CA2809328A1 - Magnetic variation method - Google Patents
Magnetic variation method Download PDFInfo
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- CA2809328A1 CA2809328A1 CA2809328A CA2809328A CA2809328A1 CA 2809328 A1 CA2809328 A1 CA 2809328A1 CA 2809328 A CA2809328 A CA 2809328A CA 2809328 A CA2809328 A CA 2809328A CA 2809328 A1 CA2809328 A1 CA 2809328A1
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- Prior art keywords
- spectrally
- magnetically active
- underground
- reference value
- attribute
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
- G01V3/08—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices
- G01V3/087—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices the earth magnetic field being modified by the objects or geological structures
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Remote Sensing (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- Physics & Mathematics (AREA)
- Geochemistry & Mineralogy (AREA)
- Electromagnetism (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
In a magnetovariational method for detecting, mapping out, and evaluating spectrally magnetically active underground occurrences, abnormal magnetic fields (2) varying over time and existing in conjunction with spectrally magnetically active rock masses (1) are measured according to location and time within an examination region on or above the earth's surface (8) as signal and/or field variables in at least one spatial direction component, the time series measured data recorded for each measurement location in the examination region are transferred by means of data processing, in particular spectral analysis, into the power spectral density in the frequency range 0.01 to 100 Hz, and at least one spectral attribute (6), in particular the power, is determined therefrom, and a distinction between an occurrence and a non-occurrence of spectrally magnetically active rock masses underground is made by comparing the attribute variable values standardized to a reference value (7) to the standardized reference value (11).
Description
r' CA 02809328 2013-02-22 MAGNETIC VARIATION METHOD
Description The invention relates to a magnetic variation method for detecting, mapping and evaluating spectrally magnetically active underground occurrences.
There is known from the prior art a magnetic variation method that does not use dedicated actively controlled transmission sources, but uses permanently present temporally varying magnetic fields that are passively received (Simpson, F. & Bahr, K.:
Practical Magnetotellurics, p. 182, Cambridge University Press, 2005). In conventional methods, these magnetic fields are caused by external induction effects from the ionosphere and magnetosphere. Furthermore, the known methods are used to determine horizontal electrical , conductivity gradients as result, but do not detect spectrally magnetically active underground occurrences.
It is an object of the invention to provide a magnetic variation method of the type mentioned at the beginning with the aid of which spectrally magnetically active underground occurrences, in particular hydrocarbon reservoirs and ore enrichments, are located, and which is substantially based on fields generated geogenically underground.
According to the invention, the object is achieved by the features of claim 1.
The subclaims constitute advantageous refinements.
In the magnetic variation method for detecting, mapping and evaluating spectrally magnetically active underground occurrences, the temporally varying anomalous magnetic fields existing in conjunction with such rock masses are measured as a function of location and time inside an examination region on or above the Earth's surface as signal and/or field variables in at least one spatial direction component, the time series measured data recorded for each measurement location are transferred by means of data processing, in particular spectral analysis, into the spectral power density in the frequency range of 0.01 to 100 Hz, and at least one spectral attribute, in particular the power, is determined herefrom, and a distinction between an occurrence and a non-occurrence of a spectrally magnetically active rock mass underground is made by comparing the attribute variable values standardized to a reference value to the standardized reference value.
Spectrally magnetically active underground occurrences are to be understood, for example, as hydrocarbon (petroleum, natural gas) or ore occurrences.
Presently, advantageous use is made of the fact that by comparison with rocks that have no hydrocarbons and/or ores, said occurrences have anomalous spectral magnetic properties. The latter can be measured, and thereby permit the identification and mapping of corresponding subterranean occurrences.
The measurements inside the examination region above the Earth's surface can, for example, be undertaken by means of a helicopter, which means that the examination region can also be very large and/or difficult to access, and the measurements can nevertheless be carried out expediently as regards economics. In the sense of the invention, the specification on or above the Earth's surface is also to be understood as the bottom of a body of water, for example a lake or sea, that is to say the measurements inside the examination region can be carried out both at the bottom of a body of water and on or above the Earth's surface.
The method enables the detection of reservoir rocks bearing hydrocarbons and of carrier layers underground, the mapping of the distribution thereof, the obtaining of qualitative pointers to the potential hydrocarbon productivity, and a temporal monitoring during the development and extraction phase.
