scholarly journals Optimized Characterization of Gas Chimneys Based on Special Seismic Processing

2019 ◽  
Vol 37 (4) ◽  
Author(s):  
José Paulo Goulart ◽  
David Castro ◽  
Wander Amorim
Keyword(s):  
Seismic Data ◽  
Seismic Signal ◽  
Low Frequencies ◽  
Important Indicator ◽  
Seismic Processing ◽  
Gas Chimney ◽  
Seismic Acquisition ◽  
Seismic Sections ◽  
Gas Chimneys ◽  
Parnaíba Basin

ABSTRACT A new computational methodology was developed to facilitate the interpretation of gas chimneys in seismic sections by analyzing the frequency spectrum of the seismic signal in the Hilbert Domain. Gas chimneys are structures associated with the migration of hydrocarbons or free gas, causing vertical chaotic disturbances in the seismic data. Its occurrence in oil reservoirs is considered an important indicator of the presence of an active petroleum system and its mapping is useful to reduce exploratory risks, increasing the probability of success of the pioneer wells. Standard seismic processing does not favor the recognition of gas chimneys, since their characteristic seismic signature is treated as noise and the low frequencies are strongly attenuated already in the period of the seismic acquisition. The set of reflections is calculated to enhance the low frequencies, making the gas chimneys easily identifiable in the seismic sections where they were not previously even perceived. The special processing flow was applied to seismic data from the Parnaíba Basin “(NE Brazil). This Paleozoic basin is especially rich in gas chimneys, which were favored by transcurrent tectonics associated with the Transbrasiliano Lineament. The gas chimneys interpretation could be validated by the observation of correlated seismic, topographic and geochemical features.KEYWORDS: special processing, gas chimney, exploratory risk, Parnaíba Basin. RESUMO. Uma nova metodologia computacional foi desenvolvida para facilitar a interpretação de chaminés de gás em seções sísmicas por meio da análise do espectro de frequência do sinal sísmico no Domínio de Hilbert. Chaminés de gás são estruturas associadas à migração de hidrocarbonetos ou gás livre, provocando perturbações caóticas verticais no dado sísmico. Sua ocorrência em reservatórios petrolíferos é considerada um importante indicador da presença de um sistema petrolífero ativo e seu mapeamento é útil para reduzir os riscos exploratórios, aumentando a probabilidade de sucesso dos poços pioneiros. O processamento sísmico padrão não favorece o reconhecimento das chaminés de gás, uma vez que a sua assinatura sísmica característica é tratada como ruído e as baixas frequências são fortemente atenuadas já no período da aquisição sísmica. O conjunto de reflexões é calculado para realçar as baixas frequências, tornando as chaminés de gás facilmente identificáveis nas seções sísmicas onde antes não eram nem percebidas. O processamento especial foi aplicado em dados sísmicos da Bacia do Parnaíba. Esta bacia paleozoica é especialmente rica em chaminés de gás, cuja presença foi favorecida pela tectônica transcorrente associada ao Lineamento Transbrasiliano. As chaminés de gás interpretadas puderam também ser validadas pela observação de feições sísmicas, topográficas e geoquímicas correlatas.Palavras-chave: processamento especial, chaminé de gás, risco exploratório, Bacia do Parnaíba.

Seismic signal processing—A new millennium perspective

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 18-20 ◽  
Author(s):  
Peter Cary
Keyword(s):  
Seismic Data ◽  
Seismic Signal ◽  
First Century ◽  
Vast Number ◽  
Seismic Processing ◽  
Almost Everywhere ◽  
The People ◽  
Conference Presentations ◽  
And Migration ◽  
Seismic Signal Processing

In the introduction to his comprehensive SEG textbook, Seismic Data Processing, Oz Yilmaz selects deconvolution, common‐midpoint stacking and migration as being the three principal processes that are applied during routine seismic processing. Since Yilmaz’s tome was first published in 1987, a vast number of papers have been published and conference presentations have been given on virtually every aspect of seismic processing. However, I think it is still accurate to say that the same three processes dominate the processing flow of the vast majority of seismic data that is processed now, at the beginning of the twenty‐first century. This is not to say that important progress has not been made in many aspects of seismic processing and that much more sophisticated processing flows are now applied to some datasets. But it is a great tribute to the real pioneers of our profession—the people who advanced our ideas of seismic processing from examining raw analog records in the field to creating crisp computer‐generated images of the subsurface with processes such as deconvolution, stack and migration—that the very same, or similar, algorithms that they invented still form the backbone of everyday processing that is done around the world today. In fact, there are times when it seems that the last great geophysicist was Carl Friedrich Gauss, because the method that he published back in 1823 of minimizing the sum of the squared errors seems to be used almost everywhere one looks in seismic processing, from deconvolution to migration.

