Lithology estimation from a multicomponent 3D-4C OBC seismic survey over a clastic reservoir in the Arabian Gulf

ABSTRACT In 2002, Saudi Aramco conducted its first 3D, 4-component (4C) ocean-bottom cable (OBC) seismic survey in the Arabian Gulf. The main objective was to delineate the middle Cretaceous Upper Khafji Sand Stringers Reservoir overlying the massive Main Khafji Sand Reservoir in the Zuluf field. The Upper Khafji Sand Stringers Reservoir in the Wasia Formation is typically characterized by weak acoustic impedance contrasts. A pre-survey modeling study, based on the logs of compressional (P) and shear-wave (S) velocities (Vp and Vs), indicated that converted compressional-to-shear waves (P-S) could better-image the structure and stratigraphy of the target reservoir. Commensurate with the objectives of the experiment, a pilot 100-square-kilometer survey was acquired with an inline swath-shooting geometry that employed two seabed receiver cables, with a symmetric split-spread deployment of the 4-C sensors. The acquisition geometry consisted of six sail lines per swath with a single-boat, dual-source, flip-flop configuration. The data were processed through dual-sensor summation, horizontal-component rotation and P-P/P-S pre-stack time migration. Post-stack enhancement using non-stationary Gabor deconvolution proved beneficial in compensating for the missing high frequencies in the acquired converted-wave data. Well-to-seismic calibration for both P-P and P-S data at five wells aided in the interpretation of the data. Five horizons were interpreted and correlated between the P-P and P-S sections. The horizons were analyzed using both amplitude and interval times such that the lateral variations of the Vp/Vs ratio of the Upper Khafji Sand Stringers Reservoir could be mapped. A region of low Vp/Vs ratios in the northwest quadrant, obtained from the isochron interval-time analysis, was correlated with higher ‘net sand’ pay at a hidden well located in the middle of this region. These results were further corroborated by seismic facies analysis and provide a qualitative reservoir quality index in the Upper Khafji Sand Stringers Reservoir.

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SEISMIC FACIES ANALYSIS ON 2D SEISMIC REFLECTION PROFILE IN BARUNA AND JAYA LINE AT NORTH EAST JAVA BASIN

JURNAL NEUTRINO ◽

10.18860/neu.v9i1.3665 ◽

2016 ◽

Vol 9 (1) ◽

pp. 15

Author(s):

Taufan Wiguna ◽

Rahadian Rahadian ◽

Sri Ardhyastuti ◽

Safira Rahmah ◽

Tati Zera

Keyword(s):

Facies Analysis ◽

Seismic Profile ◽

Seismic Facies ◽

Seismic Reflection Profile ◽

Reef Facies ◽

North East ◽

Time Migration ◽

Seismic Facies Analysis ◽

External Form ◽

Seismic Reflector

<p class="abstrak">Two dimension (2D) seismic profile of Baruna and Jaya lines at North-East Java Basin show seismic reflector characteristics that can be used to interpret sediment thickness and continuity. Those reflector characteristics that can be applied for seismic facies analysis that represent depositional environment. This study starts from seismic data processing that using Kirchhoff Post Stack Time Migration method which is 2D seismic profile as result. Seismic reflector characterization has been done to both 2D profiles. Seismic reflector characterization was grouped as (i) individual reflection, (ii) reflection configuration, (iii) reflection termination, (iv) external form. Individual reflection characteristics show high and medium amplitude, medium and low frequency, and continuous. Configuration reflection is continuous with parallel and subparallel type. Reflection termination shows onlap, and external form shows sheet drape. Local mound appearance can be interpreted as paleo-reef. Facies seismic anlysis result for this study area is shelf.</p>

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Characterizing a Mississippian tripolitic chert reservoir using 3D unsupervised and supervised multiattribute seismic facies analysis: An example from Osage County, Oklahoma

Interpretation ◽

10.1190/int-2013-0023.1 ◽

2013 ◽

Vol 1 (2) ◽

pp. SB109-SB124 ◽

Cited By ~ 22

Author(s):

