阅读说明：本技术 检测在单和双套管柱环境的环形材料中的异常 (Detecting anomalies in annular materials in single and dual casing string environments ) 是由 菲利普·蒂格 亚历克斯·斯图尔特 于 2018-02-23 设计创作，主要内容包括：提供一种用于在单、双和多套管井眼环境内测量材料体积密度的基于x射线的水泥评估工具,该工具至少包括内部长度,该内部长度包括探测器区段,其中所述探测器区段还包括x射线源；用于辐射测量检测器的辐射屏蔽；依赖探测器的电子器件；以及多个工具逻辑电子器件和PSU,其中该工具使用x射线来照射井眼周围的地层,且多个检测器用来直接测量水泥环的密度和其内密度中的任何变化。检测器用来测量套管偏位,使得其它检测器响应补偿工具偏位和集中；多个参考检测器用来监测x射线源的输出,且最短轴向偏移检测器配置成将入射光子分布到能量分类中,使得可进行光电测量。(Providing an x-ray based cement evaluation tool for measuring bulk density of materials in single, dual and multi-casing wellbore environments, the tool comprising at least an internal length comprising a detector section, wherein the detector section further comprises an x-ray source; a radiation shield for the radiometric detector; detector-dependent electronics; and a plurality of tool logic electronics and PSU, wherein the tool uses x-rays to illuminate the formation surrounding the wellbore, and a plurality of detectors are used to directly measure the density of the cement sheath and any changes in its internal density. The detector is used to measure casing misalignment so that other detector responses compensate for tool misalignment and centralization; a plurality of reference detectors are used to monitor the output of the x-ray source, and the shortest axial offset detector is configured to distribute incident photons into an energy classification such that photoelectric measurements can be made.)

1. An x-ray based cement evaluation tool for measuring material bulk density within single, dual and multi-casing wellbore environments, wherein the tool comprises:

An inner length comprising a detector segment, wherein the detector segment further comprises an x-ray source; a radiation shield for the radiometric detector; detector-dependent electronics; as well as a plurality of tool logic electronics and PSUs,

Wherein the tool uses x-rays to illuminate the formation surrounding the wellbore and a plurality of detectors are used to directly measure the density of the cement sheath and any changes in its internal density.

2. The tool of claim 1 further comprising a detector for measuring casing misalignment such that other detector responses can compensate for tool misalignment and concentration.

3. The tool of claim 1, wherein the shield further comprises tungsten.

4. The tool of claim 1, wherein the tool is configured such that through routing is allowed.

5. The tool of claim 1, wherein a plurality of reference detectors are used to monitor the output of the x-ray source.

6. The tool of claim 1, wherein the shortest axial offset detector is configured to distribute incident photons into energy classifications such that photoelectric measurements may be made.

7. The tool of claim 1, wherein x-ray source energy can be modulated to modify an optimal detector axial offset to help produce a response sensitivity function.

8. The tool of claim 1, wherein the tool is to be combinable with other measurement tools including one or more of neutron porosity, natural gamma, and array sensing tools.

9. The tool of claim 1, wherein the azimuthally segmented acoustic measurements are integrated into the tool.

10. The tool of claim 1, wherein the tool is to be used to determine the location, distribution and volume of natural or artificial fractures within the formation surrounding the cased wellbore.

11. The tool of claim 1, wherein the tool is integrated into an assembly that records simultaneous boreholes.

12. The tool of claim 1, wherein the tool is powered by a mud turbine generator.

13. The tool of claim 1, wherein the tool is powered by a battery.

14. The tool of claim 1, wherein the tool is configured such that through routing is allowed.

15. The tool of claim 1, wherein a plurality of reference detectors are used to monitor the output of the x-ray source.

16. The tool of claim 1, wherein the shortest axial offset detector is configured to distribute incident photons into energy classifications such that photoelectric measurements may be made.

17. the tool of claim 1, wherein x-ray source energy is modulated to modify an optimal detector axial offset to help produce a response sensitivity function.