The advantage attained consists, in particular, in that petroleum and natural gas accumulations underground can be detected directly, and their relative productivity can be specified as additional evaluation criterion. It is possible on the basis of such results to implement a substantial economic benefit in the exploration since, inter alia, it is possible for deep bores to be sunk specifically, and to avoid failed bores. Furthermore, the exploitation of hydrocarbon occurrences can be optimized on the basis of monitoring measurements.
Furthermore, the method enables the detection of mountain areas with ore enrichments, the mapping of their distribution and the obtaining of qualitative pointers to the potential ore concentration.
The advantage attained consists, in particular, in that ore accumulations underground can be detected directly, and their relative concentration can be specified as additional evaluation criterion. It is possible on the basis of such results to implement a substantial economic benefit in prospecting since, inter alia, it is possible for test bores to be sunk specifically, and to avoid failed bores. Furthermore, development measures such as, for example, mining installations can be optimally planned.
In a refinement, magnetic variation measurements are executed in synchronous fashion at least at two measurement locations. The synchronized measurements can be executed at two locations lying next to one another or one on top of another.
For example, two helicopters equipped with the appropriate measuring devices can fly approximately perpendicular to one another and execute the measurements, in particular at a distance of approximately 10 m to 500 m relative to one another, preferably at a spacing of 100 m to 350 from one another. This gradient measurement can be used to determine a depth distribution of the hydrocarbon bearing reservoir rocks and carrier layers underground.
Synchronized measurements of different spatial direction components can also be carried out at a measurement location.
The magnetometer can be used in a known way to measure an irregular electromagnetic field. It is also possible to ground an electrode pair and measure a voltage difference between the electrodes in order to measure the electric field component of the temporally varying magnetic field by means of this electric field sensor.
It goes without saying that the features mentioned above and still to be explained below can be used not only in the respectively specified combination, but also in other combinations. The scope of the invention is merely defined by the claims.
The invention is explained in more detail below with the aid of an exemplary embodiment with reference to the associated drawings, in which:
Figure 1 shows a profile section and a graph for the purpose of illustrating a measurement and a result of the inventive method, Figure 2 shows a representation of two frequency spectra in a diagram, and Figure 3 shows a contour plot of an edge region of an oil field.
In accordance with figure 1, the temporally varying magnetic fields that emanate from a hydrocarbon reservoir 1 underground and are represented by arrows 2 are measured as a r CA 02809328 2013-02-22 function of time at individual receiving stations (measurement locations) at the Earth's surface 8 as voltage signals by means of conventional magnetometers 3 and data acquisition devices 4. The subsequent data processing 5 is performed with the aid of a computer on the basis of spectral analytical calculation methods, the spectral power density thus being obtained for each measurement location from the time series measured data as a function of the frequency for the bandwidth 0.01 to 100 Hz (figure 2). The variable values at least of one spectral attribute 6, in particular the power, can be calculated therefrom.
Figure 2 illustrates two typical power density frequency spectra of magnetic variation measurements. The curve illustrated by a dashed line 9 shows the measurement result of a receiving station without hydrocarbons, and the curve illustrated by a continuous line 10 shows the measurement result of a receiving station with hydrocarbon accumulation underground. The hydrocarbon curve is characterized by greatly increased power density values inside a specific frequency range, while the non-hydrocarbon curve has uniformly very low values over the entire bandwidth.
The contour plot in accordance with figure 3 shows an examination region with an isoline distribution of a normalized spectral attribute that has been determined on the basis of magnetic variation measurements. Reference measurements outside this region, which were made at measurement locations at a perpendicular distance above the lateral delimitation of a known hydrocarbon occurrence result in an attribute reference value 7 (figure 1) that was used as reference value for normalizing the corresponding attribute variable values 6 obtained in the examination region. The distribution calculation of the normalized attribute variable values yields the position profile of the normalized reference value isoline 11, which characterizes the line of equal attribute values equal to the reference value 7. Normalized attribute values greater than one therefore comprise the area of a hydrocarbon occurrence in the examination region and, correspondingly, values smaller than one record the regions bearing no hydrocarbons underground. Furthermore, the normalized attribute variable values serves as a basis for a qualitative measure of the hydrocarbon productivity, illustrated as relative classes.
Description The invention relates to a magnetic variation method for detecting, mapping and evaluating spectrally magnetically active underground occurrences.
There is known from the prior art a magnetic variation method that does not use dedicated actively controlled transmission sources, but uses permanently present temporally varying magnetic fields that are passively received (Simpson, F. & Bahr, K.:
Practical Magnetotellurics, p. 182, Cambridge University Press, 2005). In conventional methods, these magnetic fields are caused by external induction effects from the ionosphere and magnetosphere. Furthermore, the known methods are used to determine horizontal electrical , conductivity gradients as result, but do not detect spectrally magnetically active underground occurrences.
