Marine seismic acquisition: efficiency and environment, new technologies applied in Australia

2017 ◽  
Vol 57 (2) ◽  
pp. 704 ◽  
Author(s):  
Martin Bayly ◽  
Michelle Tham ◽  
Peter Watterson ◽  
Binghui Li ◽  
Kevin Moran
Keyword(s):  
Environmental Impact ◽  
New Technologies ◽  
New Technology ◽  
Seismic Exploration ◽  
Exposure Level ◽  
North West ◽  
Optimal Output ◽  
Air Gun ◽  
Seismic Acquisition ◽  
Marine Seismic

The design of successful marine seismic surveys is driven by many factors, two prime issues being efficiency and environmental impact. Efficiency is primarily driven by reduction of non-productive time and creating the largest sub-surface illumination area possible in the shortest time. In addition, public opinion and governmental regulations are requiring the industry to minimise their environmental impact. One aspect is reducing the overall sound exposure level (SEL) of the source into the marine environment. Using recent Australian examples, we will discuss and demonstrate the use of two new technology groups that address these concerns. The first is the use of a new type of seismic air-gun with optimal output over the range of frequencies commonly used in seismic exploration, while limiting potential environmental effects from unnecessary high-frequency emissions. The second is continuous data acquisition along the entire boat traverse, including the turns, thereby reducing non-productive vessel time. Both are described with examples from a recent survey acquired offshore north-west Australia.

Shot repetition: An alternative seismic blending code in marine acquisition

Geophysics ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. P29-P37 ◽  
Author(s):  
Sixue Wu ◽  
Gerrit Blacquière ◽  
Gert-Jan Adriaan van Groenestijn
Keyword(s):  
Source Code ◽  
Seismic Exploration ◽  
Data Quality Control ◽  
Time Data ◽  
Alternative Source ◽  
Seismic Surveys ◽  
Air Gun ◽  
Seismic Acquisition ◽  
Marine Seismic ◽  
Source Encoding

In blended seismic acquisition, or simultaneous source seismic acquisition, source encoding is essential at the acquisition stage to allow for separation of the blended sources at the processing stage. In land seismic surveys, the vibroseis sources may be encoded with near-orthogonal sweeps for blending. In marine seismic surveys, the sweep type of source encoding is difficult because the main source type in marine seismic exploration is the air-gun array, which has an impulsive character. Another issue in marine streamer seismic data acquisition is that the spatial source sampling is generally coarse. This hinders the deblending performance of algorithms based on the random time delay blending code that inherently requires a dense source sampling because they exploit the signal coherency in the common-receiver domain. We have developed an alternative source code called shot repetition that exploits the impulsive character of the marine seismic source in blending. This source code consists of repeated spikes of ones and can be realized physically by activating a broadband impulsive source more than once at (nearly) the same location. Optimization of the shot-repetition type of blending code was done to improve the deblending performance. As a result of using shot repetition, the deblending process can be carried out in individual shot gathers. Therefore, our method has no need for a regular dense source sampling: It can cope with irregular sparse source sampling; it can help with real-time data quality control. In addition, the use of shot repetition is beneficial for reducing the background noise in the deblended data. We determine the feasibility of our method on numerical examples.

Randomized sampling and sparsity: Getting more information from fewer samples

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. WB173-WB187 ◽  
Author(s):  
Felix J. Herrmann
Keyword(s):  
Compressive Sensing ◽  
Sampling Method ◽  
New Technology ◽  
Seismic Exploration ◽  
Transform Domain ◽  
Sampled Data ◽  
Randomized Sampling ◽  
Seismic Acquisition ◽  
Small Factor ◽  
Incoherent Sampling

Many seismic exploration techniques rely on the collection of massive data volumes that are subsequently mined for information during processing. Although this approach has been extremely successful in the past, current efforts toward higher-resolution images in increasingly complicated regions of the earth continue to reveal fundamental shortcomings in our workflows. Chiefly among these is the so-called “curse of dimensionality” exemplified by Nyquist’s sampling criterion, which disproportionately strains current acquisition and processing systems as the size and desired resolution of our survey areas continue to increase. We offer an alternative sampling method leveraging recent insights from compressive sensing toward seismic acquisition and processing for data that are traditionally considered to be undersampled. The main outcome of this approach is a new technology where acquisition and processing related costs are no longer determined by overly stringent sampling criteria, such asNyquist. At the heart of our approach lies randomized incoherent sampling that breaks subsampling related interferences by turning them into harmless noise, which we subsequently remove by promoting transform-domain sparsity. Now, costs no longer grow significantly with resolution and dimensionality of the survey area, but instead depend only on transform-domain sparsity. Our contribution is twofold. First, we demonstrate by means of carefully designed numerical experiments that compressive sensing can successfully be adapted to seismic exploration. Second, we show that accurate recovery can be accomplished for compressively sampled data volumes sizes that exceed the size of conventional transform-domain data volumes by only a small factor. Because compressive sensing combines transformation and encoding by a single linear encoding step, this technology is directly applicable to acquisition and to dimensionality reduction during processing. In either case, sampling, storage, and processing costs scale with transform-domain sparsity. We illustrate this principle by means of number of case studies.

