An overview of seismic azimuth for towed streamers

Long, Andrew

doi:10.1190/1.3422448

Cited by 9 publications

(5 citation statements)

References 10 publications

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“…Meanwhile, the measurements consisted of increasing the observation azimuth, improving the illumination of subsurface geologic bodies in all directions, and enhancing the accuracy of velocity analysis and the S/N of the data, all of which are favorable for preserving true AVO and azimuth AVO characteristics (Long, 2010).…”

Section: Key Issuesmentioning

confidence: 99%

Carbonate reservoirs dominated by secondary storage space: Key issues and technical strategy

et al. 2015

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Carbonate reservoirs of the Tarim Basin in China are buried deeply, with strong later diagenesis, and seldom are controlled by geologic facies. The effective storage spaces are mainly dissolution caves and fractures with few primary pores. Fluid distribution in the reservoir is extremely complicated. All these characteristics make it a world-class challenge for oil and gas exploration and production. Conventional poststack methods ignore the complexity of the reservoir medium with low accuracy of prediction results, by which the location of the dissolution cave is determined roughly. Only faults and fracture zones can be described to a certain degree instead of quantifying the fracture detection. Aiming at the key problems of the complex carbonate reservoirs in the Tarim Basin, a series of techniques has been developed to improve the successful rate of reservoir prediction, including the following aspects: the wide-azimuth and high-density data-acquisition technique to improve the quality of the original seismic data; a series of migration techniques including prestack reverse time migration; and amplitude-preserved Q migration to improve the quality of seismic gathers and the imaging precision with the matching precision of AVO gathers. The target reservoir data dominant frequency increased by more than 15% and by nearly 20 Hz. In addition, the effective DEM-Gassmann rock-physics model is proposed for velocity prediction, by which relative error of estimated shearwave velocity reaches to less than 5%. Furthermore, an advanced inversion algorithm is introduced to improve the accuracy of extracted elastic information. By using new prestack inversion and frequency-dependent AVO inversion, the tie rate of the dissolution-cave reservoir and fluid prediction increased by more than 15%. Furthermore, the fracture-prediction tie rate can be enhanced by 20% through limited-azimuth anisotropic inversion, on the basis of which the quantitative identification of fracture fluid for actual seismic data can be realized.

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Section: Key Issuesmentioning

confidence: 99%

Carbonate reservoirs dominated by secondary storage space: Key issues and technical strategy

et al. 2015

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“…Both FD modeling and imaging and ray tracing-based analysis were pursued with 3D models built from existing GOM 3D seismic datasets and SEAM synthetic data. Whilst a uniformly-populated rose diagram of offsetazimuth distribution for the average of all survey shot locations can be easily obtained (refer to Figure 2), and as commonly published by various authors, the design of a shooting template that delivers uniform offset-azimuth sampling between adjacent bins proved far more challenging (refer also to Long, 2010). The final shooting template established with the vessel configuration for each of the survey azimuths is shown in Figure 3.…”

Section: Multi-vessel Full-azimuth Acquisition Geometrymentioning

confidence: 99%

No-compromise marine seismic: A full-azimuth survey design for total-wavefield velocity model building and imaging in the deep-water Gulf of Mexico

Long

Campbell

Fishburn

et al. 2014

SEG Technical Program Expanded Abstracts 2014

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A first-ever five-vessel towed streamer configuration with all vessels participating in a simultaneous shooting scheme is presented that delivers uniformly-sampled offset-azimuth bin populations. With a maximum offset of 16 km, the survey has been designed to illuminate all potential targets below extensive and rugose salt cover in the Garden Banks and Keathley Canyon areas of the Gulf of Mexico, including ultra-deep sub-salt plays such as the BP Tiber discovery. TTI RTM anisotropic pre-stack depth imaging of both primary and surface multiple seismic events is facilitated by true wavefield separation of dual-sensor streamer data. The latter imaging pursuit, separated wavefield imaging (SWIM) exploits subsurface sampling (illumination) substantially more dense and spatially-extensive than traditional primaries-only imaging as each of the 13,000 receivers associated with each shot become secondary sources. 18 second continuous recording will ensure several orders of multiples are recorded from all target depths. Ghost-free acquisition will also improve deep sub-salt signal penetration, whilst simultaneously providing the broadest bandwidth data required for shallow geohazard imaging.

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“…Besides spatial sampling density, acquisition azimuth is also an important factor affecting seismic imaging and reservoir characterization. Compared with narrow acquisition geometry, wide-azimuth acquisition is beneficial to improving reservoir illumination, velocity model and signal-to-noise ratio, and therefore improving the seismic imaging of complex structures and fracture characterization of fractured reservoirs (Moldoveanu and Egan, 2006;Long, 2010).…”

Section: Introductionmentioning

confidence: 99%

The First Land Full Azimuth Seismic for Fractured-Cavernous Carbonate Reservoirs Exploration in Tarim Basin, Western China

et al. 2013

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U.S.A., Ordovician carbonate reservoirs are the very important yet difficult targets in the oil and gas exploration and development of Tarim basin, western China. The main task (also main challenge) of seismic is to image and predict the storage spaces of carbonate reservoirs-the secondary dissolved caves, holes and fractures, which are buried in more than 6500m deep. The target formations are usually in very low signal-to-noise ratio due to the seismic attenuation and the caves and fractures are small and aligned in random directions. Narrow azimuth and conventional wide azimuth seismic fail to image and identify the fracturedcavernous reservoirs accurately, leading to many drilling failures. Here, the effects of some key acquisition parameters such as bin size, fold and aspect ratio on carbonate reservoirs imaging accuracy are carefully examined using seismic forward modeling and new analysis methods. A high-density full-azimuth seismic acquisition was carried out based on the above analysis and the results show that small bin size has the advantage to imaging the ultra-deep carbonate reservoirs and the fracture prediction results from full azimuth data well agree with that from imaging well logging data. A set of well drillings based on the full azimuth data have been proved to be successful.

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An overview of seismic azimuth for towed streamers

Cited by 9 publications

References 10 publications

Carbonate reservoirs dominated by secondary storage space: Key issues and technical strategy

Carbonate reservoirs dominated by secondary storage space: Key issues and technical strategy

No-compromise marine seismic: A full-azimuth survey design for total-wavefield velocity model building and imaging in the deep-water Gulf of Mexico

The First Land Full Azimuth Seismic for Fractured-Cavernous Carbonate Reservoirs Exploration in Tarim Basin, Western China

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