Note that the final step can never be successfully completed without the platform of proper target illumination and wavefield sampling. James keggin, seismic quality and technology manager for bp egypt. Yanchak, dennis 2 1 gulf of mexico deepwater exploration, bp, houston, tx. Although they are more costly than conventional 3d naz acquisitions, the main benefits of wide azimuth seismic data are an improved target illumination, a better sn ratio due to the contributions from different azimuths during the stacking of each 3d azimuth cube, and a better multiple attenuation moldoveanu, 2006. Wide azimuth acquisition waz wide azimuth acquisition can be useful when acquiring data for subsalt plays. Seismic acquisition and processing from basics to modern. On including nearsurface zone anisotropy for static. Blended source single sided full azimuth ocean bottom seismic. This course is an introductory course designed for individuals who work with seismic data. The resulting angle between the source and receivers, is about 20. Wide azimuth, longoffset seismic data allow azimuthal anisotropy and direction resulting from the presence of natural fractures and anisotropic in situ stress to be estimated.
Geophysics plays a critical role in the oil and gas industry. Because current waz interpretation is not yet mature and because of the lack of key techniques and tools for ovtdomain seismic interpretation, abundant offset and. This second edition has been extended considerably. While the development of 3d marine seismic acquisition since the 1980s has been.
Under this assumption, waves propagate from seismic sources, interact with discontinuities and return to the surface as reflected seismic waves. We are used to the convenience of acquiring overlapping shot gathers in straight lines, as we can sort the data into common. A land supercrew has yielded substantial improvements in productivity that enabled. Azimuth and offset in design of successful 3d survey, by. Secondly, offset vector tile ovt processing, which is convenient for azimuthal anisotropy analysis, is a new technique for wideazimuth seismic processing and beneficial for improving the.
Quite often accompanying this delay in reflection arrivalbest observed on farangle azimuthal gathers and manifests itself as time is a noticeable decrease in amplitude and frequency content ofvelocity variations as a function of trace shotreceiver azimuth. Wide azimuth seismic processing for uae carbonate reservoir. James and steve are among the many dedicated and innovative people who have seen that progress in wide and multi azimuth seismic technology has resulted in impressive enhancement of subsalt seismic. Find out more about seismic acquisition and processing from basics to modern concepts from hot engineering on. A progression in survey effort from one vessel towing sources and streamers sailing a survey area in two or more directions to several vessels sailing a survey area in two or more directions, some of them possibly only towing sources, represents the operational contrasts between multi azimuth maz, wide azimuth waz, and full azimuth faz 3d seismic. Heloise lynn specializes in the expression and use of anisotropy in multidimensional datasets multi azimuth, multicomponent, and time lapse, 3d azimuthal seismic acquisition design, azimuthal seismic processing, and azimuthal seismic interpretation. In common with other types of inverse problems, the results obtained from reflection seismology are usually not unique more than one model adequately fits the data and may be sensitive to relatively small errors in data collection, processing, or analysis. The application of broadband, wideazimuth and highdensity bwh seismic data processing technology in deep complex structure.
The topic of anastasia pooles electure is wide azimuth acquisition with radial domain interpolation for fluvial morphology interpretation. The azimuth information derived from prestack seismic data at target layers is very sensitive to many aspects of the analysis process, making reliability a serious issue. Conventional marine seismic data acquired using a single vessel to tow one or two seismic source arrays in front of a receiver spread. Wide azimuth seismic processing for uae carbonate reservoir characterization authors jeanluc.
The method includes deploying streamer and source vessels to acquire seismic data along a survey line. This pilot processing study enabled to set up an operational wide azimuth processing sequence on this dataset, several processing scenarii could be tested and compared. Careful processing and imaging, will collectively deliver an optimum result ramsden et al. Richazimuth towedstreamer acquisition schlumberger. Abstract wide azimuth seismic acquisition wats vastly. An ultra high density, full wide azimuth seismic survey for the future jeanjacques postel cggveritas 2nd finding petroleum event on onshore seismic. As a wide azimuth seismic processing method, the offset vector tile ovt technique provides the most effective and precise data domain in geophysics for the basic seismic processing. In addition to the full processing capabilities, tgs offers a full range of reservoir services in order to integrate the obs seismic with well logs, simultaneous andor joint. As available channel count has increased over the years, the 3d geometries have evolved into wide azimuth. Widenarrow azimuth acquisition footprints and their effects.
