WO2000058756A1 - Previsions des contraintes lors d'evenements sismiques - Google Patents

Previsions des contraintes lors d'evenements sismiques Download PDF

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Publication number
WO2000058756A1
WO2000058756A1 PCT/GB2000/001137 GB0001137W WO0058756A1 WO 2000058756 A1 WO2000058756 A1 WO 2000058756A1 GB 0001137 W GB0001137 W GB 0001137W WO 0058756 A1 WO0058756 A1 WO 0058756A1
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Prior art keywords
stress
shear
source
seismic
depth
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PCT/GB2000/001137
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English (en)
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Stuart Crampin
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The University Court Of The University Of Edinburgh
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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
    • G01V1/01—Measuring or predicting earthquakes

Definitions

  • This invention is primarily directed to the forecasting of individual large earthquakes, in which phrase "individual” excludes foreshock series which may sometimes indicate that a large earthquake is imminent. Similarly “large” excludes isolated swarms of earthquakes where larger earthquakes in the sequence may sometimes repeat at frequent intervals with very similar locations and magnitudes.
  • “Earthquake precursor” refers to observations of any physical phenomena that may indicate that a large earthquake is imminent. These phenomena are usually geophysical, although a wide range of other phenomena has sometimes been claimed to be precursors. Although in some circumstances such estimates may be useful they do not, and cannot, give time, place and magnitude of future earthquakes. Precursors are irregular and unpredictable and schemes for routine warnings of earthquakes cannot be wholly based on observations of precursors.
  • the current invention provides for a new strategy of forecasting earthquakes based on firm understanding of the underlying micro and macro geophysical phenomena leading to criticality.
  • micro-cracks in in-situ rocks dilate as stress builds up before earthquakes until a level of fracture criticality is reached when the rocks fracture and the earthquake occurs.
  • rocks are weak to shear stress, crack alignments and proximity to criticality are pervasive over very large volumes of the crust around the eventual source zone.
  • the changes in micro-crack dilation can be recognised by monitoring seismic shear-wave splitting along appropriate ray paths.
  • increasing stress would increase the aspect ratios of micro-crack distributions (make cracks swell or dilate) which could be monitored by specific changes in the three-dimensional pattern of shear-wave splitting.
  • APE anisotropic poro-elasticity
  • APE matches or is compatible with a large range of seismic and crack phenomena, including the effects on shear-wave splitting of the build-up of stress before earthquakes. If the increase can be monitored and the level of fracture criticality estimated, the time of the earthquake can be forecast; and the magnitude of the earthquake can be estimated from the slope of the increase of stress and the duration of the build up. We call this process of estimating the time and magnitude of future large (or larger) earthquakes, stress-forecasting. The location cannot be estimated directly, but once it is known that a large earthquake is imminent, local studies can often estimate the epicentre.
  • Shear-wave splitting is observed with very similar characteristics in almost all igneous, metamorphic, and sedimentary rock, below from about 500 m to 1 km depth in the Earth's crust
  • the polarisations of the faster split shear-waves are approximately parallel to the direction of maximum compressional stress
  • Geometrical constraints indicate that the splitting is controlled by the densities and aspect-ratios of distributions of the stress-aligned fluid-saturated grain-boundary cracks and low aspect-ratio pores present in almost all rocks. Consequently, shear- wave splitting can be used to monitor the effects of the stress build-up before earthquakes and stress-forecast future large earthquakes
