Riaz Alai

Petronas (Malaysia)

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D. J. Verschuur

Delft University of Technology

C.L. Slind

Petronas (Malaysia)

Jan Thorbecke

Delft University of Technology

Saeeda Hydal

Schlumberger (British Virgin Islands)

Pongga Wardaya

Pertamina (Indonesia)

Rizki Krishna Pratama

Pertamina (Indonesia)

Nik Nur Halim C Soh

Petronas (Malaysia)

M. Shah Sulaiman

Petronas (Malaysia)

M Afiq B Mokhtar

Jabatan Perkhidmatan Awam Malaysia

Yonghe Guo

State Grid Corporation of China (China)

Cooperative Institutions

Petronas (Malaysia)

Schlumberger (British Virgin Islands)

GGG (France)

University of Edinburgh

Universiti Teknologi Petronas

Chinese Academy of Sciences

Delft University of Technology

Shell (Netherlands)

Schlumberger (Norway)

University of British Columbia

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Improving Seismic Velocity Estimation Through Separation Of Seismic Diffractions And Specular Reflections

All Days (2011)

Riaz Alai M.H. Mad Zahir Amar Ghaziah M. Adnan Eric D.J. Verschuur

This reference is for an abstract only. A full paper was not submitted for this conference. Abstract For optimized imaging and subsequent interpretation of subsurface structures, we need to estimate a velocity-depth model from seismic data records. To minimize the risk in oil and gas exploration, it is crucial to estimate the velocities very accurately, since they form the basis for generating reliable imaging results. However if the earth's subsurface contains many complex discontinuities, the recorded data will contain a large amount of diffraction energy that may mask the accurate estimation of velocities primarily derived from specular reflections. Several scientists have developed methodologies to separate diffraction data from specular reflections; in this paper we illustrate the successful application of the proposed method including many of its advantages in data processing, imaging and interpretation. The separation of diffractions from specular reflections in seismic recorded data has several advantages. Although diffraction energy plays an important role in fault and fractures identification and characterization, initial data interpretation is often done on specular reflections for better understanding the mapping of subsurface structures and stratigraphy. In the examples shown in this abstract, the main emphasis is on the improved velocity estimation on specular reflection data after diffraction energy has been suppressed. Especially in the velocity analysis phase, diffraction energy may mask the desired velocity information extracted from specular reflections. Of course, during the final imaging stage the original data is used again. Based on some data examples it will be illustrated that the suppression of diffraction energy clearly improves the velocity picking and, thereby, yields a more accurate estimation of the velocity-depth model. The examples confirm that a systematic application of the methodology of separating seismic diffractions from the total recorded wave fields is essential and provides better control of locating faults and fractures optimally. On the other hand specular reflection imaging will be better interpretable.

Classification of discontinuities

Reflection

10.2523/iptc-14788-abstract

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Aiming towards imaging beneath basalt : multiple suppression offshore Faroe Islands

6th International Congress of the Brazilian Geophysical Society (2003)

Riaz Alai D. J. Verschuur

This paper discusses the successful suppression of surface related multiples from a marine seismic line recorded offshore the Faroe Islands in the Atlantic Ocean. The subsurface in this area is characterized by a mixture of igneous rocks and sediments. The presence of Tertiary basalt layers within the various sediments has created a very large acoustic impedance contrast. Propagation velocities within the basalt are much higher than those in the surrounding sedimentary layers. This dramatic difference results in a very poor imaging below the basalt. Additionally, the reflection data is contaminated by very strong multiples which mask any interpretable events eneath the basalt. In this paper some results are presented on the successful suppression of strong surface related multiples.

Large igneous province

Flood basalt

Reflection

10.3997/2214-4609-pdb.168.arq_500

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Improved subsalt imaging in Brazil Campos basin — Cascaded application of hybrid interbed demultiple, P- and S-salt velocity joint migration, and subsalt converted wave suppression

Second International Meeting for Applied Geoscience & Energy (2022)

Riaz Alai Faqi Liu Darrell Armentrout David Brookes Terry C. Johnson

The pre-salt play of Brazil Santos and Campos Basins has been the hot-spot for oil and gas companies since 2006 due to significant discoveries made and large volume of Yet-to- Find to chase. Seismic imaging plays a critical role in the success of companies from exploration to development of this major play. The pre-salt play is capped by thick salt with highly variable geometries and stratigraphy that leads to significant imaging and illumination challenges. It requires seismic data acquisition and processing programs specially tailored based on those challenges and learnings from the pre-salt imaging. In this abstract, we present the cascaded application of three critical technologies to improve the subsalt imaging in Brazil Campos basin data: hybrid interbed demultiple, P- and S-salt velocity joint migration, and subsalt converted wave suppression. We will showcase in detail through examples the significant benefits of these cascaded applications to ensure subsalt images are more accurate and the true geology can be revealed, rather than being distorted through interbed multiples and converted waves related, particularly, to the stratified salt and carbonate layers.

