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EAGE Research Workshop - Advances in Seismic Acquisition Technology
- Conference date: 20 Sep 2004 - 23 Sep 2004
- Location: Rhodes, Greece
- Published: 20 September 2004
32 results
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Seismic Reflection Investigations in Isolated Mining Districts of Northern Saskatchewan, Canada
More LessA01 COMPLEXITIES OF MODERN SEISMIC REFLECTION INVESTIGATIONS IN ISOLATED MINING DISTRICTS OF NORTHERN SASKATCHEWAN CANADA Summary 1 Multifaceted Vibroseis surveys established fundamental data acquisition parameters for implementation of the reflection method under severe climatic and logistical settings. The integrated results generated novel comprehensive high-quality subsurface images of the subsurface from near-surface to Moho depth around the McArthur mine the location of the world’s highest grade uranium deposit. The surveys utilized 3-C component Vectorsies detectors in 2-D and 3-D survey configurations. Special operational procedures were created to guarantee functionality of the data acquisition system in an extremely low temperature -35 to
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New Approach on Seismic Survey on Subglacial Lakes
Authors D. Nieto Yabar, L. Baradello, A. Bratus and E. del NegroA02 NEW APPROACH ON SEISMIC SURVEY ON SUBGLACIAL LAKES Abstract 1 The main obiective of ELSA project in December 2003 was to verify the applicability of the reflection sismic method for the definition of subglacial structures in the antarctic icecap.. The purposes of the survey were to verify: the correct operation of the recording system the acquisiton parameters p based on the theoretical models and the quality of the obtainable data by the use of different types of sources and acquisition geometries. Introduction The subglacial lakes are water bodies enclosed between the base of the glacial column and the bedrock.
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HQ & Full Fidelity 3D Land Seismic Data Acquisition – Experiences and Approaches in High Inhabited Areas
Authors S. Giammetti, S. Sandroni, V. Damiani and D. MarzoratiA03 HQ & FULL FIDELITY 3D LAND SEISMIC DATA ACQUISITION – EXPERIENCES AND APPROACHES IN HIGH INHABITED AREAS Introduction 1 The necessity of high resolution 3D seismic data is of paramount importance. Today thanks to the very dramatic development of electronics in the last few years the single sensor/single channel acquisition seems to be the optimal tool. Unfortunately the effective drawbacks discouraging the actual use of this technology are the operative constraints and high costs mainly due to the large recording channel number and the huge amount of data to be managed. This is particularly true in highly inhabited areas
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Comparison of Sensor Positioning Methods in Shallow Water Ocean Bottom Cable Seismic Surveys in the Arabian Gulf
Authors S. Slawson, S. Burns, J. Conner, K. Cook, D. Painter and M. KelleyA04 COMPARISON OF SENSOR POSITIONING METHODS IN SHALLOW WATER OCEAN BOTTOM CABLE SEISMIC SURVEYS IN THE ARABIAN GULF Abstract 1 This paper presents comparisons from various seismic receiver-positioning methods in a wide-azimuth 4component (“4C”) ocean bottom cable seismic survey. Methods presented include parallel oriented positioning (“P”) and cable orientation (“O”) runs acquired prior to 3D production data and orthogonally shot into receiver production (“Production”) data. Seismic data utilized includes direct and refracted first arrivals from field and post acquisition picking. Various cases are provided combining data from “P” “O” and “Production” acquisition. Cases include assumptions and limitations made in each
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Remote Characterization of Hydrocarbon Filled Reservoirs at the Troll Field by Sea Bed Log
Authors S. Ellingsrud, B. Farrelly, C. Ringstad and S.E. Johnstad1 A05 REMOTE CHARACTERIZATION OF HYDROCARBON FILLED RESERVOIRS AT THE TROLL FIELD BY SEA BED LOGGING Introduction SeaBed Logging (SBL) is a remote sensing technique which gives information about subsurface resistivity variations by the use of electromagnetic energy. The method has been demonstrated both theoretically (Kong et al. 2002) and in practice by several calibration and commercial surveys (Ellingsrud et al. 2002 Røsten et al. 2002 Amundsen et al. 2004 and Wicklund and Fanavoll 2004). This abstract presents preliminary results from a scientific SBL survey across the Troll Field. The overall objective of the study is to obtain an improved