  • shear-wave splitting appears to be independent of the porosity. This is because shear-wave splitting is controlled by the crack and low aspect-ratio pore distributions, whereas porosity is controlled principally by the volume of the pores (this is supported by theoretical APE studies). Shear- waves are extremely sensitive to modifications to the micro-scale geometry of fluid-filled EDA cracks and variations in shear-wave splitting have been observed before earthquakes and other phenomena. When pervasive distributions of stress-aligned fluid-saturated micro-cracks in in-situ rocks were first suggested, it was recognised that EDA-cracks would be compliant and respond to changes in stress before earthquakes. Since shear-wave splitting is sensitive to crack geometry, temporal changes in shear-wave splitting were sought. The table indicates the approximate expected response of micro-cracks to changes of stress and the corresponding changes in the behaviour of shear-wave splitting.
  • the key feature is the variation of the pattern of time-delays between split shear- waves in the shear-wave window at the free surface between ray-path directions less than and more than 15° to the face of the nearly- vertical cracks.
  • the shear- wave window is a cone of directions defined by ray paths with angles of incidence at the free surface of less than 35° to 45°; the exact angle depending on the ray-path curvature through near- surface weathering and stress-decompression anomalies, and the Poisson's ratio of the un-cracked matrix rock. Shear-waves incident within this window at the surface are not distorted by S-to-P conversions and have the same waveforms as the incident waves.
  • micro-crack geometry is similar below from about 500 m to 1 km depth in almost all rocks, the evolution of micro-cracked rock can be calculated by a model which is partially independent of rock type, porosity, and initial crack density.
  • APE models the evolution of stressed fluid-saturated micro-cracked rocks under changes of stress and other parameters.
  • the effects of increasing stress can be resolved into increasing crack density and/or increasing aspect ratio (crack swelling).
  • APE modelling confirms that the immediate effect of increasing (horizontal) stress on rocks is to increase average aspect ratios in distributions of (approximately) parallel vertical micro-cracks.
  • This increases the average time-delays in the double band, Band-1 (ray paths between 15° and 45° to the crack plane), of directions across the shear- wave window.
  • Time-delays in the remainder of the shear-wave window (Band-2) the solid angle with ray path directions within ⁇ 15° to the crack plane, are controlled primarily by the crack density of the crack distribution.
  • the data in Band-2 show no simple correlations with earthquakes.
  • increasing aspect-ratios is a simplified description strictly valid only for distributions of parallel cracks with hexagonal anisotropic symmetry (transverse isotropy).
  • APE modelling suggests that crack distributions are specified by three- dimensional patterns of variations in aspect-ratio. Such distributions have orthorhombic anisotropic symmetry and the effects of changing stress conditions are more complicated than simple changes in crack density or changes in aspect ratio.
  • the behaviour of weak orthorhombic distributions of cracks and weak hexagonal distributions of (parallel) cracks is similar for ray paths within the shear-wave window. and this is the justification for interpreting the effects as changes in aspect-ratio and changes in crack density.
  • the monitored rock needs to be below the depth where the vertical stress equals the minimum horizontal stress to avoid near-surface stress-relief heterogeneities.
  • the uppermost kilometre of the crust is typically characterised by heterogeneities, inter-granular micro-cracks, and fractures which cause severe seismic attenuation and scattering.
  • shear-wave signals either generated or recorded at the free surface are usually limited to frequencies less than, typically, 100 Hz, and such frequencies would require long source-receiver ray paths in order to obtain sufficient resolution to reliably monitor changes of less than one ms/krn with all the complications of near-surface heterogeneities and the need for powerful source generators for long ray paths.
  • VSPs vertical-seismic-profiles
  • walk-away VSPs walk-away VSPs
  • reverse VSPs reverse VSPs
  • anisotropy is an essential part of the behaviour so that instead of degrading it enhances the data by providing additional interpretable information.
  • the "normal" range of time- delays associated with temporal changes appears to be from about 2 ms/km to between 4 and 8 ms/km (2 to 20 ms/km in Iceland) where the upper end of the range is expected to be just below the value of fracture criticality for the particular rock-mass.
