Journal of Geophysics and Engineering Impact Factor & Information

Publisher: Nanjing shi you wu tan yan jiu suo; Institute of Physics (Great Britain), IOP Publishing

Journal description

Published by the Nanjing Institute of Geophysical Prospecting and the Institute of Physics, this major new publication promotes research and developments in geophysics and related areas of engineering. It has predominantly an applied science and engineering focus, but also publishes contributions in all earth-physics disciplines from global geophysics to applied and engineering geophysics.

Current impact factor: 0.90

Impact Factor Rankings

2015 Impact Factor Available summer 2015
2013 / 2014 Impact Factor 0.895
2012 Impact Factor 0.721
2011 Impact Factor 0.634
2010 Impact Factor 0.805
2009 Impact Factor 0.787
2008 Impact Factor 0.621
2007 Impact Factor 0.762
2006 Impact Factor 0.839
2005 Impact Factor 0.86

Impact factor over time

Impact factor
Year

Additional details

5-year impact 0.77
Cited half-life 4.40
Immediacy index 0.11
Eigenfactor 0.00
Article influence 0.27
Website Journal of Geophysics and Engineering website
ISSN 1742-2140
OCLC 60310620
Material type Periodical, Internet resource
Document type Journal / Magazine / Newspaper, Internet Resource

Publisher details

IOP Publishing

  • Pre-print
    • Author can archive a pre-print version
  • Post-print
    • Author can archive a post-print version
  • Conditions
    • Pre-print on author's personal website, repository or arXiv.
    • Pre-print can not be updated after submission
    • Post-print on author's personal website immediately
    • Post-print on institutional repository, subject-based repository, PubMed Central or third party eprint servers after 12 months embargo
    • Publisher's version/PDF cannot be used
    • Published source must be acknowledged with citation
    • Must link to publisher version with DOI
    • Set statements to accompany different versions (see policy)
    • Publisher last contacted on 17/02/2014
  • Classification
    ​ green

