A comparative study of multi-scaled high-resolution seismic surveys in shallow marine environments: examples from three sites, offshore Korea

2020 ◽  
Author(s):  
Young Jun Kim ◽  
Snons Cheong ◽  
Deniz Cukur ◽  
Dong-Geun Yoo
Keyword(s):  
High Resolution ◽  
Data Processing ◽  
Seismic Data ◽  
Single Channel ◽  
Seismic Source ◽  
Seismic Survey ◽  
Minimum Length ◽  
Seismic Surveys ◽  
Air Gun ◽  
Target Depth

<p>In marine seismic surveys, various acquisition systems are used depending on the survey purpose, target depth, survey environment, and conditions. A 3D survey of oil and/or gas exploration, for instance, require large-capacity air-gun arrays and six or more streamers with a minimum length of 6 km. In contrast, a high-resolution seismic survey for the shallow-water geological research and engineering needs a small capacity source such as air-gun, sparker, and boomer, deployed with a single-channel or multi-channel (24-channel) streamers. The main purpose of our seismic survey was to investigate the Quaternary geology and stratigraphy of offshore, Korea. Because the Quaternary is the most recent geological period, our target depth was very shallow at about 50 m below the sea-bottom. We used a high-frequency seismic source including a sparker of 2,000 J capacity or a 60 in<sup>3</sup> mini GI-gun and an eight-channel streamer with a 3.125 m group interval or a single-channel streamer that included 96 elements. To compare the resolution of seismic data according to the seismic source, a boomer or sparker systems were used with the single-channel streamer on a small survey ship. The seismic data processing was performed at the Korea Institute of Geoscience and Mineral Resources (KIGAM) with ProMAX, and the data processing and resolution of each survey were compared based on their acquisition systems.</p>

Locating faults in underground coal mines using high‐resolution seismic reflection techniques

Geophysics ◽  
1989 ◽  
Vol 54 (12) ◽  
pp. 1521-1527 ◽  
Author(s):  
Lawrence M. Gochioco ◽  
Steven A. Cotten
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Seismic Reflection ◽  
Coal Mines ◽  
Seismic Source ◽  
Seismic Survey ◽  
Underground Coal Mines ◽  
Vertical Displacements ◽  
Seismic Sections ◽  
Mine Development

A high‐resolution seismic reflection technique was used to locate faults in coal seams that were not visible on the surface and could only be observed in underground coal mines. An 8‐gauge buffalo gun, built by the research and development department of Consolidation Coal Company, was used as the seismic source. The coal seam at a depth of 700 ft produces a reflection with a predominant frequency of about 125 Hz. The high‐resolution seismic data permitted faults with vertical displacements of the same magnitude as the seam thickness to be detected at depths of several hundred feet beneath the surface. Several faults were detected and interpreted from the seismic sections, and the magnitudes of their displacement were estimated by matching the recorded seismic data to synthetic seismic data. Subsequent underground mine development in the study area confirmed two interpreted faults and their estimated displacements. Mining engineers were able to use the information provided by the seismic survey to plan an entry system through the fault zone so that less rock needed to be mined, resulting in a safer and more productive mine.

High‐resolution 3-D seismic survey over a coal mine reserve area in the U.S.—A case study

Geophysics ◽  
2000 ◽  
Vol 65 (3) ◽  
pp. 712-718 ◽  
Author(s):  
Lawrence M. Gochioco
Keyword(s):  
High Resolution ◽  
Coal Mine ◽  
Seismic Data ◽  
Longwall Mining ◽  
Three Dimensional ◽  
Seismic Source ◽  
Seismic Survey ◽  
Geologic Structure ◽  
Reserve Area ◽  
Mine Development

A high‐resolution three‐dimensional (3-D) seismic survey was conducted in advance of coal mine development in the Illinois basin in May 1989 to better define a geologic structure with the potential to adversely affect longwall mining conditions. The 3-D seismic data indicate that an abrupt change in seam elevation, or roll, encountered near the northern property line trends south into the reserve area and then turns southeast. A personal computer‐based workstation was used to integrate borehole and seismic data for modeling in which 3-D block diagrams of the calculated seam elevations were generated. The block diagrams show a steep slope on the west flank of the roll that gradually decreases as the roll turns to the southeast. The survey also reveals a geologic structure beneath the roll at an estimated depth of 46–62 m. Horizontal time‐slice sections of this feature suggest the presence of a paleochannel that meanders on a similar course as the roll, which apparently was connected to a larger paleochannel system. A Conoco high‐frequency vibroseis unit was successfully used as the seismic source to generate the high frequencies necessary to detect and resolve the thin coal beds.