10.1190/image2022-3740399.1

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An alternative workflow for demultiple and PZ summation for two component OBC data - A 2D case study

Riaz Alai S. Maitra

Summary Traditionally PZ summation has been done before any demultiple processes for Ocean Bottom Cable (OBC) - PP type of processing. However, every now and then this question does come up - "Would the PZ summation be more effective if the P (pressure) and Z (particle velocity) components went through the demultiple process first? ". Through this case study we have attempted to understand this question better and see if we can improve the PP image by first removing the multiples and then following this with PZ summation. The test is executed on two 2D lines acquired in an area which presents a case of large amounts of multiple generated from shallow gas bodies. Both, demultiple and PZ summation processes have been optimized separately for each case (i.e. demultiple before and after deghosting). We will show from our examples that the PZ summation done on demultiple data gives a better PZ summation result and also ends up producing cleaner gathers and stacks as compared to performing demultiple after PZ summation. This leads us to establish a new paradigm for an alternative approach to processing PP data, especially in multiple rich environments.

Component (thermodynamics)

10.1190/segam2014-1234.1

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Abstract: Separation of Seismic Diffractions and Specular Reflections: A Tool for Improved Processing, Imaging and Interpretation (Geophysics Poster 21)

Riaz Alai Muhammad Zahir Amar Ghaziah Eric D.J. Verschuur

Geophysical Imaging

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Improving Predrilling Views by Pseudo Seismic Borehole Data

Riaz Alai

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Establishing Novel Views on Reservoir Compartmentalization Utilizing Systematic Data-driven Seismic Processing Frameworks

Proc of Indonesian Petroleum Association 42nd Annual Convention (2018)

Riaz Alai

Compartmentalization (fire protection)

10.29118/ipa19.g.126

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The generation of pseudo VSP data: Field data example

Riaz Alai Kees Wapenaar

PreviousNext No AccessSEG Technical Program Expanded Abstracts 1994The generation of pseudo VSP data: Field data exampleAuthors: Riaz Alá'iC. P. A. WapenaarRiaz Alá'iDelft University of Technology, The Netherlands and C. P. A. WapenaarDelft University of Technology, The Netherlandshttps://doi.org/10.1190/1.1932127 SectionsAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail Permalink: https://doi.org/10.1190/1.1932127FiguresReferencesRelatedDetails SEG Technical Program Expanded Abstracts 1994ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 1994 Pages: 1679 publication data© 1994 Copyright © 1994 Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 10 Feb 2005 CITATION INFORMATION Riaz Alá'i and C. P. A. Wapenaar, (1994), "The generation of pseudo VSP data: Field data example," SEG Technical Program Expanded Abstracts : 463-466. https://doi.org/10.1190/1.1932127 Plain-Language Summary PDF DownloadLoading ...

10.1190/1.1932127

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In Search for Optimal Seismic Data Acquisition through Illumination

Riaz Alai Jan Thorbecke

In this paper a strategy is outlined to analyze illuminating beams for optimally locating target zones, and optimally acquiring all necessary seismic data. Illumination analysis of wave propagation through the earth’s subsurface plays a very important role, in locating shadow zones and target prospects, to optimize the success of exploration wells. Using illuminating beams for optimal data acquisition design and data processing provides a unique integrated and cascaded tool for insight and interpretation of target prospects. The quality and accuracy of seismic images is being calculated from weighted energy distributions along areas that are dominantly contributing to potential oil and gas reservoirs. During illumination analysis, migration parameters are being determined to locate target images in shortest time. The a priori integration of seismic data acquisition design and optimal imaging of target zones minimizes the overall expenses for seismic data acquisition, data processing, and high costs of exploration wells.

Data Processing

10.3997/2214-4609.20145782

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Enhanced Intra-Carbonate Imaging through High-Resolution Model Building and Least-Squares Kirchhoff, Offshore Sarawak

Asia Petroleum Geoscience Conference and Exhibition (APGCE) (2022)

A. Azmi K.S. Tan J. McLeman T. Rayment Riaz Alai

Summary Imaging of intra-carbonates is a recognized challenge for carbonate reservoirs in Central Luconia, Offshore Sarawak, Malaysia. This is primarily due to issues such as migration noise, limited illumination, and the need for highly accurate subsurface models in this complex environment. In this paper, we present the application of an advanced depth velocity model building workflow together with a single-iteration least-squares Kirchhoff depth migration (LS-KDM) to resolve both the kinematic and dynamic complexities surrounding carbonate sequences. The work presented uses numerous velocity model building techniques, including full-waveform inversion (FWI), to derive a high-resolution, geologically conformal velocity model that resolves the sediments surrounding, and within the carbonates. Illumination uncertainties and migration noise that plague a conventional migration technique such as Kirchhoff depth migration (KDM) are addressed through the use of a single-iteration image domain LS-KDM. We compare the LS-KDM derived reflectivity to that of the KDM to demonstrate the former's ability to improve image illumination, reduce migration artifacts and increase amplitude fidelity.

Least-squares function approximation

Model building

Carbonate platform

10.3997/2214-4609.202270211

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