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Passive Seismic Acquisition, Methodology & Operational Overlook
Authors N. Martakis, S. Kapotas and G.A. TselentisA07 PASSIVE SEISMIC ACQUISITION METHODOLOGY & OPERATIONAL OVERLOOK Abstract 1 With an increase in exploration activity in geologically complex areas such as fold and thrust belts geophysical methods have to adjust accordingly. Exploration in these areas is promising since they can indicate future “play openers” it is however challenging as well as expensive and it is driving experts in the application of state-of-the-art techniques one such technique is Passive Seismic Tomography. Planning the acquisition of such survey requires both feasibility and acquisition modeling in order to address survey duration and resolution issues the methodology behind these steps will be presented
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Sparse 3D Acquisition in Colombian Foothills – Tangara 3D Survey
Authors J.M. Mougenot, R. Petton and A. CorreaA10 SPARSE 3D ACQUISITION IN COLOMBIAN FOOTHILLS – TANGARA 3D SURVEY Abstract 1 A 3D survey was acquired in 2002-2003 over the Tangara structure in the Llanos basin of Colombia. The sparse 3D design already used by several operators in the foothills of Argentina and Bolivia has also been implemented to acquire this survey. This sparse design is characterised by large shot line and receiver line intervals adapted to the target depth. The lines are also slalomed to avoid the obstacles of this difficult mountainous environment. The processing was performed independently by three processing centres. The Tangara 3D survey confirms
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What Is the 'Point' of High-Resolution 2D 2,880-Channel Acquisition
Authors P.I. Pecholcs, B.R. Maddison and R. Hastings-JamesA11 WHAT IS THE “POINT” OF HIGH-RESOLUTION 2D 2 880-CHANNEL ACQUISITION? Abstract 1 A 2D high-resolution 2 880-channel seismic crew has recently operated in Saudi Arabia for 3 years. The initial single-source line/single-receiver line configuration with “point” receiver arrays (all-pass spatial filter) recorded low signal-to-noise seismic shot gathers which were difficult to enhance in processing resulting in poor seismic imaging. Through uncorrelated noise-strip and synthetic modeling analysis it was confirmed that unfiltered back-scattered energy and coherent/random ambient noise sources were primary causes of degradation of the seismic images. Subsequent in-field acquisition testing revealed that the in-line spatial sampling could be
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The Relationships Between Pre-Stack Migration Resolution and 3D Spatial Sampling with the High Density 3D Method
By A.S. LongA12 THE RELATIONSHIPS BETWEEN PRE-STACK MIGRATION RESOLUTION AND 3D SPATIAL SAMPLING WITH THE HIGH DENSITY 3D METHOD Introduction 1 High Density 3D (HD3D) acquisition pursues a straightforward strategy: The use of dense trace acquisition and tight 3D spatial sampling to provide an optimal platform for subsequent processing operations. In recent years several HD3D surveys both land and marine have provided substantial improvements over the existing data. The following discussion attempts to isolate the significance of certain key elements in the HD3D story notably the issue of resolution after migration. We acknowledge that several issues contribute to improved temporal and spatial
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Sparse 3D Seismic Data Acquisition for Minimum Effort, Cost and Environmental Impact in the Po Valley Italy
More LessA13 SPARSE 3D SEISMIC DATA ACQUISITION FOR MINIMUM EFFORT COST AND ENVIRONMENTAL IMPACT IN THE PO VALLEY ITALY Abstract 1 M. WILKES¹ M. DAVIES¹ L. VILLANI ² H. CROOK¹ K. LATHAM ³ and M. BUNT 4 ¹Bg Group 100 Thames Valley Park Drive Reading Berkshire RG6 1PT UK ²Bg Internationalbv Piazza Cavour 2 Milano 20121 Italy ³Imc Geophysics Limited Po Box 18 Sutton-Ashfield Notts NG17 2NS UK 4 Rps Hydrosearch Goldsworth House Denton Way Woking Surrey GU21 3LF UK Hydrocarbon exploration in the Po Valley Italy has historically relied upon 2D seismic data due to the logistical effort high cost
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High Density 3D – Improved Imaging in Complex Geology