18. The tool of claim 1, wherein the tool is to be combinable with other measurement tools including one or more of neutron porosity, natural gamma, and array sensing tools.

19. The tool of claim 1, wherein the azimuthally segmented acoustic measurements are integrated into the tool.

20. The tool of claim 1, wherein the tool is to be used to determine the location, distribution and volume of natural or artificial fractures within the formation surrounding the cased wellbore.

Technical Field

The present invention relates generally to methods and devices (means) for detecting anomalies in annular materials, and in particular, but non-limiting embodiments, to methods and devices for detecting anomalies in annular materials in single casing string environments and dual casing string environments.

Background

Within the oil and gas industry, the need to meter the mass of cement (cement) through multiple casings is as important as the ability to determine the condition of the annulus. The industry currently employs various methods for verifying the hydraulic seal behind a single casing string. Typically, an ultrasonic tool is run in the well to determine whether cement is bonded to the exterior of the casing, thereby indicating the presence of cement in the annulus between the casing and the outer casing or between the casing and the formation. Finally, pressure testing is required to ensure that zone isolation is achieved, as the ultrasonic tool is highly dependent on the bond between the ring material and the sleeve, the quality of the sleeve, and the mechanical properties of the material in the ring that is capable of working properly. In addition, the ultrasonic tool treats the material in the ring as a single isotropic and uniform volume, and any actual deviation from this ideal results in errors in the measurement.

Current tools may provide information about the cement bond of the innermost casing, however lack the ability to discriminate to various depths in the cement or annulus material. This can lead to the possibility that fluid migration paths may exist at the cement-formation boundary, within the cement itself, or between the casing and the outer casing, thereby resulting in loss of zonal isolation.

No currently available technology is effective to be able to determine the radial and azimuthal location of anomalies within an annulus (up to the cement-formation boundary) to ensure that there are no fluid paths that could pose a risk to zonal isolation and well integrity.

Disclosure of Invention

An x-ray based cement evaluation tool for measuring material bulk density in single, dual and multi-casing wellbore environments is provided, the tool comprising at least an inner length comprising a detector (sonde) section, wherein the detector section further comprises an x-ray source; a radiation shield for the radiometric detector; detector-dependent electronics; and a plurality of tool logic electronics and PSU, wherein the tool uses x-rays to illuminate the formation surrounding the wellbore, and a plurality of detectors are used to directly measure the density of the cement sheath and any changes in its internal density. The detectors are used to measure casing offset (standoff) so that other detector responses compensate for tool offset and centralization; a plurality of reference detectors are used to monitor the output of the x-ray source, and the shortest axial offset detector is configured to distribute incident photons into an energy classification such that photoelectric measurements can be made.

Drawings

FIG. 1 shows an x-ray based cement evaluation tool deployed into a wellbore by a wireline conveyance, wherein the density of a cement sheath is measured by the tool.

FIG. 2 shows multi-azimuthal x-ray beams, such that the x-ray beams produce pseudo-conical x-rays.

Figure 3 shows the x-ray source and detector located within the tool housing.

Figure 4 shows the x-ray source and detector located within the tool housing.

Figure 5 shows the x-ray source and detector located within the tool housing.

FIG. 6 shows an optoelectronic measurement of the casing resulting from the interaction of the x-ray beam with the wellbore fluid and the casing, which may be taken by a 2-order detector or a 1-order detector, to determine the bulk of the material associated with corrosion within the casing material.

Figure 7 shows the energy of the output x-ray beam as a function of depth of investigation for optimal axial offset variation of each detector set with respect to sensitivity and modulation.

Fig. 8 shows a spectral representation of a 1 st order detector showing intensity versus photon energy.

Detailed Description

The invention describes a method and apparatus for determining the density of a material surrounding a wellbore in an enclosure that improves resolution and does not require direct physical contact (i.e., non-lining) with the well casing. The invention described and claimed herein consists of a method and apparatus using a pseudo-conical x-ray beam located in a non-lining, concentrically positioned borehole logging tool for the purpose of detecting density variations within the annular material surrounding the borehole within a single or multi-string casing bore environment.

