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WO2015175745A1 - Procédés et appareil d'évaluation géologique - Google Patents

Procédés et appareil d'évaluation géologique Download PDF

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Publication number
WO2015175745A1
WO2015175745A1 PCT/US2015/030701 US2015030701W WO2015175745A1 WO 2015175745 A1 WO2015175745 A1 WO 2015175745A1 US 2015030701 W US2015030701 W US 2015030701W WO 2015175745 A1 WO2015175745 A1 WO 2015175745A1
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Prior art keywords
borehole
configuration
geological
spectra
energy
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Ceased
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PCT/US2015/030701
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English (en)
Inventor
James Grau
Jeffrey MILES
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Schlumberger Canada Ltd
Services Petroliers Schlumberger SA
Schlumberger Technology BV
Schlumberger Technology Corp
Schlumberger Holdings Ltd
Prad Research and Development Ltd
Original Assignee
Schlumberger Canada Ltd
Services Petroliers Schlumberger SA
Schlumberger Technology BV
Schlumberger Technology Corp
Schlumberger Holdings Ltd
Prad Research and Development Ltd
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Filing date
Publication date
Priority claimed from US14/279,935 external-priority patent/US9568639B2/en
Priority claimed from US14/279,843 external-priority patent/US9575208B2/en
Application filed by Schlumberger Canada Ltd, Services Petroliers Schlumberger SA, Schlumberger Technology BV, Schlumberger Technology Corp, Schlumberger Holdings Ltd, Prad Research and Development Ltd filed Critical Schlumberger Canada Ltd
Publication of WO2015175745A1 publication Critical patent/WO2015175745A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
    • G01V5/04—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging
    • G01V5/08—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays
    • G01V5/12—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using gamma or X-ray sources
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
    • G01V5/04—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging

Definitions

  • the additional gamma ray scattering from both the metal casing and cement reduces the total number of detected gamma rays. Moreover, this also changes the spectral character of the detected gamma ray spectra since the effects of scattering are very dependent on the energies of the gamma rays. It is possible to measure an energy spectrum for a given geological constituent(s) in a reference (e.g., open-hole) environment, and then transform the measured spectrum to account for the changes in scattering (e.g., from a casing, etc).
  • a reference e.g., open-hole
  • a method for estimating at least one geological constituent may include obtaining a measured energy spectrum for the at least one geological constituent for a first borehole configuration, generating a calculated energy spectrum for the at least one geological constituent for the first borehole configuration, and generating a calculated energy spectrum for the at least one geological constituent for a second borehole configuration different than the first borehole configuration.
  • the method may further include determining a relationship between the calculated energy spectra for the first and second borehole configurations, and generating an estimated energy spectrum for the at least one geological constituent for the second borehole configuration based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole configurations.
  • a related apparatus is for estimating at least one geological constituent and may include a processor and a memory cooperating therewith to obtain a measured energy spectrum for the at least one geological constituent for a first borehole configuration, generate a calculated energy spectrum for the at least one geological constituent for the first borehole configuration, and generate a calculated energy spectrum for the at least one geological constituent for a second borehole configuration which is different than the first borehole configuration.
  • the processor and memory may further cooperate to determine a relationship between the calculated energy spectra for the first and second borehole configurations, and generate an estimated energy spectrum for the at least one geological constituent for the second borehole configuration based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole configurations.
  • a related non-transitory computer-readable medium may have computer-executable instructions for causing a computer to at least obtain a measured energy spectrum for the at least one geological constituent for a first borehole configuration, generate a calculated energy spectrum for the at least one geological constituent for the first borehole configuration, and generate a calculated energy spectrum for the at least one geological constituent for a second borehole configuration which is different than the first borehole configuration.
  • Computer- executable instructions may also be provided to cause the computer to determine a relationship between the calculated energy spectra for the first and second borehole configurations, and generate an estimated energy spectrum for the at least one geological constituent for the second borehole configuration based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole configurations.
  • a borehole tool calibration method may include obtaining a measured energy spectrum for at least one geological constituent based upon a first borehole tool, generating a calculated energy spectrum for the at least one geological constituent for the first borehole tool, and generating a calculated energy spectrum for the at least one geological constituent for a second borehole tool different than the first borehole tool.
