, Fourier transform 532 allows for optimization of the frequency profde, yielding from a distinct pulse shape 534 in time. In one example, at least one processor and memory having instructions may be used with a signal generator to allow the signal generator to generate the acoustic waveform represented as a distinct pulse shape 534.

[0046] FIGURE 5C illustrates aspects 560 of undesirable frequency variations resulting from square pulse waveforms for cement evaluation and wellbore geometry measurement herein, according to at least one example herein. For instance, square waveforms or pulses 562 may beused but have frequency-dependent sensitivities 564 throughout the frequency domain. This is not the case with the distinct pulse shape 534 generated by acoustic pulse shaping for cement evaluation and wellbore geometry measurement herein. The square waveforms 562 may be unipolar or bipolar (only bipolar is illustrated). The square waveforms 562 may be designed and used for transmitting acoustic waves as “bipolar square waves”, where the x axis is defined by time.

[0047] A Fourier transform of this square waveform 562 may result in a sine function that has zero crossings 566. Zero crossings may be represented in part by a Fourier of a rectangular function, which may result in an equation of co=2njr, where n is non-zero. This may be undesirable at least because such a function may limit achieved bandwidth and prevent accurate qualitative or quantitative analysis. For instance, an angular frequency (omega) may be set to 2mr, which may correspond to a sinusoidal wave that completes one cycle every 2TT radians. A number of zero crossings (n) may be set to 1 initially. With these settings, an array tracking the crossings over time may return an empty list, indicating there are no zero crossings within the considered frequency interval. As such, the system and method herein may use time-based pulse shapes which include a predetermined degree of freedom associated with bandwidth control, for the acoustic waveform and the acoustic scanning. In some examples, the time-based pulse shapes may allow the desired excitation and avoid undesired or unwanted excitation modes.

[0048] FIGURE 5D illustrates a dual band pulse 580 used in acoustic pulse shaping for simultaneous cement evaluation using a lower frequency band and wellbore geometry measurement using a higher frequency band herein, according to at least one example herein. For example, 2 different frequency bands may be applied to cement evaluation and wellbore geometry measurement. One frequency band may be for cement evaluation and another one for geometricanalysis. Then 2 pulses that have different center frequencies and bandwidths can be added to provide a dual-band waveform 582, which may be transmitted as one pulse as a dual-band frequency excitation, as part of the system herein. In one example, at least one processor and memory having instructions may be used with a signal generator to allow the signal generator to generate the acoustic waveform represented as a dual-band waveform 582.

[0049] FIGURE 6 illustrates ranges of casing thickness estimation 600 from broadband-shaped pulse-echo pulses that may be most subject to detection impacts and that most benefit from the acoustic pulse shaping herein, in accordance with at least one example. The pulse echo may use measurements from at least one transducer which may be a 380 kHz transducer or a 480 kHz transducer. As such, the system and method herein may facilitate an excitation of a single broadband frequency that has a controlled frequency profile or the simultaneous excitation of the at least two distinct ranges of frequency bands as part of a dual-band frequency excitation. As illustrated, the analysis from the pulse echo performed demonstrated an almost + / - 20% metal loss / gain in accuracy. As such, the casing thickness estimation 600 from pulse echo illustrates that transducer frequency profile impacts detection. This may be case-dependent, but the most affected frequencies 602 are certain resonant frequency ranges that are predictable. These frequencies 602, if used with a tool 200 for a casing or cement analysis, may be most responsive to acoustic pulse shaping using Fourier transform and simultaneous excitation of low and high ranges of frequency bands.

[0050] FIGURE 7 illustrates a process flow or method 700 for an example system, as described with respect to one or more of FIGURES 1-6, in accordance with at least one example. The method includes a step to generate 702 an acoustic waveform that may be for transmitting and that may include at least one frequency-selective waveform which avoids regions avoids regions thatare parasitic to an acoustic measurement to be performed. For example, the regions may be low sensitivity regions that are parasitic to the acoustic measurement, such as the use of square waveforms, to be performed. In some examples, the frequency-selective waveform which avoids low sensitivity regions may include a sine function, a cosine function, and a windowing function. The windowing function may include a hamming window function, but other windowing functions may be used. The method 700 includes a step to perform 704 acoustic scanning within a downhole environment using the acoustic waveform. The use of the acoustic waveform may avoid zero crossings in the frequency domain. The method 700 includes a step to allow 706 qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement, for the acoustic measurement, using received waveforms from the acoustic waveform.