The arrangement of the collimated detectors allows to collect data relating in particular to the interaction area (depth of investigation of the azimuthal distribution) of known azimuthal and radial positioning. As the tool is moved axially within the well, a three-dimensional map of the density of the annulus material surrounding the wellbore may be generated so that changes in the density of the annulus material may be analyzed to find problems with cement integrity and zone isolation, such as channels or holes in the annulus material that may transmit pressure.

Exemplary methods include a combination of known and new technologies in new applications regarding radiation physics and cement and casing measurements for use within the oil and gas industry. Such a method is also embodied by a device that can be used to implement a method for use in a water, oil or gas well. The exemplary method is useful for monitoring and determining cement integrity, zonal isolation, and well integrity within a cemented single or multi-string wellbore environment.

Referring now to the drawings, FIG. 1 shows an x-ray based cement evaluation tool [101] deployed into a wellbore [105] by a wireline conveyance [102, 103], wherein the density of a cement sheath [104] is measured by the tool [101 ].

FIG. 2 illustrates multi-azimuthal x-ray beams [201] such that the x-ray beams [201] produce pseudo-conical x-rays. However, unlike a true cone, the individual fingers of the pseudo-cone [201] can be used to reduce the amount of crosstalk in the signals between the detectors [203], i.e., anomalies [204] in the borehole and annular material [202] surrounding the casing [205] will be detected by the detectors [203] positioned at different azimuths at different rates so that the most likely azimuthal location of the anomaly can be determined.

figure 3 shows the x-ray source and detector [307, 308] located within the tool housing [310 ]. The tool is positioned within a fluid [306] filled cased wellbore. The first casing [305] is bonded to the second casing [303] by a cement [304] filled annulus. The second casing [303] is bonded to the formation [301] by a second cement [302] filled annulus. As the cone-shaped x-ray beam [309] interacts with the medium [301, 302, 303, 304, 305, 306] surrounding the borehole, counts are detected at each axially offset detector group [307, 308 ]. The fluid and casing detector [308] data will be primarily attributable to single event scattering mechanisms, while the anomaly detector set [307] data will be primarily comprised of multiple scattering event mechanisms.

FIG. 4 shows the x-ray source and detector [410, 411, 412, 413, 414, 415] located within the tool housing [407 ]. The tool is located in a fluid [406] filled cased wellbore. The first casing [405] is bonded to the second casing [403] by a cement [404] filled annulus. The second casing [403] is bonded to the formation [401] by a second cement [402] filled annulus. As the x-ray beam [409] (shown here as a cone) interacts with the medium [401, 402, 403, 404, 405, 406] around the tool housing [407], the counts detected at each axially offset detector group [410, 411, 412, 413, 414, 415] are a convolution of the various attenuation factors summed up by the detected photons as they travel through and back through each 'layer' of the tool housing [401, 402, 403, 404, 405, 406 ]. As the axial offset (from the source) for the detector set increases, so does the amount of convolution of the detected signal. An additional function is the mean free path length of the various materials as a function of x-ray photon energy. The 1 st order detector [410] data will be primarily attributable to single event scattering mechanisms, while the 3-nth order [412 to 415] detector group data will be primarily composed of multiple (compton) scattering event mechanisms. The data from each detector can be deconvolved by using data collected by the corresponding azimuthally coherent detector with a lower axial offset (lower radial depth of investigation). Using a multi-step approach, the signal from each detector can be deconvoluted such that the result is a measurement of the density of the material within the depth of investigation (region of interest) of a particular detector.