DETERMINING 3D SEISMIC CHARACTERISTICS OF CONDUIT SYSTEM OF CHANGCHANG SAG, QIONGDONGNAN BASIN

2020 ◽  
pp. 1-50
Author(s):  
Yufeng Li ◽  
Renhai Pu ◽  
Gongcheng Zhang ◽  
Qiang Han ◽  
Chao Yuan ◽  
...  
Keyword(s):  
High Amplitude ◽  
Water Area ◽  
Qiongdongnan Basin ◽  
3D Seismic ◽  
Weak Zone ◽  
Low Frequencies ◽  
Gas Chimney ◽  
Conduit System ◽  
Deep Water Area ◽  
Gas Chimneys

Although some giant gas fields found in the deep-water area of the Qingdongnan Basin, China, are often associated with mud diapirs and/or gas chimneys, no comprehensive 3D work has been undertaken to characterize them. We conducted 3D seismic investigation using root mean squares (RMS), coherence, and instantaneous frequency attributes to provide better understanding of the conduit systems in the Qiongdongnan Basin. The results show that the conduit system that we investigated can be separated vertically into four zones in the following order. (1) A structurally diapiric weak zone at the base, followed by (2) an injected or reinjected sandstones zone, (3) a gas chimney zone, and (4) a mud volcanic zone at the top. The morphology of the structurally weak zone is elliptical, formed by the intersection of NW–SE– and nearly E–W–trending tectonic faults. We infer that this zone provides pathways for the ascent of the diapiric mud that was probably sourced by the underlying overpressured mudstones. The injected or reinjected sandstones zone is characterized by high amplitude anomalies (HAAs), and was probably fed by the lobes of underlying submarine fans. The gas chimney zone which is characterized by low frequencies and weak amplitudes, is probably composed of a mixture of uprising mud and free gas formed from the underlying overpressured mudstones; whereas, the mud volcano which has a Christmas-tree pattern, and composed of a central crater, the southern flank of which is a mudflow, formed when the uprising mud migrating upward through faults got to the paleo sea floor. Finally, we have proposed schematic illustrations that would aid in understanding the different stages of the formation and internal architecture of this conduit system.

scholarly journals Accelerometer Sensor Specifications to Predict Hydrocarbon Using Passive Seismic Technique

2016 ◽  
Vol 2016 ◽  
pp. 1-28 ◽  
Author(s):  
M. H. Md Khir ◽  
Atul Kumar ◽  
Wan Ismail Wan Yusoff
Keyword(s):  
Oil And Gas ◽  
Optimal Solution ◽  
Seismic Energy ◽  
Oil And Gas Industry ◽  
Seismic Signal ◽  
Accelerometer Sensor ◽  
Low Frequencies ◽  
Technological Gap ◽  
Passive Seismic ◽  
Seismic Acquisition

The ambient seismic ground noise has been investigated in several surveys worldwide in the last 10 years to verify the correlation between observed seismic energy anomalies at the surface and the presence of hydrocarbon reserves beneath. This is due to the premise that anomalies provide information about the geology and potential presence of hydrocarbon. However a technology gap manifested in nonoptimal detection of seismic signals of interest is observed. This is due to the fact that available sensors are not designed on the basis of passive seismic signal attributes and mainly in terms of amplitude and bandwidth. This is because of that fact that passive seismic acquisition requires greater instrumentation sensitivity, noise immunity, and bandwidth, with active seismic acquisition, where vibratory or impulsive sources were utilized to receive reflections through geophones. Therefore, in the case of passive seismic acquisition, it is necessary to select the best monitoring equipment for its success or failure. Hence, concerning sensors performance, this paper highlights the technological gap and motivates developing dedicated sensors for optimal solution at lower frequencies. Thus, the improved passive seismic recording helps in oil and gas industry to perform better fracture mapping and identify more appropriate stratigraphy at low frequencies.