A seismic shift cggveritas wideazimuth technology represents seismic shift in gulf of mexico. In an industry where the pace for new acquisition technology is often slow, the rapid acceptance of marine wideazimuth towed streamer acquisition methods as the new standard in deep water gulf of. Technological evolution creates super basin renaissance. Sep 19, 2017 a progression in survey effort from one vessel towing sources and streamers sailing a survey area in two or more directions to several vessels sailing a survey area in two or more directions, some of them possibly only towing sources, represents the operational contrasts between multi azimuth maz, wide azimuth waz, and full azimuth faz 3d seismic. A marine seismic data acquisition method using one or more seismic vessels to obtain a combination of multiazimuth and wide azimuth geometries. The course is designed to familiarize the student with the latest developments in marine seismic acquisition including wide azimuth with its many geometry variants, broadband techniques boosting the high and low frequencies, seabed receivers for both pwave and convertedwave recording, simultaneous source acquisition, and methodologies to improve. In an industry where the pace for new acquisition technology is often slow, the rapid acceptance of marine wide azimuth towed streamer acquisition methods as the new standard in deep water gulf of. Progressing from 2d to 3d seismic data has been the foremost advantage in defining and delineating most of the complex geology and the associated hydrocarbon accumulations in the world. The application of broadband, wideazimuth and highdensity. A rich azimuth seismic dataset can be formed by combining the data where multiple wide azimuth surveys intersect. The survey was designed to address the subsurface challenges of the permian basin such as shallow karsting. Many technological developments of the past 10 years have been included. The first edition of this book was a slightly modified version of my dissertation defended in february 2001.
During this presentation she will demonstrate how an. The ideas and results discussed in this book should help one to achieve a better understanding of the structure of 3d acquisition geometries. The method requires a controlled seismic source of energy, such as dynamite or tovex blast, a specialized air gun or a seismic vibrator, commonly known by the trademark name vibroseis. Seismic signatures and analysis of reflection data in. The hti velocity anisotropy was unexpected, being suspected only after the initial poor stack response compared to vintage 2d sections in the area, and the sparse 3d design made it difficult to identify. Jul 27, 2011 a narrated presentation that provides an overview of wide azimuth data processing. Although the main text for this edition was ready by the end of 2010, some developments in the field of seismic data acquisition that occurred in 2011 and 2012 have still been included.
This geometry allows the data to be subdivided into azimuth sectors, so that stacks of different illumination directions can be generated. B shows zerodegree azimuth angle gathers from swim, which are sampled much more finely than the gathers from imaging with primaries only shown in a. Widenarrow azimuth acquisition footprints and their. Analysing the plots of the offset and azimuth distributions.
The method described in the following section is appropriate for 3d wide azimuth waveequation imaging. Preferably, the source vessels will be positioned along side of the towed streamer configuration and most preferably. Supervise seismic data processing activities to preserve azimuthally dependent parameters such as travel times, frequency, phase, and avo. Wideazimuth towedstreamer acquisition schlumberger oilfield. Offset vector tile domain wideazimuth prestack seismic. A first challenge was to reprocess these data ensuring. Yet new technology specifically wide azimuth seismic data acquisition and processing workflows, combined with new drilling techniques and tools have led operators to major discoveries on the mexican side, snedden said. Finally rose diagram is compared for wide azimuth geometry in two shooting schemes.
Conventional seismic imaging is based on the concept of single scattering. As available channel count has increased over the years, the 3d geometries have evolved into wide azimuth, long offset layouts. Processing technology of broadband, wideazimuth and high. Blended source single sided full azimuth ocean bottom. Since 2005, secondary 3d seismic acquisition has been conducted in the raoyang sag, using the uniform observation acquisition system with wide azimuth, high coverage, and high density. Wideazimuth processing for reservoir characterization. Subsequent processing is exactly as for nonblended conventional acquisition.