Atish Roy ◽

Benjamin L. Dowdell ◽

Kurt J. Marfurt

Keyword(s):

Ground Truth ◽

Seismic Facies ◽

Seismic Survey ◽

Computer Assisted ◽

Seismic Attribute ◽

Self Organizing Maps ◽

Seismic Facies Analysis ◽

Tripolitic Chert ◽

Mississippi Lime ◽

Osage County

Seismic interpretation is based on the identification of reflector configuration and continuity, with coherent reflectors having a distinct amplitude, frequency, and phase. Skilled interpreters may classify reflector configurations as parallel, converging, truncated, or hummocky, and use their expertise to identify stratigraphic packages and unconformities. In principal, a given pattern can be explicitly defined as a combination of waveform and reflector configuration properties, although such “clustering” is often done subconsciously. Computer-assisted classification of seismic attribute volumes builds on the same concepts. Seismic attributes not only quantify characteristics of the seismic reflection events, but also measure aspects of reflector configurations. The Mississippi Lime resource play of northern Oklahoma and southern Kansas provides a particularly challenging problem. Instead of defining the facies stratigraphically, we need to define them either diagenetically (tight limestone, stratified limestone and nonporous chert, and highly porous tripolitic chert) or structurally (fractured versus unfractured chert and limestone). Using a 3D seismic survey acquired in Osage County Oklahoma, we use Kohonen self-organizing maps to classify different diagenetically altered facies of the Mississippi Lime play. The 256 prototype vectors (potential clusters) reduce to only three or four distinct “natural” clusters. We use ground truth of seismic facies seen on horizontal image logs to fix three average attribute data vectors near the well locations, resulting in three “known” facies, and do a minimum Euclidean distance supervised classification. The predicted clusters correlate well to the poststack impedance inversion result.

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A new seismic methodology to significantly improve deeper data character and interpretability on the North West Shelf

The APPEA Journal ◽

10.1071/aj08045 ◽

2009 ◽

Vol 49 (2) ◽

pp. 572

Author(s):

Andrew Long ◽

Guillaume Cambois ◽

Gregg Parkes ◽

Anders Mattsson ◽

Terje Lundsten

Keyword(s):

Beam Steering ◽

Ocean Bottom ◽

Flip Flop ◽

Surface Reflection ◽

North West ◽

The North ◽

Dual Sensor ◽

Shot Point ◽

Different Depths ◽

Marine Seismic

The sea-surface reflection generates interferences between up- and down-going waves that ultimately limit the bandwidth of marine seismic data. This phenomenon known as ghosting actually occurs twice—on the source side and on the receiver side. Ghost attenuation or elimination to increase the signal bandwidth has been the focus of extensive research. The receiver ghost can be removed using dual-sensor ocean-bottom devices (Barr and Sanders, 1989), a dual-sensor towed streamer (Carlson et al, 2007) or an over/under streamer acquisition (Brink and Svendsen, 1987). The over/under technique can also be used to remove the source ghost (Moldoveanu, 2000) but it requires flip-flop shooting of two sources at two different depths, ultimately halving the survey shot-point density. Alternatively, the source ghost can be attenuated using a beam steering technique originally developed some 60 years ago for dynamite land acquisition (Shock, 1950). The principle is to detonate charges at various depths in a sequence that constructively builds the down-going wave at the expense of the up-going wave. This way the energy of the ghost (the surface-reflected up-going wave) is reduced compared to that of the primary pulse. In this paper we adapt the beam steering approach to airgun arrays in the marine environment.