FIG. 5 shows the x-ray source and detector [510, 511, 512, 513, 514, 515] located within the tool housing [507 ]. The tool is positioned within a fluid [506] filled cased wellbore. The first casing [505] is bonded to the second casing [503] by a cement [504] filled ring. The second casing [503] is bonded to the formation [501] by a second cement [502] filled annulus. As the x-ray beam [509] (shown here as a cone) interacts with the medium surrounding the borehole, the counts detected at each axially offset detector set [510, 511, 512, 513, 514, 515] are a convolution of the various attenuation factor sums of the detected photons as they travel through and back through each 'layer' of the tool surroundings [501, 502, 503, 504, 505, 506 ]. The data from each detector can be deconvoluted using the data collected by the 1 st order detector set [510] to compensate for variations in fluid thickness [506] and casing [505] individually. Using the single-step approach, the signals from each detector can be compensated such that the result is a measurement of the density of the material within the investigation depth (the region of interest) combined with a function of the attenuation and scattering cross-section of the material in the lower investigation depth (or lower axial offset).

FIG. 6 shows an optoelectronic measurement of casing [603] produced by the interaction of an x-ray beam [601] with borehole fluid [604] and casing [603], which may be taken by a 2-order detector [606] or a 1-order detector [605] to determine the bulk amount of material associated with corrosion [607] within the casing material. This measurement may also be combined with the radial offset measurement contributed by the 1 st order detector [605] to determine a 'casing quality' indicator measurement. The sleeves are typically classified into size groups by their outer diameter and by weight per unit length. The dimensional variability of the cannula is manifested by the inner diameter. Thus, as the inner diameter changes, erosion of the inner casing surface facing the wellbore fluid can be determined by inner diameter measurement alone using the measured intensity of the x-ray beam [601] (by the 1 st order detector [605]) moving axially back and forth on the inner surface of the casing.

FIG. 7 shows the energy of the output x-ray beam [701] as a function of study depth, varied and modulated for the optimal axial offset of each detector set [707] with respect to sensitivity. A reduction in the energy [708] of the x-ray beam will result in a reduction in the optimal axial offset of the detector set [709 ]. However, since the physical detector [707] remains static, the collected information related to the modulation of the x-ray beam can be used to determine the level of variation of the sensitivity function for the region surrounding the borehole. In effect, acts like a synthetic aperture and improves radial resolution.

FIG. 8 shows a spectral representation of a 1 st order detector showing intensity [801] versus photon energy [802 ]. A 1 st order detector may be used to collect the spectrum of incident photons, or based on an energy threshold, with a particular energy window [803, 804] used to distinguish between counts originating from compton scattering events and those originating from photovoltaics. In this regard, the photoelectric energy will be represented by counts within a low energy window [803] and Compton within a higher energy window [804 ]. The ratio of the counts collected in the two windows gives the basis for the photoelectric measurement.

In one embodiment, an x-ray based cement evaluation tool [101] is deployed into a wellbore [105] by a wireline conveyance [102, 103], wherein the density of a cement sheath [104] is measured by the tool [101 ].

In further embodiments, a cylindrical collimator is used to give the directionality of the output of an x-ray source located within the pressure housing of the borehole logging tool [101 ]. The multi-azimuth x-ray beam [201] can be made to produce pseudo-conical x-rays. However, unlike a true cone, the individual fingers of the pseudo-cone [201] can be used to reduce the amount of crosstalk in the signals between the detectors [203], i.e., anomalies [204] in the borehole and annular material [202] surrounding the casing [205] will be detected by the detectors [203] positioned at different azimuths at different rates so that the most likely azimuthal location of the anomaly can be determined. The x-ray source and detector [307, 308] are located within a tool housing [310 ]. The tool is positioned within a fluid [306] filled cased wellbore. The first casing [305] is bonded to the second casing [303] by a cement [304] filled annulus. The second casing [303] is bonded to the formation [301] by a second cement [302] filled annulus. As the cone-shaped x-ray beam [309] interacts with the medium [301, 302, 303, 304, 305, 306] surrounding the borehole, counts are detected at each axially offset detector group [307, 308 ]. The fluid and casing detector [308] data will be primarily attributable to single event scattering mechanisms, while the anomaly detector set [307] data will be primarily comprised of multiple scattering event mechanisms. The x-ray source and detector [410, 411, 412, 413, 414, 415] are located within the tool housing [407 ]. As the x-ray beam [409] interacts with the medium [401, 402, 403, 404, 405, 406] surrounding the tool housing [407], the counts detected at each axially offset detector group [410, 411, 412, 413, 414, 415] are a convolution of the various attenuation factors summed up by the detected photons as they travel through and back through each radial layer of the tool housing [401, 402, 403, 404, 405, 406 ]. As the axial offset (from the source) for the detector set increases, so does the amount of convolution of the detected signal. An additional function is the mean free path length of the various materials as a function of x-ray photon energy. The 1 st order detector [410] data will be primarily attributable to single event scattering mechanisms, while the 3-nth order [412 to 415] detector group data will be primarily composed of multiple (compton) scattering event mechanisms.