  • the method may further include determining a relationship between the calculated energy spectra for the first and second borehole tools, and determining a calibration parameter for the second borehole tool based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole tools.
  • a related apparatus is for calibrating a borehole tool and may include a processor and a memory cooperating therewith to obtain a measured energy spectrum for at least one geological constituent based upon a first borehole tool, generate a calculated energy spectrum for the at least one geological constituent for the first borehole tool, generate a calculated energy spectrum for the at least one geological constituent for a second borehole tool different than the first borehole tool, determine a relationship between the calculated energy spectra for the first and second borehole tools, and determine a calibration parameter for the second borehole tool based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole tools.
  • a related non-transitory computer-readable medium may have computer-executable instruction for causing a computer to at least obtain a measured energy spectrum for at least one geological constituent based upon a first borehole tool, generate a calculated energy spectrum for the at least one geological constituent for the first borehole tool, generate a calculated energy spectrum for the at least one geological constituent for a second borehole tool different than the first borehole tool, determine a relationship between the calculated energy spectra for the first and second borehole tools, and determine a calibration parameter for the second borehole tool based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole tools.
  • FIG. 1 is a schematic diagram, partially in block form, of a well logging apparatus which may be used for estimating at least one geological constituent in accordance with an example embodiment.
  • FIG. 2 is a flow diagram illustrating a method for estimating geological constituents across different borehole configurations in accordance with an example embodiment.
  • FIG. 3 is a flow diagram illustrating a method for estimating geological constituents in accordance with an example embodiment using full Monte Carlo calculations.
  • FIG. 4 is a graph of measured vs. calculated open-hole capture standard spectra for silicon.
  • FIG. 5 is a graph of cased-hole vs. open-hole calculated capture standard spectra for silicon.
  • FIG. 6 is a graph of the ratio of cased-hole to open-hole capture standard spectra for silicon.
  • FIG. 8 is a graph illustrating the effects of casing thickness on the ratio of cased to open-hole capture spectra for silicon.
  • FIG. 9 is a graph of a cased-hole silicon standard transformed from the measured open-hole standard in accordance with an example embodiment.
  • FIG. 10 is a flow diagram illustrating a method for estimating geological constituents in accordance with an example embodiment using scattering functions.
  • FIG. 11 is a graph of flux at the detector for mono-energetic gamma rays originating from the formation.
  • FIG. 12 is a graph in which the detector response is added to the scattering response functions from FIG. 1 1.
  • FIG. 13 is a graph in which the detector response and energy resolution are added to the scattering response functions from FIG. 12.
  • FIG. 14 is a graph of relative full-energy propagation efficiency at the detector for mono-energetic gamma rays originating from the formation.
  • FIG. 15 is a graph illustrating calculated capture standard spectra for sulfur from a high-density and a low-density formation.
  • FIG. 16 is a graph of the ratio between the calculated capture standard spectra from FIG. 15.
  • FIG. 17 is a graph of an example of a spectrum with nominal energy resolution, and one which has been transformed by the method illustrated in FIG. 3 to have improved resolution (e.g., narrower peaks).
  • a well logging system 30 is first described.
  • a borehole 32 is drilled in a formation 31 with drilling equipment, and may use drilling fluid or mud.
  • One or more portions of the borehole 32 may be lined with a casing 35, which may include metal (e.g., steel) cylindrical tubing, coiled tubing, cement, or both.
  • Other configurations may include: non-metallic casings such as fiberglass, high strength plastic, nano-material reinforced plastics etc; screens as used in some completions to prevent or reduce sanding; and slotted liners that may be used in completion of horizontal wells, for example.
  • a logging device or tool 40 is suspended in the borehole 32 on an armored multiconductor cable 33 to provide a wireline configuration, although other configurations such as logging while drilling (LWD), measurement while drilling (MWD), Slickline, coiled tubing or configurations such as logging while tripping may also be used.
  • the length of the cable 33 substantially determines the depth of the device 40 within the borehole 32.
  • a depth gauge apparatus may be provided to measure cable displacement over a sheave wheel (not shown), and thus the depth of logging device 40 in the borehole 32.
  • Control and communication circuitry 51 is shown at the surface of the formation 31, although portions thereof may be downhole.
