Academic literature on the topic 'Seismic reflection method. Formations Formations'
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Journal articles on the topic "Seismic reflection method. Formations Formations"
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Liu, Xiaobo, Jingyi Chen, Jing Zeng, Fuping Liu, Handong Huang, Zhencong Zhao, and Yaneng Luo. "An adaptive stratified joint PP and PS AVA inversion using accurate Jacobian matrix." GEOPHYSICS 86, no. 4 (June 18, 2021): R447—R461. http://dx.doi.org/10.1190/geo2019-0785.1.
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Amplitude variation with incidence angle (AVA) analysis is an essential tool for discriminating lithology in hydrocarbon reservoirs. Compared to traditional AVA inversion using only compressional wave (P-wave) information, joint AVA inversion using PP and PS seismic data provides better estimation of rock properties (e.g., density, P- and shear wave [S-wave] velocities). Currently, the most used AVA inversions depend on the approximations of the Zoeppritz equations (e.g., the Shuey and Aki-Richards approximations), which are not suitable for formations with strong contrast interfaces and seismic data with large incidence angles. Based on the previous derivation of the accurate Jacobian matrix, we have found that the sign of each partial derivative of reflection coefficient with respect to the P-, S-wave velocities and density changes across the interface represents a good indicator for the reflection interfaces. Accordingly, we adopt an adaptive stratified joint PP and PS AVA inversion using the accurate Jacobian matrix that can automatically obtain the layer information and can be further used as a constraint in the inversion of in-layer rock properties (density and P- and S-wave velocities). Due to the use of the exact Zoeppritz equations and accurate Jacobian matrix, this proposed inversion method is more accurate than traditional AVA inversion methods, has higher computational efficiency, and can be applied to seismic wide-angle reflection data or seismic data acquired for formations with strong contrast interfaces. The model study shows that this proposed inversion method works better than the classic Shuey and Aki-Richards approximations at estimating reflection interfaces and in-layer rock properties. It also works well in handling a part of the complex Marmousi 2 model and real seismic data.
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Zang, Kai, Jiuchuan Wei, Linsong Yu, Fang Wan, Zunfang Hu, and Yang Li. "Calibration Method of Petroleum Underground Horizon Based on High Precision Gravity and Magnetic Exploration." Earth Sciences Research Journal 24, no. 3 (October 12, 2020): 345–55. http://dx.doi.org/10.15446/esrj.v24n3.90315.
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Because the high-precision calibration results of the petroleum underground layer are of great significance for oil production efficiency, research on the calibration method of the petroleum underground layer based on high precision gravity and magnetic exploration is researched. The gravity magnetic model is used to retrieve the bedrock depth, and the results of the basement structure and sedimentary rock distribution of the gravity and magnetic geology in the petroleum underground horizon of the Tongbai basin are obtained. On this basis, the geological data, logging data, seismic data, and VSP data are comprehensively used, and the layered calibration method is used to calibrate the petroleum underground layer of the Tongbai basin. Considering the seismic datum and the core elevation in the area, the rock formation is divided by various logging curves. The average time difference and density of the divided rock layers are interpolated at equal depth intervals to obtain velocity sequences and density sequences at equal time intervals and finally realize time-depth conversion. When the drilling geological horizon is unified, the synthetic record of the seismic reflection layer is compared with the geological horizon to realize the horizon calibration of the seismic reflection layer. When the local stratification is not uniform, the seismic reflection layer is calibrated by tracking the seismic reflection layer, high-precision velocity analysis, and various synthetic records to verify the reliability of the geological horizon. The results show that the proposed method can accurately survey the geological conditions of the Tongbai basin. It detected 14 basement faults, and the NW-trending and NE-trending faults controlled the basin, while the north-south faults controlled the later evolution of the basin. The method can be used for the horizon calibration of inclined wells, which is suitable not only for anisotropic media but also for formations with a less lateral variation of local formation lithology. Moreover, its usage is flexible, and it can be corrected by multiple speed data.
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Tang, Le, and Xinding Fang. "Generation of 6-C synthetic seismograms in stratified vertically transversely isotropic media using a generalized reflection and transmission coefficient method." Geophysical Journal International 225, no. 3 (February 3, 2021): 1554–85. http://dx.doi.org/10.1093/gji/ggab044.
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SUMMARY We develop a generalized reflection and transmission coefficient method (GRTM) for generating six-component (6-C) synthetic seismograms in horizontally layered vertically transversely isotropic (VTI) media. Compared with the traditional seismic modelling approaches that only consider translational motion, our method can simultaneously produce three-component translational and three-component rotational data excited by a point vector force or a moment tensor source in a layered half-space. Horizontally layered models are widely used in near surface applications as the properties of near surface formations generally show small lateral variations and change mainly along the depth direction. The use of the VTI constitutive relation can make our method applicable to more general situations because it takes into account the characteristics of sedimentary formations. We compare our method with a finite-difference method (FDM) for a variety of velocity models and acquisition geometries. The numerical results demonstrate that accurate 6-C synthetic seismograms can be calculated using our method. The computational efficiency of our method for 6-C seismic modelling is much higher than the finite-difference method, because it can reduce a 3-D modelling problem to 2.5-D by eliminating the azimuthal dimension. Also, our method does not require to perform additional spatial interpolations to obtain the rotational components. These advantages make our method suitable to serve as a forward modelling tool for rotational seismology.
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Lin, C. N., Yu Yong Jiao, and Q. S. Liu. "Site Experiment for Predicting Hazardous Geological Formations ahead of Tunnel Face." Key Engineering Materials 326-328 (December 2006): 461–64. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.461.
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In the construction of railways in western part of China, more and more long tunnels have been excavated these years, and several ones are under construction at the moment. Because of the complex geologies like faults, fractured zones, karst cavities as well as water bearing formations, the stability and safety of tunnels have been challenging topics in the construction process. In this regard, the advance knowledge of the location, size, and spatial information of the uncertainties ahead of the face is very important to the contractors. In this paper, by using the Tunneling Seismic Prediction (TSP) technique, site experiments are performed to predict hazardous formations ahead of face in a railway tunnel. Through interpretation of the testing data, the wave velocities and the mechanical parameters of the surrounding rock are obtained, and the faults/fractures are recognized. The study shows that compared to time-consuming core drilling method, the wave reflection based TSP method can predict major uncertain formations in long range ahead of the face in short time. The downtime, as we know, is one of the key factors in speeding the tunnel construction. For the prediction accuracy, the TSP technique is able to provide enough information due to its multiple proof-test procedure.
