A comparison of three multiple‐attenuation methods applied to a hard water‐bottom data set

1999 ◽  
Vol 18 (1) ◽  
pp. 120-126 ◽  
Author(s):  
Ken H. Matson ◽  
Dick Paschal ◽  
Arthur B. Weglein
Keyword(s):  
Hard Water ◽  
Data Set ◽  
Multiple Attenuation ◽  
Water Bottom

Attenuation of waterborne coherent noise by application of hyperbolic velocity filtering during the tau‐p transform

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 20-33 ◽  
Author(s):  
Ikka Noponen ◽  
Joe Keeney
Keyword(s):  
Hard Water ◽  
Apparent Velocity ◽  
Data Input ◽  
Coherent Noise ◽  
Data Set ◽  
Marine Areas ◽  
Velocity Filtering ◽  
Water Bottom

By limiting data input to the forward‐inverse tau‐p transform pair, velocity filtering which varies with time and offset can be achieved. The limiting procedure, called hyperbolic velocity filtering, suppresses coherent noise while retaining reflection events. It is based on knowledge of the stacking velocities, but only approximate values are needed. A suitable application for hyperbolic velocity filtering is in hard water‐bottom marine areas where laterally propagating noise, diffracted by shallow scatterers, gives rise to reflection‐like events with high apparent velocity in the CMP gathers. Such diffractions do not, however, generally have reflection‐like moveouts in shot or receiver gathers. Hyperbolic velocity filtering offers moveout discrimination at all offset distances and traveltimes. When it is applied to shot (and receiver) gathers from a hard water‐bottom area such as offshore Florida, a striking reduction of noise occurs in the stacked section. Comparison with similar application of fixed‐limit (f-k) velocity filtering shows the hyperbolic filtering to be more effective for this data set.

scholarly journals ATENUASI WATER-BOTTOM MULTIPLE DENGAN METODE TRANSFORMASI PARABOLIC RADON

2016 ◽  
Vol 12 (3) ◽  
pp. 145
Author(s):  
Subarsyah Subarsyah ◽  
Tumpal Benhard Nainggolan
Keyword(s):  
Radon Transform ◽  
Seismic Data ◽  
Wide Distribution ◽  
Seismic Section ◽  
Optimal Separation ◽  
Multiple Attenuation ◽  
Parabolic Radon Transform ◽  
Water Bottom

Interferensi water-bottom multipel terhadap reflektor primer menimbulkan efek bersifat destruktif yang menyebabkan penampang seismik menjadi tidak tepat akibat kehadiran reflektor semu. Teknik demultiple perlu diaplikasikan untuk mengatenuasi multipel. Transformasi parabolic radon merupakan teknik atenuasi multipel dengan metode pemisahan dalam domain radon. Multipel sering teridentifikasi pada penampang seismik. Untuk memperbaiki penampang seismik akan dilakukan dengan metode transformasi parabolic radon. Penerapan metode ini mengakibatkan reflektor multipel melemah dan tereduksi setelah dilakukan muting dalam domain radon terhadap zona multipel. Beberapa reflektor primer juga ikut melemah akibat pemisahan dalam domain radon yang kurang optimal, pemisahan akan optimal membutuhkan distribusi offset yang lebar. Kata kunci: Parabolic radon, multipel, atenuasi Water-bottom mutiple interference often destructively interfere with primary reflection that led to incorrect seismic section due to presence apparent reflector. Demultiple techniques need to be applied to attenuate the multiple. Parabolic Radon transform is demultiple attenuation technique that separate multiple and primary in radon domain. Water-bottom mutiple ussualy appear and easly identified on seismic data, parabolic radon transform applied to improve the seismic section. Application of this method to data showing multiple reflectors weakened and reduced after muting multiple zones in the radon domain. Some of the primary reflector also weakened due to bad separation in radon domain, optimal separation will require a wide distribution of offsets. Keywords: Parabolic radon, multiple, attenuation

scholarly journals Improving adaptive subtraction in seismic multiple attenuation

Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. V59-V67 ◽  
Author(s):  
Shoudong Huo ◽  
Yanghua Wang
Keyword(s):  
Least Squares ◽  
Seismic Data ◽  
Primary Energy ◽  
Multiple Models ◽  
Multiple Model ◽  
Data Set ◽  
Multiple Attenuation ◽  
Matching Filter ◽  
Theoretical Analyses ◽  
Different Order