The azimuth information of seismic data was enhanced by using wide. The course compares wideazimuth towed streamer seismic acquisition as. Novel seismic processing approach is even more important in case of the. Gc azimuth and offset in design of successful 3d survey by. It addresses the imaging issues common to this area by recording a wider range of azimuths and offsets than conventional narrow azimuth acquisition techniques. Seismology of azimuthally anisotropic media and seismic.
Us7391673b2 method of wide azimuth seismic acquisition. Mine wide installations utilize multiple, autonomous seismic networks located both underground and on the surface. It is generally ascribed either to complex fracturing under differential horizontal stresses or gravitational effects that make the media stiffer in one direction than another. A marine seismic data acquisition method that uses one or more vessels to tow source arrays and streamers to record seismic signals, along with one or more sourceonly vessels sailing parallel to, but at some specified distance from, the recording vessels. Azimuthal processing for fracture prediction and image. Case studies in atwater valley, mississippi canyon and green canyon areas propes, russell 1. The book presents a systematic analysis of seismic signatures for azimuthally anisotropic media and describes anisotropic inversionprocessing methods for wideazimuth reflection data and vsp vertical seismic profiling surveys. Advanced marine seismic acquisition techniques eage.
B shows zerodegree azimuth angle gathers from swim, which are sampled much more finely than the. May 23, 2010 based wideazimuth surveys for improved subsalt imaging, geophysics, upon the convenience of established narrowazimuth naz 73 4, x4x6. Steve hill, andreas ruger segs course notes series, accepted, to be published in 2020. Recent advances in insitu stress estimation through. Wide azimuth processing for reservoir characterization. In combination with fine seismic data interpretation, structural details and fault features. Construct workflows using multiattribute seismic data to characterize unconventional reservoirs. In fact, most early 3d seismic surveys were narrow azimuth, although it was probably a matter of necessity as much as intentional design. The sourceonly vessels provide offset sources that generate reflections from a wide range of azimuths. A variety of short to long offset source positions are used for a wide range of sourcereceiver azimuths. This casestudy demonstrates seismic processing in the presence of horizontal transverse isotropic hti velocity anisotropy encountered in a lowfold land 3d survey in new zealand. This can be done by measuring how seismic velocities and amplitudes vary as a function of the acquisition azimuth. Seismic anisotropy an overview sciencedirect topics.
Wide azimuth acquisition is one of the primary techniques being used in gulf of mexico surveys. Seismic anisotropy is the dependence of velocity on propagation direction or angle of the seismic signal within the geological medium. Narrowazimuth seismic data schlumberger oilfield glossary. Seismic prospecting an overview sciencedirect topics. Wideazimuth towedstreamer acquisition schlumberger. Wide azimuth seismic acquisition wats vastly improves subsalt resolution in the deepwater gom. Chasing the faults within a permian carbonate using wide.
Pwave seismic processing that can identify these variations in the subsurface and take advantage of them will produce sharper images and improved fracture predictions. This is a very effective and efficient method of acquiring wide azimuth seismic in deep water in extremely challenging environments, tim explains. Seismic amplitude is an invaluable daytoday tool for graduate students and industry professionals in geology, geophysics, petrophysics, reservoir engineering, and all subsurface disciplines making regular use of seismic data. Land seismic data was acquired over a permian carbonate field with a wide azimuth acquisition template, such that the recorded 3d seismic data is inherently sourcetodetector azimuth rich. On wide azimuth pp surface seismic data, hti anisotropy is this azimuth. Schlumberger announces completion of multiclient wide. Reflection seismology or seismic reflection is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the earths subsurface from reflected seismic waves. Blended source single sided full azimuth ocean bottom seismic acquisition c. Offset vector tile for wideazimuth seismic processing. Obstacles in the analysis of azimuth information from prestack seismic data. Obstacles in the analysis of azimuth information from. In particular the sequence for attenuation of multiples was considered efficient, bringing a lot of character to the final result.