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Chamarczuk, M., M. Malinowski, D. Draganov, A. Grant, M. Asgharzadeh, and M. Urosevic. "Characterization of drilling-related noise and curvelet-based evaluation of seismic-interferometric reflections for imaging of iron-bearing formations in Pilbara, Western Australia." Geophysical Journal International 226, no. 1 (March 17, 2021): 377–404. http://dx.doi.org/10.1093/gji/ggab059.
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SUMMARY Here we analyse ambient noise (AN) data generated during drilling of exploration boreholes and recorded using a dense array deployed over one of the numerous shallow iron-ore mineralization targets in the Pilbara region (Western Australia). Drilling and drilling-related operations were reoccurring in a sequence as described by the drillers’ field notes, which created the rare opportunity to analyse AN data in time segments when only one type of technical process was predominantly active. Consequently, most of the recorded AN sources did not overlap in time and space. We extract the recordings in 15-min-long segments matching the time-span of single field-note entry and identify individually acting AN sources associated with specific field operations. The temporal variations of noise spectrograms and AN cross-correlations show dependency on the sequence of a few consecutive field operations and specific frequency–amplitude patterns associated with single field operations. These changes are directly reflected by the events visible in the retrieved virtual-source gathers (VSG), implying significant changes in noise temporal and spatial stationarity. Some VSGs represent the mixed contributions of surface and air waves. To remove the contributions of these arrivals to the reflection imaging, we visually inspect all data and select only field operations acting as stationary-phase sources specifically for the reflection retrieval. This was done for different receiver configurations inside PilbArray, and as a result, we obtain a collection of VSGs containing coherent body-wave reflections. Database of visually inspected VSGs is used to develop and benchmark a semi-automatic curvelet-based method for accurate parametrization of the reflection events retrieved from passive data and to compare the imaging quality of the different field operations. Common-midpoint stacks from manually and automatically selected VSGs show reflectivity consistent with the one obtained from the active-source data and related to the structure hosting shallow iron mineralization. Our results demonstrate the capacity of AN seismic interferometry to retrieve body-wave reflections and image shallow mineralization. They also provide an intermediate step toward automating the passive reflection imaging with similar data sets.
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Miao, Xiao‐Gui, Wooil M. Moon, and B. Milkereit. "A multioffset, three‐component VSP study in the Sudbury Basin." GEOPHYSICS 60, no. 2 (March 1995): 341–53. http://dx.doi.org/10.1190/1.1443770.
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A multioffset, three‐component vertical seismic profiling (VSP) experiment was carried out in the Sudbury Basin, Ontario, as a part of the LITHOPROBE Sudbury Transect. The main objectives were determination of the shallow velocity structure in the middle of the Sudbury Basin, development of an effective VSP data processing flow, correlation of the VSP survey results with the surface seismic reflection data, and demonstration of the usefulness of the VSP method in a crystalline rock environment. The VSP data processing steps included rotation of the horizontal component data, traveltime inversion for velocity analysis, Radon transform for wavefield separation, and preliminary analysis of shear‐wave data. After wavefield separation, the flattened upgoing wavefields for both P‐waves and S‐waves display consistent reflection events from three depth levels. The VSP-CDP transformed section and corridor stacked section correlate well with the high‐resolution surface reflection data. In addition to obtaining realistic velocity models for both P‐ and S‐waves through least‐square inversion and synthetic seismic modeling for the Chelmsford area, the VSP experiment provided an independent estimation for the reflector dip using three component hodogram analysis, which indicates that the dip of the contact between the Chelmsford and Onwatin formations, at an approximate depth of 380 m in the Chelmsford borehole, is approximately 10.5° southeast. This study demonstrates that multioffset, three‐component VSP experiments can provide important constraints and auxiliary information for shallow crustal seismic studies in crystalline terrain. Thus, the VSP technique bridges the gap between the surface seismic‐reflection technique and well‐log surveys.
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Mathisen, M. E., and M. Budny. "Seismic lithostratigraphy of deep subsalt Permo‐Carboniferous gas reservoirs, Northwest German Basin." GEOPHYSICS 55, no. 10 (October 1990): 1357–65. http://dx.doi.org/10.1190/1.1442783.
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Recent improvements in land seismic data quality have made it possible to initiate lithostratigraphic interpretations of deep (4000–5500 m; 2.2–2.8 s) subsalt Permo‐Carboniferous gas reservoirs in the Northwest German Basin. The first modeling and interpretation results indicate that the reflection character of Permian reservoir dolomites and sandstones can be interpreted to predict lithology and porosity variations using reflection character analysis. These formations are commonly thick enough to be resolved (>20 m) and typically have velocities 1000 to 2000 m/s slower than overlying and underlying nonreservoir rocks. Deeper Upper Carboniferous reservoir sandstones occur within a discontinuous low‐amplitude seismic facies which can be clearly differentiated from a continuous high‐amplitude facies formed by the less prospective Upper Carboniferous coal measures. The accuracy of Permian reflection character interpretations is dependent on the availability of high‐frequency, zero‐phase, relative amplitude seismic data. New 3-D data are appropriate but of limited availability. To provide suitable 2-D data, wavelet processing of selected variable vintage lines was completed. More routine use of wavelet processing and lithostratigraphic interpretation methods should help to better define reservoir facies and stratigraphic traps, lower prospect risk, and increase success ratios.
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Zhang, Feng, Lin Wang, and Xiang-Yang Li. "Characterization of a shale-gas reservoir based on a seismic amplitude variation with offset inversion for transverse isotropy with vertical axis of symmetry media and quantitative seismic interpretation." Interpretation 8, no. 1 (February 1, 2020): SA11—SA23. http://dx.doi.org/10.1190/int-2019-0050.1.
