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WO2009136387A2 - Combinaison d’ensembles de données sismiques et de largeurs de bande se chevauchant - Google Patents

Combinaison d’ensembles de données sismiques et de largeurs de bande se chevauchant Download PDF

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Publication number
WO2009136387A2
WO2009136387A2 PCT/IB2009/053473 IB2009053473W WO2009136387A2 WO 2009136387 A2 WO2009136387 A2 WO 2009136387A2 IB 2009053473 W IB2009053473 W IB 2009053473W WO 2009136387 A2 WO2009136387 A2 WO 2009136387A2
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Prior art keywords
traces
trace
seismic
tracelow
tracehigh
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WO2009136387A3 (fr
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Christian Deplante
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TotalEnergies SE
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Total SE
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/28—Processing seismic data, e.g. for interpretation or for event detection
    • G01V1/36—Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy
    • G01V1/364—Seismic filtering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/28—Processing seismic data, e.g. for interpretation or for event detection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V2210/00—Details of seismic processing or analysis
    • G01V2210/20—Trace signal pre-filtering to select, remove or transform specific events or signal components, i.e. trace-in/trace-out
    • G01V2210/27—Other pre-filtering

Definitions

  • the present invention relates generally to the field of geosciences and more particularly, to seismic data processing. Specifically, the invention relates to a method for combining seismic datasets having overlapping bandwidths to provide enhanced subsurface images and without duplicating the overlapping information.
  • the method may be referred to as 'spectral fusion' as this reflects the actual nature of the operations being performed.
  • subsurface used here may include a water layer at the top for offshore or lacustre environments.
  • one or several sources emit elastic waves in the form of pressure or ground motion modulation from specific locations (wavefield), at or just below the surface or in a borehole. This wavefield expands away from the source(s) through the subsurface.
  • a fraction of the incident wavefield is also reflected from the fraction of the global heterogeneities in the elastic material properties of the subsurface (such as acoustic impedance) which interacts with the incident signal.
  • reflectivity The most continuous part of the subsurface geometry of such changes is termed reflectivity.
  • the seismic traces are then processed and imaged to produce a 2D or 3D image of the reflectivity, either as a function of two-way travel-time or of depth derived from the seismic data.
  • reflectivity can be transformed for better geological interpretation into relative acoustic or elastic impedance models of the surveyed subsurface region, for instance by vertical integration.
  • the bandwidth of the seismic data, ultimately controlled by the acquisition stage, plays a fundamental role: the only part of the elastic properties which can be reconstructed is the one within (or seen by) the emission/reception bandwidth.
  • the reflected wavefield is generated by a progressive constructive and destructive interference process, which only occurs within the emitted bandwidth and must be recorded in order to reconstruct the reflectivity field. This bandwidth is strongly dependent upon the type of seismic emission and reception devices used, on its actual coupling to the subsurface, and on surface or near-surface effects.
  • the number of individual recordings is basically the product of the number of sources multiplied by the number of receivers simultaneously recording their signals, whereas the size of each recording is proportional to listening time and maximum frequency to be preserved.
  • the reflectivity or impedance volumes are then interpreted to identify the reservoir lithology as well as fluid content.
  • the volumes can be used to distinguish hydrocarbon bearing regions, look for groundwater accumulations, identify potential hazards, and/or to plot a drilling profile.
  • the obvious way of improving the resolution of the final seismic images is to increase the bandwidth of data acquired.
  • Any given seismic acquisition design is always a compromise between low and high frequency content. For instance it is technically impossible to design a repetitive source with a powerful emission across the whole spectrum from a fraction of Hertz to one kilohertz.
  • pressure sources are used. They cannot be placed at the sea surface because no energy would be radiated downwards: marine sources must emit underwater. The sea surface acts as a mirror that reflects a pressure wave with opposite polarity, causing a ghost source signal. This produces a sine-shaped spectrum of emission, with a series of notches at frequencies being integer multiples of V/4z where z is source depth and V is water velocity. The same pattern occurs on the reception side. In general, only the first arch of the response is usable, resulting in a marine acquisition band of approximately constant width between one and three octaves,which moves down along the frequency scale as emission/reception equipment is moved down below sea surface.
  • more than one type of survey can be conducted in an area. Additionally more than one type of seismic sensor can be operated on a single survey.
  • the option chosen here is to combine different seismic data covering the same surveyed area, with different but overlapping bandwidths resulting for instance from various emission/reception depths. By combining data with overlapping spectra, a larger bandwidth can be recovered with the proposed invention.