The Value of Seismic Data in Conventional and Unconventional Fields

2021 ◽  
Author(s):  
Nawaf Alghamdi ◽  
Hamad Alghenaim
Keyword(s):  
Saudi Arabia ◽  
Seismic Data ◽  
Net Present Value ◽  
Positive Impact ◽  
3D Seismic ◽  
Seismic Processing ◽  
High Reward ◽  
Seismic Acquisition ◽  
The Republic ◽  
Conventional Field

Abstract The paper illustrates the value of seismic data in different environments after assessing the benefits and costs of processes such as seismic acquisition, seismic processing and seismic interpretation. Global examples from conventional and unconventional fields are discussed to show how seismic data plays a significant role in determining low-risk and high-reward wells and also eliminating the high-risk and low-reward wells. This paper shows an example of a conventional field in the state of Kansas, USA, where the net present value (NPV) increased by more than 17 times when 3D seismic data was acquired, while in an unconventional field the commercial success rate rose from 30% to 70% due to 3D seismic acquisition. However, two offshore fields in the Republic of Trinidad and Tobago are discussed to show that the NPV as impacted by advanced seismic processing was more than 111 ($M). Another example comes from Viking Field, a conventional field in Canada, where the NPV was increased from 3800 ($M) to 5000 ($M) when the seismic data was re-processed. Furthermore, the value of investing in seismic data was investigated and quantified by comparing two synthetically modeled scenarios in Saudi Arabia. Overall, the four examples from North America, Central America and Saudi Arabia illustrate that investment in seismic data has a positive impact on both conventional and unconventional fields. That provides strong evidence to encourage more investments in geophysical technologies.

APPLICATION OF THE EMPIRICAL MODE DECOMPOSITION METHOD TO GROUND-ROLL NOISE ATTENUATION IN SEISMIC DATA

2013 ◽  
Vol 31 (4) ◽  
pp. 619 ◽  
Author(s):  
Luiz Eduardo Soares Ferreira ◽  
Milton José Porsani ◽  
Michelângelo G. Da Silva ◽  
Giovani Lopes Vasconcelos
Keyword(s):  
Empirical Mode Decomposition ◽  
Seismic Data ◽  
Low Frequency ◽  
High Amplitude ◽  
Seismic Line ◽  
Seismic Processing ◽  
Mode Decomposition ◽  
Ground Roll ◽  
Fortran 90 ◽  
Emd Method

ABSTRACT. Seismic processing aims to provide an adequate image of the subsurface geology. During seismic processing, the filtering of signals considered noise is of utmost importance. Among these signals is the surface rolling noise, better known as ground-roll. Ground-roll occurs mainly in land seismic data, masking reflections, and this roll has the following main features: high amplitude, low frequency and low speed. The attenuation of this noise is generally performed through so-called conventional methods using 1-D or 2-D frequency filters in the fk domain. This study uses the empirical mode decomposition (EMD) method for ground-roll attenuation. The EMD method was implemented in the programming language FORTRAN 90 and applied in the time and frequency domains. The application of this method to the processing of land seismic line 204-RL-247 in Tacutu Basin resulted in stacked seismic sections that were of similar or sometimes better quality compared with those obtained using the fk and high-pass filtering methods.Keywords: seismic processing, empirical mode decomposition, seismic data filtering, ground-roll. RESUMO. O processamento sísmico tem como principal objetivo fornecer uma imagem adequada da geologia da subsuperfície. Nas etapas do processamento sísmico a filtragem de sinais considerados como ruídos é de fundamental importância. Dentre esses ruídos encontramos o ruído de rolamento superficial, mais conhecido como ground-roll . O ground-roll ocorre principalmente em dados sísmicos terrestres, mascarando as reflexões e possui como principais características: alta amplitude, baixa frequência e baixa velocidade. A atenuação desse ruído é geralmente realizada através de métodos de filtragem ditos convencionais, que utilizam filtros de frequência 1D ou filtro 2D no domínio fk. Este trabalho utiliza o método de Decomposição em Modos Empíricos (DME) para a atenuação do ground-roll. O método DME foi implementado em linguagem de programação FORTRAN 90, e foi aplicado no domínio do tempo e da frequência. Sua aplicação no processamento da linha sísmica terrestre 204-RL-247 da Bacia do Tacutu gerou como resultados, seções sísmicas empilhadas de qualidade semelhante e por vezes melhor, quando comparadas as obtidas com os métodos de filtragem fk e passa-alta.Palavras-chave: processamento sísmico, decomposição em modos empíricos, filtragem dados sísmicos, atenuação do ground-roll.

scholarly journals Pitfalls and limitations in seismic attribute interpretation of tectonic features

2015 ◽  
Vol 3 (1) ◽  
pp. SB5-SB15 ◽  
Author(s):  
Kurt J. Marfurt ◽  
Tiago M. Alves
Keyword(s):  
Seismic Data ◽  
Seismic Attributes ◽  
Seismic Attribute ◽  
3D Data ◽  
Amplitude Data ◽  
Seismic Sections ◽  
Push Down ◽  
Data Coherence ◽  
Level Of Experience ◽  
Tectonic Features