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The Lower Silurian shale-gas formation in the south of the Sichuan Basin represents a strong transverse isotropy with vertical axis of symmetry (VTI) feature. Successful characterization of shale-gas formation requires handling the great influence of anisotropy in the seismic wave propagation. Seismic amplitude variation with offset (AVO) inversion for VTI media using PP-waves only is a difficult issue because more than three parameters need to be estimated and such an inverse problem is highly ill posed. We have applied an AVO inversion method for VTI media based on a modified approximation of the PP-wave reflection coefficient. This approximation consists of only three model parameters: the acoustic impedance (attribute [Formula: see text]), shear modulus proportional to the anellipticity parameter (attribute [Formula: see text]), and the approximated horizontal P-wave velocity (attribute [Formula: see text]), which can be well-inverted and have great interpretation capability in shale-gas reservoir characterization. A statistical-rock-physics method was then applied to the inverted attributes for quantitative interpretation of the shale-gas reservoir. A Markov random field is combined with Bayesian rule to improve the continuity and accuracy of the interpretation results. Shales can be successfully discriminated from surrounding formations by using the attribute pair [Formula: see text]-[Formula: see text], and the organic-rich gas-bearing shale can be successfully identified by using the attribute pair [Formula: see text]-[Formula: see text]. Comparison between the prediction results and well logs demonstrates the feasibility of the inversion and quantitative interpretation approaches.
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Sinha, Ajit K. "Stratigraphic mapping of sedimentary formations in southern Ontario by ground electromagnetic methods." GEOPHYSICS 55, no. 9 (September 1990): 1148–57. http://dx.doi.org/10.1190/1.1442931.
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Multifrequency and transient electromagnetic (EM) soundings were done at several locations in southern Ontario to evaluate the possibility of stratigraphic mapping of gently dipping sedimentary formations by ground EM techniques. The possibility of detecting structural features such as folds, faults, and grabens in the formations was also explored. The two EM techniques were used to map a buried river valley near the village of Copetown, about 75 km southwest of Toronto. The valley, buried under fairly resistive glacial till and dolomite formations was mapped at depths ranging from 100 to 200 m. The interpreted shape and depth of the valley agreed well with information from a high resolution seismic reflection survey and data from wells penetrating the bedrock. Transient EM (TEM) data, using square transmitter loops with side dimensions comparable to the transmitter‐receiver separation for the multifrequency system, was found to be less affected by the presence of shallow conductors and lateral inhomogeneities than the multifrequency data, and had greater depth of investigation. TEM soundings were made on five additional profiles in the area. Lithologic logs from old oil and gas wells located near the profiles provided information for comparison with EM sounding interpretations. The depths to various dolomite, shale, and limestone formations interpreted from EM data agreed well with drillhole information. The EM soundings also detected structures in the Paleozoic formations such as faults and folds that were not previously known. The soundings confirmed the existence of a graben at one site at a depth of 100 m, which was postulated from logs from a cluster of closely spaced drillholes by geologists. The survey results indicated that EM sounding methods can be used for stratigraphic mapping in areas where detailed geological information is unavailable either because the bedrock is concealed by overburden, or when drillholes are sparsely distributed.
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Willis, Mark E., Daniel R. Burns, Rama Rao, Burke Minsley, M. Nafi Toksöz, and Laura Vetri. "Spatial orientation and distribution of reservoir fractures from scattered seismic energy." GEOPHYSICS 71, no. 5 (September 2006): O43—O51. http://dx.doi.org/10.1190/1.2235977.
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We present the details of a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations we have made from 3D finite-difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fracture corridors impart a coda signature, which is a ringing tail of scattered energy, to any seismic waves which are transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: (1) the difference in angle between the orientation of the fractures and the acquisition direction, (2) the fracture spacing, (3) the wavelength of the illuminating seismic energy, and (4) the compliance, or stiffness, of the fractures. This coda energy is most coherent when the acquisition direction is parallel to the strike ofthe fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. Our method uses surface seismic reflection traces to derive a transfer function that quantifies the change in an apparent source wavelet before and after propagating through a fractured interval. The transfer function for an interval with no or low amounts of scattering will be more spikelike and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. When a 3D survey is acquired with a full range of azimuths, the variation in the derived transfer functions allows us to identify subsurface areas with high fracturing and to determine the strike of those fractures. We calibrated the method with model data and then applied it to the Emilio field with a fractured reservoir. The method yielded results which agree with known field measurements and previously published fracture orientations derived from PS anisotropy.
Dissertations / Theses on the topic "Seismic reflection method. Formations Formations"
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Janiszewski, Frank David. "Seismic reflection and gravity constraints on the bedrock configuration in the greater East Missoula area." CONNECT TO THIS TITLE ONLINE, 2007. http://etd.lib.umt.edu/theses/available/etd-05232007-120605/.
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Brennan, Jeanne L. "Interpretation of Vibroseis reflections from within the Catoctin Formation of central Virginia." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/76030.
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Large amplitude seismic reflections from within the Catoctin Formation of central Virginia are interpreted to originate from acoustically thin beds of interlayered metabasalts and metasediments. Large acoustic impedance contrasts exist between epidotised layers ( epidosites and volcanic breccia) and non-epidotised layers (greenstones and phyllites) within the Catoctin Formation. Acoustic impedance contrasts also exist between greenstones (metabasalts) and phyllites (metasediments). Constructive interference of small amplitude reflections from thin beds result in large amplitude, reverberating reflections.
Thin bed reflections that approximate the first derivative of the source wavelet constructively interfere to give even larger amplitude reflections than those originating by conventional tuning. Computer modeling based on two geologic sections of thin beds of epidosites interlayered with greenstones and of greenstones interlayered with phyllites and epidosites indicates that large amplitude reflections result from constructive interference of thin bed reflections.Master of Science
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Prada, Dacasa Manuel. "The structure and formation of the Tyrrhenian basin in the Western Mediterranean back-arc setting = Formación y estructura de la cuenca del Tirreno en el contexto de retrarco del Mediterráneo Occidental." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/245750.
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In this thesis I present a geophysical study that aims to define the structure and petrological nature of the main geological domains in the Central Tyrrhenian basin, and to investigate the mechanisms involved in their formation.
The geophysical data used in this thesis was acquired during the MEDOC (2010) survey within the framework of the MEDOC project, which was designed to improve our understanding of the origin and evolution of rifted margins. The present work is based on the analysis, processing, modeling, and interpretation of coincident Wide-Angle Seismic (WAS), Multichannel Seismic (MCS), and gravity data corresponding to the two longest transects acquired during the MEDOC survey in the Central Tyrrhenian basin, the southern Line GH/MEDOC-6 (~450 km) and the northern Line EF/MEDOC-4 (~400 km). Both lines run across the Central Tyrrhenian basin from Sardinia to the Campania margin.