[0051] FIGURE 8 illustrates computer and network aspects 800 for a system for qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement using acoustic pulse shaping, according to at least one embodiment. In at least one embodiment, these computer and network aspects 800 may include a distributed system. In at least one embodiment, the computer and network aspects 800 may include one or more computing devices 812, 814. In at least one embodiment, one or more computing devices 812, 814 may be adapted to execute and function with a client application, such as with browsers or a stand-alone application, and are adapted to execute and function over one or more network(s) 806.

[0052] In at least one embodiment, a server 804, having components 804A-N may be communicatively coupled with computing devices 812, 814 via network 806 and via a receiver device 808, if provided. In at least one embodiment, components 812, 814 include processors, memory and random-access memory (RAM). In at least one embodiment, server 804 may be adapted to operate services or applications to manage functions and sessions associated withdatabase access 802 and associated with computing devices 812, 814. Tn at least one embodiment, server 804 may be associated with a signal provisioning or detector device 808 of a downhole tool 820.

[0053] In at least one embodiment, a server 804 may be at a wellsite location, but may also be at a distinct location from a wellsite location. In at least one embodiment, such a server 804 may support a tool 820 for analysis of a downhole environment 822. Such a tool 820 may be partly downhole and partly at a surface level. Such a tool 820 may include subsystems 818A, 818B to perform functions described herein.

[0054] The subsystems may be an electrical (elec.) subsystem 818A to provide power. The provision of power may be by coupling from an external power source, in one example. Another subsystem that may be a feedback (FB) subsystem 818B may be provided in the tool 820 to change an acoustic waveform provided to the downhole environment 822. The tool 820 may include a modeling subsystem 816 to generate an acoustic waveform having a sine function a cosine function, and a windowing function. The subsystems herein may be encased in one or more computing devices having at least one processor and memory so that the at least one processor can perform functions based in part on instructions from the memory executed in the at least one processor. In at least one embodiment, even though illustrated together, the system boundary 818 may be around a distributed system having subsystems 818A, 818B, 816 in different geographic locations, including downhole and surface areas.

[0055] A signal provisioning or detector device 808 may include a transmitter 202 (including a signal generator) and one or more receivers 204, of a downhole tool 820, which may be provided to test the downhole environment 822. In at least one embodiment, the system illustrated may be adapted to transmit, either through wires or wireless, information received therein, from a signalprovisioning or detector device 808, back to the surface.

[0056] In at least one embodiment, such information may be received in a receiver device and transmitted from there. In at least one embodiment, a server 804 may function as a signal provisioning or detector device (with a transmitter providing the actual signal and receiving a return signal) but may also perform other functions. In at least one embodiment, one or more component 804A-N may be adapted to function as a signal provisioning or detector device within a server 804. In at least one embodiment, one or more components 804A-N may include one or more processors and one or more memory devices adapted to function as a detector or receiver device, while other processors and memory devices in server 804 may perform other functions.

[0057] In at least one embodiment, a server 804 may also provide services or applications that are software-based in a virtual or a physical environment (such as to support the simulations referenced herein). In at least one embodiment, when server 804 is a virtual environment, then components 804A-N are software components that may be implemented on a cloud. In at least one embodiment, this feature allows remote operation of a system for analysis of a reservoir using a wireline system that is a tool, as discussed at least in reference to Figures 1-7. In at least one embodiment, this feature also allows for remote access to information received and communicated between any of the aforementioned devices. In at least one embodiment, one or more components 804A-N of a server 804 may be implemented in hardware or firmware, other than a software implementation described herein. In at least one embodiment, combinations thereof may also be used.

[0058] In at least one embodiment, one computing device 810-814 may be a smart monitor or a display having at least a microcontroller and memory having instructions to enable display of information monitored by a signal provisioning or detector device. In at least one embodiment,one computing device 810-812 may be a transmitter device to transmit directly to a receiver device or to transmit via a network 806 to a receiver device 808 and to a server 804, as well as to other computing devices 812, 814.

[0059] In at least one embodiment, other computing devices 812, 814 may include portable handheld devices that are not limited to smartphones, cellular telephones, tablet computers, personal digital assistants (PDAs), and wearable devices (head mounted displays, watches, etc.). In at least one embodiment, other computing devices 812, 814 may operate one or more operating systems including Microsoft Windows Mobile®, Windows® (of any generation), and / or a variety of mobile operating systems such as iOS®, Windows Phone®, Android®, BlackBerry®, Palm OS®, and / or variations thereof.