Seismic attributes are routinely used to accelerate and quantify the interpretation of tectonic features in 3D seismic data. Coherence (or variance) cubes delineate the edges of megablocks and faulted strata, curvature delineates folds and flexures, while spectral components delineate lateral changes in thickness and lithology. Seismic attributes are at their best in extracting subtle and easy to overlook features on high-quality seismic data. However, seismic attributes can also exacerbate otherwise subtle effects such as acquisition footprint and velocity pull-up/push-down, as well as small processing and velocity errors in seismic imaging. As a result, the chance that an interpreter will suffer a pitfall is inversely proportional to his or her experience. Interpreters with a history of making conventional maps from vertical seismic sections will have previously encountered problems associated with acquisition, processing, and imaging. Because they know that attributes are a direct measure of the seismic amplitude data, they are not surprised that such attributes “accurately” represent these familiar errors. Less experienced interpreters may encounter these errors for the first time. Regardless of their level of experience, all interpreters are faced with increasingly larger seismic data volumes in which seismic attributes become valuable tools that aid in mapping and communicating geologic features of interest to their colleagues. In terms of attributes, structural pitfalls fall into two general categories: false structures due to seismic noise and processing errors including velocity pull-up/push-down due to lateral variations in the overburden and errors made in attribute computation by not accounting for structural dip. We evaluate these errors using 3D data volumes and find areas where present-day attributes do not provide the images we want.

On the Processing of Non-Rectangularly Sampled Multi-Dimensional Geophysical Data

1991 ◽  
Vol 02 (01) ◽  
pp. 223-226
Author(s):  
VIRGIL BARDAN
Keyword(s):  
Seismic Data ◽  
Geophysical Data ◽  
Seismic Sections

In this paper the processing of triangularly sampled 2-D seismic data is illustrated by examples of synthetic and field seismic sections.

Using Logging and Seismic Data to Identify Boundaries Between Different OWC Units in a Deepwater Carbonate Reservoirs

2021 ◽  
Author(s):  
Kangxu Ren ◽  
Junfeng Zhao ◽  
Jian Zhao ◽  
Xilong Sun
Keyword(s):  
Seismic Data ◽  
Carbonate Rocks ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Sedimentary Process ◽  
Core Samples ◽  
Tight Carbonate ◽  
Porosity And Permeability ◽  
Seismic Sections ◽  
Parameters Inversion

Abstract At least three very different oil-water contacts (OWC) encountered in the deepwater, huge anticline, pre-salt carbonate reservoirs of X oilfield, Santos Basin, Brazil. The boundaries identification between different OWC units was very important to help calculating the reserves in place, which was the core factor for the development campaign. Based on analysis of wells pressure interference testing data, and interpretation of tight intervals in boreholes, predicating the pre-salt distribution of igneous rocks, intrusion baked aureoles, the silicification and the high GR carbonate rocks, the viewpoint of boundaries developed between different OWC sub-units in the lower parts of this complex carbonate reservoirs had been better understood. Core samples, logging curves, including conventional logging and other special types such as NMR, UBI and ECS, as well as the multi-parameters inversion seismic data, were adopted to confirm the tight intervals in boreholes and to predicate the possible divided boundaries between wells. In the X oilfield, hundreds of meters pre-salt carbonate reservoir had been confirmed to be laterally connected, i.e., the connected intervals including almost the whole Barra Velha Formation and/or the main parts of the Itapema Formation. However, in the middle and/or the lower sections of pre-salt target layers, the situation changed because there developed many complicated tight bodies, which were formed by intrusive diabase dykes and/or sills and the tight carbonate rocks. Many pre-salt inner-layers diabases in X oilfield had very low porosity and permeability. The tight carbonate rocks mostly developed either during early sedimentary process or by latter intrusion metamorphism and/or silicification. Tight bodies were firstly identified in drilled wells with the help of core samples and logging curves. Then, the continuous boundary were discerned on inversion seismic sections marked by wells. This paper showed the idea of coupling the different OWC units in a deepwater pre-salt carbonate play with complicated tight bodies. With the marking of wells, spatial distributions of tight layers were successfully discerned and predicated on inversion seismic sections.

