2646:. When an otherwise isotropic rock contains a distribution of dry or liquid-filled cracks which have preferred orientation it is named crack induced anisotropy. The presence of aligned cracks, open or filled with some different material, is an important mechanism at shallow depth, in the crust. It is well known that the small-scale, or microstructural, factors include (e.g. Kern & Wenk 1985; Mainprice et al. 2003): (1) crystal lattice preferred orientation (LPO) of constituent mineral phases; (2) variations in spatial distribution of grains and minerals; (3) grain morphology and (4) aligned fractures, cracks and pores, and the nature of their infilling material (e.g. clays, hydrocarbons, water, etc.). Because of the overall microstructural control on seismic anisotropy, it follows that anisotropy can be diagnostic for specific rock types. Here, we consider whether seismic anisotropy can be used as an indicator of specific
3906:
used, which results in a much better image, along with the fact that PreSM honours velocity changes more accurately than post-stack migration. The PreSM is extremely sensitive to the accuracy of the velocity field. Thus the inadequacy of isotropic velocity models is not suitable for the pre stack depth migration. P-wave anisotropic prestack depth migration (APSDM) can produce a seismic image that is very accurate in depth and space. As a result, unlike isotropic PSDM, it is consistent with well data and provides an ideal input for reservoir characterization studies. However, this accuracy can only be achieved if correct anisotropy parameters are used. These parameters cannot be estimated from seismic data alone. They can only be determined with confidence through analysis of a variety of geoscientific material – borehole data and geological history.
4760:. In shear-wave splitting, the S wave splits into two orthogonal polarizations, corresponding to the fastest and slowest wavespeeds in that medium for that propagation direction. The period range for mantle splitting studies is typically 5-25-sec. In seismic tomography, one must have a spatial distribution of seismic sources (earthquakes or man-made blasts) to generate waves at multiple wave-propagation azimuths through a 3-D medium. For receiver functions, the P-to-S converted wave displays harmonic variation with earthquake back azimuth when the material at depth is anisotopic. This method allows determination of layers of anisotropic material at depth beneath a station.
1723:
3919:
the top or base of an anisotropic material, and a second exploits the polarizing effect that the fractures have on a transmitted shear-wave. In both cases, the individual fractures are below the resolving power of the seismic signal and it is the cumulative effect of the fracturing that is recorded. Based on the idea behind them, both approaches can be divided into two steps. The first step is to get the anisotropy parameters from seismic signals, and the second steps is to retreat the information of fractures from anisotropy parameters based on the fracture induce anisotropy model.
3818:
1082:
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oriented single component geophones. However, while expensive 3 component seismometers are much more powerful in their ability to collect valuable information about the Earth that vertical component seismometers simply cannot. While seismic waves do attenuate, large earthquakes (moment magnitude > 5) have the ability to produce observable shear waves. The second law of thermodynamics ensures a higher attenuation of shear wave reflected energy, this tends to impede the utilization of shear wave information for smaller earthquakes.
3142:
208:. Such shear wave splitting can be directly analyzed only on three component geophones recording either in the subsurface, or within the effective shear window at the free surface if there are no near surface low-velocity layers. Observation of these shear waves show that measuring the orientation and polarization of the first arrival and the delay between these split shear waves reveal the orientation of cracks and the crack density . This is particularly important in reservoir characterization.
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700:
1718:{\displaystyle {\begin{aligned}V_{p}(\theta )&={\sqrt {\frac {C_{11}\sin ^{2}(\theta )+C_{33}\cos ^{2}(\theta )+C_{55}+{\sqrt {M(\theta )}}}{2\rho }}}\\V_{SV}(\theta )&={\sqrt {\frac {C_{11}\sin ^{2}(\theta )+C_{33}\cos ^{2}(\theta )+C_{55}-{\sqrt {M(\theta )}}}{2\rho }}}\\V_{SH}(\theta )&={\sqrt {\frac {C_{66}\sin ^{2}(\theta )+C_{55}\cos ^{2}(\theta )}{\rho }}}\\M(\theta )&=\left^{2}+\left(C_{13}+C_{55}\right)^{2}\sin ^{2}(2\theta )\\\end{aligned}}}
709:
348:
3813:{\displaystyle {\begin{aligned}&C_{33}=\rho V_{P}^{2}(0^{\circ })\\&C_{11}=\rho V_{P}^{2}(90^{\circ })\\&C_{55}=\rho V_{SH}^{2}(90^{\circ })\\&C_{66}=\rho V_{SV}^{2}(90^{\circ })\\&C_{13}=\left^{2}}{4}}\right]^{1/2}-C_{44}\\&\epsilon ={\frac {C_{11}-C_{33}}{2C_{33}}}\\&\gamma ={\frac {C_{66}-C_{44}}{2C_{44}}}\\&\delta ={\frac {(C_{13}+C_{44})^{2}-(C_{33}-C_{44})^{2}}{2C_{33}(C_{33}-C_{44})}}\end{aligned}}}
110:(it is called transverse isotropy because there is isotropy in either the horizontal or vertical plane) or polar anisotropy. The difference between them is in their axis of symmetry, which is an axis of rotational invariance such that if we rotate the formation about the axis, the material is still indistinguishable from what it was before. The symmetry axis is usually associated with regional stress or gravity.
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22:
1056:{\displaystyle {\underline {\underline {\mathsf {C}}}}={\begin{bmatrix}C_{11}&C_{13}&C_{13}&0&0&0\\C_{13}&C_{33}&C_{33}-2C_{44}&0&0&0\\C_{13}&C_{33}-2C_{44}&C_{33}&0&0&0\\0&0&0&C_{44}&0&0\\0&0&0&0&C_{66}&0\\0&0&0&0&0&C_{66}\end{bmatrix}}}
695:{\displaystyle {\underline {\underline {\mathsf {C}}}}={\begin{bmatrix}C_{11}&C_{11}-2C_{66}&C_{13}&0&0&0\\C_{11}-2C_{66}&C_{11}&C_{13}&0&0&0\\C_{13}&C_{13}&C_{33}&0&0&0\\0&0&0&C_{44}&0&0\\0&0&0&0&C_{44}&0\\0&0&0&0&0&C_{66}\end{bmatrix}}}
1815:
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developed by Total. The following two plots clearly reveal the resolution improvement of the PSDM method. The top plot is a convention 3D survey without anisotropy effect. The bottom plot used PSDM method. As can be seen in the bottom plot, more small structure features are revealed due to the reduce of error and improved resolution.
161:. From 1898 till his death in 1916, Rudzki attempted to advance the theory of anisotropy, he attempted to determine the wavefront of a transversely isotropic medium (TI) in 1898 and in 1912 and 1913 he wrote on surface waves in transversely isotropic half space and on Fermat's principle in anisotropic media respectively.
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the anisotropy parameter obtained through core measurement technique only represent the anisotropy property of rock near the borehole at just several specific depth, rending this technique often provides little help on the field seismic survey application. The measurements on each shale plug require at least one week.
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transducer ultrasonic systems at variable saturation and pressure conditions. Usually, three directions of wave propagation on core samples are the minimum requirement to estimate the five elastic coefficients of the stiffness tensor. Each direction in core plug measurement yields three velocities (one P and two S).
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many cases, cracks are preferentially aligned with their flat faces oriented in the direction of minimum compressive stress. In active tectonic areas, such as near faults and volcanoes, anisotropy can be used to look for changes in preferred orientation of cracks that may indicate a rotation of the stress field.
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In the situation of complex geology, e.g. faulting, folding, fracturing, salt bodies, and unconformities, pre-stack migration (PreSM) is used due to better resolution under such complex geology. In PreSM, all traces are migrated before being moved to zero-offset. As a result, much more information is
3133:
Another way to get the wave propagation velocity at three directions is to arrange the ultrasonic transducer onto several specific location of the core sampler. This method avoids the difficulties encounter during the cutting of shale core sample. It also reduces the time of measurement by two thirds
2729:. These fundamental works enable to parametrize the transverse isotropic (TI) models with only three parameters, while there are five full independent stiff tensor element in transverse isotropic (VTI or HTI) models. This simplification made the measurement of seismic anisotropy a plausible approach.