  • a recorder 52 is also illustratively included for recording well-logging data, as well as a processor 50 for processing the data.
  • the processor 50 may be implemented using one or more computing devices with appropriate hardware (e.g., microprocessor, etc.) and non-transitory computer-readable medium components having computer-readable instructions for performing the various operations described herein.
  • recorder 52 may also be located in the tool, as may be the case in LWD tools, which may only send a certain amount of data to the surface while storing the bulk of the data in memory downhole to be read out at the surface after tripping out of the hole. In Slickline implementations there may be no communication with the surface, and data will be recorded and may be processed downhole for later retrieval and potentially further processing at the surface or a remote location.
  • the tool 40 may include one or more type of logging devices that take measurements from which formation characteristics may be determined.
  • the logging device may be an electrical type of logging device (including devices such as resistivity, induction, and electromagnetic propagation devices), a nuclear logging device, a sonic logging device, or a fluid sampling logging device, as well as combinations of these and other devices.
  • Devices may be combined in a tool string and/or used during separate logging runs. Also, measurements may be taken during drilling, tripping, and/or sliding.
  • determination from deep three-dimensional electromagnetic measurements, of distance and direction to faults or deposits such as salt domes or hydrocarbons; determination, from acoustic shear and/or compressional wave speeds and/or wave attenuations, of formation porosity, permeability, and/or lithology; determination of formation anisotropy from electromagnetic and/or acoustic measurements; determination, from attenuation and frequency of a rod or plate vibrating in a fluid, of formation fluid viscosity and/or density; determination, from resistivity and/or nuclear magnetic resonance (NMR) measurements, of formation water saturation and/or permeability; determination, from count rates of gamma rays and/or neutrons at spaced detectors, of formation porosity and/or density; and determination, from electromagnetic, acoustic and/or nuclear measurements, of formation bed thickness.
  • NMR nuclear magnetic resonance
  • the present disclosure provides a reliable technique for transforming elemental standard spectra that have been carefully measured in a reference (e.g., open-hole) environment to elemental standard spectra appropriate for another (e.g., cased-hole) environment by accounting for the differences in gamma-ray scattering between the two environments.
  • the measured open-hole standard spectrum for each element may be multiplied by the ratio of calculated (e.g., via Monte Carlo modeling) standards for that element in the cased-hole and open-hole environments, respectively.
  • An advantage of the approaches outlined herein are that they avoid the task of measuring cased-hole elemental standard spectra for each casing size that might be encountered during oil field measurements, a task which is difficult, time consuming, and the results of which are potentially inaccurate.
  • the present approach provides for calculating the elemental standard spectra based on Monte Carlo calculations of the gamma ray scattering response as a function of gamma ray energy. In addition to the cased-hole application, this also can be used to transform elemental standards to account for other environmental variation such as formation density, hole size, and other downhole conditions, as well as certain tool-to-tool variations.
  • the techniques described herein may be used with various gamma-ray techniques and/or devices, including wireline or LWD tools, chemical or electronic source of neutrons, as well as inelastic or capture reactions. It should be noted that the approaches described herein are not reserved to inelastic or capture reactions, as they may also apply to gamma rays from activation and to natural gamma rays or gamma rays emitted by radioactive contaminants in the ground.
  • the approach set forth herein may be used with one or more sets of elemental standards that have been measured and extracted in one environment (e.g. open-hole), which may then be transformed or extrapolated to another environment (e.g., using Monte Carlo calculations) to quantify the differences in spectral shape between the different environments. It should be noted that the present approach may also be applied to improve open hole standards if such standard measurements are done in environments that are not representative of or similar to the environment in which other standard measurements are taken. An example may be measuring a standard spectrum for iron using an iron pipe surrounding the tool in a large water tank.
  • Such spectrum is not entirely representative of an iron signal from iron distributed in a geological formation, however, for the purposes of this discussion the term "geological formation" is used to cover such elements in a geological environment or in such a stand-alone implementation.
  • the transformation may be a ratio of the Monte Carlo calculated spectral shapes of each elemental standard for the different environments. While Monte Carlo calculations of elemental spectra by themselves may not be sufficiently accurate to replace the measured spectra, the ratios of such Monte Carlo calculations may be sufficiently accurate to account for the environmental changes, thus allowing for the transformation or extrapolation of the measured elemental spectra to a different borehole configuration or environment.