  • the range is probably dependent on local petrological, geological, and tectonic conditions. If the value could be identified for any particular area and if this value is stable, then proximity to criticality of any seismic episode would provide a valuable guide to the timing of a large earthquake.
  • Stress-forecasting uses changes in shear-wave splitting in Band- 1 of the shear- wave window to monitor crack aspect-ratios and estimate the time and magnitude that crack distributions reach fracture criticality. There are three principal hypotheses.
  • the magnitude of the impending earthquake is a function of the rapidity and duration of the stress build-up before fracture criticality is reached: if stress accumulates in a small volume, the buildup is fast but the resulting earthquake is comparatively small; whereas if stress accumulates over a larger volume, the increase is slower but the eventual earthquake is larger.
  • controlled source seismology preferably artificial sources
  • the present invention provides a method for stress forecasting a seismic event comprising detecting, at at least one location at a first depth below the Earth's surface, shear-waves emitted from a seismic source at at least one angle between 0° and 90° to the vertical, the source being spaced horizontally from the at least one location and at a second depth greater than or equal to the first depth.
  • the shear-wave splitting is monitored in a particular geometry between boreholes, rather than at the localised site of individual boreholes.
  • micro-crack changes are identified through shear- wave splitting and the technique is applicable irrespective of the absolute magnitudes of rock stress.
  • said first and second depths are both greater than about 500 m and more preferably they are greater than 1 km. Said second depth is preferably greater than about 1.5 km.
  • shear- waves propagating at less than 50°, preferably between 15° and 45°, to the vertical are detected.
  • time-delays between orthogonal polarisations of the shear-waves are analysed, to deduce information concerning the stress condition of surrounding rock.
  • the approach to criticality and the likelihood of a major seismic event Preferably two features of variations in shear-wave time-delays are used to provide the possible occurrence time and magnitude of impending earthquakes: the duration of the increase in time-delays; and the size of the time-delay relative to fracture criticality.
  • the invention also provides apparatus for stress-forecasting a seismic event, comprising at least one borehole seismic source and at least one borehole seismic receiver, the at least one source being deeper than or at the same depth as the at least one receiver and the at least one source being adapted to generate shear waves upwardly at 0° to 90° to the vertical in the direction of the at least one receiver
  • the azimuthal direction of the at least one receiver from the at least one source is at an angle greater than 30°to an average crack strike, and more preferably greater than 45° or 60° to the average crack strike.
  • a monitored site comprises one said seismic source and two said seismic receivers.
  • the two receivers are placed in separate wells at azimuths spaced in angle from the source well, preferably at azimuths within 90°, say approximately 60°, apart.
  • a plurality of monitored sites may be used to provide increased geographical coverage of an active region.
  • the receiver wells should be in azimuths approximately ⁇ 30° from the direction of minimum compressional stress of the surrounding rock, but it should be understood that all other azimuths within ⁇ 90° are within the scope of the invention.
  • the controlled seismic source is preferably deployed in a vertical borehole, at a depth in excess of 1 km, preferably of the order of 2 km. This is preferably a temporary deployment only for the duration of the measurement to allow the use of equipment that does not have to be rated for continual exposure to high temperature environments.
  • the receivers are advantageously placed in separate boreholes at depth and distance combinations that yield the appropriate range of angles (i.e. between 0 and 50 degrees) from the vertical axis for the seismic ray-paths, preferably but not restricted to SV waves.
  • these installations should be chosen according to local geology to place the receiver in an area of relatively intact and homogeneous rock. This is likely to be true only at depths in excess of 0.5 km, preferably at approximately 1 km.