3121:
Another technique used to estimate the anisotropy parameter is directly measure them from the core which is extracted through a special hollow drill bit during drill process. Since coring a sample will generate large extra cost, only limited number of core samples can be obtained for each well. Thus
2760:
The
Walkway VSP array several seismic surface sources at different offset from the well. Meanwhile, a vertical receiver array with constant interval between receivers is mounted in a vertical well. The sound arrival times between multiple surface sources and receivers at multiple depths are recorded
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Seismic velocity anisotropy in shale can be estimated from several methods, including deviated-well sonic logs, walkway VSP, and core measurement. These methods have their own advantages and disadvantages: the walkway VSP method suffers from scaling issues, and core measure is impractical for shale,
203:
Shear waves have been observed to split into two or more fixed polarizations which can propagate in the particular ray direction when entering an anisotropic medium. These split phases propagate with different polarizations and velocities. Crampin (1984) amongst others gives evidence that many rocks
4697:
In the Earth's crust, anisotropy may be caused by preferentially aligned joints or microcracks, by layered bedding in sedimentary formations, or by highly foliated metamorphic rocks. Crustal anisotropy resulting from aligned cracks can be used to determine the state of stress in the crust, since in
4679:
In this case, the operator conducted several seismic surveys on a gas field in the north sea over the period of 1993-1998 . The early survey does not take anisotropy into account, while the later survey employs the PreStack Depth
Migration imaging. This PSDM was done on a commercial seismic package
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The following plot shows typical velocity distribution vs density in a deviated well. The color of each data point represents the frequency of this data point. The red color means a high frequency while the blue color represents a low frequency. The black line shows a typical velocity trend without
4127:
The behavior of shear waves as they pass through anisotropic media has been recognized for many years, with laboratory and field observations demonstrating how the shear wave splits into two polarized components with their planes aligned parallel and perpendicular to the anisotropy. For a fractured
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If the fractures are vertically aligned, they will produce azimuthal anisotropy (the simplest case being horizontal transverse isotropy, or HTI) such that reflectivity of an interface depends on azimuth as well as offset. If either of the media bounding the interface is azimuthally anisotropic, the
3918:
After considering applications of anisotropy that improved seismic imaging, two approaches for exploiting anisotropy for the analysis of fractures in the formation are worthy of discussing. Ones uses azimuthal variations in the amplitude versus offset (AVO) signature when the wave is reflected from
3129:
The variation of wave propagation direction can be achieved by either cutting three samples at 0°, 45° and 90° from the cores or by using one core plug with transducers attached at these three angles. Since most shales are very friable and fissured, it is often difficult to cut shale core plug. Its
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The origin of seismic anisotropy is non-unique, a range of phenomena may cause Earth materials to display seismic anisotropy. The anisotropy may be strongly dependent on wavelength if it is due to the average properties of aligned or partially aligned heterogeneity. A solid has intrinsic anisotropy
172:
that velocities along the foliation were about 20% higher than those across the foliation. However the appreciation of anisotropy increased with the proposition of a new model for the generation of anisotropy in an originally isotropic background and a new exploration concept by
Crampin (1987). One
4709:
may exhibit anisotropy. For both, the anisotropy may appear as a (continuous) dependence of velocity upon the direction of propagation. For S-waves, it may also appear as a (discrete) dependence of velocity upon the direction of polarization. For a given direction of propagation in any homogeneous
3896:
The last technique can be used to measure the seismic anisotropy is related to the sonic logging information of a deviated well. In a deviated well, the wave propagation velocity is higher than the wave propagation velocity in a vertical well at the same depth. This difference in velocity between
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Seismic anisotropy relies on shear waves, shear waves carry rich information which can sometimes impede its utilization. Shear waves survey for anisotropy requires multi component (usually 3 component) geophones which are oriented at angles, these are more expensive than the widely used vertical
3125:
From the context of this article, wave propagation in a vertically transverse medium can be described with five elastic constants, and ratios among these parameters define the rock anisotropy. This anisotropy parameter can be obtained in the laboratory by measuring the velocity travel speed with
2685:
In addition, the establishment of correlation between anisotropy parameters, fracture orientation, and density, lead to practical reservoir characterization techniques. The acquisition of such information, fracture spatial distribution and density, the drainage area of each producing well can be
3909:
During recent years, the industry has started to see the practical use of anisotropy in seismic imaging. We show case studies that illustrate this integration of the geosciences. We show that much better accuracy is being achieved. The logical conclusion is that, this integrated approach should
2677:
In the past two decades, the seismic anisotropy has dramatically been gaining attention from academic and industry, due to advances in anisotropy parameter estimation, the transition from post stack imaging to pre stack depth migration, and the wider offset and azimuthal coverage of 3D surveys.
2656:
In sedimentary rocks, anisotropy develops during and after deposition. For anisotropy to develop, there needs to be some degree of homogeneity or uniformity from point to point in the deposited clastics. During deposition, anisotropy is caused by the periodic layering associated with changes in
4141:
Two examples will be discussed in there to show the anisotropy application in
Petroleum E&P area. The first related to anisotropy parameter estimation via deviated well sonic logging tool. And the second example reflects the image quality improvement by PreStack Depth Migration technology.
2708:
imaging (the major of petroleum exploration seismic surveys). Although the anisotropy-induced distortion is less significant since the poststack processing of narrow-azimuth data is not sensitive to velocity. The advancement of seismic anisotropy is largely contributed by the
Thomsen's work on
2678:
Currently, many seismic processing and inversion methods utilize anisotropic models, thus providing a significant enhancement over the seismic imaging quality and resolution. The integration of anisotropy velocity model with seismic imaging has reduced uncertainty on internal and bounding-
164:
With all these, the advancement of anisotropy was still slow and in the first 30 years (1920–1950) of exploration seismology only a few papers were written on the subject. More work was done by several scientists such as Helbig (1956) who observed while doing seismic work on
94:
if the value of one or more of its properties varies with direction. Anisotropy differs from the property called heterogeneity in that anisotropy is the variation in values with direction at a point while heterogeneity is the variation in values between two or more points.
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medium, the faster shear wave is generally aligned with the strike direction and the time delay between the split shear waves related to the fracture density and path length traveled. For layered medium, the shear wave polarized parallel to the layering arrives first.
2980:
4720:
In crustal geophysics, the anisotropy is usually weak; this enables a simplification of the expressions for seismic velocities and reflectivities, as functions of propagation (and polarization) direction. In the simplest geophysically plausible case, that of
4630:
2169:{\displaystyle {\begin{aligned}V_{P}(\theta )&\approx V_{P0}(1+\delta \sin ^{2}\theta \cos ^{2}\theta +\epsilon \sin ^{4}\theta )\\V_{SV}(\theta )&\approx V_{S0}\left\\V_{SH}(\theta )&\approx V_{S0}(1+\gamma \sin ^{2}\theta )\end{aligned}}}
2686:
dramatically increased if taking the fractures into account during the drilling decision process. The increased drainage area per well will result in fewer wells, greatly reducing the drilling cost of exploration and production (E&P) projects.
2337:
The approximate expressions for the wave velocities are simple enough to be physically interpreted, and sufficiently accurate for most geophysical applications. These expressions are also useful in some contexts where the anisotropy is not weak.
4289:
4710:
medium, only two polarization directions are allowed, with other polarizations decomposing trigonometrically into these two. Hence, shear waves naturally "split" into separate arrivals with these two polarizations; in optics this is called
105:
with 21 independent elements. However, in practice observational studies are unable to distinguish all 21 elements, and anisotropy is usually simplified. In the simplest form, there are two main types of anisotropy, both of them are called
5029:
Jeffrey S., Rob R., Jean A., et al. www.cgg.com/technicalDocuments/cggv_0000000409.pdf
Reducing Structural Uncertainties Through Anisotropic Prestack Depth Imaging: Examples from the Elgin/Franklin/Glenelg HP/HT Fields Area, Central North
4065:
2612:{\displaystyle {\begin{aligned}\epsilon &={\frac {C_{11}-C_{33}}{2C_{33}}}\\\delta &={\frac {(C_{13}+C_{44})^{2}-(C_{33}-C_{44})^{2}}{2C_{33}(C_{33}-C_{44})}}\\\gamma &={\frac {C_{66}-C_{44}}{2C_{44}}}\end{aligned}}}
2703:
The anisotropy parameter is most fundamental to all other anisotropy application in E&P area. In the early days of seismic petroleum exploration, the geophysicists were already aware of the anisotropy-induced distortion in
2694:
Among several applications of seismic anisotropy, the following are the most important: anisotropic parameter estimation, prestack depth anisotropy migration, and fracture characterization based on anisotropy velocity models.