  • an example approach for estimating one or more geological constituents illustratively includes obtaining a measured energy spectrum for at least one geological constituent for a first borehole configuration, at Block 62, generating a calculated energy spectrum for the at least one geological constituent for the first borehole configuration (Block 63), and generating a calculated energy spectrum for the at least one geological constituent for a second borehole configuration different than the first borehole configuration (Block 64).
  • the first borehole configuration may be an open-hole (uncased) borehole configuration
  • the second borehole configuration may be a cased or lined hole configuration (e.g., cement and/or steel casing, etc.).
  • the method further illustratively includes determining a relationship (e.g., a ratio) between the calculated energy spectra for the first and second borehole configurations, at Block
  • the estimated energy spectrum may then be used to determine a relative amount (e.g., a percentage) of the geological constituent(s) present adjacent to the second borehole, at Block 67, by comparison with measured element spectra for various constituents in the formation.
  • a relative amount e.g., a percentage
  • the flow diagram 70 of FIG. 3 an example embodiment for transforming standard spectra using full Monte Carlo calculations is now described.
  • the first borehole configuration is an open borehole
  • the second borehole configuration is a cased borehole.
  • the flow diagram 70 summarizes an example approach for transforming measured open-hole spectral standards using ratios of full Monte Carlo calculated spectra.
  • the standard energy spectra plot 81 for silicon calculated (e.g., via Monte Carlo modeling) matches the measured standard spectra plot 82 for silicon relatively closely.
  • Adjustment parameters may be applied to the calculated spectra as appropriate, such as those of the detector system, including the energy-to-channel calibration (e.g., the gain, offset, and linearity of the measurement system) and the energy dependence of the energy resolution. These parameters may then be applied to the Monte Carlo calculations for different elements in the various environments (Blocks 74, 75), or after determining the above-noted ratio, for example. [0040] More particularly, referring to the graph 85 of FIG. 5, Monte Carlo calculations of the silicon standard spectra 86, 87 in both open-hole and cased-hole environments, respectively, are shown.
  • a steel casing 0.231 inches thick was used, along with a cement liner 0.50 inches thick, although other casing or liner configurations or dimensions may be used in different embodiments.
  • the spectra have been normalized to be equal at high energies. The calculations appear fairly similar above 3 MeV, but below this level more down-scattering is present in the cased-hole environment, as well as more attenuation of the observable full-energy peaks.
  • the cased-hole to open-hole ratios for silicon calculated for four different steel casing thicknesses show that it is desirable to calculate the transform for each different environment to provide desired accuracy.
  • the graph 105 of FIG. 9 compares the measured open-hole silicon standard spectrum 106 to the cased-hole silicon standard spectrum 107, which has been transformed to be appropriate for the environment of 0.231 inch casing and 0.50 inch cement using the techniques described herein.
  • elemental standard spectra were calculated using Monte Carlo calculations to track the entire history of the reactions from neutron production to gamma ray detection. While this technique may overall be the most accurate method available for most modeling applications, other approaches may also be suitable for certain applications. For example, referring now to the flow diagram 110 of FIG. 10, elemental standards calculations using gamma ray scattering functions may have some advantages when applied to transforming elemental standard spectra for different environments.
  • the premise here is to decouple the Monte Carlo calculation of gamma ray scattering from the underlying emission spectrum for a given element, at Block 112. This is possible because the scattering effects vary as a function of the logging
  • gamma ray production cross sections for each element are generally known, as will be appreciated by those skilled in the art.
  • Monte Carlo calculations may be used to generate a set of gamma ray "scattering functions" which represents the energy-dependent flux at the surface of the detector that results when gamma rays of a single energy are produced in the formation (Blocks 113, 114).
  • the detector- specific response to this incident flux may be calculated and optimized as before, and then folded into the scattering functions, at Blocks 115, 116.
  • the standard spectrum for each element may then be calculated as a linear combination of the appropriate scattering functions weighted by the gamma ray production cross sections for that element for each gamma ray energy.
  • part of the detector response has been added to the gamma ray scattering functions, showing the energy deposited in the detector system and not merely the flux striking the surface of the detector due to the mono-energetic formation gamma rays.