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Seismic acquisition and imaging strategies for unlocking subsurface complexities in Malaysian basins

The Leading Edge ◽

10.1190/tle39080583.1 ◽

2020 ◽

Vol 39 (8) ◽

pp. 583-590

Author(s):

Sandeep K. Chandola ◽

Abdul Aziz Muhamad ◽

Tang Wai Hoong ◽

Faizan Akasyah Ghazali ◽

Ashraf Khalil

Keyword(s):

Survey Design ◽

Waveform Inversion ◽

Integrated Approach ◽

Seismic Survey ◽

Reverse Time ◽

Converted Wave ◽

Imaging Technologies ◽

Time Migration ◽

Seismic Acquisition ◽

Exploration And Development

Seismic data acquisition and imaging technologies have made important contributions to hydrocarbon discoveries and enhancing recovery from existing reservoirs in Malaysian basins. PETRONAS has been leveraging these technologies to address the exploration and development challenges encountered in Malaysian basins and other parts of the world and to support its play-based exploration. Some of the key technology applications include imaging below shallow gas and carbonates, imaging of complex geology for exploring deep water and deep plays, and high-resolution imaging of shallow clastic plays. Dual and multimeasurement streamers, multiazimuth and full-azimuth seismic, triple- and penta-source blended acquisition, and two- and four-component seabed seismic technologies have been integrated with high-end processing and imaging technologies such as advanced demultiple techniques, deblending, full-waveform inversion, reverse time migration, and PS-converted wave imaging to address complex subsurface challenges. In this article, we present an overview of the evolution and application of innovative seismic acquisition and imaging technologies in Malaysian basins. Selected case histories demonstrate how these technologies have enabled explorers to unlock subsurface complexities, adding value to exploration and development activities. We share the advancements in 3D seismic survey design, marine streamer acquisition, seabed seismic acquisition, and seismic imaging technologies, and how an integrated approach helped PETRONAS address geologic challenges to enhance its exploration success.

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Converted-wave Processing of an Ocean Bottom Cable Dataset from the Arabian Gulf

Proceedings 76th EAGE Conference and Exhibition 2014 ◽

10.3997/2214-4609.20140641 ◽

2014 ◽

Author(s):

M.J. Grimshaw ◽

J.P. Holden ◽

E. Murray ◽

K. Shaukat ◽

B. Beck ◽

...

Keyword(s):

Arabian Gulf ◽

Ocean Bottom ◽

Converted Wave

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Vector-based elastic reverse time migration based on scalar imaging condition

Geophysics ◽

10.1190/geo2016-0146.1 ◽

2017 ◽

Vol 82 (2) ◽

pp. S111-S127 ◽

Cited By ~ 52

Author(s):

Qizhen Du ◽

ChengFeng Guo ◽

Qiang Zhao ◽

Xufei Gong ◽

Chengxiang Wang ◽

...

Keyword(s):

Alternative Methods ◽

Polarity Reversal ◽

Reverse Time ◽

Reverse Time Migration ◽

S Wave ◽

Converted Wave ◽

Imaging Condition ◽

Time Migration ◽

Wavefield Separation ◽

Wave Modes

The scalar images (PP, PS, SP, and SS) of elastic reverse time migration (ERTM) can be generated by applying an imaging condition as crosscorrelation of pure wave modes. In conventional ERTM, Helmholtz decomposition is commonly applied in wavefield separation, which leads to a polarity reversal problem in converted-wave images because of the opposite polarity distributions of the S-wavefields. Polarity reversal of the converted-wave image will cause destructive interference when stacking over multiple shots. Besides, in the 3D case, the curl calculation generates a vector S-wave, which makes it impossible to produce scalar PS, SP, and SS images with the crosscorrelation imaging condition. We evaluate a vector-based ERTM (VB-ERTM) method to address these problems. In VB-ERTM, an amplitude-preserved wavefield separation method based on decoupled elastic wave equation is exploited to obtain the pure wave modes. The output separated wavefields are both vectorial. To obtain the scalar images, the scalar imaging condition in which the scalar product of two vector wavefields with source-normalized illumination is exploited to produce scalar images instead of correlating Cartesian components or magnitude of the vector P- and S-wave modes. Compared with alternative methods for correcting the polarity reversal of PS and SP images, our ERTM solution is more stable and simple. Besides these four scalar images, the VB-ERTM method generates another PP-mode image by using the auxiliary stress wavefields. Several 2D and 3D numerical examples are evaluated to demonstrate the potential of our ERTM method.

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