Anisotropic parameters and pwave velocity for orthorhombic media. Fuyong yan1, dehua han1, samik sil 2, and xuelian chen3, 1university of houston, texas, 2occidental petroleum, texas, 3china university of petroleum summary 11. Pwave anisotropy is usually meant, unless swave anisotropy is specified, but anisotropy of pwaves usually implies anisotropy for swaves and viceversa. Additionally, we explore the effect of fluids in modifying the anisotropy resulting from these causes. Although the five elastic constants of a transversely isotropic. Anisotropic pstm migrations in the big horn basin, wy. Any continuing constant cyclic phenomenon may be represented graphically by a sine or cosine wave. The ellipticity is associated with the shape of the wavefront expanding from a point source. Basic theory and applications in exploration and reservoir characterization by ilya tsvankin and vladimir grechka.
This book incorporates significant new developments in isotropic and anisotropic reflection processing, while organizing them to improve the interpretation of seismic reflection data and optimizing the modeling of hydrocarbon reservoirs. Pdf seismic anisotropy in exploration and reservoir. The most common form of anisotropy the transverse isotropy, is dealt with in detail. The wave equation is used in specific processing procedures such as tomog. Understanding seismic anisotropy in exploration and. There are several reasons why the anisotropy of the crystalline crust has not traditionally been investigated. Compressional and shear wave anisotropy, shear wave birefringence, and the anisotropy of magnetic susceptibility were measured on a series of dunites sampled from the dinardichellenic ophiolites. A strategy for automated analysis of passive microseismic data to image seismic anisotropy and fracture characteristics andreas wuestefeld. Permeability anisotropy and seismic anisotropy wayne pennington, matthias imhof, roger turpening permeability is a measure of the flow of fluids through a rock, a parameter that can be anisotropic, a function of direction of flow.
Modelling orthorhombic anisotropic effects for reservoir. Correlations between the seismic anisotropy parameters for shales. The densities of these materials ranged from 3330 kgm 3to 2620 kgm and indicate degrees of serpentinization from 2. Anisotropy may be analyzed in terms of the symmetry of the medium. However, with recent advances in acquisition, processing and interpretation of elastic data, the reasons for ignoring anisotropy are no longer valid.
Hence, the estimation of a good velocity model is crucial. Seismic reflection processing with special reference to anisotropy. Fuyong yan1, dehua han1, xuelian chen2, and samik sil3, 1university of houston, texas, 2china university of petroleum, 3occidental petroleum, texas summary. Understanding seismic anisotropy in exploration and exploitation. The edinburgh anisotropy project is a long running industryacademic research consortium working on all aspects of seismic anisotropy, with a particular emphasis on anisotropic rock physics, fracture detection and convertedwave seismic methods. Siska2 most descriptions of anisotropy make reference to reduced distances and conversion of anisotropic models to isotropic counterparts and equations are presented for a certain class of rangeanisotropic models. To gain a better understanding of the earths subsurface anisotropy should be considered. Seismic anisotropy of the deep earth from a mineral and rock.
Interval anisotropic parameters estimation in a least. In this study we present a stepbystep theoretical modelling approach, using established seismic wave propagation theories in anisotropic media, to generate unique anisotropic reflection patterns observed from threedimensional puremode pressure 3dpp, fullazimuth and fulloffset seismic reflection data acquired over a naturally fractured tight carbonate field, onshore texas, usa. Pdf attributes of routine reflection processing and pitfalls. An extensive treatment of specific processingsteps and. Steve hearn a thesis submitted for the degree of bachelor of science with honours at the university of queenslandin 2016 exploration geophysics laboratory school of earth sciences november 26, 2016 i. Seismic anisotropy is the dependence of velocity on propagation direction or angle of the seismic signal within the geological medium. Sensitivity analysis of seismic anisotropy parameter estimation. In theory, the walkaway vsp can be used to invert shearwaves to yield an estimate of the shearwave anisotropy.
It will be a valuable reference to geologists, geophysicists, and petroleum engi. This particular book seismic reflection processing. The general elasticity tensor stiffness or its inverse compliance is a 3x3x3x3 tensor relating stress and strain. Elliptical anisotropy is a special case of transverse isotropy and has been shown to be rare in sedimentary rocks thomsen 1986, sayers 1994. Seismic refractionwideangle reflection profiles dss, which provide excellent. Reflection seismic 1 script research collection eth zurich. Sensitivity of the elastic anisotropy and seismic reflection amplitude of the eagle ford shale to the presence of kerogen. Anisotropy, at elevated pressures caused mainly by preferred orientation of clays illite parallel to bedding, ranges from 20% v p and 19% v s for a sample of new albany shale to 30% v p and 35% v s for a sample of chattanooga shale.
