This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Acoustic logging operations are used to collect data regarding the rock formation around a wellbore. Typically, an acoustic logging tool in the form of a wireline tool or logging while drilling tool is positioned within the wellbore to collect this data. The acoustic logging tool emits one or more acoustic signals in multiple directions at the surrounding wellbore wall or formation. The acoustic signal travels through the formation and returns to the logging tool having been altered by the formation. As different characteristics of the formation alter the signal differently, the returning signal carries data regarding the characteristics of the formation. Thus, by processing and analyzing the returning signal, the formation characteristics can be obtained.
Acoustic logging tools generally utilize an acoustic source such as an acoustic transducer, which produces an acoustic output. Depending on the parameters of the logging operation, it may be desired for the acoustic output to have a strong output at certain frequencies or over a certain frequency range.
Illustrative embodiments of the present disclosure are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein:
The illustrated figures are only exemplary and are not intended to assert or imply any limitation with regard to the environment, architecture, design, or process in which different embodiments may be implemented.
The following discussion is directed to various embodiments of the present disclosure. The drawing figures are not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but are the same structure or function.
Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The present disclosure is directed towards an acoustic logging device which utilizes dual acoustic transducers to increase the acoustic output pressure at certain frequencies.
Referring to the drawings,
In some embodiments, the acoustic logging operating 100 may be a wireline operation, in which an acoustic logging device 120 is lowered into the well 114 via a wireline 122. In some embodiments, the wireline 122 is suspended from a wireline truck 102 parked at the well site 106. The wireline truck 102 may include a wireline spool 126 which supplies the wireline. The wireline truck 102 may also include a hoist 124 which suspends the wireline 122 and acoustic logging device 120 in the well 114. In some embodiments, the wireline 122 may be suspended by various other well site structures such as a rig.
In some embodiments, the acoustic logging device 120 is configured to emit acoustic signals 130 to the wellbore wall 115 and through the formation 112 and detect the returning acoustic data signal 132. The returning acoustic data signal 132 is altered from the original acoustic signal 130 based on the mechanical properties of the formation, such as compressional velocity, shear velocity, and the like. Thus, the acoustic data signal 132 carries this data and can be filtered and/or processed to obtain the formation data.
Referring to
Each of the acoustic transducers 204a, 204b further includes a first piezoelectric element 208a and a second piezoelectric element 208b. The first piezoelectric element 208a is coupled to the first side 212a of the substrate 206 and the second piezoelectric element 208b is coupled to the second side 212b of the substrate 206 such that the substrate 206 is disposed between the first and second piezoelectric elements 208a, 208b. In some embodiments, the first and second piezoelectric elements 208a, 208b have the same width as the substrate 206 and are shorter than the substrate 206 such that the first and second ends 210a, 210b of the substrate 206 extend beyond the first and second piezoelectric elements 208a, 208b. In some embodiments, the first and second piezoelectric elements 208a, 208b are aligned with each other.
The piezoelectric elements 208a, 208b of the acoustic transducers share an electrical ground where coupled to the substrate 206. When the same AC voltage is applied to the piezoelectric elements 208a, 208b, the first piezoelectric element 208a may contract while the second piezoelectric element 208b expends, or vice versa, due to piezoelectric stresses induced by the applied voltage. This causes vibration or back and forth arcing of the acoustic transducers 204a, 204b, each of which generates an acoustic output.
Referring to
In some embodiments, the first and second acoustic transducers 204a, 204b can be identical. In such embodiments. The first and second acoustic transducers 204a, 204b have the same resonance frequencies. Thus, the totally acoustic pressure output from the set of acoustic transducers 204 is the sum of the acoustic pressure output of each of the first and second acoustic transducers 204a, 204b.
In some embodiments, the first and second acoustic transducers 204a, 204b can have slightly different size parameters, such as different substrate lengths, widths, or thicknesses. Such variations may create an offset between the resonance frequencies of the first and second acoustic transducers 204a, 204b. In such embodiments, when excited with the same voltage, the acoustic output frequencies of the first and second acoustic transducers 204a, 204b are offset. Thus, the combination of the respective acoustic outputs is spread across a small frequency range and the total acoustic pressure output is relatively smoother around the resonant frequencies due to the superposition effect.
In some embodiments, the substrate lengths, widths, or thicknesses can vary up to 40%. In some embodiments, the first and second acoustic transducers 204a, 204b are configured to generate acoustic outputs between 1-1.5 kHz at approximately 200 Pa/kV combined. In some embodiments, the first and second acoustic transducers 204a, 204b to generate significant combined acoustic outputs between 1-4 kHz. In some embodiments, the frequency of the first acoustic output generated by the first acoustic transducer 204a and the second acoustic transducer 204b differ up to 2 kHz. In other embodiments, the first and second acoustic transducers are configured to generate acoustic outputs of lower or higher frequencies and/or with various amounts of offset.
In some embodiments, the set of acoustic transducers 204 can include more than two acoustic transducers, each of which is fixed to the support structure 202 at its ends. In some embodiments, all the acoustic transducers in a particular set of transducers can be formed on the same substrate, such as illustrated in
In certain example embodiments, the acoustic logging tool 120 includes a plurality of sets of acoustic transducers 204 configured to propagate acoustic outputs in various directions in order to obtain the mechanical properties of various portions of the well.
In addition to the embodiments described above, many examples of specific combinations are within the scope of the disclosure, some of which are detailed below:
An acoustic logging tool, comprising:
The acoustic logging tool of example 1, wherein the substrate of the first acoustic transducer and the substrate of the second acoustic transducer are integral and continuous.
The acoustic logging tool of example 2, wherein:
The acoustic logging tool of example 3, wherein the substrate joint portion is fixed to the support structure.
The acoustic logging tool of example 1, wherein the first acoustic transducer and the second acoustic transducer are longitudinally aligned.
The acoustic logging tool of example 1, wherein the first acoustic transducer is longer than the second acoustic transducer.
The acoustic logging tool of example 1, wherein the substrate of the first acoustic transducer is thicker than the substrate of the second acoustic transducer.
The acoustic logging tool of example 1, comprising a flowbore formed therethrough.
The acoustic logging tool of example 1, comprising a plurality of sets of acoustic transducers, each of the plurality of sets of acoustic transducers facing a different direction.
An acoustic logging tool, comprising:
The acoustic logging tool of example 10, wherein the first and second piezoelectric elements are the same size and aligned with each other, and the third and fourth piezoelectric elements are the same size and aligned with each other.
The acoustic logging tool of example 10, wherein vibration of the substrate due to the first and second piezoelectric elements is isolated between the first end and the mid-portion, and vibration of the substrate due to the second and third piezoelectric elements is isolated between the third and fourth piezoelectric elements is isolated between the mid-portion and the second end.
The acoustic logging tool of example 10, wherein the distance between the first end and the mid-portion is longer than the distance between the mid-portion and the second end.
The acoustic logging tool of example 11, wherein the first and second piezoelectric elements are larger than the third and fourth piezoelectric elements by up to 40%.
The acoustic logging tool of example 10, further comprising co-located X and Y dipoles.
A method of performing acoustic logging, comprising:
The method of example 16, where the first acoustic signal and second acoustic signal have frequencies within 2 kHz of each other.
The method of example 16, wherein the first acoustic transducer and the second acoustic transducer are formed on different portions of a single substrate.
The method of example 16, wherein the first acoustic transducer is longitudinally aligned with the second acoustic transducer.
The method of example 16, comprising applying the same voltage to the first and second acoustic transducers.
While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US2015/054240 | 10/6/2015 | WO | 00 |