MULTIPLE ELIMINATION USING WAVEFIELD TRANSFORMATIONS OFF THE COAST OF WESTERN AUSTRALIA

1997 ◽  
Vol 37 (1) ◽  
pp. 777
Author(s):  
M.G. Lamont ◽  
N.F. Uren
Keyword(s):  
Western Australia ◽  
Stationary Time Series ◽  
Velocity Inversion ◽  
Sea Floor ◽  
Event Prediction ◽  
Predictive Deconvolution ◽  
Constant Stretch ◽  
The Right ◽  
Multiple Elimination ◽  
Water Bottom

There are two principle reasons why water bottom multiples off the coast of Western Australia can be very difficult to attenuate:A strongly reflective sea floor (often caused by shallow carbonates) gives multiples large amplitudes compared with the primary events they overlay.A widely occurring velocity inversion, beneath the carbonates, causes multiples and primaries to have similar moveouts.A range of processes are commercially available to attenuate multiples, including FK Demultiple, Radon Demultiple, and Predictive Deconvolution. These methods can be very successful under the right conditions. Two dimensional autoconvolution methods, although very promising, still have drawbacks and are extremely computationally expensive.Two new wavefield transformations, Multiple MoveOut (MMO) and IsoStretch Radial Trace (ISR), have been developed to precondition data prior to the removal of surface related multiples by existing techniques. These form the basis of a new multiple attenuating procedure.MMO shifts the data so that the simple water bottom multiples become periodic with the primary event. Water bottom pegleg multiples become approximately periodic.ISR interpolates oblique traces of constant stretch which also approximately map constant angles of incidence on the sea floor. The water bottom primary and multiple events form stationary time series after ISR. They are then amenable to removal by Event Prediction (one dimensional autoconvolution) or Predictive Deconvolution.The results of the new procedure are demonstrated on field data from off-shore Western Australia. It is shown to be more effective at removing both simple and pegleg water bottom multiples than traditional techniques. Finally, it is not computer intensive and does not require velocity analysis prior to its application (besides estimate of water velocity).

Coherent noise in marine seismic data

Geophysics ◽  
1983 ◽  
Vol 48 (7) ◽  
pp. 854-886 ◽  
Author(s):  
Ken Larner ◽  
Ron Chambers ◽  
Mai Yang ◽  
Walt Lynn ◽  
Willon Wai
Keyword(s):  
Seismic Data ◽  
Noise Suppression ◽  
Seismic Source ◽  
Coherent Noise ◽  
Critical Data ◽  
Predictive Deconvolution ◽  
Scattered Energy ◽  
Marine Seismic ◽  
The Many ◽  
Water Bottom

Despite significant advances in marine streamer design, seismic data are often plagued by coherent noise having approximately linear moveout across stacked sections. With an understanding of the characteristics that distinguish such noise from signal, we can decide which noise‐suppression techniques to use and at what stages to apply them in acquisition and processing. Three general mechanisms that might produce such noise patterns on stacked sections are examined: direct and trapped waves that propagate outward from the seismic source, cable motion caused by the tugging action of the boat and tail buoy, and scattered energy from irregularities in the water bottom and sub‐bottom. Depending upon the mechanism, entirely different noise patterns can be observed on shot profiles and common‐midpoint (CMP) gathers; these patterns can be diagnostic of the dominant mechanism in a given set of data. Field data from Canada and Alaska suggest that the dominant noise is from waves scattered within the shallow sub‐buttom. This type of noise, while not obvious on the shot records, is actually enhanced by CMP stacking. Moreover, this noise is not confined to marine data; it can be as strong as surface wave noise on stacked land seismic data as well. Of the many processing tools available, moveout filtering is best for suppressing the noise while preserving signal. Since the scattered noise does not exhibit a linear moveout pattern on CMP‐sorted gathers, moveout filtering must be applied either to traces within shot records and common‐receiver gathers or to stacked traces. Our data example demonstrates that although it is more costly, moveout filtering of the unstacked data is particularly effective because it conditions the data for the critical data‐dependent processing steps of predictive deconvolution and velocity analysis.

LONG-PERIOD SURFACE-RELATED MULTIPLE SUPPRESSION IN 2D MARINE SEISMIC DATA USING PREDICTIVE DECONVOLUTION AND COMBINATION OF SURFACE-RELATED MULTIPLE ELIMINATION AND PARABOLIC RADON FILTERING

2021 ◽  
Author(s):  
Pimpawee Sittipan ◽  
Pisanu Wongpornchai
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Petroleum Reservoirs ◽  
The United States ◽  
Multiple Reflections ◽  
Long Period ◽  
Predictive Deconvolution ◽  
Short Period ◽  
Marine Seismic ◽  
Multiple Elimination