[0060] In at least one embodiment, other computing devices 812, 814 may support applications designed as internet-related applications, electronic mail (email), short or multimedia message service (SMS or MMS) applications and may use other communication protocols. In at least one embodiment, other computing devices 812, 814 may also include general purpose personal computers and / or laptop computers running such operating systems as Microsoft Windows®, Apple Macintosh®, and / or Linux®. In at least one embodiment, other computing devices 812, 814 may be workstations running UNIX® or UNIX-like operating systems or other GNU / Linux operating systems, such as Google Chrome OS®. In at least one embodiment, thin-client devices, including gaming systems (Microsoft Xbox®) may be used as other computing devices 812, 814.

[0061] In at least one embodiment, network(s) 806 may be any type of network that can support data communications using various protocols, including TCP / IP (transmission control protocol / Intemet protocol), SNA (systems network architecture), IPX (Internet packet exchange), AppleTalk®, and / or variations thereof. In at least one embodiment, network(s) 806 may be anetworks that is based on Ethernet, Token-Ring, a wide-area network, Internet, a virtual network, a virtual private network (VPN), a local area network (LAN), an intranet, an extranet, a public switched telephone network (PSTN), an infra-red network, a wireless network (such as that operating with guidelines from an institution like the Institute of Electrical and Electronics (IEEE) 802.11 suite of protocols, Bluetooth®, and / or any other wireless protocol), and / or any combination of these and / or other networks.

[0062] In at least one embodiment, a server 804 runs a suitable operating system, including any of operating systems described throughout herein. In at least one embodiment, server 804 may also run some server applications, including HTTP (hypertext transport protocol) servers, FTP (file transfer protocol) servers, CGI (common gateway interface) servers, JAVA® servers, database servers, and / or variations thereof. In at least one embodiment, a database 802 is supported by a database server feature of a server 804 provided with front-end capabilities. In at least one embodiment, such database server features include those available from Oracle®, Microsoft®, Sybase®, IBM® (International Business Machines), and / or variations thereof.

[0063] In at least one embodiment, a server 804 can provide feeds and / or real-time updates for media feeds. In at least one embodiment, a server 804 is part of multiple server boxes spread over an area but functioning for a presently described process for analysis of a porous formation. In at least one embodiment, server 804 includes applications to measure network performance by network monitoring and traffic management. In at least one embodiment, a provided database 802 enables information storage from a wellsite, including user interactions, usage patterns information, adaptation rules information, and other information.

[0064]

[0001] The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modificationsand changes may be made thereunto without departing from the broader spirit and scope of the disclosure as set forth in the claims. Further, any of the many examples discussed here may be combined by a person of ordinary skill using the present disclosure to understand the effects of such combinations.

Claims

CLAIMSWhat is claimed is:

1. A system (200; 800) for use with a downhole environment, the system characterized by: at least one processor (804A) and memory (804B) including instructions that when executed by the at least one processor cause the system to: generate (702), by a signal generator (808) of the system, an acoustic waveform which includes at least one frequency-selective waveform which avoids regions that are parasitic to an acoustic measurement to be performed; perform (704), using a transmitter (202) and one or more receivers (204), acoustic scanning within the downhole environment using the acoustic waveform; and perform (706) qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement, as part of the acoustic measurement, using received waveforms from the acoustic waveform.

2. The system of claim 1, wherein the instructions, when executed by the at least one processor, further cause the system to: maintain one or more of a logging speed, a logging resolution, or a spatial resolution during at least the acoustic scanning based in part on simultaneously exciting at least two distinct ranges of frequency bands.

3. The system of claim 2, wherein the instructions, when executed by the at least one processor, further cause the system to: perform acoustic pulse shaping for the acoustic scanning based in part on aFourier transform or a predetermined frequency domain analysis, along with the simultaneous excitation of the at least two distinct ranges of frequency bands.

4. The system of claim 2, wherein the instructions, when executed by the at least one processor, further cause the system to: perform acoustic pulse shaping based in part on a Fourier transform, along with an excitation of a single broadband frequency that has a controlled frequency profile or the simultaneous excitation of the at least two distinct ranges of frequency bands as part of a dualband frequency excitation.

5. The system of claim 1, wherein the instructions, when executed by the at least one processor, further cause the system to: use time-based pulse shapes which include a predetermined degree of freedom associated with bandwidth control, for the acoustic waveform and the acoustic scanning, wherein the time-based pulse shapes allow excitation of desired modes and avoid excitation of undesired modes that are parasitic to the acoustic measurement.