DEMETER HIGH RESOLUTION 3D SEISMIC SURVEY—REVITALISED DEVELOPMENT AND EXPLORATION ON THE NORTH WEST SHELF, AUSTRALIA

2006 ◽  
Vol 46 (1) ◽  
pp. 101 ◽  
Author(s):  
K.J. Bennett ◽  
M.R. Bussell
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
New Technologies ◽  
Seismic Survey ◽  
Future Application ◽  
3D Seismic ◽  
Gas Field ◽  
North West ◽  
The North ◽  
Exploration And Development

The newly acquired 3,590 km2 Demeter 3D high resolution seismic survey covers most of the North West Shelf Venture (NWSV) area; a prolific hydrocarbon province with ultimate recoverable reserves of greater than 30 Tcf gas and 1.5 billion bbls of oil and natural gas liquids. The exploration and development of this area has evolved in parallel with the advent of new technologies, maturing into the present phase of revitalised development and exploration based on the Demeter 3D.The NWSV is entering a period of growing gas market demand and infrastructure expansion, combined with a more diverse and mature supply portfolio of offshore fields. A sequence of satellite fields will require optimised development over the next 5–10 years, with a large number of wells to be drilled.The NWSV area is acknowledged to be a complex seismic environment that, until recently, was imaged by a patchwork of eight vintage (1981–98) 3D seismic surveys, each acquired with different parameters. With most of the clearly defined structural highs drilled, exploration success in recent years has been modest. This is due primarily to severe seismic multiple contamination masking the more subtle and deeper exploration prospects. The poor quality and low resolution of vintage seismic data has also impeded reservoir characterisation and sub-surface modelling. These sub-surface uncertainties, together with the large planned expenditure associated with forthcoming development, justified the need for the Demeter leading edge 3D seismic acquisition and processing techniques to underpin field development planning and reserves evaluations.The objective of the Demeter 3D survey was to re-image the NWSV area with a single acquisition and processing sequence to reduce multiple contamination and improve imaging of intra-reservoir architecture. Single source (133 nominal fold), shallow solid streamer acquisition combined with five stages of demultiple and detailed velocity analysis are considered key components of Demeter.The final Demeter volumes were delivered early 2005 and already some benefits of the higher resolution data have been realised, exemplified in the following:Successful drilling of development wells on the Wanaea, Lambert and Hermes oil fields and identification of further opportunities on Wanaea-Cossack and Lambert- Hermes;Dramatic improvements in seismic data quality observed at the giant Perseus gas field helping define seven development well locations;Considerably improved definition of fluvial channel architecture in the south of the Goodwyn gas field allowing for improved well placement and understanding of reservoir distribution;Identification of new exploration prospects and reevaluation of the existing prospect portfolio. Although the Demeter data set has given significant bandwidth needed for this revitalised phase of exploration and development, there remain areas that still suffer from poor seismic imaging, providing challenges for the future application of new technologies.

WARROON GAS DISCOVERY SUPPORTS EXPLORATION OF ANTICLINES

1981 ◽  
Vol 21 (1) ◽  
pp. 85
Author(s):  
B. R. BROWN
Keyword(s):  
Seismic Data ◽  
Acoustic Impedance ◽  
Gas Condensate ◽  
Seismic Survey ◽  
Seismic Surveys

Warroon, a small gas condensate discovery in the western Surat Shelf, was mapped as a faulted anticline from seismic data shot in April 1979. The discovery well was drilled in August 1979 on the then highest known point of the mapped closure. The well flowed up to 8 MMcf/D from about 2.4 m (eight feet) of Showgrounds Sandstone over the gross interval 2 048 to 2 060 m (6 720 to 6 760 ft). Subsequently, two small seismic surveys comprising 62 km and including experimental shooting and acoustic impedance processing have been shot over the anticline. A step-out will be considered in the 1981 drilling program.The discovery of gas and condensate in Warroon, and in the Glen Fosslyn discovery in an adjacent permit, optimistically suggests that the prospective area of the Wunger Ridge may be extended. A major seismic survey comprising over 450 km of 12-fold 96 channel recording was shot in the Spring of 1980. The interpretation of the data could lead to proposals to drill a number of wildcats on structures similar in appearance to Warroon.