2281:
188:, which clearly show the effects of shear wave splitting, and wide azimuth 3D data which show the effects of azimuthal anisotropy, and the availability of more powerful computers, anisotropy began to have great impact in
136:
Transverse isotropy is sometimes called transverse anisotropy or anisotropy with hexagonal symmetry. In many cases the axis of symmetry will be neither horizontal nor vertical, in which case it is often called "tilted".
5022:
Stephen A. H. and J-Michael K. GEOPHYSICS, VOL. 68, NO. 4, P1150–1160. Fracture characterization at
Valhall: Application of P-wave amplitude variation with offset and azimuth (AVOA) analysis to a 3D ocean-bottom data
2766:
4991:
Helbig, K., Thomsen, L., 75-plus years of anisotropy in exploration and reservoir seismics: A historical review of concepts and methods: Geophysics. VOL. 70, No. 6 (November–December 2005): p. 9ND–23ND
2657:
sediment type which produces materials of different grain size, and also by the directionality of the transporting medium which tends to order the grains under gravity by grain sorting. Fracturing and some
320:
4150:
In this case, the sonic velocity in a deviated well is obtained by dipole sonic logging tool . The formation is mostly composed of shale. In order to use the TI model, several assumptions are made:
1751:
3927:
Aligned subseismic-scale fracturing can produce seismic anisotropy (i.e., seismic velocity varies with direction) and leads to measurable directional differences in traveltimes and reflectivity.
3147:
2351:
1820:
1733:
1087:
5033:
Helbig, K., 1984, Shear waves – what they are and how they are and how they can be used: Applied
Seismic Anisotropy: Theory, Background, and Field Studies, Geophysics Reprint series, 20, 5–22.
4745:
or small scale convection. Anisotropy has long been used to argue whether plate tectonics is driven from below by mantle convection or from above by the plates, i.e. slab pull and ridge push.
129:
Horizontal transverse isotropy (HTI), transverse isotropy with a horizontal axis of symmetry, is associated with cracks and fractures and is found where regional stress is the dominant factor.
173:
of the main points by
Crampin was that the polarization of three component shear waves carries unique information about the internal structure of the rock through which they pass, and that
2642:
when it is homogeneously and sinuously anisotropic down to the smallest particle size, which may be due to crystalline anisotropy. Relevant crystallographic anisotropy can be found in the
4671:
is plot vs density in the following plot. As be seen in the plot, most of the data point falls on the trend line. It validate the correctness of the estimate of anisotropy parameter.
704:
The above is the elastic modulus for a vertical transverse isotropic medium (VTI), which is the usual case. The elastic modulus for a horizontal transverse isotropic medium (HTI) is:
4741:) aligned with the mantle flow direction called lattice preferred orientation (LPO). Due to their elongate crystalline structure, olivine crystals tend to align with the flow due to
3936:
4506:
1065:
For an anisotropic medium, the directional dependence of the three phase velocities can be written by applying the elastic moduli in the wave equation is; The direction dependent
3846:
2312:
4998:
Crampin, S., 1984, Evaluation of anisotropy by shear wave splitting: Applied
Seismic Anisotropy: Theory, Background, and Field Studies, Geophysics Reprint series, 20, 23–33.
3897:
deviated well and vertical well reflects the anisotropy parameters of the rocks near the borehole. The detail of this technique will be shown on an example of this report.
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Seismic anisotropy has been observed to be weak, and Thomsen (1986) rewrote the velocities above in terms of their deviation from the vertical velocities as follows;
4117:
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4379:
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4087:
3111:
3058:
2727:
2181:
1771:
3137:
Once the velocities at three directions are measured by one of the above two methods, the five independent elastic constants are given by the following equations:
3011:
5053:
4993:
3031:
4717:
Crustal anisotropy is very important in the production of oil reservoirs, as the seismically fast directions can indicate preferred directions of fluid flow.
3931:
AVO will have an azimuthal dependence. The P-P wave reflection coefficient have the following relation with the azimuthal if anisotropy exist in the layers:
133:
The transverse anisotropic matrix has the same form as the isotropic matrix, except that it has five non-zero values distributed among 12 non-zero elements.
2744:
as well as seal rocks that trap oil and gas. In seismic exploration, shales represent the majority of the wave propagation medium overlying the petroleum
200:
Since the understanding of seismic anisotropy is closely tied to the shear wave splitting, this section begins with a discussion of shear wave splitting.
43:
30:
220:
5004:
Thomsen, L., 1986, Weak elastic anisotropy: Applied Seismic Anisotropy: Theory, Background, and Field Studies, Geophysics Reprint series, 20, 34–46
2341:
The Thomsen parameters are anisotropic and are three non-dimensional combinations which reduce to zero in isotropic cases, and are defined as
2736:, which may be due to the fact that shale and silts are the most abundant sedimentary rocks in the Earth's crust. Also in the context of
4892:
101:
can be defined as the dependence of seismic velocity on direction or upon angle. General anisotropy is described by a 4th order
2975:{\displaystyle t^{2}(x)=t_{0}^{2}+{\frac {x^{2}}{V_{nmo}^{2}}}-{\frac {2\eta x^{4}}{V_{nmo}^{2}(_{nmo}^{2}+(1+2\eta )x^{2})}}}
204:
are anisotropic for shear wave propagation. In addition, shear wave splitting is almost routinely observed in three-component
5054:
http://www.geo.arizona.edu/geo5xx/geo596f/Readings/Helbig%20and%20Thomsen,%202005,%20historical%20review%20anisotropy%201.pdf
4994:
http://www.geo.arizona.edu/geo5xx/geo596f/Readings/Helbig%20and%20Thomsen,%202005,%20historical%20review%20anisotropy%201.pdf
5026:
Tushar P. and Robert V. SPE 146668. Improved Reservoir Characterization through Estimation of Velocity Anisotropy in Shales.
1728:
5073:
146:
5016:
Tsvankin, I., : Geophysics, 62, 1292-1309.1997, Anisotropic parameters and P-wave velocity for orthorhombic media.
215:
as one in which each component of stress is dependent on every component of strain, the following relationship exists:
4358:
the effect of anisotropy. Since the existence of anisotropy effect, the sound velocity is higher than the trend line.
2761:
during measurement. These arrival times are used to derive the anisotropy parameter based on the following equations
5058:
5019:
Tsvankin, I., Seismic signatures and analysis of reflection data in anisotropic media: Elsevier Science Publ, 2001,.
5008:
5078:
5048:
35:
4831:
Savage, M. (1999). "Seismic anisotropy and mantle deformation: What have we learned from shear wave splitting?".
3910:
extend the use of anisotropic depth imaging from complex geology only, to routine application on all reservoirs.
205:
4625:{\displaystyle V_{P}(0)={\frac {V_{P}(\phi )}{1+\delta \sin ^{2}\phi \cos ^{2}\phi +\epsilon \sin ^{4}\phi }}}
114:
Vertical transverse isotropy (VTI), transverse isotropy with a vertical axis of symmetry, is associated with
5001:
Ikelle, L.T., Amundsen, L., Introduction to Petroleum Seismology, Investigations in Geophysics series No.12.
4772:
3868:
quantifies the velocity difference for wave propagation along and perpendicular to the symmetry axis, while
189:
5007:
Anderson et al., Oilfield Anisotropy: Its Origins and Electrical Characteristics: Oil field review, 48–56.