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Sandstone reservoirs have generally high porosity in the Shawan formation of the Chunguang oil field, Junggar basin, because they developed in geological conditions of shallow and weak compaction. High porosity always links lower acoustic velocities in sandstone. However, when it is more than a certain value (approximately 27.5%), the porosity is not in accordance with acoustic velocities. In addition, cast thin sections illustrated incoherence between pore types and porosity. Fluids and mineral content are the two main factors changing acoustic velocities. This means that acoustic velocities of the high-porosity sandstone are mainly affected by the mineral content and fluid properties. Hence, data from litho-electric analysis are used to measure velocities of the compression shear waves, and thin sections are used to identify the mineral content. By the application of cross-plot maps, relations of acoustic velocities and mineral contents are proposed. Mineral contents include mainly quartz, feldspar, and tuff. In normal rock physical models, the shale content is calculated from well logs. The mineral grain is often regarded as pure quartz grain or average mineral composition. However, the application of the normal rock physics model will be inaccurate for high-porosity sandstone. Experience regression functions of the velocity model are established to estimate acoustic velocities. Also, mineral content logs could be predicted by using the P-wave acoustic log, and the rock physics model would be enhanced by using these logs of dynamic mineral contents. Shear wave velocity could also be estimated more accurately.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/629
  • Ana Osella, Patricia Martinelli, Vivian Grunhut, Matías de la Vega, Néstor Bonomo, Marcelo Weissel
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    ABSTRACT: We performed a geophysical study at a historical site in Buenos Aires, Argentina, corresponding to the location of a Jesuit Mission established during the 17th century, remaining there until the 18th century. The site consisted of a church, cloisters, a school, orchards and a procurator’s office; also several tunnels were built, connecting the mission with different public buildings in the town. In the 19th century the Faculty of Sciences of the University of Buenos Aires was built in a sector of the site originally occupied by an orchard, functioning until its demolition in 1973. At present, this area is a cobbled square. With the aim of preserving and restoring the buried structures, work was carried out in this square looking for tunnels and remains of the basement of the old building.Considering the conductive features of the subsoil, mainly formed by clays and silt, the complex characteristics of the buried structures, and the urban localization of the study area with its consequent high level of environmental electromagnetic noise, we performed pre-feasibility studies to determine the usefulness of different geophysical methods. The best results were achieved from the geoelectrical method. Dipole–dipole profiles with electrode spacings of 1.5 and 3 m provided enough lateral and vertical resolution and the required penetration depth. Reliable data were obtained as long as the electrodes were buried at least 15 cm among the cobble stones. Nine 2D electrical resistivity tomographies were obtained by using a robust inversion procedure to reduce the effect of possible data outliers in the resulting models. The effect on these models of different error estimations was also analyzed. Then, we built up a pseudo-3D model by laterally interpolating the 2D inversion results. Finally, by correlating the resulting model with the original plans, the remains of the expected main structures embedded in the site were characterized. In addition, an anomaly was identified that indicates the presence of a tunnel not previously reported.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/674
  • Raoof Gholami, Vamegh Rasouli, Bernt Aadnoy, Ramin Mohammadi
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    ABSTRACT: Estimation of in situ stresses is a key step in many petroleum engineering applications, ranging from wellbore stability to sanding analysis and hydraulic fracturing design. Direct techniques conventionally used to determine in situ stresses are indeed very time consuming and expensive. These measurements would also be restricted as to the depth of acquisition, and generalization of the results to entire rock masses may not yield representative results. In this paper, applications of three indirect methods–Zoback’s polygon, shear moduli, and poroelastic–are studied to assess their applicability in providing reliable stress estimation under isotropic and anisotropic conditions. Determination of elastic, strength, and in situ stress parameters according to the assumption of each method for one of the vertical wells drilled in south Iran indicated that the shear moduli method is an appropriate approach for prediction of maximum horizontal stress within an interval where sufficient field data including leak-off tests are acquired. However, the poroelastic method seems to be a better method in prediction of in situ stresses under anisotropic conditions. This might be due to the presence of excessive shale formations in subsurface layers, causing structural or intrinsic anisotropy-based methods such as poroelastic equations to deliver more accurate results. However, making general conclusions based on studying a single vertical wellbore may not be sufficient, and therefore further studies are required.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/657
  • [Show abstract] [Hide abstract]