The processing of MCS data provides the tectonic structure and geometry of the sedimentary basins, whereas the modeling of WAS data from travel-time tomography provides 2D seismic velocity models from which the velocity distribution of the crust and uppermost mantle, and the geometry of the crust-mantle boundary are inferred. The WAS models are then converted to density models using existing empirical relationships for different lithologies in order to test which of the different hypothesis concerning the petrological nature of the basement (e.g. continental/oceanic crust or exhumed mantle) explain better the observed gravity data. The results obtained together with the integration of geological data from rock sampling of the seabed reveals the existence of three geological domains in the Central Tyrrhenian, that is: continental crust, magmatic crust, and exhumed mantle.
The comparison between the results of Line EF/MEDOC-4 (northern line) with those of the Line GH/MEDOC-6 (southern line) reveals that the velocity and tectonic structure of the three geological domains differ in some regions from north to south. These differences are most likely attributed to the southward increase of extension that characterizes the Tyrrhenian basin.
The basement configuration presented in this thesis led to a completely new definition of geological domains in the Central Tyrrhenian. According to the presented distribution of the basement, rifting in the Central Tyrrhenian basin would have started with continental crust extension, continued with back-arc spreading leading to generation of magmatic back-arc crust, and followed by mantle exhumation intruded by later magmatic episodes. The interpretation of these results differ from current conceptual models of the formation of rifting systems involving mantle exhumation and indicate that the response of the continental lithosphere to extension processes may be more complex than previously assumed.
Finally, to explain the mechanism involved in the formation of these domains, I examine the modes of back-arc basin formation proposed to explain the formation of the western Pacific basins [Martinez et al., 2007; Dunn and Martinez, 2011], as well as the causes that may have led to mantle exhumation [Pérez-Gussinyé, et al., 2006]. In summary, the proposed conceptual model is based on a slab rollback and depleted mantle setting, in which production of extension-related melting is limited, thus, crustal accretion is attributed to hydrous flux melting. The model presents 5 stages of opening that includes: (I) a normal subduction scenario followed by (II) development of the back-arc rift, (III) initiation of back-arc spreading, (IV) mantle exhumation, and finally (V) emplacement of large volcanic edifices in the central parts of the basin.La tesis que presento se centra en el estudio de la estructura cortical y de los procesos de formación de la cuenca del Tirreno, con el principal propósito de ampliar el conocimiento sobre los mecanismos involucrados en la evolución de márgenes divergentes. Para ello, en esta tesis se realiza el procesado, análisis, modelización, e interpretación geológica de dos perfiles geofísicos adquiridos durante la campaña de sísmica marina MEDOC (2010) en el mar Tirreno. Ambos perfiles geofísicos incluyen datos de sísmica de gran ángulo (SGA), de reflexión multicanal (SRM) y de gravimetría, a partir de los cuales he obtenido los resultados siguientes: 1.Dos modelos de velocidad de propagación de ondas P (Vp) y de la geometría del Moho. 2.Análisis estadístico de incertidumbre de los parámetros de cada modelo de velocidad. 3.Modelado gravimétrico a partir de la conversión a densidad de los modelos de Vp. Con este método se pretende constreñir la petrología de los diferentes dominios geológicos a partir del empleo de diferentes relaciones empíricas de velocidad-densidad para diferentes tipos de roca. 4.Dos perfiles de SRM stackados y migrados en tiempo, de los cuales procesé uno de ellos (MEDOC 4). La interpretación conjunta de estos resultados junto con un análisis exhaustivo de las velocidades de los modelos, e información geológica de las rocas del lecho marino, han permitido caracterizar la naturaleza cortical (continental/oceánico) de los principales dominios geológicos en la cuenca del Tirreno central, los cuales incluyen: corteza continental, corteza de retroarco de carácter magmático y manto exhumado. Estos resultados junto con observaciones de la geomorfología de la batimetría, han dado paso a la discusión de la distribución en planta de dichos dominios geológicos en toda el área de estudio. Finalmente, propongo un modelo de apertura de cuenca en el cual se especula sobre la formación de los diferentes dominios geológicos identificados anteriormente. Dicho modelo se basa en los modos de apertura de cuencas de retroarco propuestos para las cuencas del Pacífico occidental, y en estudios de modelización numérica realizados para explicar la exhumación del manto en los márgenes pasivos del Atlantico Norte.
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Lee, Yi-Hen, and 李奕亨. "Investigating S-wave Velocity Structure of Sungshan Formation in Taipei Basin Using Reflection Seismic Method." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/77073945511492763704.
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碩士國立中央大學
應用地質研究所
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The purpose of this study is to find the S-wave velocity structure of Sungshan formation in Taipei Basin using shallow reflection seismic method. Taipei Basin is known as a structural basin with unconsolid sediment lying above Tertiary bed rock. Sungshan formation, the uppermost layer, is filled with mud-sand or sand-mud. We proposed a simple and efficient S-wave reflection seismic survey to explore this layer including its sublayer structure and S-wave velocity. Besides these,the method can also provide useful lithological information for engineering application such as shear modulus, stress condition, Poison''s ratio, etc. Basing on the S-wave velocity distribution, we attempt to divide Taipei Basin into four areas with three types of velocity structure. The first velocity layer has S-wave velocity: 165 to 185 m/s and the thickness about 15 m, the second has the velocity: 220 to 260 m/s and the thickness about 20 m, and the third layer has the velocity: 300 to 350 m/s down to the bottom of Sungshan formation. This S-wave velocity structure is found to have close relations with the sedimentation history of Sungshan formation.The influence of three river system: Da-Han, Hsin-Tien, and Kee-Long river on the sediment deposit is very obvious. Finally, the structure of S-wave velocity also reveals close tie with the site effect and natural frequency vibration of Taipei Basin under the impact of earthquake. It could be of great significance in strong motion study of Taipei Basin.
Books on the topic "Seismic reflection method. Formations Formations"
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Gogonenkov, G. N. Seismic prospecting for sedimentary formations. Rotterdam: A.A. Balkema, 1990.
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Seismic prospecting for sedimentary formations. New Delhi: Oxford & IBH Pub. Co., 1990.