The data from each detector is deconvolved using data collected by the corresponding azimuthally coherent detector with lower axial offset (lower radial depth of investigation). Using a multi-step approach, the signal from each detector can be deconvoluted such that the result is a measurement of the density of the material within the depth of investigation (region of interest) of a particular detector.

In further embodiments, the data from each detector may be deconvolved using data collected by the 1 st order detector set [510] to separately compensate for variations in fluid thickness [506] and casing [505 ]. Using the single-step approach, the signals from each detector can be compensated such that the result is a measurement of the density of the material within the investigation depth (the region of interest) combined with a function of the attenuation and scattering cross-section of the material in the lower investigation depth (or lower axial offset).

The single scatter bias of the 1 st order detector set makes the set ideal for measuring the offset between the casing and the tool housing through the well fluid. Since the tool is positioned primarily coaxial (i.e., non-lining) with the well casing, it is expected that the tool will remain primarily centralized. However, any slight variation in the well casing diameter (ovality) or inefficiency of the centralizer mechanism of the tool will result in a longer path length for x-rays passing through the wellbore fluid. For this reason, the 1 st order detector is the primary compensation mechanism for changes in path length and attenuation for higher order detectors. Additionally, a comparison of each of the azimuthally distributed 1 st order detectors may be employed so that the physical location of the tool within the casing (as a function of offset from the centerline) may be determined. For example, the signal from one side of an eccentric tool will be different from the opposite side of the tool, the use of three or more azimuth detectors in a group may help determine whether the tool is centered (as useful information), and the use of 5 or more detectors may achieve this with the added benefit of providing a means to generate an elliptical function to determine ovality of the casing.

Similar techniques may be applied to higher order detector groups. Wherein those detector sets associated with the region of interest (or radius of interest) associated with the 'outer' well casing can be used to impart an elliptic function to determine where the innermost casing is located compared to the outermost casing, and thus can account for a measure of multi-string casing eccentricity.

The comparison of the axial offset azimuthal groupings of the detectors can also be used to determine the radial location of the expected 'density anomaly'. In this regard, if an anomaly is located within the outer annulus between the outer casing and the formation, only the higher order detector set should detect a change in incident photon intensity/count, while the depth of investigation of the lower order detector set would be too low to detect the anomaly. As the x-ray beam passes through all of those regions of interest, anomalies detected by the lower order detector set will be detected by both the lower order anomaly detector and the higher order detector. Anomalies located at lower (internal) investigation depths will have convolution effects on higher order detectors. This difference between the effect on the higher order and lower order detectors serves as a basis for determining the radial location of density anomalies within the annular material located around the wellbore.

In one embodiment, the data collected from each azimuthal plane may be processed to produce a two-dimensional density map (pixels) of the material extending from the surface of the tool a significant distance into the formation surrounding the borehole, thereby capturing all density data for the material as a function of axial and radial position. In further embodiments, the data collected from each 'azimuth' may be compared to adjacent azimuths to determine the azimuthal position of the anomaly, so that a two-dimensional map may be merged into a three-dimensional map (voxel) of density data for the material as a function of axial position, azimuthal angle, and radial position.