184:
With these new developments and the acquisition of better and new types of data such as three component 3D
2748:. In conclusion, seismic properties of shale are important for both exploration and reservoir management.
2682:
positions, thus greatly reduce the risk of investment decision based heavily on seismic interpretation.
185:
3825:
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145:
Anisotropy was first recognised in the 19th century following the theory of Elastic wave propagation.
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174:
4284:{\displaystyle V_{P}(\phi )=V_{P}(0)(1+\delta \sin ^{2}\phi \cos ^{2}\phi +\epsilon \sin ^{4}\phi )}
1807:. The Thomsen parameters are used to simplify these expressions and make them easier to understand.
5083:
4780:
3130:
edges break off easily. Thus the cutting sample method can only be used for hard, competent rocks.
2745:
158:
107:
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4726:
178:
4381:
plot can be drawn. On the basis of this plot, a no liner regression will give us an estimate of
4060:{\displaystyle R_{PP}=A+(b_{11}\cos ^{2}\phi +2b_{12}\cos \phi \sin \phi +b_{22}\sin ^{2}\phi )}
4941:"Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions"
4447:
4404:
4337:
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4820:. SEG-EAGE Distinguished Instructor Series. Vol. 5. Society of Exploration Geophysicists.
4757:
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1804:
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153:(1856) took anisotropy into account in their articles on wave propagation. Anisotropy entered
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87:
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212:
71:
2314:) (in geophysics, this is usually, but not always, the vertical direction). Note that
5067:
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4711:
3822:
The P-wave anisotropy of a VTI medium can be described by using Thomsen's parameters
2666:
5043:
4756:
of surface waves and body waves, and converted-wave scattering in the context of a
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anisotropy notation and also by the discovery of the P-wave time-process parameter
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67:
5059:
https://www.slb.com/~/media/Files/resources/oilfield_review/ors94/1094/p48_56.pdf
5009:
https://www.slb.com/~/media/Files/resources/oilfield_review/ors94/1094/p48_56.pdf
2669:, and alteration etc. are post depositional processes that can cause anisotropy.
5049:
https://web.archive.org/web/20050909171919/http://geophysics.asu.edu/anisotropy/
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region (a couple hundred kilometer thick layer about the core-mantle boundary).
4784:
4768:
2741:
150:
4965:
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2276:{\displaystyle V_{P0}={\sqrt {C_{33}/\rho }}~;~~V_{S0}={\sqrt {C_{44}/\rho }}}
1753:
is the angle between the axis of symmetry and the wave propagation direction,
154:
91:
4974:
4868:
Physical Properties of Crystals: Their Representation by Tensors and Matrices
4161:
Satisfying the above conditions, the following equation hold for a TI model:
2334:
may be further linearized, but this does not lead to further simplification.
4776:
2650:
2626:
Anisotropy has been reported to occur in the Earth's three main layers: the
21:
2285:
are the P and S wave velocities in the direction of the axis of symmetry (
2690:
The application of the anisotropy in petroleum exploration and production
166:
5013:
Thomsen, L., : Geophysics, 51, 1954–1966, Weak elastic anisotropy.
4738:
4737:
In the mantle, anisotropy is normally associated with crystals (mainly
4706:
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123:
115:
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2673:
The importance of anisotropy in hydrocarbon exploration and production
2705:
169:
4421:. The following plot show the non-linear regression and its result.
4796:
3888:
controls the P-wave propagation for angles near the symmetry axis.
3134:
since three pairs of ultrasonic transducer work at the same time.
119:
75:
4818:
Understanding seismic anisotropy in exploration and exploitation
2733:
2732:
Most anisotropy parameter estimation work is based on shale and
315:{\displaystyle \sigma _{ij}=C_{ijkl}e_{kl}\quad i,j,k,l=1,2,3}
15:
211:
In a linearly elastic material, which can be described by
4748:
The favored methods for detecting seismic anisotropy are
4635:
By doing the above correction calculation, the corrected
738:
377:
343:
The elastic modulus matrix for an anisotropic case is
4725:, the analysis is most conveniently done in terms of
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is the azimuth from data acquisition grid, the terms
4075:
3939:
3874:
3854:
3828:
3145:
3099:
3066:
3039:
3019:
2990:
2769:
2715:
2349:
2320:
2291:
2184:
1818:
1779:
1759:
1746:{\displaystyle {\begin{aligned}\theta \end{aligned}}}
1731:
1085:
712:
351:
223:
4795:and could be generating anisotropy observed in the
4663:
4624:
4492:
4456:
4436:
4413:
4393:
4373:
4346:
4326:
4306:
4283:
4119:are coefficients describing anisotropy parameter.
4111:
4081:
4059:
3880:
3860:
3840:
3812:
3105:
3085:
3052:
3025:
3005:
2974:
2721:
2611:
2326:
2306:
2275:
2168:
1795:
1765:
1745:
1717:
1055:
694:
314:
177:may contain information about the distribution of
4904:Thomsen, Leon (1986). "Weak Elastic Anisotropy".
2752:since shale is hard to be cored during drilling.
66:is the directional dependence of the velocity of
5044:http://www1.gly.bris.ac.uk/~wookey/MMA/index.htm
4939:Long, Maureen D.; Silver, Paul G. (2009-06-27).
4887:. Cambridge University Press 2003 (paperback).
1073:through the material can be found by using the
157:in the late 19th century and was introduced by
8:
4361:From the well logging data, the velocity vs
4154:Rock should be in normally pressured regime.
4675:Example of prestack depth migration Imaging
4137:Example of anisotropy in petroleum E&P
4964:
4646:
4640:
4607:
4585:
4569:
4539:
4532:
4514:
4508:
4475:
4469:
4464:into the following equation, the correct
4449:
4429:
4406:
4386:
4366:
4339:
4319:
4299:
4266:
4244:
4228:
4197:
4175:
4169:
4132:Examples of the application of anisotropy
4100:
4094:
4074:
4042:
4032:
4001:
3979:
3969:
3944:
3938:
3873:
3853:
3827:
3794:
3781:
3768:
3753:
3743:
3730:
3714:
3704:
3691:
3681:
3661:
3646:
3633:
3626:
3606:
3591:
3578:
3571:
3554:
3537:
3533:
3517:
3504:
3491:
3472:
3462:
3446:
3433:
3417:
3404:
3399:
3383:
3369:
3351:
3338:
3330:
3314:
3296:
3283:
3275:
3259:
3241:
3228:
3223:
3207:
3189:
3176:
3171:
3155:
3146:
3144:
3098:
3071:
3065:
3044:
3038:
3018:
2989:
2960:
2929:
2918:
2905:
2900:
2884:
2873:
2861:
2848:
2837:
2826:
2816:
2810:
2801:
2796:
2774:
2768:
2714:
2596:
2581:
2568:
2561:
2535:
2522:
2509:
2494:
2484:
2471:
2455:
2445:
2432:
2422:
2399:
2384:
2371:
2364:
2350:
2348:
2319:
2298:
2293:
2290:
2263:
2257:
2251:
2239:
2213:
2207:
2201:
2189:
2183:
2147:
2122:
2093:
2068:
2052:
2027:
2012:
1999:
1993:
1968:
1939:
1916:
1894:
1878:
1853:
1827:
1819:
1817:
1784:
1778:
1758:
1732:
1730:
1690:
1680:
1669:
1656:
1637:
1614:
1599:
1586:
1556:
1541:
1528:
1465:
1455:
1430:
1420:
1412:
1387:
1351:
1342:
1317:
1307:
1282:
1272:
1264:
1239:
1203:
1194:
1169:
1159:
1134:
1124:
1116:
1094:
1086:
1084:
1039:
995:
951:
907:
895:
879:
867:
838:
822:
810:
798:
769:
757:
745:
733:
716:
713:
711:
678:
634:
590:
546:
534:
522:
493:
481:
469:
453:
424:
412:
396:
384:
372:
355:
352:
350:
263:
244:
228:
222:
4157:Rock should have similar burial history.
141:History of the recognition of anisotropy
46:of all important aspects of the article.
4808:
4314:is the deviated angle of the well, and
4146:Example of deviated well sonic logging
717:
356:
192:seismology in the past three decades.
