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[PDF] The Kwanza-Campos conjugate pair: mirror twins? Revisiting and exploring new frontiers
Author: Matthew Plummer, Jeff Tilton
First Break - 4 May 2021The authors reveal the similarities between two basins that can advance the identification of additional exploration potential on both sides of the South Atlantic.
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[PDF] New Shallow Seismic Insights
Author: Andrew Long
Industry Insights - 31 May 2021We will continue to use high-resolution seismic to understand the subsurface risks and opportunities in marine areas as we transition to renewables and lower carbon energy sources as a complement to fossil fuels. CO2 storage in aquifers must be monitored for shallow seal integrity and offshore wind farms require geotechnical ground models and seismic characterization of the near surface. This article addresses the question of whether we will necessarily require entirely new seismic acquisition solutions, or whether existing methods can be adapted to provide new value and insights.
Towed-streamer seismic using tailored acquisition configurations provide an efficient method of accessing high-resolution datasets for several purposes, and some examples are given below. I also show how full wavefield imaging solutions can high-grade existing seismic data to significantly enhance the resolution and quality of shallow images.
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[PDF] From a regional AVA screening to focused elastic attributes estimation: an integrated solution from seismic acquisition to reservoir characterization
Author: Cyrille Reiser, Elena Polyaeva, Scott Opdyke
SEG - 1 October 2020Understanding the elastic properties of reservoirs in exploration can be very challenging - due mainly to the lack of well information, limited regional geological understanding, and the quality and reliability of seismic data available.
This case study illustrates how this challenge can be addressed through an integrated solution from broadband seismic acquisition to elastic properties, applied recently to the underexplored deep-water Orphan Basin, offshore Eastern Canada.
A multisensor seismic dataset covering close to 22,500 km2 was acquired over three seasons (from 2017 to 2019) and now constitutes a great platform for understanding the geology as well as extracting elastic properties. The understanding of the prospectivity was performed at the regional scale, then on more localized area using one of the very few wells present in the area. On this localized area the newest depth imaging technologies with Full Waveform Inversion (FWI) and Least-Squares Migration (LSM) were used. In addition, a three term Amplitude Versus Angle (AVA) inversion was performed and matched at the well without using the well actively in the process but by using the broadband seismic data only: velocity and amplitude.
Turnaround time was also a key element in this regional project. To significantly reduce this, an integrated team of imaging and quantitative interpretation specialists was dedicated to the project from the start. Pre-stack AVO QC was performed iteratively during the processing to ensure that the final pre-stack data was fit for purpose and AVO/AVA compliant for further Quantitative Interpretation (QI) analysis.
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[PDF] APPEA 2021: The Road to Net Zero
Author: Andrew Long
Industry Insights - 23 June 2021The 2021 Australian Petroleum Production & Exploration Association (APPEA) conference was dominated by the net zero recommendations of the recent International Energy Agency (IEA) report, although a new offshore acreage round was released, and the LNG export market is expected to grow substantially.
I discuss the implications of the net zero goals for decarbonization of a global-scale natural gas and coal exporter, the opportunities and challenges to developing a hydrogen economy, perspectives on carbon capture and storage (CCS), the ever-present specter of environmental approvals for all energy suppliers, and the economic implications to petroleum companies of all scales from the responsibilities of infrastructure decommissioning.
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[PDF] Seismic Surveys Have Little Impact on Demersal Fishes
Author: Andrew Long
Industry Insights - 30 August 2021A large-scale three-year experiment recently quantified the impacts of exposure to a commercial seismic source on an assemblage of tropical demersal fishes targeted by commercial fisheries on the North West Shelf of Western Australia. Monitoring of the composition, abundance, behavior, and movement of the fishes was pursued in multiple before-after-control-impact and dose–response experimental frameworks using acoustic telemetry and underwater video. The multidisciplinary team of scientists, technical staff and industry experts found there were no short-term (days) or long-term (months) effects of exposure on the composition, abundance, size structure, behavior, or movement of this fauna. These multiple lines of evidence suggest that seismic surveys have little impact on demersal fishes in this environment.
Elements of results from the published study are summarized and highlighted.
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[PDF] Seismic Processing - What is Required?