Modeling air gun signatures in marine seismic exploration considering multiple physical factors

2010 ◽  
Vol 7 (2) ◽  
pp. 158-165 ◽  
Author(s):  
Guo-Fa Li ◽  
Ming-Qiang Cao ◽  
Hao-Lin Chen ◽  
Cheng-Zhou Ni
Keyword(s):  
Seismic Exploration ◽  
Physical Factors ◽  
Air Gun ◽  
Marine Seismic

scholarly journals Estimating source signatures from source-over-spread marine seismic data

Geophysics ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. P39-P48
Author(s):  
Kristian Svarva Helgebostad ◽  
Martin Landrø ◽  
Vetle Vinje ◽  
Carl-Inge Nilsen
Keyword(s):  
Field Data ◽  
Forward Modeling ◽  
Inversion Algorithm ◽  
Surface Reflection ◽  
Air Gun ◽  
Recent Developments ◽  
Seismic Acquisition ◽  
The Difference ◽  
Marine Seismic ◽  
Bubble Oscillations

Recent developments in marine seismic acquisition include deploying a source vessel above a towed-streamer spread. We have developed an inversion algorithm to estimate source signatures for such acquisition configurations, by minimizing the difference between the recorded and a modeled direct wave. The forward modeling is based upon a physical modeling of the air bubble created by each air gun in the source array, and a damped Gauss-Newton approach is used for the optimization. Typical inversion parameters are empirical damping factors for the bubble oscillations and firing time delays for each air gun. Variations in streamer depth are taken into account, and a constant sea-surface reflection coefficient is also estimated as a by-product of the inversion. For data acquired in shallow waters, we have developed an extension of the forward modeling to include reflections from the water bottom to stabilize the inversion. The algorithm is tested on synthetic- and field-data examples, and the estimated source signature for the field-data example is used in a designature processing flow.

How can we reduce the environmental impact of marine seismic surveys?

2019 ◽  
Vol 59 (2) ◽  
pp. 909
Author(s):  
Andrew Long ◽  
Mickael Bastard ◽  
Endrias Asgedom ◽  
Jens Fredrik Wisløff ◽  
Magnus Christiansen
Keyword(s):  
Environmental Impact ◽  
Acoustic Pressure ◽  
Acoustic Energy ◽  
Seismic Sources ◽  
Exposure Level ◽  
Seismic Surveys ◽  
Sound Exposure ◽  
Environmental Controls ◽  
Marine Source ◽  
Marine Seismic

Marine seismic sources emit acoustic energy in the form of the seismic wavefield used for the remote sensing of subsurface impedance contrasts in the earth. The environmental impact of seismic sources is typically measured in terms of impulsive acoustic pressure (the sound pressure level, SPL) and the accumulated acoustic energy (the sound exposure level, SEL). We use global examples of the following marine source concepts to quantify the relative SPL and SEL in each scenario: • Large arrays of air guns activated simultaneously with no significant overlap in emitted acoustic pressure, • Small arrays of air guns activated simultaneously or in rapid succession with overlap in emitted acoustic pressure, • Individual air guns activated continuously with overlap in emitted acoustic pressure, and • Towed marine vibrators operated continuously. Continuous sources clearly have the lowest SPL and SEL. Examples from various basin settings are shown where benefits in data quality and survey efficiency may also complement the lower environmental impact. Another surprising geophysical outcome is that continuous sources with low SPL do not have compromised signal penetration to deep target depths compared to traditional large arrays of air guns activated simultaneously. These outcomes are relevant to how future marine seismic surveys might be designed to meet stricter environmental controls as well as presenting various new opportunities for how the surveys could be acquired more efficiently and processed.

scholarly journals On low frequencies emitted by air guns at very shallow depths — An experimental study

Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. P61-P71 ◽  
Author(s):  
Daniel Wehner ◽  
Martin Landrø ◽  
Lasse Amundsen
Keyword(s):  
Large Volume ◽  
Field Experiments ◽  
Field Measurements ◽  
Seismic Source ◽  
Sea Surface ◽  
Frequency Signal ◽  
Low Frequencies ◽  
Air Gun ◽  
Seismic Acquisition ◽  
Marine Seismic

