scholarly journals On tomography velocity uncertainty in relation with structural imaging

Geophysics ◽  
2021 ◽  
pp. 1-71
Author(s):  
Jérémie Messud ◽  
Patrice Guillaume ◽  
Gilles Lambaré
Keyword(s):  
Decision Making ◽  
Oil And Gas ◽  
Model Building ◽  
Model Space ◽  
Velocity Model ◽  
Industrial Applications ◽  
Theoretical Concepts ◽  
The North ◽  
Structural Uncertainties ◽  
The Impact

Evaluating structural uncertainties associated with seismic imaging and target horizonscan be of critical importance for decision-making related to oil and gas exploration andproduction. An important breakthrough for industrial applications has been madewith the development of industrial approaches to velocity model building. We proposean extension of these approaches, sampling an equi-probable contour of the tomographyposterior probability density function (pdf) rather than the full pdf, and usingnon-linear slope tomography. Our approach allows to assess the quality of uncertainty relatedassumptions (linearity and Gaussian hypothesis within the Bayesian theory)and estimate volumetric migration positioning uncertainties (a generalization of horizonuncertainties), in addition to the advantages in terms of computational efficiency.We derive the theoretical concepts underlying this approach and unify our derivationswith those of previous publications. As the method works in the full model space ratherthan in a preconditioned one, we split the analysis into the resolved and unresolvedtomography spaces. We argue that the resolved space uncertainties are to be used infurther steps leading to decision-making and can be related to the output of methodsthat work in a preconditioned model space. The unresolved space uncertainties representa qualitative byproduct specific to our method, strongly highlighting the mostuncertain gross areas, thus useful for QCs. These concepts are demonstrated on asynthetic dataset. In addition, the industrial viability of the method is illustrated ontwo different 3D field datasets. The first one consists of a merge of different seismic surveys in the North Sea and shows corresponding structural uncertainties. The second one consists of a marine dataset and shows the impact of structural uncertainties on gross-rock volume computation.

Maximising the Value of Multi-Sensor Streamer Data via MAZ Processing

2021 ◽  
Author(s):  
Hui Zhang ◽  
Jianfeng Yao ◽  
Xiang Li ◽  
Kai Zhao
Keyword(s):  
Model Building ◽  
Signal To Noise Ratio ◽  
Velocity Model ◽  
Seismic Survey ◽  
High Definition ◽  
North West ◽  
The North ◽  
Dual Sensor ◽  
The Impact ◽  
Water Bottom

Abstract The North West Shelf of Australia contains a late Paleozoic to Cenozoic sedimentary succession, which attains a thickness of over 10 km and is dominated by Triassic to Lower Cretaceous sediments. The deeper plays exist at multiple stratigraphic levels including oil-prone Jurassic sediments and faulted gas-prone Triassic sediments. The area has been proven difficult as far as seismic imaging is concerned, particularly over the Madeline trend. The presence of a hard, rugose water bottom, strong reflectors beneath the water bottom, and shallow Tertiary carbonates make the Dampier Sub-basin vulnerable to multiple contamination, amplitude distortion, lower signal-to-noise ratio (S/N) and unreliable AVO response. Poor seismic quality in the data has been a significant barrier to reducing exploration risk. In the 1990s, East Dampier (1992, blue polygon in Figure 1) and Keast (1997, yellow polygon in Figure 1) seismic data were acquired in East-West and North-South directions respectively, in an effort to better understand the impact from the shallow complex overburden. To address these challenges, the Demeter survey was acquired in 2003 (black polygon in Figure 1) with a denser acquisition grid. The overall seismic quality was improved, but the results still contained a significant level of residual multiples. Later, the Fortuna survey, the most comprehensive multi-sensor seismic survey on the North West Shelf of Australia to date, was acquired in 2014 with the aim to provide better subsurface imaging (pink polygon in Figure 1) from different acquisition perspectives. The data was processed with advanced processing technology, including shallow water demultiple, deghosting and high definition tilted orthorhombic velocity model building (Birdus et al., 2017). However, the final results were still suffering from a number of challenges, specifically: 1) strong residual multiple in near offsets, 2) low S/N ratio, particularly at reservoir level, and 3) inconsistency from near to far stack resulting in unreliable AVO. In this paper, the Dixon area (green polygon), considered as the most challenging area in the Dampier Sub-basin, was chosen as the testing area for our work. By integrating high-end imaging technology, for example dual-sensor deghosting, multi-survey surface related multiple elimination (MAZ-SRME), and multi-azimuth processing (MAZ stack), we will illustrate how we have overcome many of these imaging challenges.