  • US 4,715,021 describes a method for filtering and combining seismic data having different spectral characteristics.
  • Seismic signals are transmitted into the subsurface and a resulting data trace for each seismic signal is recorded.
  • a correlating signal is generated for each data trace, such that the sum of the correlations of each correlating signal with it's associated trace is an approximately minimum phase signal whose frequency amplitude spectrum is the sum of the frequency amplitude spectra of the seismic signals.
  • the correlating signals are generated by obtaining reference signals representing the seismic signals prior to propagation through the earth formation, concatenating these reference signals and inserting a zero-amplitude signal between each reference signal, and then performing a least-squares deconvolution on the concatenated signal.
  • the correlating signal for each trace is identified as the portion of the deconvolved signal which corresponds temporally to the reference signal associated with such trace. This technique requires the knowledge (or prior estimation) of source signals.
  • US 4,837,752 describes a common bandwidth determination method for two seismic datasets which includes developing a weighted average of first least-squares filters assuming the data from the first dataset is the input and the data from the second dataset is the desired output, developing a weighted average of second least-squares filters assuming the data from the second dataset is the input and the data from the first dataset is the desired output, determining a first transfer function from the first weighted average filter design and a second transfer function from the second weighted average filter design, plotting respective amplitude and phase spectra using each of the first and second transfer functions, plotting the product of the amplitude spectra and the sum of the phase spectra and determining the common bandwidth where the amplitude spectra is one and the phase spectra is zero.
  • a disadvantage in the use of this technique is that a large portion of the low and high frequency data recorded in the two seismic datasets being combined, is removed. Valuable information is lost as the common bandwidth will always be narrower than the bandwidth of each of the original datasets.
  • a further disadvantage of this technique is that it requires an operator to make the determination by viewing the product of the amplitude spectra and the sum of the phase spectra. This limits the technique as it cannot be implemented in an automated process.
  • a further method for combining seismic data sets is disclosed in US 2006/0190181. This method has application in merging data sets of different vintages, merging data sets collected using different acquisition technologies, and merging data sets acquired using different types of sensors, for example merging hydrophone and geophone measurements in ocean bottom seismic data.
  • a desired data trace is to be determined from a set of measured data traces, and the following steps are applied: (a) model filters are constructed which express the deterministic relationship between the desired data trace and each available measured trace that depends on the desired data trace; (b) the noise properties associated with each measured data trace are determined; (c) a sufficient statistic for the desired data trace is formed by application of an appropriate filter to each measured trace and summing the filter outputs; (d) the sufficient statistic is further processed by a single- input single-output estimator to construct an estimate of the desired data trace from the sufficient statistic.
  • this technique relies on adapting data to match it to or create a 'desired' output. In this way the true data characteristics are lost as the original data is manipulated to behave as an operator believes it should on the basis of preconceived ideas about the expected results.
  • a method of fusioning seismic reflectivities from two data sets in the spectral domain for the determination of subsurface formations and hydrocarbon bearing accumulations including the steps of:
  • the data sets are merged without artificially increasing the amplitude at the overlapping frequencies resulting in a combined trace with increased bandwidth over either of the first or second traces.
  • the step of determining the overlapping portion is by application of a Wiener zero phase filter to each trace.
  • this filter has an amplitude spectrum equal to the cross- correlation of the traces divided by the autocorrelation of the respective trace.
  • TraceLow and TraceHigh may comprise a plurality of seismic traces.
  • step (c) is performed using known techniques and may be made in the common bandwidth of TraceLow and TraceHigh.
  • step (e) determines the common part of the spectrum between A and B, of support, C; to yield spectra, C(A) and C(B), respectively.
  • Step (f) may then comprise the steps of:
  • the weighted is the half-sum.
  • the amplitudes of the input traces are matched before they are added together. This provides a simpler implementation of the method, However, the input amplitude unbalance will then result in an output spectrum favouring the strongest input data.
  • an average ratio, k, of the spectral amplitudes of A and B in their common bandwidths may be computed and used to scale the final sum.
  • k can be externally computed and input to drive the relative scaling of two 3D volumes to be "fused" into one output dataset.
  • k may be used as a map to drive the relative scaling.