In seismic multiple attenuation, once the multiple models have been built, the effectiveness of the processing depends on the subtraction step. Usually the primary energy is partially attenuated during the adaptive subtraction if an [Formula: see text]-norm matching filter is used to solve a least-squares problem. The expanded multichannel matching (EMCM) filter generally is effective, but conservative parameters adopted to preserve the primary could lead to some remaining multiples. We have managed to improve the multiple attenuation result through an iterative application of the EMCM filter to accumulate the effect of subtraction. A Butterworth-type masking filter based on the multiple model can be used to preserve most of the primary energy prior to subtraction, and then subtraction can be performed on the remaining part to better suppress the multiples without affecting the primaries. Meanwhile, subtraction can be performed according to the orders of the multiples, as a single subtraction window usually covers different-order multiples with different amplitudes. Theoretical analyses, and synthetic and real seismic data set demonstrations, proved that a combination of these three strategies is effective in improving the adaptive subtraction during seismic multiple attenuation.

scholarly journals Atmospheric Radiocarbon at the End of the Last Glacial: An Estimate Based on AMS Radiocarbon Dates on Terrestrial Macrofossils From Lake Sediments

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 795-804 ◽  
Author(s):  
Hugo Zbinden ◽  
Michael Andree ◽  
Hans Oeschger ◽  
Brigitta Ammann ◽  
Andre Lotter ◽  
...  
Keyword(s):  
Mass Spectroscopy ◽  
Calibration Curve ◽  
Hard Water ◽  
Sedimentation Rates ◽  
Local Effects ◽  
Data Set ◽  
Radiocarbon Dates ◽  
Pollen Zone ◽  
Plant Remains ◽  
The Last Glacial

The main purpose of this work is to reconstruct the atmospheric Δ 14C in the glacial-postglacial transition, 14,000 – 10,000 BP, a range not covered by the tree-ring calibration curve. We measured 14C/12C ratios on series of terrestrial macrofossils from sediments of two Swiss lakes. We selected exclusively plant remains of recognizable terrestrial origin that are not affected by hard water and thus reflect atmospheric 14C concentration. Due to the scarcity of such material, we used accelerator mass spectroscopy. Cores of two lakes were measured to eliminate local effects and to check the reproducibility of results. This required a reliable, 14C-independent correlation of the cores, obtained through local pollen zone boundaries 14C ages were obtained as a function of the depth in the cores. If sedimentation rates are known ages can be converted into Δ 14C values. We also attempted estimating sedimentation rates; calculations are based on the Swedish varve chronology. Results were combined to form an entire data set. The Δ 14C curve shows an increase with time during the Allerød and decreases during Preboreal and Bølling periods. Probabilities for these 14C variations are discussed.

scholarly journals Practical Implementation of Multiple Attenuation Methods on 2D Deepwater Seismic Data : Seram Sea Case Study

2017 ◽  
Vol 32 (1) ◽  
Author(s):  
Tumpal Bernhard Nainggolan ◽  
Deny Setiady
Keyword(s):  
Seismic Data ◽  
Input Data ◽  
Complex Structure ◽  
Least Square ◽  
Inversion Method ◽  
Practical Implementation ◽  
Proper Solution ◽  
Multiple Attenuation ◽  
Multiple Elimination ◽  
Water Bottom