Authors R.M. Lansley and J.W. BogardusA14 HIGH DENSITY 3D – IMPROVED IMAGING IN COMPLEX GEOLOGY Abstract 1 3D seismic surveys have seen increasing usage since the mid-1970s and have been recognized as a primary reason for increased oil exploration success in the last two decades. In the early years most survey designs were restricted by a combination of cost equipment limitations and a lack of understanding of the benefits of good spatial sampling and good offset sampling. Also due to some of the above limitations many surveys were designed with a narrow range of azimuths. Recently there have been significant improvements in technology that now
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Rough Sea Deghosting Using Wave Heights Derived from Low Frequency Pressure Recordings - A Case Study
Authors J.O.A. Robertsson, E. Kragh, R. Laws, L. Amundsen, T. Rösten, T. Davies, K. Zerouk and A. StrudleyA15 ROUGH SEA DEGHOSTING USING WAVE HEIGHTS DERIVED FROM LOW FREQUENCY PRESSURE RECORDINGS – A CASE STUDY Abstract 1 By recording very low frequencies of pressure below 0.5 Hz we are able to estimate the wave heights directly above each hydrophone in the seismic streamer as a function of time. Because of the bandwidth separation this can be done without affecting the simultaneously acquired seismic recordings. These wave height estimates are used to derive deterministic deghosting operators that compensate for the rough sea reflection response. We apply the method to a 2D line acquired in the North Sea using a
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The Impact of Field Survey Characteristics on Surface-Related Multiple Attenuation
Authors B. Dragoset, I. Moore and C. KostovA16 THE IMPACT OF FIELD SURVEY CHARACTERISTICS ON SURFACE-RELATED MULTIPLE ATTENUATION Summary 1 Three particular field survey characteristics – inline spatial sampling source stability and cable feathering – affect the quality of multiples predicted by surface-related multiple attenuation (SRME) algorithms. Careful survey design advanced data acquisition technologies and additional data processing steps can limit their impact. Introduction SRME is commonly practiced as a two-step process. First a multidimensional convolution-like iterative process predicts surface multiples using operators that consist of the recorded seismic traces themselves (Verschuur and Berkhout 1997). Second the predicted multiples are adaptively subtracted from the original traces. Under
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The Next Advances in 3D Marine Acquisition
By R.J. de KokA17 THE NEXT ADVANCES IN 3D MARINE ACQUISITION 1 R. de Kok Geophenture Nijlande 27 9452VA Nijlande The Netherlands 1. Introduction Advances in electronics enabled the acquisition of high fold 3D and 4D seismic data. Over the last decades the number of recorded channels has increased continuously while the cost per trace dropped correspondingly. Within the scope of the technological advances quality limiting issues have only partly been addressed while efforts have mainly been directed towards further decreases in costs. This tendency has applied both to speculative- and proprietary- surveys. It has become apparent that the additional cost for quality
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Acquisition Geometry Influence on Angle-Dependent Amplitudes in a 3D Subsalt Situation
Authors E.J. van Veldhuizen and G. BlaquièreA18 ACQUISITION GEOMETRY INFLUENCE ON ANGLE- DEPENDENT AMPLITUDES IN A 3D SUBSALT SITUATION Abstract 1 A subsurface image that is obtained from seismic data after data processing can be biased by the acquisition geometry: it contains an acquisition footprint. For a proper evaluation of the influence of the acquisition geometry on image quality in areas of complex geology for example in subsalt situations a method is needed that can handle complex situations with irregular structures and large contrasts. Focal beam analysis is a method with a strong link to wave theory and therefore enables a quantitative analysis of image quality
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Infill Decisions Based on Estimated Reflection Amplitudes
Authors M. Brink, N. Jones, J. Doherty, R. Laurain and V. VinjeA19 INFILL DECISIONS BASED ON ESTIMATED REFLECTION AMPLITUDES 1 M. BRINK 1 N. JONES 2 J. DOHERTY 2 R. LAURAIN 3 and V. VINJE 3 1 CGG 1 rue Léon Migaux 91341 Massy France 2 CGG London 3 NORSAR Oslo SUMMARY A velocity/depth model from a seismic data set was used together with the P1/90 navigation data to estimate the subsurface illumination and the migration amplitudes along key horizons. These simulated migration amplitudes can be generated during the acquisition to assess the need for infill shooting. INTRODUCTION Coverage specifications are believed to ensure the successful completion of a 3D survey.