Find full textBook chapters on the topic "Seismic reflection method. Formations Formations"
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Childs, C., J. J. Walsh, and J. Watterson. "A Method for Estimation of the Density of Fault Displacements below the Limits of Seismic Resolution in Reservoir Formations." In North Sea Oil and Gas Reservoirs—II, 309–18. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0791-1_26.
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Herz, Norman, and Ervan G. Garrison. "Archaeogeophysical Exploration." In Geological Methods for Archaeology. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195090246.003.0013.
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Geophysical techniques are a commonplace tool in today's archaeology as a result of an extensive collaboration between scientists and archaeologists on both sides of the Atlantic. This "cross-fertilization" has produced growing subdisciplines, of which archaeological geophysics is one example. As may be recalled from our introductory chapter, K. Butzer defined geoarchaeology as archaeology done using a geological methodology. G. Rapp and J. A. Gifford describe archaeological geology as the use of geological techniques to solve archaeological problems. Fagan has called geoarchaeology a "far wider enterprise than geology," involving (1) geochemical and geophysical techniques to locate sites and features; (2) studies of site formation and spatial context; (3) geomorphology, palynology, paleobotany; (4) absolute and relative dating procedures; and (5) taphonomic studies. Archaeological geophysics is a major aspect of archaeological geology. The application of geophysical exploration techniques in archaeology is also known as archaeogeophysics. Geophysical methods of potential usefulness to archaeological geology fall within the following classes: 1. seismic: reflection/refraction 2. electrical & electromagnetic: resistivity and conductivity 3. magnetic 4. radar 5. microgravity 6. thermography All have been used on a variety of archaeological problems. The application of geophysical techniques has grown as (1) the access to the instruments and (2) the methodological understanding of the users have increased. Access to geophysical instrumentation has been made easier by the steady development in solid-state design and computerization, which has reduced size and costs as it has in almost every technical field. The beneficiaries are the geologists and archaeologists. The first to recognize the applicability of geophysical methods to archaeology were the geologists—more specifically, the geophysicists. Working in association with their archaeological colleagues, the earth scientists translated the objectives of the archaeologists into practice. Such cooperation was very productive but suffered from the same kinds of problems that dogged the early usage and acceptance of radiocarbon dating. The archaeologists' untutored enthusiasm, coupled with their lack of a true understanding of the physics and atmospheric chemistry inherent in that technique, led to a backlash of skepticism when dates reported by the first radiocarbon researchers were found to be in error.
Conference papers on the topic "Seismic reflection method. Formations Formations"
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Osukuku, Godfred, Abiud Masinde, Bernard Adero, Edmond Wanjala, and John Ego. "Integrated Geophysical Interpretation of Kerio Valley Basin Stratigraphy, Kenya Rift." In SPE/AAPG Africa Energy and Technology Conference. SPE, 2016. http://dx.doi.org/10.2118/afrc-2670415-ms.
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Abstract This research work attempts to map out the stratigraphic sequence of the Kerio Valley Basin using magnetic, gravity and seismic data sets. Regional gravity data consisting of isotactic, free-air and Bouguer anomaly grids were obtained from the International Gravity Bureau (BGI). Magnetic data sets were sourced from the Earth Magnetic Anomaly grid (EMAG2). The seismic reflection data was acquired in 1989 using a vibrating source shot into inline geophones. Gravity Isostacy data shows low gravity anomalies that depict a deeper basement. Magnetic tilt and seismic profiles show sediment thickness of 2.5-3.5 Km above the basement. The Kerio Valley Basin towards the western side is underlain by a deeper basement which are overlain by succession of sandstones/shales and volcanoes. At the very top are the mid Miocene phonolites (Uasin Gishu) underlain by mid Miocene sandstones/shales (Tambach Formation). There are high gravity anomalies in the western and southern parts of the basin with the sedimentation being constrained by two normal faults. The Kerio Valley Basin is bounded to the west by the North-South easterly dipping fault system. Gravity data was significantly of help in delineating the basement, scanning the lithosphere and the upper mantle according to the relative densities. The basement rocks as well as the upper cover of volcanoes have distinctively higher densities than the infilled sedimentary sections within the basin. From the seismic profiles, the frequency of the shaley rocks and compact sandstones increases with depths. The western side of the basin is characterized by the absence of reflections and relatively higher frequency content. The termination of reflectors and the westward dip of reflectors represent a fault (Elgeyo fault). The reflectors dip towards the west, marking the basin as an asymmetrical syncline, indicating that the extension was towards the east. The basin floor is characterized by a nearly vertical fault which runs parallel to the Elgeyo fault. The seismic reflectors show marked discontinuities which may be due to lava flows. The deepest reflector shows deep sedimentation in the basin and is in reasonable agreement with basement depths delineated from potential methods (gravity and magnetic). Basement rocks are deeper at the top of the uplift footwall of the Elgeyo Escarpment. The sediments are likely of a thickness of about 800 M which is an interbed of sandstones and shales above the basement.
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Datir, Harish, Knut Arne Birkedal, Sachin Kriplani, Hege Porten, and Niles Andre Aarseth. "ENHANCING THE RESERVOIR PERFORMANCE BY ACCESSING THE RESERVOIR SWEET SPOTS GUIDED BY FAR-FIELD SONIC IMAGING: AN INTEGRATED CASE STUDY FROM THE NORWEGIAN NORTH SEA." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0057.