It is an object of the invention to provide a magnetic variation method of the type mentioned at the beginning with the aid of which spectrally magnetically active underground occurrences, in particular hydrocarbon reservoirs and ore enrichments, are located, and which is substantially based on fields generated geogenically underground.
According to the invention, the object is achieved by the features of claim 1.
The subclaims constitute advantageous refinements.
In the magnetic variation method for detecting, mapping and evaluating spectrally magnetically active underground occurrences, the temporally varying anomalous magnetic fields existing in conjunction with such rock masses are measured as a function of location and time inside an examination region on or above the Earth's surface as signal and/or field variables in at least one spatial direction component, the time series measured data recorded for each measurement location are transferred by means of data processing, in particular spectral analysis, into the spectral power density in the frequency range of 0.01 to 100 Hz, and at least one spectral attribute, in particular the power, is determined herefrom, and a distinction between an occurrence and a non-occurrence of a spectrally magnetically active rock mass underground is made by comparing the attribute variable values standardized to a reference value to the standardized reference value.
Spectrally magnetically active underground occurrences are to be understood, for example, as hydrocarbon (petroleum, natural gas) or ore occurrences.
Presently, advantageous use is made of the fact that by comparison with rocks that have no hydrocarbons and/or ores, said occurrences have anomalous spectral magnetic properties. The latter can be measured, and thereby permit the identification and mapping of corresponding subterranean occurrences.
The measurements inside the examination region above the Earth's surface can, for example, be undertaken by means of a helicopter, which means that the examination region can also be very large and/or difficult to access, and the measurements can nevertheless be carried out expediently as regards economics. In the sense of the invention, the specification on or above the Earth's surface is also to be understood as the bottom of a body of water, for example a lake or sea, that is to say the measurements inside the examination region can be carried out both at the bottom of a body of water and on or above the Earth's surface.
The method enables the detection of reservoir rocks bearing hydrocarbons and of carrier layers underground, the mapping of the distribution thereof, the obtaining of qualitative pointers to the potential hydrocarbon productivity, and a temporal monitoring during the development and extraction phase.
The advantage attained consists, in particular, in that petroleum and natural gas accumulations underground can be detected directly, and their relative productivity can be specified as additional evaluation criterion. It is possible on the basis of such results to implement a substantial economic benefit in the exploration since, inter alia, it is possible for deep bores to be sunk specifically, and to avoid failed bores. Furthermore, the exploitation of hydrocarbon occurrences can be optimized on the basis of monitoring measurements.
Furthermore, the method enables the detection of mountain areas with ore enrichments, the mapping of their distribution and the obtaining of qualitative pointers to the potential ore concentration.
The advantage attained consists, in particular, in that ore accumulations underground can be detected directly, and their relative concentration can be specified as additional evaluation criterion. It is possible on the basis of such results to implement a substantial economic benefit in prospecting since, inter alia, it is possible for test bores to be sunk specifically, and to avoid failed bores. Furthermore, development measures such as, for example, mining installations can be optimally planned.
In a refinement, magnetic variation measurements are executed in synchronous fashion at least at two measurement locations. The synchronized measurements can be executed at two locations lying next to one another or one on top of another.
For example, two helicopters equipped with the appropriate measuring devices can fly approximately perpendicular to one another and execute the measurements, in particular at a distance of approximately 10 m to 500 m relative to one another, preferably at a spacing of 100 m to 350 from one another. This gradient measurement can be used to determine a depth distribution of the hydrocarbon bearing reservoir rocks and carrier layers underground.
Synchronized measurements of different spatial direction components can also be carried out at a measurement location.
The magnetometer can be used in a known way to measure an irregular electromagnetic field. It is also possible to ground an electrode pair and measure a voltage difference between the electrodes in order to measure the electric field component of the temporally varying magnetic field by means of this electric field sensor.
It goes without saying that the features mentioned above and still to be explained below can be used not only in the respectively specified combination, but also in other combinations. The scope of the invention is merely defined by the claims.
The invention is explained in more detail below with the aid of an exemplary embodiment with reference to the associated drawings, in which:
Figure 1 shows a profile section and a graph for the purpose of illustrating a measurement and a result of the inventive method, Figure 2 shows a representation of two frequency spectra in a diagram, and Figure 3 shows a contour plot of an edge region of an oil field.