Seismic observations of anisotropy shear wave splitting swave birefringence loverayleigh incompatibility shderived models of the upper mantel have higher velocities than psv derived models body waves pn velocities are azimuth dependent travel. Applied seismic anisotropy for fractured reservoir characterization asaf. Albeit its underlying theory is simpler than the general theory of anisotropy, elliptical anisotropy occurs in nature only rarely. Summary when mantle rocks are subject to large strain, the mineral grains of olivine and some other minerals align, causing the velocity of seismic waves passing though this material to vary as a function of direction of propagation and polarization seismic anisotropy. The amplitude is the peak value to which each cycle rises or falls in reference to a. Beghein department of earth, planetary and atmospheric sciences, 77 massachusetts avenue, building 54526, cambridge, ma 029, usa j. 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. Elastic anisotropy, widely recognized as a typical feature of sedimentary formations, has a strong influence on seismic velocities and amplitudes. Particular attention is given to moveout analysis and pwave timedomain processing for transverse isotropy with a vertical vti and tilted tti symmetry axis. Vsp data to help investigate overburden anisotropy and to confirm our anisotropy measurements from conventional streamer data. It is investigated whether a better approximation can be found from inversion of compressional wave data, converted wave data or the use of. Seismic reflection processing request pdf researchgate. With special reference to anisotropy was multicolored and of course has pictures on there. The velocity of a seismic wave also exhibits anisotropy.
Radial anisotropy in seismic reference models of the mantle article pdf available in journal of geophysical research atmospheres 111b2 february 2006 with 33 reads how we measure reads. Seismic and magnetic anisotropy of serpentinized ophiolite. Applied seismic anisotropy for fractured reservoir. The book tackles important issues surrounding seismic anisotropy, or the observation that seis mic waves propagate with different speeds in different directions,depending on the properties of the crust.
Seismic azimuthal anisotropy and fracture analysis from pp. Lawton department of geology and geophysics university of calgary dr. Seismic anisotropy measurement from both seismic and vsp. Seismic reflection processing with special reference to anisotropy burns 2005 eos, transactions american geophysical union wiley online library skip to article content. In the triclinic system, there are no special relationships. Seismic shale characterization research at the edinburgh. A particular type of anisotropy the transverse isotropy, has been the main subject. Seismic anisotropy can be defined as the dependence of seismic velocity on direction or upon angle. Seismic signatures and analysis of reflection data in anisotropic. Seismic reflection processing springer for research. Understanding anisotropy computations ucla statistics. Seismic anisotropy is commonly defined as the direction dependent. Analysis of azimuthal anisotropy in coalscale 3d seismic re.
At most, anisotropy has usually been considered noise that must be filtered out, not as a useful indicator of rock properties. The degree of clay mineral alignment in the shales is constrained by orientation indices produced. Studies for acceptance, a thesis entitled seismic azimuthal anisotropy and fracture analysis from pp reflection data submitted by ye zheng in partial fulfilment of the requirements of the degree of doctor of philosophy. Theoretical studies of the process of generating the earths. Negligence of anisotropy in migration may result in significant deviation of an imaged reflector from its true position. A special mention goes to allen brummert, aaron girard, stephen schneider, scott schapper, ken steele, and seann day for technical discussions, revisions, suggestions. Seismic reflection processing with special reference to. Pdf radial anisotropy in seismic reference models of the. Exploration seismology experiences and applications are also finding their way into wholeearth imaging problems and vice versa with great success. Schlumberger, 1 richmond avenue, houston, tx, 77042. Seismic velocity anisotropy has been known for many years to be an important factor in correctly imaging subsurface structures with reflection seismic methods alkhalifah et al. Upadhyays book, seismic reflection processing with special reference to anisotropy, is introduced. Each circle can be described by the amplitude and the wavelength. Seismic reflection processing coherently presents the physical concepts, mathematical details and methodology for optimizing results of reservoir modelling.
A strategy for automated analysis of passive microseismic. As we know that book seismic reflection processing. We investigate the effect of various types of deformation mechanisms on the reflection coefficients of p and s waves underside reflections off the 410 km discontinuity, to develop a diagnostic tool to detect the style of deformation at boundary layers. With special reference to anisotropy has many kinds or type. Flat sedimentary layers, though laterally homogeneous over smallscale, often exhibit a simple kind of anisotropy called vertical transverse isotropy vti. Understanding anisotropy computations1 marian eriksson2 and peter p. Use of a single grid and radius slip surface use of anisotropic. The events in depth domain crp gathers are correctly flattened and the semblance is properly aligned to the zero reference line, indicative of the quality for the adopted velocity model. Seismic processing 3 reflection seismology spectral. This short course discusses the growing importance of the seismic anisotropy of rock masses in seismic acquisition, processing, and interpretation. Radial anisotropy in seismic reference models of the mantle.
This thesis aims to quantify the anisotropy parameters. Seismic anisotropy in microseismic event location analysis. It is generally ascribed either to complex fracturing under differential horizontal stresses or gravitational effects that make the media stiffer in one direction than another. Radial anisotropy in seismic reference models of the mantle c. Trampert department of geosciences, utrecht university, budapestlaan 4, po box 80021, 3508 ta utrecht, the netherlands h. First, we present rockphysics modeling strategies for elastic anisotropy in a. Seismic anisotropy an overview sciencedirect topics. Seismic anisotropy of shales johnston 1995 journal. The use of body waves in quantifying seismic anisotropy. The text contains exercises and problems, and solutions are provided for the exercises. A number of fixed offset vsps were acquired in some of the pierce area exploration wells. Seismic reflection processing with special reference to anisotropy burns 2005 eos, transactions american geophysical union wiley online library skip to. Correlations between the seismic anisotropy parameters for. Analysis of azimuthal anisotropy in coalscale 3d seismic.