    ABSTRACT: A lot of research on the 2D or 3D effects of large-scale basins (within several kilometers depth) have been conducted in the past. However, different 2D aspects of small-scale sedimentary basins (within tens of meters depth) remain in the developing stage. Here, an attempt is made to analyze different aspects of small-scale basins using both numerical and empirical investigations. In the first step, the 2D effects of small-scale basins on strong motion characteristics are numerically examined both in the time and frequency domains. In addition, the effects of input motion are also explained by the results of model excitation in different orthogonal directions. Then, the numerical outcomes are verified by the analysis of actual earthquake data recorded at a downhole array in the Fujisawa small basin, Japan. In the second step, since available recorded earthquake data in small basins with a clear understanding of subsurface geology are very limited, different 2D aspects of the small basin are parametrically investigated. For this purpose, extensive parametrical studies are carried out on the main features of a small basin such as slope angle, shape, infill soil properties, and basin thickness by using the finite difference numerical method. The horizontal and vertical peak ground accelerations of 2D with respect to 1D ones are defined as the horizontal and vertical aggravation factors (AGH and AGV ). The AGH and AGV factors show large sensitivity to infill soil properties, shape and thickness, and small sensitivity to slope angle. The values of AGH and AGV factors vary in the range of 0.5–2 with large variations around small basin edges due to wave coupling, conversion, scattering and focusing in the vicinity of small basin edges. These cause a complicated pattern of 2D de-amplification and amplification, which mostly affect the motion in the high frequency range (>1 Hz). Finally, the outcomes provide numerical and field evidence on the 2D effects of small basins, and give some recommendations for design codes.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/535
  • [Show abstract] [Hide abstract]
    ABSTRACT: Contamination of seismic signal with noise is one of the main challenges during seismic data processing. Several methods exist for eliminating different types of noises, but optimal random noise attenuation remains difficult. Based on multi-scale, multi-directional locality of curvelet transform, the curvelet thresholding method is a relatively new method for random noise elimination. However, the high redundancy of a 3D curvelet transform makes its computational time and memory for massive data processing costly. To improve the efficiency of the curvelet thresholding denoising, a low-redundancy curvelet transform was introduced. The redundancy of the low-redundancy curvelet transform is approximately one-quarter of the original transform and the tightness of the original transform is also kept, thus the low-redundancy curvelet transform calls for less memory and computational resource compared with the original one. Numerical results on 3D synthetic and field data demonstrate that the low-redundancy curvelet denoising consumes one-quarter of the CPU time compared with the original curvelet transform using iterative thresholding denoising when comparable results are obtained. Thus, the low-redundancy curvelet transform is a good candidate for massive seismic denoising.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/566
  • [Show abstract] [Hide abstract]
    ABSTRACT: Blended acquisition significantly improves the seismic acquisition efficiency. However, the direct imaging of blended data is not satisfactory due to the crosstalk contamination. Assuming that the distribution of subsurface reflectivity is sparse, in this paper, we formulate the seismic imaging problem of blended data as a Basis Pursuit denoise (BPDN) problem. Based on compressed sensing, we propose a L1 norm constrained migration method applying to the direct imaging of blended data. The Fast Iterative Shrinkage-Thresholding Algorithm, which is stable and computationally efficient, is implemented in our method. Numerical tests on the theoretical models show that the crosstalk introduced by blended sources is effectively attenuated and the migration quality has been improved enormously.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/620
  • [Show abstract] [Hide abstract]
    ABSTRACT: Horizontal drilling and multi-stage hydraulic fracturing have been common and efficient practices in exploitation of tight reservoirs. Establishing corresponding mathematical models and analyzing transient pressure behaviors of this type of well-reservoir configuration can provide a better understanding of fluid flow patterns in formation as well as estimations of important parameters. Most current models proposed for fractured horizontal wells in tight reservoirs do not incorporate either reservoir permeability loss during the production, which is believed to be non-ignorable or finite conductivity of hydraulic fractures.A coupling model for a multi–fractured horizontal well (MFHW) in tight reservoirs is presented in this article, in which finite conductivity of hydraulic fractures and stress-dependant reservoir permeability are taken into account simultaneously. A semi-analytical solution is obtained in the Laplace domain by using source function theory, Laplace transformation, perturbation technique, discretization of fractures, and superposition principle. Analysis of transient pressure responses indicates that several characteristic flow periods of fractured horizontal wells in tight reservoirs can be identified, including linear flow in fracture, bi-linear flow, linear flow in reservoir, pseudo-radial flow around fractures, and pseudo-radial flow around the horizontal wellbore and fractures. Parametric analysis shows that fracture conductivity, fracture spacing, fracture length, permeability modulus, and skin effect can significantly influence the transient pressure responses of fractured horizontal wells in tight reservoirs. The model presented in this article can be applied to obtain important parameters pertinent to reservoir or fractures by type curve matching, and it can also provide useful information for optimizing fracture parameters. Finally, the model presented in this article can also be easily extended to dual-porosity cases.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/638