Some of the important petroleum reservoirs accumulate beneath the seas and oceans. Marine seismic reflection method is the most efficient method and is widely used in the petroleum industry to map and interpret the potential of petroleum reservoirs. Multiple reflections are a particular problem in marine seismic reflection investigation, as they often obscure the target reflectors in seismic profiles. Multiple reflections can be categorized by considering the shallowest interface on which the bounces take place into two types: internal multiples and surface-related multiples. Besides, the multiples can be categorized on the interfaces where the bounces take place, a difference between long-period and short-period multiples can be considered. The long-period surface-related multiples on 2D marine seismic data of the East Coast of the United States-Southern Atlantic Margin were focused on this research. The seismic profile demonstrates the effectiveness of the results from predictive deconvolution and the combination of surface-related multiple eliminations (SRME) and parabolic Radon filtering. First, predictive deconvolution applied on conventional processing is the method of multiple suppression. The other, SRME is a model-based and data-driven surface-related multiple elimination method which does not need any assumptions. And the last, parabolic Radon filtering is a moveout-based method for residual multiple reflections based on velocity discrimination between primary and multiple reflections, thus velocity model and normal-moveout correction are required for this method. The predictive deconvolution is ineffective for long-period surface-related multiple removals. However, the combination of SRME and parabolic Radon filtering can attenuate almost long-period surface-related multiple reflections and provide a high-quality seismic images of marine seismic data.

Reproduction in the common sheath-tailed bat, Taphozous georgianus (Thomas) (Microchiroptera : Emballonuridae), in Western Australia

1973 ◽  
Vol 21 (3) ◽  
pp. 375 ◽  
Author(s):  
DJ Kitchener
Keyword(s):  
Corpus Luteum ◽  
Western Australia ◽  
Reproductive Tract ◽  
Vas Deferens ◽  
Gestation Period ◽  
Early Winter ◽  
Male And Female ◽  
The Common ◽  
The Right

The reproductive and associated organs of both male and female T. georgianus are briefly described. In females, only the right ovary is functional and pregnancies occur only in the right horn. They are monovular and the corpus luteum occupies most of the ovary and is deeply embedded in its stroma. Females are monotocous and the gestation period is probably about 4 months, young being born from October to February. They are monestrous and there is an autumn and early winter dioestrousanoestrous period. Spermatozoa are not stored in the reproductive tract of females and copulation appears to coincide with the oestrous condition. In males, spermatogenesis proceeds throughout the year and spermatozoa are present in the epididymis and vas deferens in all months that males were collected (no records for December). Spermatozoa are also found in the ampulla of Henle and vesicula seminalis in most months of the year. The position of the testes varies with season: in summer they descend to the scrota1 sacs; in autumn, winter, and spring they are more abdominal.

Deep‐water peg legs and multiples: Emulation and suppression

Geophysics ◽  
1986 ◽  
Vol 51 (12) ◽  
pp. 2177-2184 ◽  
Author(s):  
J. R. Berryhill ◽  
Y. C. Kim
Keyword(s):  
Wave Equation ◽  
Seismic Data ◽  
Water Layer ◽  
Original Data ◽  
Equation Method ◽  
Multiple Reflections ◽  
Step Method ◽  
Arrival Times ◽  
Sea Floor ◽  
Water Bottom

This paper discusses a two‐step method for predicting and attenuating multiple and peg‐leg reflections in unstacked seismic data. In the first step, an (observed) seismic record is extrapolated through a round‐trip traversal of the water layer, thus creating an accurate prediction of all possible multiples. In the second step, the record containing the predicted multiples is compared with and subtracted from the original. The wave‐equation method employed to predict the multiples takes accurate account of sea‐floor topography and so requires a precise water‐bottom profile as part of the input. Information about the subsurface below the sea floor is not required. The arrival times of multiple reflections are reproduced precisely, although the amplitudes are not accurate, and the sea floor is treated as a perfect reflector. The comparison step detects the similarities between the computed multiples and the original data, and estimates a transfer function to equalize the amplitudes and account for any change in waveform caused by the sea‐floor reflector. This two‐step wave‐equation method is effective even for dipping sea floors and dipping subsurface reflectors. It does not depend upon any assumed periodicity in the data or upon any difference in stacking velocity between primaries and multiples. Thus it is complementary to the less specialized methods of multiple suppression.

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).

scholarly journals On the Bennelongia barangaroo lineage (Crustacea, Ostracoda) in Western Australia, with the description of seven new species

2013 ◽  
Author(s):  
Koen Martens ◽  
Stuart Halse ◽  
Isa Schön
Keyword(s):  
New Species ◽  
Western Australia ◽  
Molecular Evidence ◽  
Nominal Species ◽  
Rock Pools ◽  
Additional Species ◽  
Coi Sequences ◽  
The Right ◽  
Genetic Species Concept ◽  
Genetic Species