42:Please consider expanding the lead to
3013:is the arrival time from source with
7:
3901:Anisotropic prestack depth migration
3060:is the arrival time of zero offset,
4771:could be aligned in LPO. Below the
3113:is Thompson anisotropy parameter.
14:
4684:Limitations of seismic anisotropy
3841:{\displaystyle \epsilon ,\delta }
2307:{\displaystyle \mathbf {e} _{3}}
2294:
20:
4123:Fractures: shear-wave splitting
2699:Anisotropy parameter estimation
272:
34:may be too short to adequately
4658:
4652:
4551:
4545:
4526:
4520:
4487:
4481:
4278:
4212:
4209:
4203:
4187:
4181:
4054:
3962:
3923:Fractures-azimuthal variations
3800:
3774:
3750:
3723:
3711:
3684:
3514:
3510:
3484:
3481:
3469:
3423:
3410:
3386:
3357:
3344:
3302:
3289:
3247:
3234:
3195:
3182:
3000:
2994:
2966:
2953:
2938:
2915:
2893:
2890:
2786:
2780:
2541:
2515:
2491:
2464:
2452:
2425:
2159:
2131:
2108:
2102:
2045:
2033:
1954:
1948:
1928:
1862:
1839:
1833:
1708:
1699:
1629:
1623:
1571:
1565:
1503:
1497:
1480:
1474:
1445:
1439:
1402:
1396:
1362:
1356:
1332:
1326:
1297:
1291:
1254:
1248:
1214:
1208:
1184:
1178:
1149:
1143:
1106:
1100:
44:provide an accessible overview
1:
196:Concept of seismic anisotropy
4775:, the three main minerals,
336:or stiffness constant, and
5100:
4883:, T. Mukerji, J. Dvorkin.
4870:. Oxford University Press.
4354:are anisotropy parameter.
2653:within the Earth's crust.
4966:10.1007/s10712-009-9075-1
4885:The Rock Physics Handbook
4457:{\displaystyle \epsilon }
4414:{\displaystyle \epsilon }
4347:{\displaystyle \epsilon }
3914:Fracture characterization
3861:{\displaystyle \epsilon }
4763:In the transition zone,
4664:{\displaystyle V_{P}(0)}
4493:{\displaystyle V_{P}(0)}
1805:elastic stiffness matrix
1773:is mass density and the
4437:{\displaystyle \delta }
4394:{\displaystyle \delta }
4327:{\displaystyle \delta }
3892:Deviated well sonic log
3881:{\displaystyle \delta }
3086:{\displaystyle V_{nmo}}
2740:, organic shale is the
2327:{\displaystyle \delta }
126:is the dominant factor.
4665:
4626:
4494:
4458:
4438:
4415:
4395:
4375:
4348:
4328:
4308:
4285:
4113:
4112:{\displaystyle b_{ij}}
4083:
4061:
3882:
3862:
3842:
3814:
3107:
3087:
3054:
3027:
3007:
2976:
2723:
2613:
2328:
2308:
2277:
2170:
1797:
1796:{\displaystyle C_{ij}}
1767:
1747:
1719:
1057:
696:
316:
4945:Surveys in Geophysics
4833:Reviews of Geophysics
4666:
4627:
4495:
4459:
4439:
4416:
4396:
4376:
4374:{\displaystyle \phi }
4349:
4329:
4309:
4307:{\displaystyle \phi }
4286:
4114:
4084:
4082:{\displaystyle \phi }
4062:
3883:
3863:
3843:
3815:
3108:
3106:{\displaystyle \eta }
3088:
3055:
3053:{\displaystyle t_{0}}
3028:
3008:
2977:
2724:
2722:{\displaystyle \eta }
2614:
2329:
2309:
2278:
2171:
1798:
1768:
1766:{\displaystyle \rho }
1748:
1720:
1058:
697:
317:
5074:Elasticity (physics)
4816:Thomsen, L. (2002).
4750:shear wave splitting
4639:
4507:
4468:
4448:
4428:
4405:
4385:
4365:
4338:
4318:
4298:
4168:
4093:
4073:
3937:
3872:
3852:
3826:
3143:
3097:
3064:
3037:
3017:
3006:{\displaystyle t(x)}
2988:
2767:
2713:
2622:Origin of anisotropy
2347:
2318:
2289:
2182:
1816:
1803:are elements of the
1777:
1757:
1729:
1083:
1075:Christoffel equation
710:
349:
221:
175:shear wave splitting
4957:2009SGeo...30..407L
4918:1986Geop...51.1954T
4866:Nye, J. F. (2000).
4845:1999RvGeo..37...65S
4781:silicate perovskite
3409:
3343:
3288:
3233:
3181:
2934:
2910:
2889:
2842:
2806:
122:and is found where
108:transverse isotropy
4754:seismic tomography
4727:Thomsen Parameters
4693:Crustal anisotropy
4661:
4622:
4490:
4454:
4434:
4424:Put the estimated
4411:
4391:
4371:
4344:
4324:
4304:
4281:
4109:
4079:
4057:
3878:
3858:
3838:
3810:
3808:
3395:
3326:
3271:
3219:
3167:
3103:
3083:
3050:
3023:
3003:
2972:
2914:
2896:
2869:
2822:
2792:
2719:
2665:and dewatering of
2661:processes such as
2609:
2607:
2324:
2304:
2273:
2166:
2164:
1793:
1763:
1743:
1741:
1715:
1713:
1053:
1047:
728:
724:
692:
686:
367:
363:
312:
99:Seismic anisotropy
64:Seismic anisotropy
5079:Petroleum geology
4926:10.1190/1.1442051
4853:10.1029/98RG02075
4758:receiver function
4743:mantle convection
4733:Mantle anisotropy
4620:
4500:can be obtained.