  • These receiver installations are preferably permanent, to yield repeatability of seismic receiver performance.
  • the sensitivity of shear-wave velocities to the crack distributions along the ray path are used as an analogue measurement of the stress state of rocks lying between the source and receivers. Any deviation from the "normal" range of time-delays associated with temporal changes indicates an approach to the value of fracture criticality for that particular rock-mass. The range of values will be dependent on local petrological, geological, and tectonic conditions. Proximity to criticality provides a valuable guide to the timing of a large earthquake.
  • Stress-forecasting is based on a new understanding of the essentially anisotropic nature of rock deformation based on micro-scale physics, where the anisotropy is exploited in analysis of shear-wave polarisation's and time-delays. Since it is a physics-based system, it allows reliable and correct interpretation of anomalous or irregular behaviour. This invention provides a method to practically implement stress- forecasting.
  • Figure 1 comprises graphs of shear-wave time delays and seismic events at a first station
  • Figure 2 comprises graphs of shear-wave time delays and seismic events at a second station.
  • seismic wave transmitter existing wells in suitable locations and of sufficient depth would be used for the seismic wave transmitter. If no adjacent wells were available for the receivers, these could be sunk in locations at suitable azimuths to the main borehole.
  • Any seismic source which could yield a broad spectrum of seismic shear waves could be considered,. These include but are not limited to a simple conventional air-gun' source, which creates an explosive air bubble or an orbital vibrator, for example as manufactured by Conoco, which has a spinning eccentric disc rotated successively clockwise and anti-clockwise.
  • Any device normally used for seismic measurements could be considered as a receiver, including but not restricted to three-component seismic recorders of velocity, acceleration, or displacement which can be processed to yield two orthogonal shear- wave signals. Further processing of the received signals is also required to yield a figure for the phase difference, or difference in transit time between the two orthogonal seismic wave components.
  • the receiver could be suitably clamped, cemented or sanded in place.
  • Forecasts could be issued in a crescendo of urgency: a possible earthquake with a limited magnitude in a limited area immediately, or successively larger earthquakes in larger possible areas, if the increase in time-delays continues for further periods of time without a large earthquake.
  • Any build-up of deformation may be expected to vary very slowly in any particular area depending on convection currents, plate tectonics, distance from subduction zones, and similar phenomena Since the magnitude of the earthquake would depend on the amount of deformation energy available it is likely that the longer the build-up of deformation the larger the eventual earthquake
  • an example forecast could be as follows (distances and times are approximate and could vary with region and time).
  • a magnitude 6 earthquake may occur at any time within 50 km, say, of the monitoring site
  • Figures 1 and 2 show variations in 1997 and 1998 of normalised time-delays in both bands of the shear- wave window at two stations named BJA and KRI respectively.
  • the time-delay data show the expected large scatter, making inferences subject to misleading recognised or unrecognised location-induced trends if the data are sparse, consequently the interpretation below is based principally on Station BJA which has more adequate data.
  • the middle cartoons in Figure 1 show nine-point moving averages through the time- delays in Band-1 (15°- 45°).
  • BJA has a series of five pronounced minima.
  • a series of least-squares lines through the data are drawn, where each line begins just before the time of a minimum of the moving average (there is some subjectivity here), and ends at the time of a larger earthquake, when there is a comparatively abrupt decrease in time- delays.
  • the straight-lines show increasing time-delays, implying increasing crack aspect-ratios.
  • the upper cartoons show nine-point moving averages through the time-delays in Band-2 (0° - 15° with irregular behaviour, and we have been unable to find any correlation with the earthquakes.
  • the present invention can be used for stress forecasting volcanic eruptions as well as earthquakes.