In accordance with figure 1, the temporally varying magnetic fields that emanate from a hydrocarbon reservoir 1 underground and are represented by arrows 2 are measured as a r CA 02809328 2013-02-22 function of time at individual receiving stations (measurement locations) at the Earth's surface 8 as voltage signals by means of conventional magnetometers 3 and data acquisition devices 4. The subsequent data processing 5 is performed with the aid of a computer on the basis of spectral analytical calculation methods, the spectral power density thus being obtained for each measurement location from the time series measured data as a function of the frequency for the bandwidth 0.01 to 100 Hz (figure 2). The variable values at least of one spectral attribute 6, in particular the power, can be calculated therefrom.
Figure 2 illustrates two typical power density frequency spectra of magnetic variation measurements. The curve illustrated by a dashed line 9 shows the measurement result of a receiving station without hydrocarbons, and the curve illustrated by a continuous line 10 shows the measurement result of a receiving station with hydrocarbon accumulation underground. The hydrocarbon curve is characterized by greatly increased power density values inside a specific frequency range, while the non-hydrocarbon curve has uniformly very low values over the entire bandwidth.
The contour plot in accordance with figure 3 shows an examination region with an isoline distribution of a normalized spectral attribute that has been determined on the basis of magnetic variation measurements. Reference measurements outside this region, which were made at measurement locations at a perpendicular distance above the lateral delimitation of a known hydrocarbon occurrence result in an attribute reference value 7 (figure 1) that was used as reference value for normalizing the corresponding attribute variable values 6 obtained in the examination region. The distribution calculation of the normalized attribute variable values yields the position profile of the normalized reference value isoline 11, which characterizes the line of equal attribute values equal to the reference value 7. Normalized attribute values greater than one therefore comprise the area of a hydrocarbon occurrence in the examination region and, correspondingly, values smaller than one record the regions bearing no hydrocarbons underground. Furthermore, the normalized attribute variable values serves as a basis for a qualitative measure of the hydrocarbon productivity, illustrated as relative classes.
Claims (8)
1. A magnetic variation method for detecting, mapping and evaluating spectrally magnetically active underground occurrences, characterized in that a) temporally varying anomalous magnetic fields (2) existing in conjunction with spectrally magnetically active rock masses (1) are measured as a function of location and time inside an examination region on or above the Earth's surface (8) as signal and/or field variables in at least one spatial direction component, b) the time series measured data recorded for each measurement location in the examination region are transferred by means of data processing, in particular spectral analysis, into the spectral power density in the frequency range of 0.01 to 100 Hz, and at least one spectral attribute (6), in particular the power, is determined herefrom, and c) a distinction between occurrence and non-occurrence of spectrally magnetically active rock masses underground is made by comparing the attribute variable values standardized to a reference value (7) to the standardized reference value (11).
2. The method as claimed in claim 1, characterized in that the normalized attribute variable values obtained as a function of location in the examination region are used to determine their lateral distribution, which is displayed as an isoline map, as a result of which areas with spectrally magnetically active underground occurrences are delimited in terms of measuring accuracy on the basis of the position profile of the normalized reference value isoline (11) determined by a distribution calculation and imaged.
3. The method as claimed in claim 1, characterized in that the spectrally magnetically active underground occurrences are hydrocarbon reservoirs, the normalized variable values of at least one spectral attribute being used as relative evaluation measure for the hydrocarbon productivity.
4. The method as claimed in claim 1, characterized in that the spectrally magnetically active underground occurrences are ore enrichment zones, the normalized variable values of at least one spectral attribute being used as relative evaluation measure for the ore concentration.
5. The method as claimed in claim 1, characterized in that magnetic variation measurements are executed in synchronous fashion at least at two measurement locations.
6. The method as claimed in one of claims 1 to 3, characterized in that during production from a hydrocarbon reservoir magnetic variation measurements are executed inside an examination region at different instants such that changes in the hydrocarbon productivity are detected by forming the difference between the normalized attribute variable values at different instants.
7. The method as claimed in one of claims 1 to 6, characterized in that reference measurements at at least one measurement location above a lateral limit of a spectrally magnetically active underground occurrence are used to determine a reference value (7) of at least one spectral attribute that is used as reference value for normalizing the corresponding attribute variable values (6) obtained in the examination region, and serves for determining the normalized reference value (11).