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Vibrator Source Signal Estimation Method by Data Combination
More LessA20 VIBRATOR SOURCE SIGNAL ESTIMATION BY DATA COMBINATION Abstract 1 There is a vibratory source signal estimation technique which is based on the combination of two types of data. They are the measured vibratory acceleration data and the relative information calculated from geophone signals. It has been shown before that the fundamental part of the measured ground force signal – derived from the acceleration functions – can be used to approximate the far field displacement velocity function. Since the higher harmonics are not represented properly especially the odd ones they are estimated from the direct arrivals of the uncorrelated field
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3-D Filter Design on a Hexagonal Grid for Point-Receiver Land Acquisition
Authors A. Özbek, L. Hoteit and G. DumitruA21 3-D FILTER DESIGN ON A HEXAGONAL GRID FOR POINT-RECEIVER LAND ACQUISITION 1 Abstract: Recording seismic data through point receivers rather than analogue receiver arrays has several potential advantages. Design of optimal 3-D digital filters is important to realize this potential. Hexagonal (staggered) spatial sampling is more efficient than rectangular sampling for seismic signals but requires development of special techniques for the design of 3-D filters. We present a method based on the APOCS (Alternating Projections onto Convex Sets) approach for designing optimal 3-D FIR (finite impulse response) filters for digital group-forming. Introduction: Recording seismic data through point receivers rather
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Multi-Dimensional Filtering on Seismic Data Sampled on an Irregular Grid
More LessA22 MULTI-DIMENSIONAL FILTERING OF SEISMIC DATA SAMPLED ON AN IRREGULAR GRID Abstract 1 In this paper we introduce a new technique for multi-dimensional filtering of irregularly sampled seismic data. In this context filtering may be used for coherent noise and interference attenuation as well as the generation of seismic images. The filtering operation consists of the convolution of the filter operator with the seismic data. The filter operator is usually computed on a regular grid (rectangular or hexagonal) that corresponds to the nominal sampling of the seismic data. Unfortunately in the physical world the seismic data are often sampled at
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Ground Viscosity and Stiffness Measurements Using Different Vibrator Control Systems
Authors R. Ley, P. Ras, W. Adolfs and M. Al-HomailiA23 GROUND VISCOSITY AND STIFFNESS MEASUREMENTS USING DIFFERENT VIBRATOR CONTROL SYSTEMS Abstract 1 In early December 2003 Saudi Aramco conducted an experiment measuring ground viscosity (Gv) and stiffness (Gs) using two types of vibrator control systems currently available on its seismic crews. These measured ground attributes (Gv and Gs) are used to derive near surface velocity data that can be then used to interpolate between uphole locations. The measurements were taken over 2x2km grid an area large enough to sample varying terrain conditions: unconsolidated sand and limestone outcrop. The grid spacing of the measurements was similar to the spacing used
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Principles Behind Vector Acquisition
Authors P.W. Maxwell, D.N. Burch and C.J. CrissA25 PRINCIPLES BEHIND VECTOR ACQUISITION Summary 1 The subject of vector acquisition is a new but developing topic initiated through the advances in seismic sensor technology with the introduction of digital MEMS based accelerometers that make multi-component measurement economically viable. The term vector acquisition can also be expressed as full wave-field recording. Traditionally seismic acquisition has employed pwave geophones sensing in a single axis nominally vertical. However the true earth motion is only fully described in a three dimensional space. The multiplicity of wave trains arriving at the receiver can make the local ground move in any direction. If the
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Recent Advances in Point Receiver Technology – Are Field Arrays a Requirement Any Longer?