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  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • Remote Sensing (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

L'invention concerne un procédé permettant de prévoir des contraintes lors d'événement sismiques, notamment de tremblements de terre et d'éruptions volcaniques. Ce procédé consiste à détecter les ondes équivolumiques émises par une source sismique selon au moins un angle, de préférence inférieur à environ 50 degrés de la verticale, à au moins un emplacement situé à une première profondeur sous la surface terrestre et à une seconde profondeur au moins égale à la première, espacées horizontalement du ou des points d'emplacement précités. Ces ondes équivolumiques sont détectée, de préférence, à deux emplacements dans des forages distincts, et les délais retard entre les polarisations orthogonales des ondes équivolumiques sont analysés.
PCT/GB2000/001137 1999-03-26 2000-03-24 Previsions des contraintes lors d'evenements sismiques WO2000058756A1 (fr)

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GBGB9906893.4A GB9906893D0 (en) 1999-03-26 1999-03-26 Stress-forecasting time and magnitude of large earthquakes in stress-monitoring sites

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005031390A1 (fr) * 2003-08-27 2005-04-07 Science Horizons, Inc. Systemes de prevision des seismes et leurs procedes d'utilisation
WO2007092596A2 (fr) * 2006-02-09 2007-08-16 Schlumberger Canada Limited Procédés et appareil utilisés pour prévoir la production d'hydrocarbure d'une implantation de forage
WO2018216827A1 (fr) * 2017-05-23 2018-11-29 지랜드 주식회사 Dispositif et procédé associés à l'atténuation des secousses sismiques
CN112505763A (zh) * 2020-10-30 2021-03-16 中国石油天然气集团有限公司 横波地震数据质量检测方法及系统

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4566084A (en) * 1982-09-30 1986-01-21 The United States Of America As Represented By The United States Department Of Energy Acoustic velocity measurements in materials using a regenerative method
US5771170A (en) * 1994-02-14 1998-06-23 Atlantic Richfield Company System and program for locating seismic events during earth fracture propagation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4566084A (en) * 1982-09-30 1986-01-21 The United States Of America As Represented By The United States Department Of Energy Acoustic velocity measurements in materials using a regenerative method
US5771170A (en) * 1994-02-14 1998-06-23 Atlantic Richfield Company System and program for locating seismic events during earth fracture propagation

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
CRAMPIN S: "SHEAR-WAVE SPLITTING IN A CRITICAL CRUST: THE NEXT STEP", REVUE DE L'INSTITUT FRANCAIS DU PETROLE,FR,EDITIONS TECHNIP. PARIS, vol. 53, no. NO. SPEC.), September 1998 (1998-09-01), pages 749 - 763, XP000831999, ISSN: 1294-4475 *
CRAMPIN S: "The fracture criticality of crustal rocks", GEOPHYSICAL JOURNAL INTERNATIONAL, AUG. 1994, UK, vol. 118, no. 2, August 1994 (1994-08-01), pages 428 - 438, XP000925325, ISSN: 0956-540X *
TROKHAN A M: "FUNDAMENTAL METROLOGICAL PROBLEMS. PHYSICAL MEASUREMENTS IN EARTHQUAKE PREDICTION", MEASUREMENT TECHNIQUES,US,CONSULTANTS BUREAU. NEW YORK, vol. 40, no. 6, 1 June 1997 (1997-06-01), pages 505 - 510, XP000778900, ISSN: 0543-1972 *
YUN LIU ET AL: "Shear-wave anisotropy and the stress field from borehole recordings at 2.5 km depth at Cajon Pass", GEOPHYSICAL JOURNAL INTERNATIONAL, MAY 1997, BLACKWELL SCIENCE FOR R. ASTRON. SOC.;DEUTSCHE GEOPHYS. GESELLSCHAFT; EUR. GEOPHYS. SOC, UK, vol. 129, no. 2, May 1997 (1997-05-01), pages 439 - 459, XP000925269, ISSN: 0956-540X *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005031390A1 (fr) * 2003-08-27 2005-04-07 Science Horizons, Inc. Systemes de prevision des seismes et leurs procedes d'utilisation
WO2007092596A2 (fr) * 2006-02-09 2007-08-16 Schlumberger Canada Limited Procédés et appareil utilisés pour prévoir la production d'hydrocarbure d'une implantation de forage
WO2007092596A3 (fr) * 2006-02-09 2007-12-13 Schlumberger Ca Ltd Procédés et appareil utilisés pour prévoir la production d'hydrocarbure d'une implantation de forage
US7486589B2 (en) 2006-02-09 2009-02-03 Schlumberger Technology Corporation Methods and apparatus for predicting the hydrocarbon production of a well location
EA014144B1 (ru) * 2006-02-09 2010-10-29 Прэд Рисерч Энд Дивелопмент Лимитед Способы и устройства для прогнозирования добычи углеводородов с места заложения скважины
US8780671B2 (en) 2006-02-09 2014-07-15 Schlumberger Technology Corporation Using microseismic data to characterize hydraulic fractures
WO2018216827A1 (fr) * 2017-05-23 2018-11-29 지랜드 주식회사 Dispositif et procédé associés à l'atténuation des secousses sismiques
CN112505763A (zh) * 2020-10-30 2021-03-16 中国石油天然气集团有限公司 横波地震数据质量检测方法及系统

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