Deepwater reservoir prediction using broadband seismic-driven impedance inversion and seismic sedimentology in the South China Sea

2018 ◽  
Vol 6 (4) ◽  
pp. SO17-SO29 ◽  
Author(s):  
Yaneng Luo ◽  
Handong Huang ◽  
Yadi Yang ◽  
Qixin Li ◽  
Sheng Zhang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Seismic Data ◽  
Seismic Velocity ◽  
The South China Sea ◽  
Hydrocarbon Exploration ◽  
The South ◽  
Low Frequencies ◽  
China Sea ◽  
Impedance Inversion

In recent years, many important discoveries have been made in the marine deepwater hydrocarbon exploration in the South China Sea, which indicates the huge exploration potential of this area. However, the seismic prediction of deepwater reservoirs is very challenging because of the complex sedimentation, the ghost problem, and the low exploration level with sparse wells in deepwater areas. Conventional impedance inversion methods interpolate the low frequencies from well-log data with the constraints of interpreted horizons to fill in the frequency gap between the seismic velocity and seismic data and thereby recover the absolute impedance values that may be inaccurate and cause biased inversion results if wells are sparse and geology is complex. The variable-depth streamer seismic data contain the missing low frequencies and provide a new opportunity to remove the need to estimate the low-frequency components from well-log data. Therefore, we first developed a broadband seismic-driven impedance inversion approach using the seismic velocity as initial low-frequency model based on the Bayesian framework. The synthetic data example demonstrates that our broadband impedance inversion approach is of high resolution and it can automatically balance between the inversion resolution and stability. Then, we perform seismic sedimentology stratal slices on the broadband seismic data to analyze the depositional evolution history of the deepwater reservoirs. Finally, we combine the broadband amplitude stratal slices with the impedance inversion results to comprehensively predict the distribution of deepwater reservoirs. Real data application results in the South China Sea verify the feasibility and effectiveness of our method, which can provide a guidance for the future deepwater hydrocarbon exploration in this area.

scholarly journals Dynamics of the Askja caldera July 2014 landslide, Iceland, from seismic signal analysis: precursor, motion and aftermath

2017 ◽  
Author(s):  
Anne Schöpa ◽  
Wei-An Chao ◽  
Bradley Lipovsky ◽  
Niels Hovius ◽  
Robert S. White ◽  
...  
Keyword(s):  
Seismic Data ◽  
Signal Analysis ◽  
Slope Failure ◽  
Stable State ◽  
Seismic Signal ◽  
Early Warning Systems ◽  
High Energy ◽  
Stick Slip ◽  
Short Period ◽  
Large Landslide

Abstract. Using data from a network of 58 seismic stations, we characterise a large landslide that occurred at the southeastern corner of the Askja caldera, Iceland, on 21 July 2014, including its precursory tremor and mass wasting aftermath. Our study is motivated by the need for deeper generic understanding of the processes operating not only at the time of catastrophic slope failure, but also in the preparatory phase and during the transient into the subsequent stable state. In addition, it is prompted by the high hazard potential of the steep caldera lake walls at Askja as tsunami waves created by the landslide reached famous tourist spots 60 m above the lake level. Since direct observations of the event are lacking, the seismic data give valuable details on the dynamics of this landslide episode. The excellent seismic data quality and coverage of the stations of the Askja network made it possible to jointly analyse the long- and short-period signals of the landslide to obtain information about the triggering, initiation, timing, and propagation of the slide. The seismic signal analysis and a landslide force history inversion of the long-period seismic signals showed that the Askja landslide was a single, large event starting at the SE corner of the caldera lake at 23:24:05 UTC and propagating to the NW in the following 2 min. The bulk sliding mass was 7–16 × 1010 kg, equivalent to a collapsed volume of 35–80 × 106 m3, and the centre of mass was displaced horizontally downslope by 1260 ± 250 m during landsliding. The seismic records of stations up to 30 km away from the landslide source area show a tremor signal that started 30 min before the main landslide failure. It is harmonic, with a fundamental frequency of 2.5 Hz and shows time-dependent changes of its frequency content. We attribute the complex tremor signal to accelerating and decelerating stick-slip motion on failure planes at the base and the sides of the landslide body. The accelerating motion culminated in aseismic slip of the landslide visible as a drop in the seismic amplitudes down to the background noise level 2 min before the landslide high-energy signal begins. We propose that the seismic signal of the precursory tremor may be developed as an indicator for landslide early-warning systems. The 8 hours after the main landslide failure are characterised by smaller slope failures originating from the destabilised caldera wall decaying in frequency and magnitude. We introduce the term afterslides for this subsequent, declining slope activity after a large landslide.

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