  • This detector response is determined in a separate Monte Carlo calculation, which may be specific to the material and size of the detector being used for the measurements.
  • the detector energy resolution is also added to the scattering functions.
  • Other parameters of the energy-to-channel calibration e.g., gain, offset, nonlinearity may also be matched to various measured spectra.
  • the elemental standard spectrum may then be calculated as a linear combination of the appropriate scattering functions weighted by the gamma ray production cross sections for each gamma ray energy.
  • an energy-dependent transform may be derived by taking the ratio of two calculated elemental standards, namely one for the appropriate cased-hole environment and one for the open-hole environment of the measured standard (Blocks 117-119). This spectral ratio may be multiplied by the measured open-hole standard, as discussed above.
  • the method of FIG. 10 illustratively concludes at Block 120.
  • the best available gamma ray production cross sections for each element may be used even though they might not have been incorporated into the existing Monte Carlo code.
  • the elemental standard spectra for any element for which gamma ray production cross sections are known may be calculated extremely quickly. The addition of new elemental standards to the spectral analysis may not warrant a new set of Monte Carlo calculations.
  • the scattering function approach may be less accurate than using full Monte Carlo simulations of the elemental spectra.
  • One notable advantage of the fully detailed simulation is that it accounts for how the logging environment affects the transport and scattering of neutrons.
  • the spatial distribution of neutrons around the tool determines the shape of the gamma ray source in the formation, borehole, and completion.
  • the scattering functions in their simplest form use a constant spatial distribution of gamma rays in the formation, in reality the originating gamma ray distribution depends on parameters including, but not limited to: formation hydrogen index; formation density; borehole size;
  • the transforms may be used for additional properties of the logging environment as well. While the derivation of cased-hole standard spectra may be the application of particular interest for the above-described ratio-transformation approaches, the true shape of the spectrum for each element is affected by other properties of the logging environment as well. This is true for properties of open-hole environments as well as the details of the completion in a cased-hole environment. Therefore, the approaches described herein have potential applications for transforming standard spectra, whether open-hole or cased-hole, based on other properties of the formation or borehole that affect neutron and gamma ray scattering.
  • a potential application would be to transform open-hole standards based on formation density.
  • a set of spectral ratios based on formation density at various intervals may be derived from full Monte Carlo calculations for each element, as in this example for sulfur. Also, the approach using scattering functions may be developed here, using Monte Carlo to calculate the scattering behavior for mono-energetic gamma rays originating in formations of various densities. Each approach has advantages and disadvantages as discussed above, but this example indicates that the accuracy of the full Monte Carlo calculation may be desirable for capturing the subtle spectral differences seen in FIG. 15.
  • Variation in liquid-filled porosity therefore causes simultaneous changes in neutron and gamma ray transport that partially cancel one another in the final shape of the detected spectrum.
  • a change in gas-filled porosity would have much less effect on hydrogen index, and the neutron transport would exhibit yet a different behavior when the density changes.
  • the above-described ratio transforms may also be used to address tool-to-tool variation in spectral response.
  • elemental standard spectra are derived from laboratory measurements with a tool which is chosen for its good performance.
  • Each tool has a slightly different spectral response, and it is a routine part of the analysis to make adjustments to the elemental standards to optimize them for the downhole measurements by other tools.
  • These adjustments include the spectral response parameters previously discussed, including nonlinearity and the degradation of energy resolution.
  • some aspects of tool-to-tool variation are more challenging to adjust for, and they may be good candidates for treatment with the method of calculated ratio transforms.
  • the above-described "ratio of calculated standards" technique may be used for tool calibration with respect to detector response, and it takes advantage of being able to adjust the detector response in the calculations.
  • This allows for detector calibration to account for (1) differences in peak- shape, and (2) differences in the position of the escape peaks. That is, the shapes of energy peaks and/or the separation between the full energy peak and escape peaks in a spectral response may be different in different detectors, e.g., as a result of detector crystal differences, etc.
  • a measured energy spectrum for at least one geological constituent for a first borehole tool may be obtained at Block 262, along with generating a calculated energy spectrum for the at least one geological constituent for the first borehole tool (Block 263), and generating a calculated energy spectrum for the at least one geological constituent for a second borehole tool, which is different than the first borehole tool (Block 264), as discussed above.