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    ABSTRACT: The Simav Earthquake that occurred on 19 May 2011 in western Turkey was investigated on the basis of seismological data and geological observations. Approximately WNW– ESE trending surface ruptures were observed on the Simav Fault. The focal mechanism parameters of the earthquake (Mw = 5.8) and its aftershocks (Mw > 3.5) were estimated using time-domain moment tensor inversion. A total of 2245 events were located with Geiger’s conventional absolute location method then relocated using the double difference (DD) algorithm. The calculated locations at a depths between 2 and 16 km were found to be consistent with Coulomb stress variation in the area. Average variance reduction (VR) of the solutions was calculated as ~70%. The focal parameters of strike dip and slip of the main shock, occurring at a depth of 11 km dipping towards the NNE, were estimated at 277, 62 and -92, respectively. The most striking indication of the study is that the area is dominated by normal faults with mainly WNW–ESE trends. It is also concluded that earthquakes in the region are caused by an active and regional NNE–SSW (N 12° E) trending (σ3 axis) extension regime. The mean stress ratio is 0.80, indicating a triaxial stress state. This extension is probably associated with a slab–pull force and /or roll-back due to the complex subduction process of the African Plate beneath Anatolian block along both the Hellenic and Cyprus arcs in the eastern Mediterranean region.
    Journal of Geophysics and Engineering 08/2015; 12(5):552-565.
  • [Show abstract] [Hide abstract]
    ABSTRACT: As a powerfully diagnostic tool for structural interpretation, reservoir characterization, and hydrocarbon detection, quality factor Q provides useful information in seismic processing and interpretation. Popular methods, like the spectral ratio (SR) method, central frequency shift (CFS) method and peak frequency shift (PFS) method, have their respective limitations in dealing with field seismic data. The lack of a reliable method for estimating Q from reflection seismic data is an issue when utilizing the Q value for hydrocarbon detection. In this article, we derive an approximate equation and propose a dominant and central frequency shift (DCFS) method by combining the quality factor Q, the travel time, and dominant and central frequencies of two successive seismic signals along the wave propagating direction. Based on multi-layered analysis, we then proposed a method to obtain continuous volumetric Q estimation results. A test using synthetic data and statistical experiments showed the proposed method can achieve higher accuracy and robustness compared with existing methods. Application of field data also shows its potential and effectiveness to estimate seismic attenuation.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/577
  • [Show abstract] [Hide abstract]
    ABSTRACT: Reverse time migration (RTM) is an accurate seismic imaging method for imaging the complex subsurface structure. Traditional common shot RTM suffers from low efficiency due to the large number of single shot gathers, especially for marine seismic data. Phase encoding is commonly used to reduce the computational cost of RTM. Phase encoding in the frequency domain is usually related to time shift in the time domain. Therefore, phase-encoding-based RTM needs time padding to avoid information loss which degrades the efficiency of the time-domain wavefield extrapolator. In this paper, an efficient time-domain RTM scheme based on the amplitude encoding is proposed. This scheme uses the orthogonal cosine basis as the encoding function, which has similar physical meaning to plane wave encoding (i.e. plane-wave components with different surface shooting angles). The proposed scheme can generate a qualified imaging result as well as common shot RTM but with less computational cost. Since this scheme does not need time padding, it is more efficient than the phase encoding schemes and can be conveniently implemented in the time domain. Numerical examples on the Sigsbee2a synthetic dataset demonstrate the feasibility of the proposed method.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/601
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    ABSTRACT: Gas shale has shown considerable force in gas production worldwide, but little attention has been paid to its electrical properties, which are essential for reservoir evaluation and differentiating absorbed gas and free gas. In this study, experiments are designed to research water saturation establishment methods and electrical properties of gas shale. Nuclear magnetic resonance (NMR) with short echo space (TE) is used to identify water saturation and distribution of saturated pores which contribute to the conductivity. The experimental results indicate that NMR with shorter TE can estimate porosity and fluid distribution better than NMR with longer TE. A full range of water saturation is established by the combination of new-type spontaneous imbibition and semi-permeable plate drainage techniques. Spontaneous imbibition gains water saturation from 0% to near irreducible water saturation, and, semi-permeable plate drainage desaturates from 100% to irreducible water saturation. The RI-Sw curve shows a nonlinear relationship, and can be divided into three parts with different behaviors. The comparative analysis of transverse relaxation time (T 2) distribution and RI-Sw curves, indicates that free water, and water trapped by capillarity in the non-clay matrix, differ in terms of electrical conductivity from water absorbed in clay. The new experiments prove the applicability of imbibition, drainage and NMR in investigating electrical properties of gas shale and differentiating fluid distribution which makes contribution to conductivity.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/610