scholarly journals Seismic reflection imaging of a geothermal aquifer in an urban setting

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1285-1294 ◽  
Author(s):  
Lee Liberty
Keyword(s):  
Seismic Reflection ◽  
Seismic Source ◽  
Urban Setting ◽  
Seismic Survey ◽  
Quality Data ◽  
Signal Quality ◽  
Fracture Permeability ◽  
Air Gun ◽  
Explosive Source ◽  
Geothermal Aquifer

A seismic reflection survey that was conducted in downtown Boise, Idaho, to help city planners site a new well for injection of spent geothermal water illustrates some methods to safely and successfully employ a seismic reflection survey in an urban setting. The objective of the seismic survey was to estimate the depth and continuity of a basalt and rhyolite volcanic sequence. Well siting was based on geothermal aquifer depth, location of interpreted faults, projected thermal impact of injection on existing wells, surface pipe extension costs, and public land availability. Seismic acquisition tests and careful processing were used to ensure high‐quality data while minimizing the potential for damage along city streets. A video camera placed in a sewer and a blast vibration monitor were used to confirm that energy from the seismic source (a 75-in3 land air gun) did not damage nearby buildings, street surfaces, or buried utilities along the survey lines. Walkaway seismic tests were also used to compare signal quality of the air‐gun source to an explosive source for imaging targets up to 800 m depth. These tests show less signal bandwidth from the air‐gun source compared to the buried explosive source, but the air‐gun signal quality was adequate to meet imaging objectives. Seismic reflection results show that the top of this rhyolite/basalt sequence dips (∼8–11°) southwest away from the Boise foothills at depths of 200 to 800 m. Seismic methods enabled interpretation of aquifer depths along the profiles and located fault zones where injected water may encounter fracture permeability and optimally benefit the existing producing system. The acquisition and processing techniques used to locate the Boise injection well may succeed for other hydrogeologic and environmental studies in urban settings.

Fluid dynamics at the base of hydrate-bearing sediments at the Vestnesa Ridge inferred from 5 years of high-resolution 4D seismic surveying

2020 ◽  
Author(s):  
Malin Waage ◽  
Stefan Bünz ◽  
Kate Waghorn ◽  
Sunny Singhorha ◽  
Pavel Serov
Keyword(s):  
High Resolution ◽  
Gas Hydrate ◽  
Seismic Data ◽  
Time Lapse ◽  
Stability Zone ◽  
Seismic Surveys ◽  
Free Gas ◽  
4D Seismic ◽  
Hydrate Bearing Sediments ◽  
Hydrate Stability