In marine seismic acquisition, the enhancement of frequency amplitudes below 5 Hz is of special interest because it improves imaging of the subsurface. The frequency content of the air gun, the most commonly used marine seismic source, is mainly controlled by its depth and the volume. Although the depth dependency on frequencies greater than 5 Hz has been thoroughly investigated, for frequencies less than 5 Hz it is less understood. However, recent results suggest that sources fired very close to the sea surface might enhance these very low frequencies. Therefore, we conduct dedicated tank experiments to investigate the changes of the source signal for very shallow sources in more detail. A small-volume air gun is fired at different distances from the water-air interface, including depths for which the air bubble bursts directly into the surrounding air. The variations of the oscillating bubble and surface disturbances, which can cause changes of the reflected signal from the sea surface, are explored to determine whether an increased frequency signal below 5 Hz can be achieved from very shallow air guns. The results are compared with field measurements of a large-volume air gun fired close to the sea surface. The results reveal an increased signal for frequencies below 5 Hz of up to 10 and 20 dB for the tank and field experiments, respectively, for the source depth at which the air gun bubble bursts directly into the surrounding air. For large-volume air guns, an increased low-frequency signal might also be achieved for sources that are slightly deeper than this bursting depth. From these observations, new design considerations in the geometry of air-gun arrays in marine seismic acquisition are suggested.

“Single bubble” air‐gun array for deep exploration

Geophysics ◽  
1993 ◽  
Vol 58 (3) ◽  
pp. 366-382 ◽  
Author(s):  
F. Avedik ◽  
V. Renard ◽  
J. P. Allenou ◽  
B. Morvan
Keyword(s):  
Energy Content ◽  
Low Frequency ◽  
Pulse Generation ◽  
Acoustic Energy ◽  
Petroleum Exploration ◽  
Single Bubble ◽  
Seismic Exploration ◽  
Deep Penetration ◽  
Air Gun ◽  
Marine Seismic

Large tuned air‐gun arrays operated in off‐shore petroleum exploration are also used for deep penetration marine seismic reflection surveys conducted to define structures in the earth’s crust. Because of the attenuation of higher frequencies, the useful upper frequency limit of these records is usually about 50–60 Hz. The aim of this paper is to report on a method of seismic pulse generation that preferentially concentrates the air gun’s energy in the low range of the seismic frequency band by centering the output on the first “bubble pulse” instead of the initial (primary) pulse. Experimental results show that, due to the increased low‐frequency energy content of this “single bubble” pulse, air‐gun arrays considerably reduced both in size and volume can generate the necessary acoustic energy for deep seismic exploration.

Minimizing Acoustic Environmental Impact of Marine Seismic Exploration

2018 ◽  
Author(s):  
John R. Tulett ◽  
Robert M. Laws ◽  
Mehul Supawala ◽  
Jon-Fredrik Hopperstad ◽  
David Gerez
Keyword(s):  
Environmental Impact ◽  
Seismic Exploration ◽  
Marine Seismic

scholarly journals NEW TECHNOLOGIES OF SEISMIC EXPLORATION IN UKRAINE

2021 ◽  
pp. 78-83
Author(s):  
Ivan GAFYCH ◽  
Ievgenii SOLODKYI ◽  
Sergii IARESHCHENKO ◽  
Yurii RENKAS
Keyword(s):  
Oil And Gas ◽  
New Technologies ◽  
New Technology ◽  
Pilot Project ◽  
High Density ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Mountain Areas ◽  
Oil And Gas Producers ◽  
Field Works

Development of technologies, growth of trends of reducing impact on environment and challenging tasks, which oil and gas producers face, make introduction of new technologies in seismic exploration field unavoidable. As a key tool of prospecting, exploration and reconnaissance of hydrocarbons, seismic exploration is usually restricted by terrain conditions. Urban, wooded and marshy lands, protected areas, river valleys, mountain areas often make seismic exploration impossible or signifi cantly impact its quality and efficiency.   One of the modern trends enabling resolution of the issues related to impact on environment is to switch to cable-free registration systems (wireless seismic), so called low impact seismic. Due to the use of cable-free equipment, this new technology makes it possible to reduce impact on environment during field works, as equipment is delivered to the place of installation with no special heavy machinery involved.  On the other hand, cable-free systems of seismic acquisition allow to resolve complex tasks of exploration and appraisal studies. Firstly, carry out exploration of hard-to-reach territories, including protected environmental areas, which until now remain unexplored or slightly explored. Managing seismic cables in such conditions is very complicated or impossible. Cable-free technologies allow easily resolving such issues due to both minimum impact on environment and simple and quick placement of receivers. Flexibility and easy scaling of wireless seismic adds to its advantages versus conventional survey. Kilometres of wires are not needed, which allows to easily increase the number of receiver channels and conduct high-density full azimuth seismic survey with single seismic receivers at deep structures, thus, significantly increasing quality of the data received.  The pilot project successfully completed at Khoroshivska area by joint efforts of DTEK Oil&Gas LLC and LLC Denimex Geo LLC confi rms in full advantages of wireless solutions revealing new opportunities for the use of seismic exploration at areas previously hard to reach and allowing implementation of high density acquisition projects. 

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