3804:
3668:
3613:
3527:
3093:is NMO velocity,
3026:{\displaystyle x}
2970:
2843:
2738:petroleum geology
2603:
2545:
2406:
2271:
2234:
2231:
2225:
2221:
2021:
1488:
1487:
1377:
1376:
1365:
1229:
1228:
1217:
1077:and are given by
715:
714:
354:
353:
103:elasticity tensor
61:
60:
5091:
4979:
4978:
4968:
4936:
4930:
4929:
4901:
4895:
4878:
4872:
4871:
4863:
4857:
4856:
4828:
4822:
4821:
4813:
4723:polar anisotropy
4670:
4668:
4667:
4662:
4651:
4650:
4631:
4629:
4628:
4623:
4621:
4619:
4612:
4611:
4590:
4589:
4574:
4573:
4554:
4544:
4543:
4533:
4519:
4518:
4499:
4497:
4496:
4491:
4480:
4479:
4463:
4461:
4460:
4455:
4443:
4441:
4440:
4435:
4420:
4418:
4417:
4412:
4400:
4398:
4397:
4392:
4380:
4378:
4377:
4372:
4353:
4351:
4350:
4345:
4333:
4331:
4330:
4325:
4313:
4311:
4310:
4305:
4290:
4288:
4287:
4282:
4271:
4270:
4249:
4248:
4233:
4232:
4202:
4201:
4180:
4179:
4118:
4116:
4115:
4110:
4108:
4107:
4088:
4086:
4085:
4080:
4066:
4064:
4063:
4058:
4047:
4046:
4037:
4036:
4006:
4005:
3984:
3983:
3974:
3973:
3952:
3951:
3887:
3885:
3884:
3879:
3867:
3865:
3864:
3859:
3847:
3845:
3844:
3839:
3819:
3817:
3816:
3811:
3809:
3805:
3803:
3799:
3798:
3786:
3785:
3773:
3772:
3759:
3758:
3757:
3748:
3747:
3735:
3734:
3719:
3718:
3709:
3708:
3696:
3695:
3682:
3673:
3669:
3667:
3666:
3665:
3652:
3651:
3650:
3638:
3637:
3627:
3618:
3614:
3612:
3611:
3610:
3597:
3596:
3595:
3583:
3582:
3572:
3563:
3559:
3558:
3546:
3545:
3541:
3532:
3528:
3523:
3522:
3521:
3509:
3508:
3496:
3495:
3477:
3476:
3467:
3466:
3451:
3450:
3438:
3437:
3422:
3421:
3408:
3403:
3384:
3374:
3373:
3363:
3356:
3355:
3342:
3337:
3319:
3318:
3308:
3301:
3300:
3287:
3282:
3264:
3263:
3253:
3246:
3245:
3232:
3227:
3212:
3211:
3201:
3194:
3193:
3180:
3175:
3160:
3159:
3149:
3117:Core measurement
3112:
3110:
3109:
3104:
3092:
3090:
3089:
3084:
3082:
3081:
3059:
3057:
3056:
3051:
3049:
3048:
3032:
3030:
3029:
3024:
3012:
3010:
3009:
3004:
2981:
2979:
2978:
2973:
2971:
2969:
2965:
2964:
2933:
2928:
2909:
2904:
2888:
2883:
2867:
2866:
2865:
2849:
2844:
2841:
2836:
2821:
2820:
2811:
2805:
2800:
2779:
2778:
2728:
2726:
2725:
2720:
2618:
2616:
2615:
2610:
2608:
2604:
2602:
2601:
2600:
2587:
2586:
2585:
2573:
2572:
2562:
2546:
2544:
2540:
2539:
2527:
2526:
2514:
2513:
2500:
2499:
2498:
2489:
2488:
2476:
2475:
2460:
2459:
2450:
2449:
2437:
2436:
2423:
2407:
2405:
2404:
2403:
2390:
2389:
2388:
2376:
2375:
2365:
2333:
2331:
2330:
2325:
2313:
2311:
2310:
2305:
2303:
2302:
2297:
2282:
2280:
2279:
2274:
2272:
2267:
2262:
2261:
2252:
2247:
2246:
2232:
2229:
2223:
2222:
2217:
2212:
2211:
2202:
2197:
2196:
2175:
2173:
2172:
2167:
2165:
2152:
2151:
2130:
2129:
2101:
2100:
2084:
2080:
2073:
2072:
2057:
2056:
2032:
2031:
2026:
2022:
2020:
2019:
2007:
2006:
1994:
1976:
1975:
1947:
1946:
1921:
1920:
1899:
1898:
1883:
1882:
1861:
1860:
1832:
1831:
1802:
1800:
1799:
1794:
1792:
1791:
1772:
1770:
1769:
1764:
1752:
1750:
1749:
1744:
1742:
1724:
1722:
1721:
1716:
1714:
1695:
1694:
1685:
1684:
1679:
1675:
1674:
1673:
1661:
1660:
1642:
1641:
1636:
1632:
1619:
1618:
1609:
1605:
1604:
1603:
1591:
1590:
1561:
1560:
1551:
1547:
1546:
1545:
1533:
1532:
1489:
1483:
1470:
1469:
1460:
1459:
1435:
1434:
1425:
1424:
1414:
1413:
1395:
1394:
1378:
1375:
1367:
1366:
1352:
1347:
1346:
1322:
1321:
1312:
1311:
1287:
1286:
1277:
1276:
1266:
1265:
1247:
1246:
1230:
1227:
1219:
1218:
1204:
1199:
1198:
1174:
1173:
1164:
1163:
1139:
1138:
1129:
1128:
1118:
1117:
1099:
1098:
1062:
1060:
1059:
1054:
1052:
1051:
1044:
1043:
1000:
999:
956:
955:
912:
911:
900:
899:
884:
883:
872:
871:
843:
842:
827:
826:
815:
814:
803:
802:
774:
773:
762:
761:
750:
749:
729:
720:
701:
699:
698:
693:
691:
690:
683:
682:
639:
638:
595:
594:
551:
550:
539:
538:
527:
526:
498:
497:
486:
485:
474:
473:
458:
457:
429:
428:
417:
416:
401:
400:
389:
388:
368:
359:
339:
331:
327:
321:
319:
318:
313:
271:
270:
258:
257:
236:
235:
56:
53:
47:
24:
16:
5099:
5098:
5094:
5093:
5092:
5090:
5089:
5088:
5064:
5063:
5040:
4988:
4983:
4982:
4951:(4–5): 407–61.
4938:
4937:
4933:
4912:(10): 1954–66.
4903:
4902:
4898:
4879:
4875:
4865:
4864:
4860:
4830:
4829:
4825:
4815:
4814:
4810:
4805:
4789:post-perovskite
4773:transition zone
4735:
4695:
4686:
4677:
4642:
4637:
4636:
4603:
4581:
4565:
4555:
4535:
4534:
4510:
4505:
4504:
4471:
4466:
4465:
4446:
4445:
4426:
4425:
4403:
4402:
4383:
4382:
4363:
4362:
4336:
4335:
4316:
4315:
4296:
4295:
4262:
4240:
4224:
4193:
4171:
4166:
4165:
4148:
4139:
4134:
4125:
4096:
4091:
4090:
4071:
4070:
4038:
4028:
3997:
3975:
3965:
3940:
3935:
3934:
3925:
3916:
3903:
3894:
3870:
3869:
3850:
3849:
3824:
3823:
3807:
3806:
3790:
3777:
3764:
3760:
3749:
3739:
3726:
3710:
3700:
3687:
3683:
3671:
3670:
3657:
3653:
3642:
3629:
3628:
3616:
3615:
3602:
3598:
3587:
3574:
3573:
3561:
3560:
3550:
3513:
3500:
3487:
3468:
3458:
3442:
3429:
3413:
3385:
3379:
3378:
3365:
3361:
3360:
3347:
3310:
3306:
3305:
3292:
3255:
3251:
3250:
3237:
3203:
3199:
3198:
3185:
3151:
3141:
3140:
3119:
3095:
3094:
3067:
3062:
3061:
3040:
3035:
3034:
3015:
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366:
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334:elastic moduli
311:
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281:
278:
275:
269:
266:
262:
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197:
194:
181:orientations.
159:Maurycy Rudzki
142:
139:
131:
130:
127:
90:is said to be
83:
80:
59:
58:
38:the key points
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26:
19:
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10:
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4:
3:
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5028:
5025:
5021:
5018:
5015:
5012:
5010:
5006:
5003:
5000:
4997:
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4989:
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4962:
4958:
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4927:
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4919:
4915:
4911:
4907:
4900:
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4894:
4893:0-521-54344-4
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4839:(1): 65–109.