Authors D.J. Tessman, M. Bahorich and D. MonkA26 RECENT ADVANCES IN POINT RECEIVER TECHNOLOGY – ARE FIELD ARRAYS A REQUIREMENT ANY LONGER? Summary: 1 The recent introduction of full wavefield (i.e. multicomponent) point receiver technology has rekindled an ongoing debate amongst geophysicists as to the suitability of point receivers for use in the acquisition of standard compressional (P-wave) seismic data. Conventional wisdom tells most geophysicists that for a variety of reasons P-wave data should be acquired using arrays of receivers (and sources). While the spatial dimensions and number of elements deployed varies greatly throughout the world it is nonetheless common practice to employ some form of array.
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OBC Signal Fidelity
Authors M. Johnson, M. Norris and M. WalshA27 OBC SIGNAL FIDELITY Abstract 1 A simple definition of signal fidelity is “the accuracy of the reproduction of the true ground motion by the complete recording system”. This definition while simple is also quite restrictive and moves beyond the concept of “vector fidelity”. OBC signal fidelity can be compromised in many ways. A few of the more common ways are: temporal and spatial sampling recording filters spiking due to cable leakage or telemetry errors geophone resonances and noise due to gimbal mechanisms geophone noise due to cable interactions geophone coupling with the sea bottom and environmental noise (bottom currents
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Vector-Fidelity Benefits of Buried OBC Detectors at Teal South
By J.E. GaiserA28 VECTOR-FIDELITY BENEFITS OF BURIED OBC DETECTORS AT TEAL SOUTH Summary 1 Coupling of detectors on the seafloor is well understood and has been characterized by damped oscillatory systems that vary in amplitude and phase as a function of frequency. Furthermore this response is very different than the response on land due to inertial effects of water. When seafloor motion is out of phase with water motion larger resonances and phase distortions can result. However this phenomenon should be alleviated for permanently installed detectors that are buried below the seafloor and provide near-perfect coupling for time-lapse observations. At Teal South
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Field Trial of a 4C Fiber Optic Seabed System
Authors S. Maas, J. Bunn, B. Bunn, R. Metzbower, J. Bowlus and J. BielinskiA29 FIELD TRIAL OF A 4C FIBER OPTIC SEABED SYSTEM SUMMARY 1 A fiber optic 4C seabed cable has been successfully demonstrated in the North Sea. The cable design and performance is reviewed. A 2400 m array length with 4C sensor stations located every 25 m was tested in a water depth of 300 m. The cable was tested in shallow water and is relatively short in seismic acquisition terms. However we have demonstrated in the lab the optical systems capabilities beyond 3000 m depth and 12 km array lengths with channel counts in excess of 2000. In the field
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Design and Implementation of Wide-Azimuth 4C OBC Seismic in the Arabian Gulf
Authors S. Slawson, S. Burns, M. Fenton and D. PainterA30 DESIGN AND IMPLEMENTATION OF WIDE- AZIMUTH 4C OBC SEISMIC IN THE ARABIAN GULF Abstract 1 We describe the design and implementation of a ~147 km 2 full fold (~250 km 2 surface area) wideazimuth multi-component (“4C”) 3D seismic survey over the Idd El Shargi North and South Domes offshore Qatar. This survey is being used to delineate fracture orientation and fracture density in producing carbonate Shuaiba reservoirs and is one of the few wide-azimuth marine 4C surveys over carbonate reservoirs. Challenges of seismic operations in these actively producing oil fields are presented along with methods to mitigate the impact
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Solid Streamers and Single Hydrophones
Authors M. Brink and J. SpackmanA31 SOLID STREAMERS AND SINGLE HYDROPHONES Summary 1 Solid streamers are less sensitive to weather-related noise than liquid streamers. Hence with the solid streamers the operational weather window can be extended. In addition solid streamers can be towed shallower without a prohibitive increase in noise. The application of noise filters on single hydrophones in a solid streamer only yields marginal improvements over application of the same filters on hydrophone groups. These improvements do not justify the introduction of single hydrophone recording. For reduction of weather noise a hydrophone spacing of 3 m may be adequate for solid streamers. However the