Some deepwater multiple attenuation processing methods have been developed in the past with partial success. The success of surface multiple attenuation relies on good water bottom reflections for most deepwater marine situations. It brings the bigger ability to build an accurate water bottom multiple prediction model. Major challenges on 2D deepwater seismic data processing especially such a geologically complex structure of Seram Sea, West Papua – Indonesia are to attenuate surface related multiple and to preserve the primary data. Many multiple attenuation methods have been developed to remove surface multiple on these seismic data including most common least-squares, prediction-error filtering and more advanced Radon transform.Predictive Deconvolution and Surface Related Multiple Elimination (SRME) method appears to be a proper solution, especially in complex structure where the above methods fail to distinguish interval velocity difference between primaries and multiples. It does not require any subsurface info as long as source signature and surface reflectivity are provided. SRME method consists of 3 major steps: SRME regularization, multiple modeling and least-square adaptive subtraction. Near offset regularization is needed to fill the gaps on near offset due to unrecorded near traces during the acquisition process. Then, isolating primaries from multiples using forward modeling. Inversion method by subtraction of input data with multiple models to a more attenuated multiple seismic section.Results on real 2D deepwater seismic data show that SRME method as the proper solution should be considered as one of the practical implementation steps in geologically complex structure and to give more accurate seismic imaging for the interpretation.Keywords : multiple attenuation, 2D deepwater seismic, Radon transform, Surface Related Multiple Elimination (SRME). Banyak metode atenuasi pengulangan ganda dikembangkan pada pengolahan data seismik dengan tingkat keberhasilan yang rendah pada masa lalu. Keberhasilan dalam atenuasi pengulangan ganda permukaan salah satunya bergantung pada hasil gelombang pantul pada batas dasar laut dan permukaan pada hampir seluruh survei seismik laut. Hal tersebut menentukan keakuratan dalam membuat model prediksi pengulangan ganda dasar laut dan permukaan air. Tantangan utama dalam pemrosesan data seismik 2D laut dalam khususnya struktur geologi kompleks seperti Laut Seram, Papua Barat – Indonesia adalah pada kegiatan menekan pengulangan ganda permukaan sekaligus mempertahankan data primer. Beberapa metode yang dikembangkan untuk menghilangkan pengulangan ganda permukaan pada data seismik seperti least-square, filter prediksi kesalahan dan transformasi Radon.Dekonvolusi Prediktif dan Metode Surface Related Multiple Elimination (SRME) digunakan sebagai solusi yang baik pada struktur kompleks dimana metode-metode lain gagal untuk memisahkan perbedaan kecepatan interval data primer dan pengulangan ganda. Metode tersebut tidak membutuhkan informasi bawah permukaan selain parameter sumber dan reflektivitas permukaan. Metode SRME terdiri dari 3 tahapan utama : regularisasi SRME, pemodelan pengulangan ganda dan pengurangan adaktif least-square. Regularisasi near offset diperlukan untuk mengisi kekosongan pada near offset yang disebabkan oleh adanya sejumlah tras terdekat yang tidak terekam selama akuisisi. Pemodelan maju digunakan untuk memisahkan data primer dan pengulangan ganda kemudian inversi dengan pengurangan input data dengan model multiple.Hasil pada data seismik 2D laut dalam menunjukkan bahwa metode SRME layak diterapkan sebagai salah satu pengembangan metode atenuasi multiple permukaan serta untuk meningkatkan akurasi data seismik terutama untuk struktur geologi kompleks.Kata kunci : peredaman pengulangan ganda (multiple), seismik 2D laut dalam, transformasi Radon, Surface Related Multiple Attenuation (SRME).

AVO inversion of Troll Field data

Geophysics ◽  
1996 ◽  
Vol 61 (6) ◽  
pp. 1589-1602 ◽  
Author(s):  
Arild Buland ◽  
Martin Landrø ◽  
Mona Andersen ◽  
Terje Dahl
Keyword(s):  
Least Squares ◽  
Field Data ◽  
Forward Modeling ◽  
S Wave ◽  
Data Set ◽  
Wave Velocities ◽  
Avo Inversion ◽  
Common Depth Point ◽  
Elastic Inversion ◽  
Water Bottom

A stratigraphic elastic inversion scheme has been applied to a data set from the Troll East Field, offshore Norway. The objective of the present work is to obtain estimates of the P‐ and S‐wave velocities and densities of the subsurface. The inversion is carried out on τ − p transformed common depth‐point (CMP) gathers. The forward modeling is performed by convolving a wavelet with the reflectivity that includes water‐bottom multiples, transmission effects, and absorption and array effects. A damped Gauss‐Newton algorithm is used to minimize a least‐squares misfit function. Inversion results show good correlation between the estimated [Formula: see text] ratios and the lithologies in the wells. The [Formula: see text] ratio is estimated to 2.1–3.0 for shale and 1.6–2.0 for sandstones. In the reservoir, the [Formula: see text] ratio is estimated to 1.55 in the gas sand and to 1.62 below the fluid contact.

scholarly journals Multiple prediction through inversion: A fully data‐driven concept for surface‐related multiple attenuation

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 547-553 ◽  
Author(s):  
Yanghua Wang
Keyword(s):  
Seismic Data ◽  
Model Building ◽  
Data Driven ◽  
Multiple Model ◽  
Data Set ◽  
Multiple Attenuation ◽  
Multiple Prediction ◽  
Surface Operator ◽  
Previous Iteration ◽  
Conventional Scheme

This paper introduces a fully data‐driven concept, multiple prediction through inversion (MPI), for surface‐related multiple attenuation (SMA). It builds the multiple model not by spatial convolution, as in a conventional SMA, but by updating the attenuated multiple wavefield in the previous iteration to generate a multiple prediction for the new iteration, as is usually the case in an iterative inverse problem. Because MPI does not use spatial convolution, it is able to minimize the edge effect that appears in conventional SMA multiple prediction and to eliminate the need to synthesize near‐offset traces, required by a conventional scheme, so that it can deal with a seismic data set with missing near‐offset traces. The MPI concept also eliminates the need for an explicit surface operator, which is required by conventional SMA and is comprised of the inverse source signature and other effects. This method accounts implicitly for the spatial variation of the surface operator in multiple‐model building and attempts to predict multiples which are not only accurate kinematically but are also accurate in phase and amplitude.

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