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4712:birefringence
4708:
4704:
4701:Both seismic
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3405:
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3320:
3315:
3311:
3297:
3293:
3284:
3279:
3276:
3272:
3268:
3265:
3260:
3256:
3242:
3238:
3229:
3224:
3220:
3216:
3213:
3208:
3204:
3190:
3186:
3177:
3172:
3168:
3164:
3161:
3156:
3152:
3138:
3135:
3131:
3127:
3123:
3116:
3114:
3100:
3078:
3075:
3072:
3068:
3045:
3041:
3020:
2997:
2991:
2982:
2961:
2957:
2950:
2947:
2944:
2941:
2935:
2930:
2925:
2922:
2919:
2911:
2906:
2901:
2897:
2885:
2880:
2877:
2874:
2870:
2862:
2858:
2854:
2851:
2845:
2838:
2833:
2830:
2827:
2823:
2817:
2813:
2807:
2802:
2797:
2793:
2789:
2783:
2775:
2771:
2762:
2755:
2753:
2749:
2747:
2743:
2739:
2735:
2730:
2716:
2707:
2698:
2696:
2689:
2687:
2683:
2681:
2672:
2670:
2668:
2664:
2660:
2654:
2652:
2649:
2645:
2639:
2637:
2633:
2629:
2621:
2619:
2597:
2593:
2589:
2582:
2578:
2574:
2569:
2565:
2558:
2556:
2551:
2536:
2532:
2528:
2523:
2519:
2510:
2506:
2502:
2495:
2485:
2481:
2477:
2472:
2468:
2461:
2456:
2446:
2442:
2438:
2433:
2429:
2419:
2417:
2412:
2400:
2396:
2392:
2385:
2381:
2377:
2372:
2368:
2361:
2359:
2354:
2342:
2339:
2335:
2321:
2299:
2283:
2268:
2264:
2258:
2254:
2248:
2243:
2240:
2236:
2226:
2218:
2214:
2208:
2204:
2198:
2193:
2190:
2186:
2177:
2156:
2153:
2148:
2144:
2140:
2137:
2134:
2126:
2123:
2119:
2115:
2113:
2105:
2097:
2094:
2090:
2081:
2077:
2074:
2069:
2065:
2061:
2058:
2053:
2049:
2042:
2039:
2036:
2028:
2023:
2016:
2013:
2009:
2003:
2000:
1996:
1990:
1985:
1982:
1978:
1972:
1969:
1965:
1961:
1959:
1951:
1943:
1940:
1936:
1925:
1922:
1917:
1913:
1909:
1906:
1903:
1900:
1895:
1891:
1887:
1884:
1879:
1875:
1871:
1868:
1865:
1857:
1854:
1850:
1846:
1844:
1836:
1828:
1824:
1811:
1808:
1806:
1788:
1785:
1781:
1760:
1736:
1705:
1702:
1696:
1691:
1687:
1681:
1676:
1670:
1666:
1662:
1657:
1653:
1648:
1643:
1638:
1633:
1626:
1620:
1615:
1611:
1606:
1600:
1596:
1592:
1587:
1583:
1578:
1574:
1568:
1562:
1557:
1553:
1548:
1542:
1538:
1534:
1529:
1525:
1520:
1515:
1510:
1508:
1500:
1494:
1484:
1477:
1471:
1466:
1462:
1456:
1452:
1448:
1442:
1436:
1431:
1427:
1421:
1417:
1409:
1407:
1399:
1391:
1388:
1384:
1372:
1369:
1359:
1353:
1348:
1343:
1339:
1335:
1329:
1323:
1318:
1314:
1308:
1304:
1300:
1294:
1288:
1283:
1279:
1273:
1269:
1261:
1259:
1251:
1243:
1240:
1236:
1224:
1221:
1211:
1205:
1200:
1195:
1191:
1187:
1181:
1175:
1170:
1166:
1160:
1156:
1152:
1146:
1140:
1135:
1131:
1125:
1121:
1113:
1111:
1103:
1095:
1091:
1078:
1076:
1072:
1071:elastic waves
1068:
1063:
1048:
1040:
1036:
1030:
1025:
1020:
1015:
1010:
1003:
996:
992:
986:
981:
976:
971:
964:
959:
952:
948:
942:
937:
932:
925:
920:
915:
908:
904:
896:
892:
888:
885:
880:
876:
868:
864:
856:
851:
846:
839:
835:
831:
828:
823:
819:
811:
807:
799:
795:
787:
782:
777:
770:
766:
758:
754:
746:
742:
735:
730:
725:
721:
705:
702:
687:
679:
675:
669:
664:
659:
654:
649:
642:
635:
631:
625:
620:
615:
610:
603:
598:
591:
587:
581:
576:
571:
564:
559:
554:
547:
543:
535:
531:
523:
519:
511:
506:
501:
494:
490:
482:
478:
470:
466:
462:
459:
454:
450:
442:
437:
432:
425:
421:
413:
409:
405:
402:
397:
393:
385:
381:
374:
369:
364:
360:
344:
341:
335:
322:
309:
306:
303:
300:
297:
294:
291:
288:
285:
282:
279:
276:
273:
267:
264:
260:
254:
251:
248:
245:
241:
237:
232:
229:
225:
216:
214:
209:
207:
201:
195:
193:
191:
187:
182:
180:
176:
171:
168:
162:
160:
156:
152:
148:
140:
138:
134:
128:
125:
121:
117:
113:
112:
111:
109:
104:
100:
96:
93:
89:
81:
79:
77:
74:) within the
73:
70:in a medium (
69:
68:seismic waves
65:
55:
45:
39:
37:
32:
27:
23:
18:
17:
4948:
4944:
4934:
4909:
4905:
4899:
4884:
4876:
4867:
4861:
4836:
4832:
4826:
4817:
4811:
4762:
4747:
4736:
4719:
4716:
4700:
4696:
4687:
4678:
4634:
4423:
4360:
4356:
4293:
4160:
4149:
4140:
4126:
4068:
3933:
3929:
3926:
3917:
3908:
3904:
3895:
3821:
3139:
3136:
3132:
3128:
3124:
3120:
2983:
2763:
2759:
2750:
2731:
2702:
2693:
2684:
2676:
2655:
2644:upper mantle
2640:
2625:
2343:
2340:
2336:
2284:
2178:
1812:
1809:
1079:
1064:
706:
703:
345:
342:
323:
217:
210:
202:
199:
186:seismic data
183:
163:
147:George Green
144:
135:
132:
98:
97:
85:
63:
62:
49:
33:
31:lead section
4793:anisotropic
4785:bridgmanite
4769:ringwoodite
2756:Walkway VSP
2742:source rock
2651:lithologies
2648:sedimentary
1067:wave speeds
213:Hooke's law
190:exploration
151:Lord Kelvin
149:(1838) and
92:anisotropic
82:Description
5084:Geophysics
5068:Categories
4906:Geophysics
4803:References
4765:wadsleyite
2663:compaction
2659:diagenetic
155:seismology
4975:0169-3298
4777:periclase
4617:ϕ
4614:
4601:ϵ
4595:ϕ
4592:
4579:ϕ
4576:
4563:δ
4549:ϕ
4452:ϵ
4432:δ
4409:ϵ
4389:δ
4369:ϕ
4342:ϵ
4322:δ
4302:ϕ
4276:ϕ
4273:
4260:ϵ
4254:ϕ
4251:
4238:ϕ
4235:
4222:δ
4185:ϕ
4077:ϕ
4052:ϕ
4049:
4023:ϕ
4020:
4014:ϕ
4011:
3989:ϕ
3986:
3876:δ
3856:ϵ
3836:δ
3830:ϵ
3788:−
3737:−
3721:−
3676:δ
3640:−
3621:γ
3585:−
3566:ϵ
3548:−
3498:−
3479:−
3453:−
3440:−
3427:−
3419:∘
3393:ρ
3353:∘
3324:ρ
3298:∘
3269:ρ
3243:∘
3217:ρ
3191:∘
3165:ρ
3101:η
2951:η
2855:η
2846:−
2746:reservoir
2717:η
2575:−
2552:γ
2529:−
2478:−
2462:−
2413:δ
2378:−
2355:ϵ
2322:δ
2269:ρ
2219:ρ
2157:θ
2154:
2141:γ
2116:≈
2106:θ
2078:θ
2075:
2062:θ
2059:
2043:δ
2040:−
2037:ϵ
1962:≈
1952:θ
1926:θ
1923:
1910:ϵ
1904:θ
1901:
1888:θ
1885:
1872:δ
1847:≈
1837:θ
1761:ρ
1737:θ
1706:θ
1697:
1627:θ
1621:
1593:−
1575:−
1569:θ
1563:
1535:−
1501:θ
1485:ρ
1478:θ
1472:
1443:θ
1437:
1400:θ
1373:ρ
1360:θ
1349:−
1330:θ
1324:
1295:θ
1289:
1252:θ
1225:ρ
1212:θ
1182:θ
1176:
1147:θ
1141:
1104:θ
886:−
829:−
726:_
722:_
460:−
403:−
365:_
361:_
226:σ
52:July 2018
36:summarize
4881:G. Mavko
4791:are all
3033:offset,
2634:and the
167:Devonian
116:layering
88:material
4986:Sources
4953:Bibcode
4914:Bibcode
4841:Bibcode
4787:), and
4767:and/or
4739:olivine
4707:S-waves
4703:P-waves
332:is the
170:schists
124:gravity
4973:
4891:
4294:Where
4069:where
3848:. The
2984:where
2706:P-wave
2632:mantle
2233:
2230:
2224:
2176:where
1725:where
324:where
2734:silts
2680:fault
2667:clays
2628:crust
179:crack
120:shale
76:Earth
4971:ISSN
4889:ISBN
4705:and
4444:and
4401:and
2636:core
1069:for
206:VSPs
118:and
72:rock
5030:Sea
5023:set
4961:doi
4922:doi
4849:doi
4605:sin
4583:cos
4567:sin
4264:sin
4242:cos
4226:sin
4040:sin
4017:sin
4008:cos
3977:cos
2145:sin
2066:cos
2050:sin
1914:sin
1892:cos
1876:sin
1688:sin
1612:cos
1554:sin
1463:cos
1428:sin
1315:cos
1280:sin
1167:cos
1132:sin
5070::
4969:.