During plugging and abandonment operations, the quality of the casing may not be known. In further embodiments, an optoelectronic measurement of the casing [603] resulting from interaction of the x-ray beam [601] with the wellbore fluid [604] and the casing [603] may be taken by a 2-order detector [606] or a 1-order detector [605] to determine a substantial amount of material associated with corrosion [607] within the casing material. This measurement may also be combined with the radial offset measurement contributed by the 1 st order detector [605] to determine a 'casing quality' indicator measurement. The sleeves are typically classified into size groups by their outer diameter and by weight per unit length. The dimensional variability of the cannula is manifested by the inner diameter. Thus, as the inner diameter changes, erosion of the inner casing surface facing the wellbore fluid can be determined by inner diameter measurement alone using the measured intensity of the x-ray beam [601] (by the 1 st order detector [605]) moving axially back and forth on the inner surface of the casing. A 1 st order detector may be used to collect the spectrum of incident photons, or based on an energy threshold, with a particular energy window [803, 804] used to distinguish between counts originating from compton scattering events and those originating from photovoltaics. In this regard, the photoelectric energy will be represented by counts within a low energy window [803] and Compton within a higher energy window [804 ]. The ratio of the counts collected in the two windows gives the basis for the photoelectric measurement.

In further embodiments, all detectors are configured to measure energy spectra such that this spectral information can be used to perform spectral analysis of the material surrounding the wellbore for improved material identification. In further embodiments, machine learning will be used to automatically analyze the spectral (photoelectric or characteristic energy) content of the recorded data to identify key features such as corrosion, holes, cracks, scratches, and/or scale buildup. In further embodiments, machine learning will be used to automatically analyze data derived from historical records generated by the same tool in order to better determine the best location to perform a formation fracture.

In other embodiments, the collected data may be presented as a conventional 2D recording (as a function of depth), as a voxelized three-dimensional density model, as such slices or sections. In alternative embodiments, the data is further processed by machine learning, such that a neural network is trained to look for signal anomalies, or by setting simple discriminators for differences and gradients (calibrated) between sets of axially offset detector group data. This technique is particularly powerful when combined with supply voltage modulation (i.e., changing the sensitivity function). In further embodiments, the tool is used to determine the location, distribution, and volume of natural or artificial fractures within the formation surrounding a cased wellbore.

In further embodiments, the tool [101] is located within a column that records simultaneous boreholes (LWDs), rather than being transported by wireline. In further embodiments, the LWD supply tool [101] will be powered by a mud turbine. In further embodiments, the LWD delivery tool will be powered by a battery.

In further embodiments, the LWD delivery tool will be used to determine the location, distribution, and volume of natural or artificial fractures within the formation surrounding the wellbore. In yet another embodiment, the LWD supply tool will be used to determine whether the bottom hole assembly of the drilling apparatus remains within its desired geological bed by continuously measuring the azimuthal distribution of formation density.

In still further embodiments, the tool [101] can be combined with other measurement tools (such as neutron porosity, natural gamma, and/or array sensing tools).

In further embodiments, azimuthally segmented acoustic measurements (such as azimuthally measuring cement bond) may be integrated into the tool, such that the quality of the cement bond to the first casing may be determined without the need for additional tools or logging runs.

The associated exemplary method addresses the radial and azimuthal location of density variations in the material surrounding the wellbore without the use of a liner. In addition, the method does not require pre-modeling of the material surrounding the borehole (as with acoustic tools).

This technique does not rely on the quality of the physical bond between the various loop materials (such as with acoustic methods). Moreover, the techniques may be used with multiple casing strings to determine if there are any anomalies that may degrade well integrity, zonal isolation, or cement integrity.

The data collected is measured directly, rather than inferred through a model.

The technique is non-plug lined, i.e., the source and detector do not need to be in physical contact with the well casing. In some embodiments, the technique does not rely on the fluid currently in the well to work.

The foregoing description is provided for the purpose of illustration only, and is not intended to describe all possible aspects of the present invention. Although the invention has been shown and described in detail herein with respect to a number of exemplary embodiments, it will be understood by those skilled in the art that minor changes to the description, as well as various other modifications, omissions, and additions may be made without departing from the spirit or scope thereof.