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A New Look and an Old Source
Authors J. Ross, W.J. Mooney and D. MonkA33 A NEW LOOK AND AN OLD SOURCE Introduction 1 In this paper we examine the performance and operation of a controllable surface referenced weight drop system which has the capability of generating very high amplitude but manageable impacts. The source is compared to conventional dynamite and the potential benefits are demonstrated. Background Seismic surveys conducted using weight drop sources have been used for many years but have fallen out of favor recently. Two years ago we examined the potential for high impact energy sources where a weight was dropped from a high altitude. While it was possible to generate
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Optimization of Swell Noise Specifications as Part of Survey Design
Authors J.M. Mougenot, O. Zdraveva and K. KravikA34 OPTIMIZATION OF SWELL NOISE SPECIFICATIONS AS PART OF SURVEY DESIGN Abstract 1 A swell noise simulation was carried out during the survey design of a 3D acquisition planned by Total in the Norwegian Sea. The motivation for this study was that reprocessing of previous 2D data in the area had shown great sensitivity to swell noise of some programs of the forecasted 3D processing sequence (especially shot interpolation and pre-stack migration in time or in depth). Swell noise contaminated records were simulated by adding real noise records to shot points recorded in quiet conditions. The full processing sequences (Pre-Stack
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Acquisition Design Loop and Predictions of Seismic Qualities
Authors P. Meldahl, A. Jakobsen and C. StrandA35 ACQUISITION DESIGN LOOP AND PREDICTIONS OF SEISMIC QUALITIES Introduction 1 Fundamental issues in the acquisition design loop are acquisition specifications seismic qualities seismic cost and seismic payback. In this paper we discuss the design loop from a user perspective and present a method for predictions of seismic qualities based on seismic modeling. This method is efficient because it is automated simplified and separated in two loops. We define “notional seismic qualities”. These qualities can be convolved with the target response and quickly display the image quality of any target shape. By splitting the prediction of seismic qualities in two
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Rich Azimuth Marine Acquisition
By M.S. HowardA36 RICH AZIMUTH MARINE ACQUISITION 1 M.S. HOWARD 1 BHP Billiton 1360 Post Oak Blvd. Suite 500 Houston Texas 77056 USA There are many areas of complex velocity structure such as sub-salt areas in the Gulf of Mexico where improvements in depth imaging and noise removal have given better images. However there are many areas some known to contain large accumulations of hydrocarbons where the images are inadequate for cost effective appraisal and development and other areas where better images could open new exploration opportunities. Throughout the history of seismic processing computer power has been a limiting factor leading to
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Mitigating Noise in Seismic Surveys with an "Acoustic Blanket
Authors W.S. Ross, P.J. Lee, S.E. Heiney, E.N. Drake, R. Tenghamn and A. StenzelA37 MITIGATING NOISE IN SEISMIC SURVEYS WITH AN "ACOUSTIC BLANKET" Summary 1 For several years we have been conducting research on the use of bubble curtains (and more generally physical masking devices) to suppress marine noises. The research initially focussed on suppressing multiples in marine seismic acquisition by placing a bubble curtain at the bounce point of the multiple on the air-water interface. ExxonMobil conducted successful small-scale field tests of the method at its seismic test facility in Houston. ExxonMobil and Petroleum Geo-Services (PGS) conducted an offshore field test in early 2002 to establish the fundamentals of the bubble curtain
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