Study of sand wave migration over five years as observed in two windfarm development areas, and the implications for building on moving substrates in the North Sea

2014 ◽  
Vol 105 (4) ◽  
pp. 241-249 ◽  
Author(s):  
Ken P. Games ◽  
David I. Gordon
Keyword(s):  
Case Studies ◽  
Large Scale ◽  
Oil And Gas ◽  
Sand Wave ◽  
Sand Waves ◽  
Migration Rates ◽  
The North ◽  
The North Sea ◽  
Wave Migration ◽  
The Impact

ABSTRACTSand waves are well known indicators of a mobile seabed. What do we expect of these features in terms of migration rates and seabed scour? We discuss these effects on seabed structures, both for the Oil and Gas and the Windfarm Industries, and consider how these impact on turbines and buried cables. Two case studies are presented. The first concerns a windfarm with a five-year gap between the planning survey and a subsequent cable route and environmental assessment survey. This revealed large-scale movements of sand waves, with the displacement of an isolated feature of 155 m in five years. Secondly, another windfarm development involved a re-survey, again over a five-year period, but after the turbines had been installed. This showed movements of sand waves of ∼50 m in five years. Observations of the scour effects on the turbines are discussed. Both sites revealed the presence of barchans. Whilst these have been extensively studied on land, there are few examples of how they behave in the marine environment. The two case studies presented show that mass transport is potentially much greater than expected and that this has implications for choosing turbine locations, the effect of scour, and the impact these sediment movements are likely to have on power cables.

Estimation of uncertainties in fault lateral positioning on 3D PSDM seismic image: an example from the North West Shelf

2016 ◽  
Vol 56 (2) ◽  
pp. 556
Author(s):  
Sergey Birdus ◽  
Vincent Ganivet ◽  
Alexey Artemov ◽  
Ray Teakle ◽  
Paul Phythian
Keyword(s):  
Practical Interest ◽  
Velocity Model ◽  
Lateral Position ◽  
Second Step ◽  
North West ◽  
The North ◽  
Seismic Image ◽  
Estimation Of Uncertainties ◽  
The Impact ◽  
Lateral Positioning

This extended abstract presents a two-step sequence to estimate uncertainties in lateral positioning of fault planes on 3D PSDM (pre-stack depth migration) seismic images. This analysis can be applied to any localised detail on a seismic image but, in the majority of geological settings, it is most important for the faults. The first step provides an approximate evaluation of what causes the uncertainties, how the uncertainties are distributed in a 3D space, and what to expect within target zones. The authors assume that every complex detail within a 3D PSDM velocity model causes some uncertainties to the seismic image below. Thus, the uncertainties at a target level depend on the complexity of the overburden and the seismic acquisition parameters. At this step a qualitative 3D volume of lateral fault position uncertainties is created. In the second step the authors focus on a single fault of practical interest. Based on the results of the first step, the authors modify the existing 3D PSDM anisotropic velocity model by introducing additional anomalies that cause maximal changes to the lateral position of the fault on seismic image. Then the authors iteratively re-migrate a small sub-volume around the fault and check the PSDM images and residual moveout. The objective is to find out how far the velocity variations can move the image of the fault and still satisfy available seismic data. The second step gives more reliable quantitative estimations of the impact of velocity on fault positioning. A real multi-azimuth 3D seismic dataset from the North West Shelf is used to illustrate this sequence.