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The gas present in the Valhall overburden crest area interferes with the seismic data and obscures the fault detection (minor faults). Spatially resolving fractures and fracture network is essential for subsurface understanding and future well placement in this field, and it is a critical input to the dynamic reservoir model. Additionally, mapping the fracture network in poor permeable reservoir formation beyond the wellbore is crucial to identify completion intervals to maximize productivity/injectivity, and hence field value. The well 2/8-F-18 A was drilled on the crest of the Valhall field as a pilot water injector in Lower Hod formation, where core and data analysis formed the foundation for a future potential 11 well development. The well is placed in the southern section of the Valhall crest, and no major faults or strong amplitude features were mapped out in the overburden via surface seismic before drilling. In this case study, an integrated workflow is proposed and tested within the reservoir formation to identify “sweet” (permeable and fractured) zones beyond the wellbore. This is achieved using borehole acoustic data combined with image and ultrasonic imaging to characterize fracture networks beyond the borehole wall. The sonic imaging workflow identifies reflection events from fractures and faults and provides the true dip, azimuth, and location in 3-dimensions. This data is complemented by nuclear magnetic resonance (NMR), dielectric and spectroscopy data to understand reservoir petrophysics. NMR-derived permeability has also been evaluated for identifying high permeable zone in this formation, which primarily focuses on intergranular permeability of the formation a few inches away from the borehole wall. Reservoir textural heterogeneity and fractures beyond the wellbore wall make this method difficult to estimate or enhance the effective permeability estimate. The baseline assumption for the NMR permeability estimation is also not valid in Hod formation; the Timur and SDR equation needs significant change to match core permeability. Hence, the primary aim is to identify a fracture network that will help support water injection and maximize hydrocarbons production through them. The goal is to establish a workflow from the learnings of this study, performed on the pilot well, validate its findings with the near-field data (core, imaging, and ultrasonic), and optimize it if needed (described in the methodology section). The developed workflow is then intended to be used to optimize the placement of future wells. The results achieved from the integrated workflow identified a key fault and mapped it approximately 23 meters away on each side of the borehole. It also captures acoustic anomalies (high amplitudes), validated based on near-field data, resulting from a fracture network potentially filled with hydrocarbons. The final results show the sub-seismic resolution of the fracture and fault network not visible on surface seismic due to the gas cloud above the reservoir and frequency effect on the surface seismic when compared to borehole sonic data. Evidently enhancing the blurred surface image, which helps enhance the structural and dynamic model of the reservoir.
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Gordin, Yair, Thomas Bradley, Yoav O. Rosenberg, Anat Canning, Yossef H. Hatzor, and Harold J. Vinegar. "Relating Acoustic Anisotropy to Kerogen Content in Unconventional Formations - A Case Study in A Kerogen-Rich Unconventional Carbonate." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205912-ms.
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Abstract The mechanical and petrophysical behavior of organic-rich carbonates (ORC) is affected significantly by burial diagenesis and the thermal maturation of their organic matter. Therefore, establishing Rock Physics (RP) relations and appropriate models can be valuable in delineating the spatial distribution of key rock properties such as the total organic carbon (TOC), porosity, water saturation, and thermal maturity in the petroleum system. These key rock properties are of most importance to evaluate during hydrocarbon exploration and production operations when establishing a detailed subsurface model is critical. High-resolution reservoir models are typically based on the inversion of seismic data to calculate the seismic layer properties such as P- and S-wave impedances (or velocities), density, Poisson's ratio, Vp/Vs ratio, etc. If velocity anisotropy data are also available, then another layer of data can be used as input for the subsurface model leading to a better understanding of the geological section. The challenge is to establish reliable geostatistical relations between these seismic layer measurements and petrophysical/geomechanical properties using well logs and laboratory measurements. In this study, we developed RP models to predict the organic richness (TOC of 1-15 wt%), porosity (7-35 %), water saturation, and thermal maturity (Tmax of 420-435⁰C) of the organic-rich carbonate sections using well logs and laboratory core measurements derived from the Ness 5 well drilled in the Golan Basin (950-1350 m). The RP models are based primarily on the modified lower Hashin-Shtrikman bounds (MLHS) and Gassmann's fluid substitution equations. These organic-rich carbonate sections are unique in their relatively low burial diagenetic stage characterized by a wide range of porosity which decreases with depth, and thermal maturation which increases with depth (from immature up to the oil window). As confirmation of the method, the levels of organic content and maturity were confirmed using Rock-Eval pyrolysis data. Following the RP analysis, horizontal (HTI) and vertical (VTI) S-wave velocity anisotropy were analyzed using cross-dipole shear well logs (based on Stoneley waves response). It was found that anisotropy, in addition to the RP analysis, can assist in delineating the organic-rich sections, microfractures, and changes in gas saturation due to thermal maturation. Specifically, increasing thermal maturation enhances VTI and azimuthal HTI S-wave velocity anisotropies, in the ductile and brittle sections, respectively. The observed relationships are quite robust based on the high-quality laboratory and log data. However, our conclusions may be limited to the early stages of maturation and burial diagenesis, as at higher maturation and diagenesis the changes in physical properties can vary significantly.
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Menon, Pradeep, Tarek Swedan, Kamran Jan, M. S. Al-Shehhi, Piyanuch Kieduppatum, Yasmina Bouzida, Adrian Eduardo Cazeneuve, Gulzira Zhunussova, Sila Uluyuz, and Viraj Telang. "Khuff and Pre-Khuff Reservoir Fracture Characterization using the Cross Dipole Shear Wave Imaging and Borehole Imaging Data Integration." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206231-ms.
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Abstract Increasing demands for gas in UAE have led to increased focus on more tight gas reservoirs like Khuff and pre-Khuff formations, away from the conventional oil-bearing carbonate reservoirs. The case study presented is in an offshore field, Northwest of Abu Dhabi city. The structure, with an area of 50 Sq.km was first identified in 1966 and it is part of the regional N-S extending structural. The multi-discipline approach applied in this study required the integration of a suite of open-hole data over a variety of length scales. Combination of the Borehole Acoustic Reflection Imaging technique and borehole imaging logs (BHI) in 3D, provides a better understanding of the complex fracturing network and the associated formation stress orientation up to 100ft away from the wellbore. The ability to "see" away from wellbore what was previously hidden on seismic, allows unlocking further potential reserves or avoiding certain production hazards. The well has penetrated the highly economical tight clastic Pre-khuff formation and the carbonate Kuff formation, allowing the analysis over a large geological history of offshore Abu Dhabi. The coherency of all data has helped establish for the first time a baseline understanding of the role of the fractures and fault in the petrophysical properties distribution along the wellbore and the 3D structural characterization in an larger area around the wellbore (up to 100ft). The emphasize in this paper is on the Borehole Acoustic Reflection Imaging technique (DSWI), which allows the identification of both intersecting and non-intersecting of geological features with a depth of investigation up to 100 ft away from the borehole. Moreover, the combination of DSWI with BHI have been used for the anisotropy estimation away from wellbore especially in a very tight and fractured reservoir deciphering multiple fault orientation, which potentially, cancel the anisotropy estimation due to destructive interference. In addition to the presence of drilling induced fractures interfering in with the natural fracture as seen on the BHI. The detailed BHI interpretation and the petrophysical data revealed that the fracture densities and orientation vary from bottom to top interval indicating tectonic regimes affecting the field. The lithological variation due to the evolution of the depositional setting has significantly influenced the fracture distribution and their length. The presence of these induced fractures and how deep they propagate into the formation, dominates the behavior acoustic anisotropy by reaching the flexural (dipole shear) investigation zone (3 to 4ft deep). It is also interesting to see the behavior of both natural and induced fractures and their respective strike change over the different formations revealing a geomechanically complex structure.