6. The system of claim 1, wherein the instructions, when executed by the at least one processor, further cause the system to: determine a specific resonant frequency of different frequencies available for the acoustic scanning based in part on the different frequencies having different resonances for different casing thickness and tubular sizes; and use the specific resonant frequency with the acoustic scanning.

7. The system of claim 6, wherein the instructions, when executed by the at least one processor, further cause the system to:filter at least part of the different frequencies, as part of or separately from a background estimation, to generate possible resonant frequencies, wherein the specific resonant frequency is identified from the part of the different frequencies.

8. At least one processor (804A) to perform (706) qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement using received waveforms from an acoustic waveform, the acoustic waveform including at least one frequency-selective waveform which avoids regions that are parasitic to an acoustic measurement to be performed and used in an acoustic scanning, as part of the acoustic measurement, performed within a downhole environment.

9. The at least one processor of claim 8, further to: maintain one or more of a logging speed, a logging resolution, or a spatial resolution during at least the acoustic scanning based in part on simultaneously exciting at least two distinct ranges of frequency bands.

10. The at least one processor of claim 9, further to: perform acoustic pulse shaping for the acoustic scanning based in part on a Fourier transform or a predetermined frequency domain analysis, along with the simultaneous excitation of the at least two distinct ranges of frequency bands.

11. The at least one processor of claim 9, further to: perform acoustic pulse shaping based in part on a Fourier transform, along with an excitation of a single broadband frequency that has a controlled frequency profile or the simultaneous excitation of the at least two distinct ranges of frequency bands as part of a dualband frequency excitation.

12. The at least one processor of claim 8, further to: use time-based pulse shapes which include a predetermined degrees of freedom associated with bandwidth control, for the acoustic waveform and the acoustic scanning, wherein the time-based pulse shapes allow excitation of desired modes and avoid excitation of undesired modes that are parasitic to the acoustic measurement.

13. The at least one processor of claim 8, further to: determine a specific resonant frequency of different frequencies available for the acoustic scanning based in part on the different frequencies having different resonances for different casing thickness and tubular sizes; and use the specific resonant frequency with the acoustic scanning.

14. The at least one processor of claim 13, further to: determine a lack of sensitivity over the different frequencies to define a usable range of frequencies associated with the acoustic scanning; and filter at least part of the different frequencies, as part of or separately from a background estimation, to generate possible resonant frequencies, wherein the specific resonant frequency is identified from the part of the different frequencies.

15. A method (700) for a downhole environment, the method characterized by: generating (702), using a signal generator, an acoustic waveform which includes at least one frequency-selective waveform which avoids regions that are parasitic to an acoustic measurement to be performed; performing (704), using a transmitter and one or more receivers, acousticscanning within the downhole environment using the acoustic waveform; and performing (706), using at least one processor executing instructions from a memory, qualitative or quantitative analysis for cement evaluation and wellbore geometry measurement, as part of the acoustic measurement, using received waveforms from the acoustic waveform.

16. The method of claim 15, further characterized by: maintaining one or more of a logging speed, a logging resolution, or a spatial resolution during at least the acoustic scanning based in part on simultaneously exciting at least two distinct ranges of frequency bands.

17. The method of claim 16, further characterized by: performing acoustic pulse shaping for the acoustic scanning based in part on a Fourier transform or a predetermined frequency domain analysis, along with the simultaneous excitation of the at least two distinct ranges of frequency bands.

18. The method of claim 16, further characterized by: performing acoustic pulse shaping based in part on a Fourier transform, along with an excitation of a single broadband frequency that has a controlled frequency profile or the simultaneous excitation of the at least two distinct ranges of frequency bands as part of a dualband frequency excitation.

19. The method of claim 15, further characterized by: using time-based pulse shapes characterized by a predetermined degrees of freedom associated with bandwidth control, for the acoustic waveform and the acoustic scanning,wherein the time-based pulse shapes allow excitation of desired modes and avoid undesired modes that are parasitic to the acoustic measurement.

20. The method of claim 15, further characterized by: determining a specific resonant frequency of different frequencies available for the acoustic scanning based in part on the different frequencies having different resonances for different casing thickness and tubular sizes; filtering at least part of the different frequencies, as part of or separately from a background estimation, to generate possible resonant frequencies, wherein a specific resonant frequency is identified from the part of the different frequencies; and using the specific resonant frequency with the acoustic scanning.

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