8. A device for carrying out the method as claimed in claim 1, characterized in that at least one magnetometer (3) or two electrodes, and at least one data acquisition device (4) is/are coupled to a computer unit for evaluating the data.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE201010035261 DE102010035261A1 (en) | 2010-08-24 | 2010-08-24 | Method and measuring device for exploring hydrocarbon reservoirs in the subsurface |
| DE102010035261.6 | 2010-08-24 | ||
| PCT/DE2011/075126 WO2012025108A2 (en) | 2010-08-24 | 2011-06-01 | Magnetovariational method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2809328A1 true CA2809328A1 (en) | 2012-03-01 |
Family
ID=44789258
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2809328A Abandoned CA2809328A1 (en) | 2010-08-24 | 2011-06-01 | Magnetic variation method |
Country Status (5)
| Country | Link |
|---|---|
| CN (1) | CN103097915B (en) |
| CA (1) | CA2809328A1 (en) |
| DE (2) | DE102010035261A1 (en) |
| RU (1) | RU2565825C2 (en) |
| WO (1) | WO2012025108A2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102021113869B3 (en) | 2021-05-28 | 2022-07-21 | Andreas Fischer | Detection of objects with a magnetic signature in a measuring field |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| MY131017A (en) * | 1999-09-15 | 2007-07-31 | Exxonmobil Upstream Res Co | Remote reservoir resistivity mapping |
| US7109717B2 (en) * | 2002-12-10 | 2006-09-19 | The Regents Of The University Of California | System and method for hydrocarbon reservoir monitoring using controlled-source electromagnetic fields |
| US6739165B1 (en) * | 2003-02-05 | 2004-05-25 | Kjt Enterprises, Inc. | Combined surface and wellbore electromagnetic measurement system and method for determining formation fluid properties |
| US7248052B2 (en) * | 2003-05-28 | 2007-07-24 | Weaver W Barry | Electric power grid induced geophysical prospecting method and apparatus |
| NO326506B1 (en) * | 2003-07-10 | 2008-12-15 | Norsk Hydro As | A marine geophysical collection system with a cable with seismic sources and receivers and electromagnetic sources and receivers |
| NO321856B1 (en) * | 2004-10-13 | 2006-07-17 | Geocontrast As | Method for monitoring resistivity of a hydrocarbon-containing formation by means of an injected tracking fluid |
| CA2598024A1 (en) * | 2005-02-18 | 2006-08-24 | Bp Corporation North America Inc. | System and method for using time-distance characteristics in acquisition, processing and imaging of t-csem data |
| RU2301431C2 (en) * | 2005-03-24 | 2007-06-20 | Общество с ограниченной ответственностью "Сибирская геофизическая научно-производственная компания" | Mode of electrical exploration with using of spacing differentiation of the field of formation on several spreads |
| NO323889B1 (en) * | 2005-11-03 | 2007-07-16 | Advanced Hydrocarbon Mapping A | Process for mapping hydrocarbon reservoirs and apparatus for use in carrying out the process |
| CN101109822A (en) * | 2006-07-21 | 2008-01-23 | 杨杰 | Method for distinguishing ore and non-ore magnetic anomaly |
| US7574410B2 (en) * | 2006-08-22 | 2009-08-11 | Kjt Enterprises, Inc. | Fast 3D inversion of electromagnetic survey data using a trained neural network in the forward modeling branch |
| US7969152B2 (en) * | 2006-12-06 | 2011-06-28 | Technoimaging, Llc | Systems and methods for measuring sea-bed resistivity |
-
2010
- 2010-08-24 DE DE201010035261 patent/DE102010035261A1/en not_active Withdrawn
-
2011
- 2011-06-01 WO PCT/DE2011/075126 patent/WO2012025108A2/en active Application Filing
- 2011-06-01 CN CN201180040556.8A patent/CN103097915B/en not_active Expired - Fee Related
- 2011-06-01 CA CA2809328A patent/CA2809328A1/en not_active Abandoned
- 2011-06-01 RU RU2013110032/28A patent/RU2565825C2/en active
- 2011-06-01 DE DE112011102778T patent/DE112011102778A5/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| DE102010035261A1 (en) | 2012-03-01 |
| WO2012025108A3 (en) | 2013-02-21 |
| RU2565825C2 (en) | 2015-10-20 |
| WO2012025108A2 (en) | 2012-03-01 |
| RU2013110032A (en) | 2014-09-27 |
| CN103097915B (en) | 2016-03-02 |
| DE112011102778A5 (en) | 2013-06-13 |
| CN103097915A (en) | 2013-05-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |
Effective date: 20170601 |