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Rodríguez-Pradilla, Germán, David Eaton, and Melanie Popp. "2000-2020: Two Decades of Evolution of Hydraulic Fracturing-Induced Seismicity in the Western Canada Sedimentary Basin." In SPE Hydraulic Fracturing Technology Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/204157-ms.
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Abstract The goal of this work is to calibrate a regional predictive model for maximum magnitude of seismic activity associated with hydraulic-fracturing in low-permeability formations in the Western Canada Sedimentary Basin (WCSB). Hydraulic fracturing data (i.e. total injected volume, injection rate, and pressure) were compiled from more than 40,000 hydraulic-fractured wells in the WCSB. These wells were drilled into more than 100 different formations over a 20-year period (January 1st, 2000 and January 1st, 2020). The total injected volume per unit area was calculated utilizing an area of 0.2° in longitude by 0.1° in latitude (or approximately 13x11km, somewhat larger than a standard township of 6x6 miles). This volume was then used to correlate with reported seismicity in the same unit areas. Collectively, within the 143 km2 area considered in this study, a correlation between the total injected volume and the maximum magnitude of seismic events was observed. Results are similar to the maximum-magnitude forecasting model proposed by A. McGarr (JGR, 2014) for seismic events induced by wastewater injection wells in central US. The McGarr method is also based on the total injected fluid per well (or per multiple nearby wells located in the same unit area). However, in some areas in the WCSB, lower injected fluid volumes than the McGarr model predicts were needed to induce seismic events of magnitude 3.0 or higher, although with a similar linear relation. The result of this work is the calculation of a calibration parameter for the McGarr model to better predict the magnitudes of seismic events associated with the injected volumes of hydraulic fracturing. This model can be used to predict induced seismicity in future unconventional hydraulic fracturing treatments and prevent large-magnitude seismic events from occurring. The rich dataset available from the WCSB allowed us to carry out a robust analysis of the influence of critical parameters (such as the total injected fluid) in the maximum magnitude of seismic events associated with the hydraulic-fracturing stimulation of unconventional wells. This analysis could be replicated for any other sedimentary basin with unconventional wells by compiling similar stimulation and earthquake data as in this study.
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Wei, Cao, Shiqing Cheng, Yang Wang, Ruyuan Shang, Lang Zhu, and Haiyang Yu. "Pressure Transient Analysis of Wells in the Fault-Karst Carbonate Reservoirs with Vertical Beads-on-String Structure: Case Studies in Shunbei Oilfield, Tarim Basin of Northwestern China." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205966-ms.
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Abstract The newly discovered the fault-karst carbonate reservoirs in Tarim Basin are formed by large-scale tectonic fault activities and multiple-stage karstification. The ground outcrop, seismic reflection and well logging show that the large caves, vugs, tectonic fractures and matrix coexist in the reservoirs. The fractures interconnecting with caves in series to form vertical beads-on-string structure is the most common pattern. It is found that conventional models are difficult to match the recorded pressure data. To fill this gap, this work summarizes three kinds of patterns for this structure and presents three novel models to estimate formation properties. The physical models of multi-fracture-region multi-cave-region series connection are established by simplifying vertical beads-on-string structure. The corresponding mathematical models are developed, in which the flow in fracture regions obey Darcy's law, while the flow in cave regions obeys free flow. Importantly, the gravity is considered due to the flow along vertical direction. Then typical flow regimes are analyzed and sensitivity analysis is conducted. Our work shows that pressure-derivative curves show similar ‘concave’ characteristic for the cave storage regime and vug/matrix interporosity flow regime. The difference is that the pressure derivative for cave storage regime is unit slope, while this slope is not equal to unity for vug/matrix interporosity flow regime. Therefore, large cave and vug/matrix medium can be distinguished by slope of pressure derivative. More than that, the typical characteristic of vertical beads-on-string structure on type curve is that the cave storage regimes and linear flow regimes alternately appear. This characteristic helps the engineers identify vertical beads-on-string structure. A novel finding is that gravity effect could lead to unit-slope pressure and pressure derivative at late times, which is traditional recognized as the presence of a closed boundary when it may not be the case. Lastly, this methodology is applied to two cases from Shunbei Oilfield in which it is difficult to obtain good fitting quality and interpretation results using traditional methods. Besides conventional properties, the proposed methodology allows us to estimate other properties (e.g., cave height, cave radius), which are not readily obtained from conventional methods.
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Consuegra, Jose Francisco. "Pore Pressure Prediction in Sandstone Using a Lateral Transfer Approach." In SPE/IADC Middle East Drilling Technology Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/202096-ms.
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Abstract Accurate pore pressure prediction is required to determine reliable static mud weights and circulating pressures, necessary to mitigate the risk of influx, blowouts and borehole instability. To accurately estimate the pore pressure, the over-pressure mechanism has to be identified with respect to the geological environment. One of the most widely used methods for pore pressure prediction is based on Normal Compaction Trend Analysis, where the difference between a ‘normal trend' and log value of a porosity indicator log such as sonic or resistivity is used to estimate the pore pressure. This method is biased towards shales, which typically exhibit a strong relationship between porosity and depth. Overpressure in non-shale formations has to be estimated using a different method to avoid errors while predicting the pore pressure. In this study, a different method for pore pressure prediction has been performed by using the lateral transfer approach. Many offset wells were used to predict the pore pressure. Lateral transfer in the sand body was identified as the mechanism for overpressure. This form of overpressure cannot be identified by well logs, which makes the pore pressure prediction more complex. Building a 2D geomechanical model, using seismic data as an input and following an analysis methodology that considered three type of formation fluids - gas, oil and water in the sand body, all pore pressure gradients related to lateral transfer for the respective fluids were evaluated. This methodology was applied to a conventional reservoir in a field in Colombia and was helpful to select the appropriate mud weight and circulating pressure to mitigate drilling risks associated to this mechanism of overpressure. Seismic data was critical to identifying this type of overpressure mechanism and was one of the main inputs for building the geomechanical earth model. This methodology enables drilling engineers and geoscientists to confidently predict, assess and mitigate the risks posed by overpressure in non-shale formations where lateral transfer is the driving mechanism of overpressure. This will ensure a robust well plan and minimize drilling/well control hazards associated with this mode of overpressure.