  • the method further illustratively includes determining a relationship (e.g., a ratio) between the calculated energy spectra for the first and second borehole tools, at Block 265, and determining a calibration parameter (e.g., a different peak shape or peak separation) for the second borehole tool based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole tools, at Block 266which illustratively concludes the method of FIG. 18 (Block 268).
  • a relationship e.g., a ratio
  • a calibration parameter e.g., a different peak shape or peak separation
  • the standards may be calculated by adding resolution degradation both with symmetric Gaussians and with asymmetric Gaussians, where the degree of asymmetry would be determined from the difference in the H-peaks shapes in a water-tank calibration, for example.
  • a new set of detector response functions may be created with all of the escape peaks shifted, including (if necessary) the double escapes, and this would then act on every detected gamma ray.
  • a process flow for a calibration procedure in accordance with one example embodiment may be as follows:
  • One example of a non-trivial transformation is to take an elemental standard spectrum and improve its energy resolution.
  • the standards are measured with a tool that has among the best resolution available so that other tools just have to degrade the resolution of those standards (e.g., by a relatively simple convolution with a Gaussian distribution).
  • downhole measurements are made with better resolution than appears in the laboratory elemental standards.
  • An advantage of the above-described ratio transforms is that the elemental standards may be calculated with different energy resolutions, whether via the approach of fully detailed Monte Carlo calculations or the approach of scattering functions. To find the appropriate ratio for transformation, one may calculate the standard spectrum with the nominal energy resolution of the measured set of standards, and also with the better resolution of the new measurement.
  • the graph 160 of FIG. 17 shows an example of a capture silicon standard plot 161 with nominal energy resolution, and a plot 162 for a version which has been transformed by such a ratio to have improved resolution. It is a relatively straightforward exercise to degrade the improved spectrum with a traditional convolution and verify that the result is nearly equivalent to the original spectrum.
  • Another potential application of the above-described approaches relates to the tool-to- tool variation of peak shapes, and more specifically how some detector systems produce peaks that are slightly asymmetrical. It may be desirable to adapt the nominal set of elemental standard spectra to match the appropriate peak shape behavior for each tool, but this may ordinarily be a somewhat difficult operation. However, by calculating one standard spectrum using the spectral response that corresponds to the measured standards, and then calculating another spectrum with a greater degree of asymmetry, we can again produce a ratio that provides the desired
  • the present invention provides the following embodiments:
  • a method for estimating at least one geological constituent comprising:
  • each geological constituent comprises a plurality thereof; and further comprising determining a relative amount of each geological constituent based upon respective estimated energy spectra for the second borehole configuration.
  • any one of embodiments 1 to 7 wherein generating the calculated energy spectra for the first and second borehole configurations comprises calculating energy- dependent flux from gamma rays of a given energy level for the first and second borehole configurations.
  • the method of any one of embodiments 1 to 8 wherein the first borehole configuration corresponds to a first borehole diameter, and the second borehole configuration corresponds to a second borehole diameter different than the first borehole diameter.
  • the method of any one of embodiments 1 to 9 wherein the first borehole configuration corresponds to a first geological formation density, and the second borehole configuration corresponds to a second geological formation density different than the first geological formation density.
  • the method of any one of embodiments 1 to 10 wherein the first borehole configuration corresponds to a first geological formation porosity, and the second borehole
  • An apparatus for estimating at least one geological constituent comprising:
  • the apparatus of embodiment 13 wherein the relationship between the calculated energy spectra for the first and second borehole configurations comprises a ratio thereof.
  • the apparatus of embodiment 13 or 14, wherein the calculated energy spectra is generated by calculating the energy spectra for the at least one geological constituent using Monte Carlo calculations of a gamma ray scattering response as a function of gamma ray energy for the first and second borehole configurations, respectively.
  • a non-transitory computer-readable medium having computer-executable instruction for causing a computer to at least:
  • relationship between the calculated energy spectra for the first and second borehole configurations comprises a ratio thereof.
  • a borehole tool calibration method comprising:
  • the method of any one of embodiments 25 to 29, wherein generating the calculated energy spectra for the first and second borehole tools comprises calculating energy- dependent flux from gamma rays of a given energy level for the first and second borehole tools.