The ostracod genus Bennelongia De Deckker & McKenzie, 1981 is endemic to Australia and New Zealand. Extensive sampling in Western Australia (WA) revealed a high specific and largely undescribed diversity. Here, we describe seven new species belonging to the B. barangaroo lineage: B. timmsi sp. nov., B. gnamma sp. nov., B. hirsuta sp. nov., B. ivanae sp. nov., B. mcraeae sp. nov., B. scanloni sp. nov. and B. calei sp. nov., and confirm the presence of an additional species, B. dedeckkeri, in WA. For five of these eight species, we could construct molecular phylogenies and parsimonious networks based on COI sequences. We also tested for cryptic diversity and specific status of clusters with a statistical method based on the evolutionary genetic species concept, namely Birky’s 4 theta rule. The analyses support the existence of these five species and a further three cryptic species in the WA B. barangaroo lineage. The molecular evidence was particularly relevant because most species described herein have very similar morphologies and can be distinguished from each other only by the shape, size and position of the antero-ventral lapel on the right valve, and, in sexual populations, by the small differences in shape of the hemipenes and the prehensile palps in males. Four species of the WA B. barangaroo lineage occur in small temporary rock pools (gnammas) on rocky outcrops. The other four species are mainly found in soft bottomed seasonal water bodies. One of the latter species, B. scanloni sp. nov., occurs in both claypans and deeper rock pools (pit gnammas). All species, except for B. dedeckkeri, originally described from Queensland, have quite clearly delimited distributions in WA. With the seven new species described here, the genus Bennelongia now comprises 25 nominal species but several more await formal description.

Reproduction in female Eptesicus regulus (Thomas) (Vespertilionidae), in south-western Australia

1978 ◽  
Vol 26 (2) ◽  
pp. 257 ◽  
Author(s):  
DJ Kitchener ◽  
SA Halse
Keyword(s):  
Reproductive Cycle ◽  
Western Australia ◽  
Museum Specimens ◽  
Histological Techniques ◽  
The Right

The reproductive cycle of female Eptesicus regulus is outlined from histological techniques on museum specimens collected in south-western Australia over the last 15 years. E. regulus is monoestrous and gives birth to a single young in November or December. It copulates in autumn and stores sperm over winter. Ovulation and fertilization is at the end of winter. Both ovaries are functional but pregnancy occurs only in the right horn.

Initial and residual effectiveness of molybdate fertilizer in two areas of south western Australia

1985 ◽  
Vol 36 (4) ◽  
pp. 579 ◽  
Author(s):  
NJ Barrow ◽  
PJ Leahy ◽  
IN Southey ◽  
DB Purser
Keyword(s):  
Western Australia ◽  
Sodium Molybdate ◽  
Single Application ◽  
Initial Application ◽  
High Concentrations ◽  
Rate Of Decline ◽  
One Year ◽  
The Right ◽  
Molybdenum Concentration ◽  
Residual Effectiveness

A range of levels of sodium molybdate was applied to existing clover pastures at Boyup Brook and at Bakers Hill in south-western Australia. In the three subsequent years, further levels of molybdate were applied to some of the sites to assess the residual value of the initial application. The effect of the molybdate application on the molybdenum concentration in clover tops was measured. Plots of molybdenum concentration in tops versus molybdate applied curved upwards at first as each additional increment provided an increased response in concentration. However, at high concentrations of molybdate in clover tops the plots curved to the right at three out of four sites as each additional increment produced a decreased response. That is, overall, the curves were sigmoid. Increases in molybdate concentration were greatest on soils with least ability to retain molybdate as measured in the laboratory. Molybdate applied one year previously was about half as effective as currently applied molybdate. After two and three years it was about 20% as effective. A single application of rnolybdate remains effective for a long period on a soil of low ability to retain molybdate because the initial application is super-abundant - rather than because of large differences between soils in the rate of decline of effectiveness.

Ischaemic Stroke and the Echo ‘Bubble Study’: Are we Screening the Right Patients? A Multicentre Experience from Western Australia

2018 ◽  
Vol 27 ◽  
pp. S250
Author(s):  
P. Maggiore ◽  
J. Bellinge ◽  
D. Chieng ◽  
D. White ◽  
N. Lan ◽  
...  
Keyword(s):  
Ischaemic Stroke ◽  
Western Australia ◽  
The Right

Reproduction in female Chalinolobus morio (Gray) (Vespertilionidae) in South-Western Australia

1981 ◽  
Vol 29 (3) ◽  
pp. 305 ◽  
Author(s):  
DJ Kitchener ◽  
P Coster
Keyword(s):  
Reproductive Cycle ◽  
Western Australia ◽  
Reproductive Organs ◽  
Museum Specimens ◽  
Histological Techniques ◽  
The Right ◽  
Uterine Glands

The reproductive cycle of C. morio is outlined from examination of reproductive organs in situ and from histological techniques on Museum specimens collected in south-western Australia over the last 46 years. Changes in ovaries, endometria (and glands), epithelia lining tracts and Bartholin's glands are described. C. morio is monoestrous. It copulates in autumn and stores sperm in oviducts and uterine glands until ovulation in winter. Both ovaries are functional. Trans-uterine migration of the developing zygote is recorded. It normally gives birth to a single young, although occasionally to twins, between mid-September and mid-November. In the case of twins both uterine horns are gravid, otherwise only the right horn is gravid.

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