  • the input and output data comparison may be performed after an additional step, consisting in a combination of trace integration and spectral balancing, to produce "pseudo-impedance" sections. Characteristics in the subsurface image may then be identified more easily.
  • Figure 1 is a graph of a low frequency amplitude spectra and a high frequency amplitude spectra together with a summation according to an embodiment of the present invention
  • Figure 2 is a graph of a test trace together with corresponding high frequency and low frequency traces;
  • Figure 3 is a graph of the test trace together with a summation of the high and low frequency traces of Figure 2;
  • Figure 4 is a graph of the high and low frequency traces in the Fourier domain, together with a standard summation of the traces;
  • Figure 5 is a graph of the high and low frequency traces in the Fourier domain, with the overlapping portion illustrated;
  • Figure 6 is a graph of the test, the summation and the combined trace according to an embodiment of the present invention in the Fourier domain;
  • Figure 7 is a graph of the test, the summation and the combined trace according to an embodiment of the present invention in the time domain;
  • Figures 8(a)-(b) are reflectivity plots over a subsurface region for (a) low frequency data, (b) high frequency data and (c) combined data according to an embodiment of the present invention; the average respective amplitude spectra of (a) (b) and (c) is also shown, superimposed on the spectrum of a 60 Hz Ricker reference signal; and
  • Figures 9(a)-(b) are corresponding input sections after pseudo- impedance and deconvolution of (a) low frequency data and (b) high frequency data, (c) is the pseudo-impedance and deconvolution of the output combined data according to the present invention ; the average amplitude spectra of (a), (b) and (c) data is again shown, it is superimposed on the spectrum of an estimation of a source wavelet from the combined data.
  • Figure 1 of the drawings illustrates a combined trace of high and low frequency traces, also shown, according to an embodiment of the present invention. In order to arrive at this combined trace, we first consider a test trace for the purpose of illustrating the invention.
  • FIG. 2 of the drawings illustrates a seismic test trace over an 800ms time interval.
  • the test trace has been synthetically created and includes both high and low frequency components.
  • Two seismic traces are created from the test trace by applying a high and a low bandpass filter in turn to the data. These traces therefore mimic the low (TraceLow) and high (TraceHigh) frequency data and can be considered as our two seismic traces which could have been recorded at different times or via different seismic survey techniques.
  • the test trace may be considered as a target trace as it is the ideal combination of the two seismic traces generated.
  • the high and low frequency signal are now illustrated with the na ⁇ ve summation clearly illustrating an increased amplitude in the mid-frequencies where the high and low traces overlap. This is because the amplitude values are summed twice over the overlapping frequency ranges. It is obvious that such a combined trace would provide a distorted impedance plot giving no assistance in the geophysical interpretation.
  • the present invention proposes to determine the portion of the amplitude data which is common to both the high and low traces and remove it from the summation of the high and low traces. In this way the 'doubling up' of amplitudes in the mid frequency range is compensated for.
  • a Wiener filter is used. Those skilled in the art will recognise that this is similar to factorial co- kriging for time lapse filtering/extraction. In this way we first deconvolve each trace by its corresponding covahance (autocorrelation) and after we convolve each by the cross-covahance (cross-correlation) of the two traces. It is this step that allows us to combine the traces without adding the common or overlapping portion twice.
  • L is the 'non-intercepting' low frequency part of the amplitude spectrum of traceLow
  • H is the 'non-intercepting' high frequency part of the amplitude spectrum of traceHigh
  • C is the common part of the traces. This is as illustrated in Figure 5.
  • the objective is that the relative levels of the input contributions to the output spectrum are suitably equalised. If we apply this to TraceLow and TraceHigh, we obtain a combined trace as illustrated in Figure 1. It can be seen that the combined trace matches the low frequency trace at frequencies below 15 Hz and matches the high frequency trace at frequencies above 30 Hz. In the mid-frequency range the trace lies between the low and high amplitude values.
  • Figure 6 shows a comparison of the combined trace to both the target trace and the na ⁇ ve trace.
  • the combined trace more closely matches the target trace than that of the na ⁇ ve trace.
  • the principal advantage of the present invention is that it provides a method of combining seismic datasets which does not apply any modelling or fitting techniques over those which would be applied to a single dataset. In this way further artefacts are not introduced to the data prior to inversion.
  • the further advantage of the present invention is that it provides a method of combining seismic data sets which enhances the information available by incorporating the low and high frequency portions of the respective data sets. In this way the data sets are fused together in union rather than by overlap. It is a yet further advantage of the present invention to provide a method of combining seismic datasets which is simple to incorporate into prior art data processing techniques.
  • the scope of the method would be to recover larger data bandwidth corresponding to combinations of data recorded at similar times to optimize the subsequent extraction of time-lapse extraction.