  • the method of any one of embodiments 25 to 30, wherein the first and second borehole tools have different respective resolutions.
  • the apparatus of embodiment 33 determines a calibration parameter for the second borehole tool based upon the measured energy spectrum and the relationship between the calculated energy spectra for the first and second borehole tools.
  • the calculated energy spectrum for the at least one geological constituent for the second borehole tool has a plurality of energy peaks therein having a first separation therebetween; and wherein the calibration parameter corresponds to a second spectral separation between the plurality of energy peaks different than the first spectral separation.
  • the apparatus of embodiment 33 or 34 wherein the calculated energy spectrum for the at least one geological constituent for the second borehole tool has at least one energy peak therein; and wherein the calibration parameter corresponds to a different peak shape for the at least one energy peak.
  • a non-transitory computer-readable medium having computer-executable instruction for causing a computer to at least:
  • the non-transitory computer-readable medium of any one of embodiments 39 to 43, wherein the calculated energy spectra for the first and second borehole tools comprises are based upon calculated energy-dependent flux from gamma rays of a given energy level for the first and second borehole tools.

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Abstract

La présente invention concerne un procédé permettant d'estimer au moins un constituant géologique pouvant consister à obtenir un spectre d'énergie mesuré pour ledit ou lesdits constituants géologiques pour une première configuration de trou de forage, générer un spectre d'énergie calculé pour ledit ou lesdits constituants géologiques pour la première configuration de trou de forage, et générer un spectre d'énergie calculé pour ledit ou lesdits constituants géologiques pour une seconde configuration de trou de forage différente de la première configuration de trou de forage. Le procédé peut en outre consister à déterminer une relation entre les spectres d'énergie calculés pour les première et seconde configurations de trou de forage, et générer un spectre d'énergie estimé pour ledit ou lesdits constituants géologiques pour la seconde configuration de trou de forage sur la base du spectre d'énergie mesuré et de la relation entre les spectres d'énergie calculés pour les première et seconde configurations de trou de forage.
PCT/US2015/030701 2014-05-16 2015-05-14 Procédés et appareil d'évaluation géologique Ceased WO2015175745A1 (fr)

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Application Number Priority Date Filing Date Title
US14/279,935 US9568639B2 (en) 2014-05-16 2014-05-16 Borehole tool calibration method
US14/279,935 2014-05-16
US14/279,843 2014-05-16
US14/279,843 US9575208B2 (en) 2014-05-16 2014-05-16 Geological constituent estimation using calculated spectra relationships

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US6389367B1 (en) * 1999-03-10 2002-05-14 Schlumberger Technology Corporation Method and apparatus for calibrating readings of a downhole tool
US20070144740A1 (en) * 2005-12-16 2007-06-28 Baker Hughes Incorporated Method and Apparatus for Fluid Influx Detection While Drilling
US20090090505A1 (en) * 2006-08-09 2009-04-09 Mcdaniel Robert R Method and tool for determination of fracture geometry in subterranean formations based on in-situ neutron activation analysis
US20110253364A1 (en) * 2010-04-19 2011-10-20 Schlumberger Technology Corporation System and method for generating density in a cased-hole wellbore
WO2013006073A1 (fr) * 2011-07-04 2013-01-10 Baker Hughes Incorporated Amélioration de méthodes d'analyse spectrale par l'utilisation de méthodes combinées

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6389367B1 (en) * 1999-03-10 2002-05-14 Schlumberger Technology Corporation Method and apparatus for calibrating readings of a downhole tool
US20070144740A1 (en) * 2005-12-16 2007-06-28 Baker Hughes Incorporated Method and Apparatus for Fluid Influx Detection While Drilling
US20090090505A1 (en) * 2006-08-09 2009-04-09 Mcdaniel Robert R Method and tool for determination of fracture geometry in subterranean formations based on in-situ neutron activation analysis
US20110253364A1 (en) * 2010-04-19 2011-10-20 Schlumberger Technology Corporation System and method for generating density in a cased-hole wellbore
WO2013006073A1 (fr) * 2011-07-04 2013-01-10 Baker Hughes Incorporated Amélioration de méthodes d'analyse spectrale par l'utilisation de méthodes combinées

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