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    ABSTRACT: Rock electrical parameters of tight gas sandstone show large variations in the T 2 member in Dingbei Block, Ordos Basin, China. Applying the same rock electrical parameters in water saturation calculations would lead to large errors. Based on casting thin sections, x-ray diffraction, scanning electron microscopy (SEM), cathode luminescence, porosity and permeability, image analysis, and high-pressure mercury intrusion/withdrawal method, identification of the diagenetic facies are first conducted, and then their pore structure and their relationship with rock electrical parameters are investigated.Five diagenetic facies (A–E), which are identified based mainly on pore types and authigenic minerals, have different pore structure and rock electrical parameters. Conceptual models that incorporate the rock properties of each diagenetic facies have been built, before applying the electrical efficiency theory to explain the values of cementation exponent (m) and saturation exponent (n). A conventional network model, a shunt pore model, a netted pore model, and a dotted line model are utilized to mimic the intergranular pores, authigenic kaolinite intercrystal pores, carbonate-cement dissolution pores, and clay-matrix intercrystal pores, respectively. A decrease of the contents of large pores increases electrical efficiency and therefore reduces m. The saturation exponent, which depends on the distribution of water and gas, can be better understood by applying the different pore models. In the shunt and netted pore models, gas displacement starts from the larger pores and smaller pores provide alternative conduction pathways, hence sustaining electrical efficiency and decreasing n. Clay-matrix intercrystal pores are mainly micropores, since the brine in the rocks are isolated after gas displacement, reducing overall electrical efficiency and dramatically increasing the value of n in the diagenetic facies, which is dominated by clay-matrix intercrystal pores.
    Journal of Geophysics and Engineering 08/2015; 12(4). DOI:10.1088/1742-2132/12/4/587
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    ABSTRACT: The relation between porosity and permeability is not unique. We show that stress dependencies of both porosity and permeability can provide useful information clarifying this relation. We propose that comparison of the functional dependency of porosity and permeability on stress shows which part of the void space in rocks controls the permeability, the compliant porosity or the stiff porosity. The compliant porosity (including very thin cracks and grain-contact vicinities) usually controls the stress dependencies of elastic moduli of rocks. One then observes exponential-like dependencies of elastic properties on effective stress. Stress-induced deformation of stiff pores (equant pores) have less significance for stress dependencies of elastic properties on loadings of low to moderate magnitudes (several tens of MPa). However, such pores can play a significant role in the stress dependency of permeability. We propose a rather general model of permeability as a function of the stiff and compliant porosity. The model includes the possibility that, in different rocks, permeability can be controlled by stiff pores or, alternatively, by compliant pores, or, finally, by a combination of these. This model predicts a functional dependency of permeability on stress, ranging from power-law to exponential-law and to a mixed behavior of permeability in these situations, respectively. We show experimental results for four samples of sedimentary rocks from oil reservoirs of the Russian Perm region indicating these types of behavior.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/376
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    ABSTRACT: The variations of pore fluid energy encoded within resistivity well logs can be considered as a significant attribute in the determination of reservoir fluid contacts. As a paramount technique in isolation and manipulation of certain patterns hidden in masses of data, wavelet analysis can effectively unveil this attribute. In this study, the discrete wavelet transform was employed on new well logs generated by kernel principal component analysis to monitor the pore fluid energy of pay zones at two previously appraised wells. An expert wavelet-based model was extracted by revealing the latent pattern of pore fluid energy variations. This model was then used to specify the gas and oil interface in a target well contiguous with the appraised wells. The gas and oil interface obtained from the expert wavelet-based model was confirmed by the drill stem test analysis. Results of this investigation suggest that monitoring pore fluid energy with such a method can be considered a highly functional attribute in determining the gas and oil interface.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/386
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    ABSTRACT: In the Xu5 formation the sandstone reservoir and the shale reservoir are interbedded with each other. The average thickness of each formation is about 8 m, which increases the difficulty of the hydraulic fracturing treatment. The shale thickness ratio (the ratio of shale thickness to formation thickness) is 55–62.5%. The reservoir is characterized by ultra-low porosity and permeability. The brittleness index of sandstone is 0.5–0.8, and the brittleness index of shale is 0.3–0.8. Natural fractures are poorly developed and are mainly horizontal and at a low angle. The formation strength is medium and the reservoir is of the hybrid strike-slip fault and reverse fault stress regime. The difference between the minimum principal stress and the vertical stress is small, and the maximum horizontal principal stress is 20 MPa higher than the minimum horizontal principal stress and vertical stress. A mechanical model of a hydraulic fracture encountering natural fractures is built according to geological characteristics. Fracture mechanics theory is then used to establish a hydraulic fracturing model coupling the seepage–stress–damage model to simulate the initiation and propagation of a fracture. The hydraulic fracture geometry is mainly I-shaped and T-shaped, horizontal propagation dominates the extension, and vertical propagation is limited. There is a two to three meter stress diversion area around a single hydraulic fracture. The stress diversion between a hydraulic fracture and a natural fracture is advantageous in forming a complex fracture. The research results can provide theoretical guidance for tight reservoir fracturing design.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/321
