data because they generally lack the familiarperiodicity associated with marine data multiples. About. Sheriff, R. E; Geldart, L. P (August 1995). The raw data displayed in Figure 4.a shows strong second and higher order water bottom multiples from the previous shot. GEOPHYSICS, VOL. In recent years, several methods have been developed to attenuate seafloor multiples in seismic data, and a broad literature on this subject is available. A colour overlay technique is proposed which labels events (both primaries and multiples) on the section by velocity. The marine algorithm assumes that the sources and receivers are located in the water column. The identification of the short-period multiples, such as the peg-leg multiples, is especially important in successfully interpreting the surface seismic data from the southern Gulf The peg-leg, or inter-bed multiples are those which have been reflected successfully from the top and base of thin reflectors on the way to or from the main reflecting horizon. The data was acquired with streamer length of 8 km and record length 9.4 second. Now, a more rigorous and structured approach that involves separation of the multiple energy from the primary energy is … Initially, the data may be used to enhance a structural interpretation based on two-dimensional (2D) data, yielding new drilling locations. Geology (1975) from Cairo University (Egypt) and a MSc in Geophysics “Attenuation of Seismic Waves” (1983) from the University of Pittsburgh (USA). The inherent relationship between primaries and the multiples- via reflection at the surface of the earth-can be exploited to predict multiples from the measured primaries and subsequently subtract them from the measured data… Multiple attenuation methods include F-K filter, Radon transform, and Surface However, because they interact more with the subsurface medium, they may carry extra information that is not present in the primaries. If you continue without changing your browser settings, you consent to our use of cookies in accordance with our cookie policy. Short-period multiples attenuation is a difficult problem for shallow water marine seismic data processing. The resultant traces, having had the multiples removed, can be processed conventionally … Reducing multiple contamination in data is one of the greatest challenges in seismic processing, and no single approach is suitable for all scenarios. An overview of the methodology and examples of its application will be given 4 共JULY-AUGUST 2009兲; P. V59–V67, 5 FIGS. multiples are mis-migrated, but the degree of mis-migration varies smoothly with offset. In addition to direct water bottom multiples and water layer peg legs, direct multiples from deeper horizons are also addressed. Improving adaptive subtraction in seismic multiple attenuation Shoudong Huo1 and Yanghua Wang2 ABSTRACT In seismic multiple attenuation, once the multiple models have been built, the effectiveness of the processing depends as a Data Processing Seismic Engineer in Kuwait, followed by a Testing Geophysicist role in Houston, before his current position. https://wiki.seg.org/index.php?title=Dictionary:Multiple&oldid=44533, Problems in Exploration Seismology & their Solutions, the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). Research Paper | Geophysics | Nigeria | Volume 6 Issue 10, October 2017. Our strength lies in our experienced team with over 20 years of experience directly in seismic data … This has ledto the misconception that multiplereflectionsare only a problem withmarinedata. In shallow water, the critical point of seismic analysis is the attenuation of seabed multiples. The kinematics of the primary … Abstract: Methods, systems, and computer-readable media for identifying multiples contamination in a stack are provided. To demonstrate this, percentage differences in wavelet amplitudes between stack sections produced with and without processes like f-k demultiple are shown. In one embodiment, the method comprises the steps of regularizing the gather of seismic data traces, … The predicted multiple model may be inaccurate in the footprint zones, thereby affecting the success of adaptive subtraction of the multiple model from the input data. The data for a multiple reflection generated between a and b will delineate the imaginary bed (a-b)' having a reflection time equal to that of the deeper actual reflecting bed, plus the difference in the reflection times of the two actual reflecting beds:EquationCompared with the rays reflected from bed b, the seismic rays corresponding to the multiple reflection travel over an additional … The method includes selecting a subset from a set of regularly sampled seismic data based on a low-discrepancy point set. We present a technique for identifying and attenuating multiple reflections in seismic data using non-linear filters i.e. No processing sequence is definitive and techniques vary with time (and software), however the … A seismic section with a colour-coded overlay is used to demonstrate how an interpreter may incorporate this extra information to decide on two opposing geologic models for a line. Multiple reflections in seismic data are generally considered to be unwanted noise that often seriously hinder correct mapping of the subsurface geology in search of oil and gas reservoirs. Imaging using sea-surface reflections improves the illumination and resolution of shallow subsurface targets when … 359-365. Extended internal multiple prediction (XIMP) is a data-driven multiple-modeling algorithm that predicts internal multiples from recorded events using wavefield extrapolation. Residual multiples have an even greater impact on the quality of seismic data and generate great risks in oil and gas exploration and development. Marine Processing - Part 9 | Demultiples This sequence of blog posts will build up into a complete description of a 2D marine processing sequence and how it is derived. Recent advances in methods for multiple reflection elimination have … This segmentation of the data also allows us to select a range of periods of internal multiples that one wishes to construct because, in the context of the attenuation of internal multiples, it is important to avoid generating short‐period internal multiples that may constructively average to form primaries at the seismic scale. The model building for the multiples was carried out up to a Multiples and primaries can often be separated with less ambiguity on CMP gathers (during velocity analysis) than they can be after stack. Multiples are main noise in marine data, usually includes strong regular multiples related to surface and diffracted multiples which are generated by serious variation of water bottom. Seismic Multiples: Ghosts of the seabed Ghost 1 Ghost 2. Surface related multiple elimination uses the recorded data to predict multiples produced by the downward reflection at the sea-surface, without the need for any information on the subsurface. 2 GEPEA-MAPS2 - Matrices Aliments Procédés Propriétés Structure - Sensoriel . While virtually all seismic energy involves some multiples, the important distinction is between long-path and short-path multiples: a long-path multiple arrives as a distinct event whereas a short-path multiple arrives so soon after the primary that it merely adds tail to the primary (i.e., changes the waveshape). The seismic data can be processed to predict (and then remove) surface multiples (source and/or receiver) by configuring the one or more processors to perform interferometry as described above to generate the additional seismic data needed to predict the multiples using techniques such as SRME. Determination of Multiples in Surface Seismic Data Using Zero Offset Vertical Seismic Profiling (ZVSP) Techniques Examples. Multiples in Marine Data Butler et al. 2015 ExxonMobil The Ideal Seismic Response Increase in Impedance Decrease in Impedance Able to resolve boundaries of beds a few meters thick 1 meter 43 ExxonMobil Seismic - Units 10’s of Meters Thick 10 m Predominantly Shale Predominantly Shale Predominantly Sand 44. For land data, this includes azimuthally friendly noise attenuation processes, as well as removal of interbed multiples. These unwanted features may actually be somebody else’s signal, such as converted waves in what we think of as “P-wave” data – but more commonly, these unwanted “noise” features provide little or no information about the subsurface, and are referred to as random noise and … Stack sections produced with and without processes like predictive deconvolution have been applied pre-stack to suppress periodicities two. 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