New tools for 2D full-waveform inversion: applications on Brazilian Pre-Salt velocity model from Santos Basin

2020 ◽  
Author(s):  
Henrique Santos ◽  
Claus Eikmeier ◽  
Ernani Volpe
Keyword(s):  
Oil And Gas ◽  
Model Building ◽  
Waveform Inversion ◽  
Numerical Algorithms ◽  
Velocity Model ◽  
Southeastern Brazil ◽  
Full Waveform Inversion ◽  
Case Scenario ◽  
Velocity Inversion ◽  
Full Waveform

<p>In this work, we present full-waveform inversion (FWI) results of a typical Brazilian Pre-Salt model (Santos Basin) using new open-source tools. The large accumulations of oil with excellent quality and high commercial value discovered in the pre-salt carbonates of southeastern Brazil, especially in the Santos Basin, have made this province one of the most prospective in the world. Velocity model building in areas of highly complex geology (like the Santos Basin) remains a challenging step in seismic processing. FWI proved to be an efficient tool for the determination of high-resolution details in multiparameter models of complex subsurface structures, and it has been applied in different geophysical problem scales. However, since FWI is a computationally and mathematically challenging problem, many issues remain open, such as more efficient ways to deal with multiparameter inversion problems such crosstalk and different orders of magnitude in the seismic signal for different classes of parameters. Inversions for more than one class of parameters are of particular importance in the estimation of the physical properties of rocks (poroacoustic or poroelastic applications), for example, to monitoring oil and gas reservoirs and for monitoring the injection of carbon dioxide into geological structures. Also, programming complex numerical algorithms for each application is time-consuming and often evades the expertise of researchers from the geoscientific community. In this sense, a high-level computational tool for simulations and inversions would greatly improve the working time for researchers. Existing finite difference based FWI tools such as Devito, and finite elements based partial differential equations (PDE) solvers tools such as FEniCS and Firedrake are being explored and used for these purposes. In this work, we initially present an FWI acoustic isotropic inversion test (velocity inversion only), performed with the Devito software while a particular code is being developed in FEniCS and Firedrake computer programs. Devito is also a new and under development software and therefore must be tested under different conditions. Our first numerical results indicate the potential of using freely available computational programs in a real case scenario.</p>

scholarly journals A study of sub-basalt depth imaging using the local Radon attributes on the Erlend Tertiary volcanic complex - North of Shetland, UK

2008 ◽  
Vol 87 (2) ◽  
pp. 135-149
Author(s):  
A. Droujinine ◽  
J. Pajchel ◽  
K. Hitchen
Keyword(s):  
Model Building ◽  
Region Of Interest ◽  
Thick Layer ◽  
Velocity Model ◽  
Volcanic Complex ◽  
Depth Imaging ◽  
The North ◽  
Discrete Radon Transform ◽  
Imaging Results ◽  
And Migration

AbstractAcquiring conventional 3 km towed streamer data along a 2D profile in the North of Shetland (UK) enables us to use the local Radon-attributes within the context of depth processing methodology for accurate delineation of volcanic units and imaging beneath high-velocity layers. The objective is to map the radially-dipping structure of the Erlend pluton and to investigate the potential existence of relatively soft Cretaceous sediments underneath volcanic units. Success in the Erlend Volcano study requires strict attention to the separation between different groups of events. The crucial point is the generalized discrete Radon transform formulated in terms of local wavefront (dip and curvature) characteristics. This transform is utilized during pre-CMP processing and migration to minimize event-coupling artefacts. These artefacts represent cross-talk energy between various wave modes and include the unwanted part of the wavefield. We show how to produce detailed subsurface images within the region of interest (exploration prospect only) by applying the closely tied processes of prestack event enhancement and separation, well-driven time processing for velocity model building, and final event-based prestack depth imaging. Results show enhanced structural detail and good continuity of principal volcanic units and deeper reflections, suggesting a faulted 0.6 – 0.9 km thick layer of Cretaceous sediments in the proximity of well 209/09-1. Our interpretation complements existing low-resolution geophysical models inferred from gravity and wide-angle seismic data alone.