<p>The transition from gas hydrate to gas-bearing sediments at the base of the hydrate stability zone (BHSZ) is commonly identified on seismic data as a bottom-simulating reflection (BSR). At this boundary, phase transitions driven by thermal effects, pressure alternations, and gas and water flux exist. Sedimentation, erosion, subsidence, uplift, variations in bottom water temperature or heat flow cause changes in marine gas hydrate stability leading to expansion or reduction of gas hydrate accumulations and associated free gas accumulations. Pressure build-up in gas accumulations trapped beneath the hydrate layer may eventually lead to fracturing of hydrate-bearing sediments that enables advection of fluids into the hydrate layer and potentially seabed seepage. Depletion of gas along zones of weakness creates hydraulic gradients in the free gas zone where gas is forced to migrate along the lower hydrate boundary towards these weakness zones. However, due to lack of “real time” data, the magnitude and timescales of processes at the gas hydrate – gas contact zone remains largely unknown. Here we show results of high resolution 4D seismic surveys at a prominent Arctic gas hydrate accumulation – Vestnesa ridge - capturing dynamics of the gas hydrate and free gas accumulations over 5 years. The 4D time-lapse seismic method has the potential to identify and monitor fluid movement in the subsurface over certain time intervals. Although conventional 4D seismic has a long history of application to monitor fluid changes in petroleum reservoirs, high-resolution seismic data (20-300 Hz) as a tool for 4D fluid monitoring of natural geological processes has been recently identified.<br><br>Our 4D data set consists of four high-resolution P-Cable 3D seismic surveys acquired between 2012 and 2017 in the eastern segment of Vestnesa Ridge. Vestnesa Ridge has an active fluid and gas hydrate system in a contourite drift setting near the Knipovich Ridge offshore W-Svalbard. Large gas flares, ~800 m tall rise from seafloor pockmarks (~700 m diameter) at the ridge axis. Beneath the pockmarks, gas chimneys pierce the hydrate stability zone, and a strong, widespread BSR occurs at depth of 160-180 m bsf. 4D seismic datasets reveal changes in subsurface fluid distribution near the BHSZ on Vestnesa Ridge. In particular, the amplitude along the BSR reflection appears to change across surveys. Disappearance of bright reflections suggest that gas-rich fluids have escaped the free gas zone and possibly migrated into the hydrate stability zone and contributed to a gas hydrate accumulation, or alternatively, migrated laterally along the BSR. Appearance of bright reflection might also indicate lateral migration, ongoing microbial or thermogenic gas supply or be related to other phase transitions. We document that faults, chimneys and lithology constrain these anomalies imposing yet another control on vertical and lateral gas migration and accumulation. These time-lapse differences suggest that (1) we can resolve fluid changes on a year-year timescale in this natural seepage system using high-resolution P-Cable data and (2) that fluids accumulate at, migrate to and migrate from the BHSZ over the same time scale.</p>

Single water gun far‐field pressure signatures estimated from near‐field measurements

Geophysics ◽  
1985 ◽  
Vol 50 (2) ◽  
pp. 257-261 ◽  
Author(s):  
M. H. Safar
Keyword(s):  
High Resolution ◽  
Data Acquisition ◽  
Seismic Data ◽  
Near Field ◽  
Field Measurements ◽  
Reference Source ◽  
Far Field ◽  
Air Gun ◽  
Seismic Data Acquisition ◽  
Marine Seismic

An important recent development in marine seismic data acquisition is the introduction of the Gemini technique (Newman, 1983, Haskey et al., 1983). The technique involves the use of a single Sodera water gun as a reference source together with the conventional air gun or water gun array which is fired a second or two after firing the reference source. The near‐field pressure signature radiated by the reference source is monitored continuously. The main advantage of the Gemini technique is that a shallow high;resolution section is recorded simultaneously with that obtained from the main array.

scholarly journals Cetacean behavioral responses to noise exposure generated by seismic surveys: how to mitigate better?

2016 ◽  
Vol 59 (4) ◽  
Author(s):  
Clara Monaco ◽  
Jesús M. Ibáñez ◽  
Francisco Carrión ◽  
L. Mario Tringali
Keyword(s):  
Noise Exposure ◽  
Behavioral Responses ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Mitigation Measures ◽  
Seismic Surveys ◽  
Reflection Seismic ◽  
Joint Nature Conservation Committee ◽  
Air Gun ◽  
Southern Mediterranean

<p>Cetaceans use sound in many contexts, such as in social interactions, as well as to forage and to react in dangerous situations. Little information exists to describe how they respond physically and behaviorally to intense and long-term noise levels. Effects on cetaceans from seismic survey activities need to be understood in order to determine detailed acoustic exposure guidelines and to apply appropriated mitigation measures. This study examines direct behavioral responses of cetaceans in the southern Mediterranean Sea during seismic surveys with large airgun arrays (volume up to 5200 ci) used in the TOMO-ETNA active seismic experiment of summer 2014. Wide Angle Seismic and Multi-Channel Seismic surveys had carried out with refraction and reflection seismic methods, producing about 25,800 air-gun shots. Visual monitoring undertaken in the 26 daylights of seismic exploration adopted the protocol of the Joint Nature Conservation Committee. Data recorded were analyzed to examine effects on cetaceans. Sighting rates, distance and orientation from the airguns were compared for different volume categories of the airgun arrays. Results show that cetaceans can be disturbed by seismic survey activities, especially during particularly events. Here we propose many integrated actions to further mitigate this exposure and implications for management.</p>

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