4959:.
4949:30
4947:.
4943:.
4920:.
4910:51
4908:.
4847:.
4837:37
4835:.
4797:D"
4779:,
4752:,
4729:.
4714:.
4334:,
4034:22
4003:12
3971:11
3796:44
3783:33
3770:33
3745:44
3732:33
3706:44
3693:13
3663:44
3648:44
3635:66
3608:33
3593:33
3580:11
3556:44
3506:33
3493:11
3464:44
3448:33
3435:11
3415:45
3371:13
3349:90
3316:66
3294:90
3261:55
3239:90
3209:11
3157:33
2638:.
2630:,
2598:44
2583:44
2570:66
2537:44
2524:33
2511:33
2486:44
2473:33
2447:44
2434:13
2401:33
2386:33
2373:11
2259:44
2209:33
1671:55
1658:13
1601:55
1588:33
1543:55
1530:11
1457:55
1422:66
1344:55
1309:33
1274:11
1196:55
1161:33
1126:11
1041:66
997:66
953:44
909:33
897:44
881:33
869:13
840:44
824:33
812:33
800:13
771:13
759:13
747:11
680:66
636:44
592:44
548:33
536:13
524:13
495:13
483:11
471:66
455:11
426:13
414:66
398:11
386:11
86:A
78:.
4977:.
4963::
4955::
4928:.
4924::
4916::
4855:.
4851::
4843::
4783:(
4659:)
4656:0
4653:(
4648:P
4644:V
4609:4
4598:+
4587:2
4571:2
4560:+
4557:1
4552:)
4546:(
4541:P
4537:V
4530:=
4527:)
4524:0
4521:(
4516:P
4512:V
4488:)
4485:0
4482:(
4477:P
4473:V
4279:)
4268:4
4257:+
4246:2
4230:2
4219:+
4216:1
4213:(
4210:)
4207:0
4204:(
4199:P
4195:V
4191:=
4188:)
4182:(
4177:P
4173:V
4105:j
4102:i
4098:b
4055:)
4044:2
4030:b
4026:+
3999:b
3995:2
3992:+
3981:2
3967:b
3963:(
3960:+
3957:A
3954:=
3949:P
3946:P
3942:R
3833:,
3801:)
3792:C
3779:C
3775:(
3766:C
3762:2
3755:2
3751:)
3741:C
3728:C
3724:(
3716:2
3712:)
3702:C
3698:+
3689:C
3685:(
3679:=
3659:C
3655:2
3644:C
3631:C
3624:=
3604:C
3600:2
3589:C
3576:C
3569:=
3552:C
3543:2
3539:/
3535:1
3530:]
3525:4
3519:2
3515:]
3511:)
3502:C
3489:C
3485:(
3482:[
3474:2
3470:)
3460:C
3456:2
3444:C
3431:C
3424:)
3411:(
3406:2
3401:P
3397:V
3390:4
3387:(
3381:[
3376:=
3367:C
3358:)
3345:(
3340:2
3335:V
3332:S
3328:V
3321:=
3312:C
3303:)
3290:(
3285:2
3280:H
3277:S
3273:V
3266:=
3257:C
3248:)
3235:(
3230:2
3225:P
3221:V
3214:=
3205:C
3196:)
3187:0
3183:(
3178:2
3173:P
3169:V
3162:=
3153:C
3079:o
3076:m
3073:n
3069:V
3046:0
3042:t
3021:x
3001:)
2998:x
2995:(
2992:t
2967:)
2962:2
2958:x
2954:)
2948:2
2945:+
2942:1
2939:(
2936:+
2931:2
2926:o
2923:m
2920:n
2916:]
2912:V
2907:2
2902:0
2898:t
2894:[
2891:(
2886:2
2881:o
2878:m
2875:n
2871:V
2863:4
2859:x
2852:2
2839:2
2834:o
2831:m
2828:n
2824:V
2818:2
2814:x
2808:+
2803:2
2798:0
2794:t
2790:=
2787:)
2784:x
2781:(
2776:2
2772:t
2594:C
2590:2
2579:C
2566:C
2559:=
2542:)
2533:C
2520:C
2516:(
2507:C
2503:2
2496:2
2492:)
2482:C
2469:C
2465:(
2457:2
2453:)
2443:C
2439:+
2430:C
2426:(
2420:=
2397:C
2393:2
2382:C
2369:C
2362:=
2300:3
2295:e
2265:/
2255:C
2249:=
2244:0
2241:S
2237:V
2227:;
2215:/
2205:C
2199:=
2194:0
2191:P
2187:V
2160:)
2149:2
2138:+
2135:1
2132:(
2127:0
2124:S
2120:V
2109:)
2103:(
2098:H
2095:S
2091:V
2082:]
2070:2
2054:2
2046:)
2034:(
2029:2
2024:)
2017:0
2014:S
2010:V
2004:0
2001:P
1997:V
1991:(
1986:+
1983:1
1979:[
1973:0
1970:S
1966:V
1955:)
1949:(
1944:V
1941:S
1937:V
1929:)
1918:4
1907:+
1896:2
1880:2
1869:+
1866:1
1863:(
1858:0
1855:P
1851:V
1840:)
1834:(
1829:P
1825:V
1789:j
1786:i
1782:C
1709:)
1703:2
1700:(
1692:2
1682:2
1677:)
1667:C
1663:+
1654:C
1649:(
1644:+
1639:2
1634:]
1630:)
1624:(
1616:2
1607:)
1597:C
1584:C
1579:(
1572:)
1566:(
1558:2
1549:)
1539:C
1526:C
1521:(
1516:[
1511:=
1504:)
1498:(
1495:M
1481:)
1475:(
1467:2
1453:C
1449:+
1446:)
1440:(
1432:2
1418:C
1410:=
1403:)
1397:(
1392:H
1389:S
1385:V
1370:2
1363:)
1357:(
1354:M
1340:C
1336:+
1333:)
1327:(
1319:2
1305:C
1301:+
1298:)
1292:(
1284:2
1270:C
1262:=
1255:)
1249:(
1244:V
1241:S
1237:V
1222:2
1215:)
1209:(
1206:M
1201:+
1192:C
1188:+
1185:)
1179:(
1171:2
1157:C
1153:+
1150:)
1144:(
1136:2
1122:C
1114:=
1107:)
1101:(
1096:p
1092:V
1049:]
1037:C
1031:0
1026:0
1021:0
1016:0
1011:0
1004:0
993:C
987:0
982:0
977:0
972:0
965:0
960:0
949:C
943:0
938:0
933:0
926:0
921:0
916:0
905:C
893:C
889:2
877:C
865:C
857:0
852:0
847:0
836:C
832:2
820:C
808:C
796:C
788:0
783:0
778:0
767:C
755:C
743:C
736:[
731:=
718:C
688:]
676:C
670:0
665:0
660:0
655:0
650:0
643:0
632:C
626:0
621:0
616:0
611:0
604:0
599:0
588:C
582:0
577:0
572:0
565:0
560:0
555:0
544:C
532:C
520:C
512:0
507:0
502:0
491:C
479:C
467:C
463:2
451:C
443:0
438:0
433:0
422:C
410:C
406:2
394:C
382:C
375:[
370:=
357:C
338:e
330:C
326:σ
310:3
307:,
304:2
301:,
298:1
295:=
292:l
289:,
286:k
283:,
280:j
277:,
274:i
268:l
265:k
261:e
255:l
252:k
249:j
246:i
242:C
238:=
233:j
230:i
54:)
50:(
40:.
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