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Popkov, Vyacheslav, Alexander Sterenberg, Vladimir Gusev, and Andrey Tyutyaev. "COGNITIVE GEOLOGY OF SUPERIMPOSED SCATTERING OF MOBILE ORE ELEMENTS, PROPER FORMS OF MULTISCALE STRUCTURAL STRESS STABILITY, BIOGENETIC ACCESS CODE OF RESOURCES AND FIELD ARTEFACTS." In GEOLINKS International Conference. SAIMA Consult Ltd, 2020. http://dx.doi.org/10.32008/geolinks2020/b1/v2/11.
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The authors present the theory is numerical / analytical method of multi-scaled 4D geomechanics – geo-dynamics of energy integration in geo-physical rhythms of Eigen-solution of Navier-Stokes equations for multi-level geological time space of evolution in structural compacted mass transfer at the basis of Newton’s Differential Law ∫V∫TρdS·∂2ξ/∂t2 following the integration formula of A. Einstein E(u,t)=ρVC2+∫V∫Tρ‹uv›dtdx. Сreate the theory (Restoration) and Maintenance of Water Eco-System with Given Parameters. They establish the geophysical seismic rhythms of geological cycles in deep structural formations of the Volga-Urals and Siberia and Kamchatka at dissipative emission, adsorption and nuclear magnetic resonance. The authors propose the systematic velocity model of convective diffusion drift of ρ<uv> in deep phase components of heterogenic structures with complexly structured geology in off-shore and global aeration of Middle Ridges from the Urals to the Rocky Mountains. They have also considered the energy time space of more than 4,5 billion years to find the organic markers of quantum photo-synthesis and multiple circulating energy waves in physical and chemical reactions of compacted formation genesis in fissile and relict shales, including the facies with symmetrical absolutely-saturated porosity of classical fields. They establish the geophysical seismic rhythms of geological cycles in deep structural formations of the Volga-Urals and Siberia and Kamchatka at dissipative emission, adsorption and nuclear magnetic resonance. The authors propose the systematic velocity model of convective diffusion drift of ρ‹uv› in deep phase components of heterogenic structures with complexly structured geology in off-shore and global aeration of Middle Ridges from the Urals to the Rocky Mountains. They have also considered the energy time space of more than 4.5 billion years to find the organic markers of quantum photo-synthesis and multiple circulating energy waves in physical and chemical reactions of compacted formation genesis in fissile and relict shales, including the facies with symmetrical absolutely-saturated porosity of classical fields’ cognitive geology, artefacts.
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Olszowska, Daria, Gabriel Gallardo-Giozza, and Carlos Torres-Verdín. "ULTRASONIC ANGLE-DEPENDENT REFLECTIVITY IN COMPLEX ROCKS FOR IMPROVED INTERPRETATION OF SONIC AND ULTRASONIC LOGS." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0058.
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Porous rocks are rarely homogeneous. Significant spatial variations in elastic properties are often observed in rocks due to depositional, diagenetic, and structural processes. In laminated sandstones, complex carbonates, or unconventional formations, elastic properties can vary on scales from millimeters to tens of meters. Detection of inhomogeneities and their size in rocks is crucial for fracture propagation design, height containment assessment, and for improving well/reservoir productivity. Most laboratory techniques used to measure rock elastic properties fail to distinguish mid-scale anisotropy; results are subject to spatial averaging effects. We introduce a new experimental method to measure continuous compressional- and shear-wave logs of core samples based on measurements of angle-dependent ultrasonic reflection coefficients. Simultaneously with reflected waves, we detect and interpret refracted waves as an independent way to estimate acoustic wave velocities to support the analysis. Our laboratory system is equipped with an array of receivers to continuously collect measurements. At each core location, we acquire acoustic waveforms at multiple transmitter-receiver angles using a pitch-catch acquisition mode (similar to standard sonic tools). This acquisition mode uses multiple receivers, allowing us to obtain measurements at different incidence angles without moving the sample and keeping the distance traveled by reflected waves constant, thereby eliminating the need for geometrical spreading corrections in reflection-coefficient calculations. Reflectivity-vs.-angle measurements are then matched with numerical simulations to estimate rock elastic properties. Ultrasonic reflection-coefficient measurements are successfully used to estimate dynamic elastic rock properties of homogeneous and layered rock samples. For homogenous samples, values are within a 5% range when compared to those obtained with the standard acoustic transmission method. Measurements acquired on natural and artificially constructed samples show significant departures from homogeneous behavior caused by layering. Laboratory reflection-coefficient measurements enable detection of inch-scale anisotropy within the rock, leading to improved assessment of formation elastic properties. Furthermore, continuous core measurements provide high-resolution reflection-coefficient information which is complementary to open-hole ultrasonic logs.
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Antoszkiewicz, Michał, Mateusz Kmieć, Paweł Szewczuk, Marek Szkodo, and Robert Jankowski. "Microseismic Monitoring of Hydraulic Fracturing – Data Interpretation Methodology with an Example from Pomerania." In Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.001.
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Microseismic monitoring is a method for localizing fractures induced by hydraulic fracturing in search for shale gas. The aim of this paper is to conduct the data interpretation of the microseismic monitoring based on the results from Pom-erania region of Poland. The data has been collected from an array of geophones deployed on the surface. Ground vibrations have been recorded and analyzed for fracture location, magnitude and breakage mechanism. A velocity model of underlying formations has been used for successful microseismic monitoring. The model has been further tuned with signal from perfora-tion shots of known location. Imaging of events has been done using software MicSeis, which utilizes diffraction stacking of waveforms from multiple stations to image microseismic events with low signal-to-noise ratio. The imaging of microseismic events in MicSeis uses a grid search over all possible origin times and locations in the selected rock volume. The seismic moment tensors are automatically determined from the amplitudes from the grid search procedure and are used to model po-larities of events which then enhance constructive interference. Function characterizing a maximum stack per time sample have been calculated over whole volume and analyzed using the STA/LTA algorithm. Once the event has been detected in time, location has been determined through analysis of the 3D spatial image function. The procedure has been used to detect five events during hydraulic fracturing in Pomerania.