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    ABSTRACT: Internal multiples are very difficult to remove due to their complex raypaths and poor velocity discrimination with primaries. The layer-related common focus point (CFP) method has proven to be effective for internal multiple removal, however, single application leads to multiple leakage when there are several strong reflecting boundaries in the subsurface. In order to reduce this leakage, we propose successive application of the layer-related CFP method for internal multiple removal through cascaded processing of several time levels. In this paper, we concisely reformulate the theory of the boundary- and layer-related CFP methods and compare their robustness to velocity errors. For the layer-related version in particular, we illustrate the specific steps of the method using synthetic data examples. Finally, the successive layer-related CFP method is tested on Mississippi Canyon field data.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/303
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    ABSTRACT: In current research of seismic data recovery problems, the sparsity-promoting method usually produces an insufficient recovery result at the locations of null traces. The HRT (hyperbolic Radon transform) method can be applied to problems of seismic data recovery with approximately hyperbolic events. Influenced by deviations of hyperbolic characteristics between real and ideal travel-time curves, some spurious events are usually introduced and the recovery effect of intermediate and far-offset traces is worse than that of near-offset traces. Sparsity-promoting recovery is primarily dependent on the sparsity of seismic data in the sparse transform domain (i.e. on the local waveform characteristics), whereas HRT recovery is severely affected by the global characteristics of the seismic events. Inspired by the above conclusion, a two-step recovery approach combining sparsity-promoting and time-invariant HRT methods is proposed, which is based on both local and global characteristics of the seismic data. Two implementation strategies are presented in detail, and the selection criteria of the relevant strategies is also discussed. Numerical examples of synthetic and real data verify that the new approach can achieve a better recovery effect by simultaneously overcoming the shortcomings of sparsity-promoting recovery and HRT recovery.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/465
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    ABSTRACT: Fracture analysis is a geological task that treats so-called fracture attributes (location, direction (strike), slope (dip), and aperture) of the fractures that cross the borehole. It can be performed by direct measures on drill cores or interpreted on acoustic or electromagnetic images of the borehole wall. This activity has gained more importance in Brazil with the recent exploration of carbonate reservoirs of the Brazilian pre-salt. The acoustic imaging logging tool creates two images, the amplitude and the travel time. Only the amplitude image, which reflects the acoustic impedance of the borehole wall, is used to perform the fracture analysis. However, some misinterpretations may occur due to the qualitative nature of this interpretation being very dependent on the geologist’s expertise. Thus, we present a method of performing automation of the fracture analysis using acoustic amplitude images. This article is divided into two parts. In the first part, we present a mathematical model for the acoustic amplitude images along the borehole trajectory crossed by fractures. This model involves all fracture attributes in the generation of the images and is used to validate the results of fracture analysis. The second part presents the method for automatic fracture analysis. This method is composed of two stages. The first one performs fracture identification using an algorithm based on the mathematical morphology, which acts as an edge-detection tool that delimits the fracture region in the acoustic amplitude images. In the second stage, we apply an interpolating polynomial over the image region previously identified as fracture to extract the fracture attributes. The evaluation of this methodology is performed with synthetic images generated by the presented model that supports the results of the automatic fracture analysis performed using real acoustic amplitude images.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/492
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    ABSTRACT: In numerical modeling of seismic wave propagation in the earth, we encounter two important issues: the free surface and the topography of the surface (i.e. irregularities). In this study, we develop a 2D finite difference solver for the elastic wave equation that combines a 4th- order ADER scheme (Arbitrary high-order accuracy using DERivatives), which is widely used in aeroacoustics, with the characteristic variable method at the free surface boundary. The idea is to treat the free surface boundary explicitly by using ghost values of the solution for points beyond the free surface to impose the physical boundary condition. The method is based on the velocity-stress formulation. The ultimate goal is to develop a numerical solver for the elastic wave equation that is stable, accurate and computationally efficient. The solver treats smooth arbitrary-shaped boundaries as simple plane boundaries. The computational cost added by treating the topography is negligible compared to flat free surface because only a small number of grid points near the boundary need to be computed. In the presence of topography, using 10 grid points per shortest shear-wavelength, the solver yields accurate results. Benchmark numerical tests using several complex models that are solved by our method and other independent accurate methods show an excellent agreement, confirming the validity of the method for modeling elastic waves with an irregular free surface.
    Journal of Geophysics and Engineering 06/2015; 12(3). DOI:10.1088/1742-2132/12/3/435