Author: Tony Martin, Øystein Korsmo, Nizar Chemingui
EAGE Workshop on Optimizing Project Turnaround Performance - 24 February 2021In a turnaround and cost-conscious environment, do we really need to apply all the algorithmic processes in a seismic processing sequence? Full wavefield migration may be one way to eliminate certain processes. If we treat the full wavefield migrated image as part of an inverse problem in a least-squares migration, we may exclude more steps. Least-squares full wavefield migration (Lu et al., 2018) uses the raw seismic data, and many processing steps in both the data and image domain can be excluded, potentially reducing turnaround whilst maintaining, or improving, image quality for the entire data record.
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[PDF] Can Data Analytics Help Reduce Seismic Processing Turnaround
Author: Tony Martin, Suhail Butt, Andrew Long
EAGE Workshop Optimizing Project Turnaround - 24 February 2021Seismic data volumes are increasing and pressure is growing to accelerate the turnaround time of seismic processing projects. Testing, validation, and production administration are time-consuming components of a project. Testing is performed to optimize the parameters for each step in the processing sequence. It can be both computer and human resource intensive, as many testing phases require numerous repeat runs and significant interaction with the data. A Proof-of-Concept (POC) example illustrates that parameter testing can be helped by mining for parameters from a database.
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[PDF] The Greater Orphan Basin: Unraveling Newfoundland’s Emerging Energy Plays
Author: Hermann Lebit, Yermek Balabekov, Taylor Buckley
GeoExpro - 18 May 2021Recent discoveries (e.g., Cambriol and Cappahayden) at the Grand Banks, offshore Newfoundland reconfirm the increasingly promising hydrocarbon potential along the shelf and slope sections of this emerging North Atlantic basin. These discoveries, along with proven petroleum systems, evolving play concepts and ongoing 3D seismic acquisition campaigns, open up exciting running room for hydrocarbon exploration and potential to capture step-out opportunities for near-field developments. The new multisensor 3D seismic acquisition and processing technologies enabling effective demultiple, offer complete imaging of the rift-related petroleum systems and reveal new opportunities in the overlying Tertiary passive margin sequences.
The Grand Banks shelf platform offshore Newfoundland was affected by three major divergent plate tectonic systems associated with the progressive opening of the Central and North Atlantic, respectively. The eastern Grand Banks shelf edge marks an intermediate stage in the northward migration of the Atlantic system. It is dominated by the separation of Iberia from Avalonia, which completed after a Jurassic to Cretaceous rift stage, documented throughout the Grand Banks subsurface. Regional seismic data from the outer Orphan Basin, provides tectonic evidence for a pull-apart basin that is transient into Riedel-shear dominated arrays of extensional faults, towards the prolific hydrocarbon domain of the Grand Banks distal shelf.
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[PDF] Quantitative Interpretation Reveals Prospectivity of the Kwanza Shelf, Offshore Angola
Author: Roberto Ruiz, Cyrille Reiser, Avril Burrell, Jean Afonso Colsoul, Naire Judith Ricardo Cahumba Quenge
GeoExPro - 4 November 2021PGS in partnership with Agência Nacional de Petróleo, Gás e Biocombustíveis (ANPG) has recently acquired 8,304 sq. km of new multisensor GeoStreamer data over the Kwanza Shelf, 30 km off the central coast of Angola. This new 3D survey provides an unprecedented uplift in seismic imaging over the vintage 2D data. Modern processing workflows have been tailored to the unique imaging challenges of the presence of shallow water and subsurface salt. The new data unveils previously undetected pre-salt basins with many direct hydrocarbon indicators (DHIs) in both the syn-rift and post-rift sections, suggesting the presence of a working petroleum system in this underexplored area.
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[PDF] Sea Surface Reflection Coefficient Estimation
Author: Okwudili Orji, Walter Söllner, Leiv Gelius
SEG - 23 September 2013Sea surface reflection coefficient estimates are obtained from imaged sea surfaces by applying an imaging technique that is based on decomposed wavefields acquired by dual-sensor towed streamers. The accuracy of this technique in the case of imaging has been demonstrated employing controlled data scattered by realistic time varying rough sea surfaces (e.g., Pierson-Moskowiz sea surface). The scattered data was computed based on the Kirchhoff-Helmholtz integral. Here, the feasibility of recovering sea surface reflection coefficient estimates from deterministic and realistic sea surfaces is demonstrated. First, using existing studies, the sea surface reflectivity is benchmarked. Subsequently, sea surface imaging was employed to demonstrate the feasibility of recovering the sea surface reflectivity from marine seismic data.