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

L’invention concerne un procédé permettant de fusionner deux ou plus de deux ensembles de données sismiques dans le domaine spectral permettant la détermination de formations souterraines et d’accumulations d’hydrocarbures dans le domaine des sciences de la terre. Deux traces sismiques de la même région souterraine sont acquises et/ou traitées, qui comprennent des largeurs de bande différentes mais se chevauchant partiellement. Les traces sont combinées et une somme pondérée du support à partir du domaine de chevauchement est soustraite de sorte que la contribution du chevauchement ne soit ni sous-estimée, si surestimée dans les traces combinées. Le résultat est ensuite inversé pour fournir une image de réflectivité de la région souterraine dont la largeur de bande est plus importante que celle de l'une quelconque des traces initiales.
PCT/IB2009/053473 2008-05-09 2009-05-06 Combinaison d’ensembles de données sismiques et de largeurs de bande se chevauchant Ceased WO2009136387A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0808418.1 2008-05-09
GB0808418.8A GB2459887B (en) 2008-05-09 2008-05-09 Combining seismic data sets with overlapping bandwidths

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WO2009136387A2 true WO2009136387A2 (fr) 2009-11-12
WO2009136387A3 WO2009136387A3 (fr) 2010-02-25

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104280770A (zh) * 2014-09-28 2015-01-14 中国石油大港油田勘探开发研究院 致密过渡岩储层的预测方法
CN106610506A (zh) * 2015-10-26 2017-05-03 中国石油天然气股份有限公司 地震勘探薄层识别方法
US9810800B2 (en) 2014-04-30 2017-11-07 Chevron U.S.A. Inc. Method of creating and interpreting animated mosaics of multiple seismic surveys
WO2018021991A1 (fr) * 2016-07-25 2018-02-01 Schlumberger Technology Corporation Équilibrage de spectre sismique
CN110737022A (zh) * 2018-07-20 2020-01-31 中国石油化工股份有限公司 一种可控震源激发地震资料黑三角区噪音的压制方法
CN112305614A (zh) * 2020-10-20 2021-02-02 中海石油(中国)有限公司 一种气云区空间展布范围刻画方法和系统

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8279707B2 (en) * 2010-04-23 2012-10-02 Chevron U.S.A. Inc. Fusing geophysical data representing a geophysical space
CN107065011B (zh) * 2017-06-22 2018-11-02 东北石油大学 一种应用于陆相盆地储层反演的曲线频率融合方法
CN110824566B (zh) * 2018-08-10 2021-09-28 中国石油天然气股份有限公司 地震属性融合方法、装置及存储介质

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US4532618A (en) * 1982-05-20 1985-07-30 Marathon Oil Company System for and method of processing a seismic signal
US4875166A (en) * 1987-10-09 1989-10-17 Input/Output, Inc. Bandwidth enhancing seismic acquisition system and method
US4837752A (en) * 1988-09-12 1989-06-06 Exxon Production Research Co. Method for establishing a common bandwidth for processing seismic data obtained from different sources, recording equipment and surveys
EA001212B1 (ru) * 1996-09-13 2000-12-25 Пгс Тенсор, Инк. Способ сейсмического мониторинга нефтегазовых месторождений с использованием разновременных съемок
US7477992B2 (en) * 2005-02-18 2009-01-13 Exxonmobil Upstream Research Company Method for combining seismic data sets

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9810800B2 (en) 2014-04-30 2017-11-07 Chevron U.S.A. Inc. Method of creating and interpreting animated mosaics of multiple seismic surveys
CN104280770A (zh) * 2014-09-28 2015-01-14 中国石油大港油田勘探开发研究院 致密过渡岩储层的预测方法
CN106610506A (zh) * 2015-10-26 2017-05-03 中国石油天然气股份有限公司 地震勘探薄层识别方法
WO2018021991A1 (fr) * 2016-07-25 2018-02-01 Schlumberger Technology Corporation Équilibrage de spectre sismique
US10324211B2 (en) 2016-07-25 2019-06-18 Schlumberger Technology Corporation Seismic spectral balancing
CN110737022A (zh) * 2018-07-20 2020-01-31 中国石油化工股份有限公司 一种可控震源激发地震资料黑三角区噪音的压制方法
CN112305614A (zh) * 2020-10-20 2021-02-02 中海石油(中国)有限公司 一种气云区空间展布范围刻画方法和系统
CN112305614B (zh) * 2020-10-20 2024-03-29 中海石油(中国)有限公司 一种气云区空间展布范围刻画方法和系统

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Publication number Publication date
GB2459887B (en) 2012-04-25
GB0808418D0 (en) 2008-06-18
GB2459887A (en) 2009-11-11
WO2009136387A3 (fr) 2010-02-25

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