The discussion of the acquisition and processing of 3d seismic data is intended to promote an understanding of important data quality issues. Wide azimuth or waz is a term describing a seismic data acquisition technique where separate source vessels are used to record seismic reflections from areas out to the side of the recording spread. Nine 3d seismic surveys were acquired in different periods with a total area of 2032 km 2. According to a preferred aspect of the instant invention, there is provided a system and method for acquiring seismic data in a marine environment, wherein at least two source vessels are used in conjunction with a recording vessel which tows a plurality of hydrophone cables. In partnership with the dagang oilfield, we used the channel sand body seismic physical model to study the characteristics of widenarrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging.
Processing technology of broadband, wideazimuth and highdensity bwh seismic data. The magnitude and azimuth of the maximum and minimum townsend 1998 has analysed the near. Over the last years, wide azimuth waz seismic data collection techniques have. Challenges and solutions in wide azimuth seismic data processing. Technology explained successful results bp is still processing the data from the atlantis field survey and are encouraged by the results so far. Blended source single sided full azimuth ocean bottom seismic acquisition acknowledgements the authors would like to thank the apache corporation and fairfieldnodal management for permission to present this paper and the crews of the cpacer, fairfield new venture and european supporter for their sterling efforts offshore. Acquiring more azimuths for improved offshore seismic. Narrow versus wideazimuth land 3d seismic surveys researchgate.
There is a method for acquiring seismic data over a survey area. Recent advances in marine seismic acquisition and processing. Houston, march 27, 2020schlumberger in cooperation with breckenridge geophysical, llc announce the completion of the acquisition and processing of the mckenzie draw 3d wide azimuth waz multiclient survey covering 412 mi 2 in martin, andrews, dawson and gaines counties, texas. Using highdensity obc seismic data to optimize the andrew. The book presents a systematic analysis of seismic signatures for azimuthally anisotropic media and describes anisotropic inversion processing methods for wide azimuth reflection data and vsp vertical seismic profiling surveys. Seismology of azimuthally anisotropic media and seismic fracture characterization seg geophysical references series no. The survey was designed to address the subsurface challenges of the permian basin such as shallow karsting, salt. Interested in studying seismic acquisition and processing from basics to modern concepts. Feedback from students attending my course on 3d survey design has helped clarify various notsoclear discussions in the book. Figures compare a wideazimuth acquisition consisting of a patch of 12 lines with 60 stations per line in the top row a, c, e to a do. The use of multi azimuth and wide azimuth acquisition to improve target illumination was discussed earlier.
Geophysical data are used by exploration and production personnel to ascertain the presence, nature and size of subsurface rock layers and reservoirs contained therein. The following paper discusses various azimuthal processing techniques used to identify azimuthal velocity anomalies and azimuthal avo anomalies. Prestack seismic data and azimuthal waz wide azimuth seismic processing can help in the identification of sweet spots in csg resource plays through detailed reservoiroriented gather conditioning followed by prestack seismic inversion and multiattribute analysis. Wideazimuth land processing the leading edge geoscienceworld. Those individuals may be processing geophysicists, seismic interpreters or acquisition specialists. Conclusions highdensity wideazimuth land seismic has been a combined effort of both acquisition and processing. Assess the relevance of various seismic attributes from azimuth sectored prestack time migrated 3d data. Key seismic survey technologies for deep complex geological. At present, the study on acquisition footprints has become a hot spot.
Oyewoga cggveritas introduction many seismic processing techniques, particularly migration, have strict requirements on the regular spatial distribution of traces. Wide azimuth deepwater seismic society of exploration. The offset vector tile ovt is a special prestack seismic gather type, and ovt technology is a seismic processing technology suitable for wide azimuth seismic waz exploration. Seismic event locations, magnitude estimates, and other processed data are. Us20140241118a1 combined wide and narrow azimuth seismic. Abstract we present in this work an exhaustive seismic study which was performed on a subset of a wide azimuth ocean bottom cable seismic acquisition shot over a carbonate field from the u.
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