scholarly journals Belgian environmental impact assessment systems: Legal frameworks and beyond

elni Review ◽  
2008 ◽  
pp. 60-69
Author(s):  
Jan De Mulder
Keyword(s):  
Decision Making ◽  
Environmental Impact ◽  
Impact Assessment ◽  
Environmental Impact Assessment ◽  
Policy Instruments ◽  
Coastal Region ◽  
Federal State ◽  
Assessment Practice ◽  
The North ◽  
The Impact

As a result of a number of constitutional reforms in recent decades Belgium is now a federal state. The societal evolution and the historical devolution of competencies have resulted in a multi-actor policy approach at different policy levels: municipal, provincial, regional and national (federal). Competencies regarding particular policy fields like the environment are often not attributed to one policy level. The application of policy instruments in such a framework leads to complex processes and regulatory frameworks for decision-making within Belgium. The transposition of the consecutive EU Directives has resulted in a growing environmental impact assessment practice. (E)IA approaches and requirements are found in horizontal as well as in specific legislation. The application of the impact assessment frameworks has raised questions about the coherence of both proponents and authorities have to deal with these institutional features. Institutions provide not only for frameworks; they are also stakeholders in decision-making and have an interest in impact assessment. Most EIA legislation is, however, to be found at the regional level, except for the projects in the Belgian marine environment and nuclear installations which have remained a federal issue. Yet, for certain projects and even plans – e.g. on the North Sea coastline in Flanders, the only coastal region in Belgium – the decision-making process requires the application of both the federal and regional legislations. Later on the transposition of the Strategic Environmental Assessment Directive of 2001 revealed a more profound “impact” on decision-making processes. The final adoption of federal and regional SEA legislation happened in the course of 2006-2008. This article briefly outlines EIA and SEA (and emerging IA) regulations at the Belgian federal and regional policy levels. Furthermore, some particular issues regarding the involvement of stakeholders and consultants as an element of impact assessment quality requirements are explored.

Removal of dissolved and dispersed hydrocarbons from oil and gas produced water with Macro Porous Polymer Extraction technology to reduce toxicity and allow water reuse

2010 ◽  
Vol 50 (1) ◽  
pp. 637 ◽  
Author(s):  
Dick Meijer ◽  
Chris Madin
Keyword(s):  
Water Reuse ◽  
Oil And Gas ◽  
Produced Water ◽  
Oxygen Demand ◽  
Oil And Gas Industry ◽  
Industrial Applications ◽  
The Philippines ◽  
Porous Polymer ◽  
Extraction Technology ◽  
The North

Legislation worldwide and current technologies used in the treatment of offshore oil and gas/condensate produced water are mainly aimed at the removal of dispersed hydrocarbons (dispersed oil). From the beginning of this century, new insights in the North Sea area revealed that specific contaminants in produced water are toxic and their impact on the environment was assessed. This insight was later supported by work in the Philippines. A comparison of water with the same total organic carbon (TOC) levels showed in one case that the unknown toxic content was higher with an unexpected disastrous effect on the biocultures. Overall parameters like biological, chemical and total oxygen demand (BOD, COD and TOC) are of no value in identifying and managing the toxic content of waste and produced water streams. New extraction based technologies such as the Macro Porous Polymer Extraction (MPPE) technology appear to remove dispersed and dissolved toxic constituents and reduce the environmental impact. Industrial applications show a >99% toxic content reduction in produced water streams. A recent application (at Woodside Petroleum’s Pluto LNG project) is described where the ultimate reuse of produced water was as demineralised water in an LNG plant. Emerging potential is presented for floating LNG plants currently investigated in conceptual studies by the oil and gas industry. Finally, fundamental technological mechanisms are presented that are required to meet zero harmful discharge legislation.

The planning fallacy in oil and gas decision-making

2010 ◽  
Vol 50 (1) ◽  
pp. 389
Author(s):  
Matthew B. Welsh ◽  
Nigel Rees ◽  
Hugh Ringwood ◽  
Stephen (Steve) H. Begg
Keyword(s):  
Decision Making ◽  
Oil And Gas ◽  
Psychological Research ◽  
Personal Traits ◽  
Time Estimates ◽  
Complex Projects ◽  
Potential Problems ◽  
Planning Fallacy ◽  
Time Required ◽  
The Impact

The ‘planning fallacy’ describes the tendency of people to underestimate costs and times required for the completion of complex projects. Psychological research has demonstrated that a key component of this results from the packing/unpacking bias—where options or problems that are not specifically stated tend to be ignored by people when making estimates or assigning probabilities to events. We have investigated this effect as it relates to oil and gas decision making, highlighted by experimental results comparing estimates of drilling times made by both student and industry participants. Specifically, participants were provided with a drilling scenario and asked to estimate the time required to drill the well—including drilling, tripping, rigging and all potential problems. In the packed condition the options were given as just stated while, in the unpacked condition the ‘all potential problems’ category was divided into a list of specific problems. The packing effect was shown to markedly alter the time estimates made by all groups of participants—altering estimates of problem times by more than 100 hours on average. Additional analyses assessed the interactions between the packing/unpacking effect and personal traits such as optimism, tendency to procrastinate and industry experience. These findings are discussed in terms of their import for oil and gas decision makers desiring to improve prediction accuracy and, thus, economic outcomes by avoiding, or limiting, the impact of the planning fallacy.

Organizational adoption of 3D printing technology: a semisystematic literature review

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Desiree Valeria Ukobitz
Keyword(s):  
Decision Making ◽  
3D Printing ◽  
Literature Review ◽  
Strategic Decision ◽  
Future Research ◽  
Managerial Decision ◽  
Organizational Adoption ◽  
Content Type ◽  
Theoretical Concepts ◽  
The Impact

PurposeThree-dimensional (3D) printing (3DP) offers a promising value proposition across multiple manufacturing industries. Despite the variety of production benefits the technology entails, its rate of adoption is still low compared to industry forecasts. In face of this challenge, industry as well as academia requires more information and guidance. This review aims to examine the characteristics of the existing body of research on the organizational adoption of 3DP as well as its underlying theoretical concepts. The most common criteria driving adoption will be derived, such as to facilitate the managerial decision-making process. Pathways for future research will be presented.Design/methodology/approachThis study underlies a bibliometric literature review and additionally applies content analysis to systematically investigate the existing body of research and group decision criteria along the four major pillars of strategic decision-making.FindingsThe contributions of this paper are threefold. First, the bibliometric analysis reveals interesting aspects of the existing body of research. The most prominent characteristics of the contemporary literature are reflected along descriptive indicators, such as industry, method, model, origin, research outlet or adoption drivers, thus granting relevant insights into academia and practice. Second, the most notable adoption models are carefully analyzed on their inherent attributes and their application fit for the context of organizational 3DP adoption. Findings, for instance, revealed the dominance of diffusion of innovation (DOI) across the existing body of research and divulge that this construct is generally applied in combination with user-centered decision frameworks to yield more precise results. Third, an ample range of opportunities for future research are detected and thoroughly explained. Among others, the authors identified a clear lack of information on the impact environmental variables and contingency factors exerted on the organizational adoption of 3DP. Guidance in relation to the sourcing of industry data, usage of adoption frameworks and avenues for future scientific projects is supplied.Originality/valueThis study represents the first semi-systematic literature review on the organizational adoption of 3DP. Thus, it not only offers a valuable evaluation guide for potential adopters but also determines a future research agenda.

Revitalizing seismic data with new imaging solutions to positively impact field development

2019 ◽  
Vol 38 (1) ◽  
pp. 20-26
Author(s):  
Gareth Venfield ◽  
Michael Townsend ◽  
Paul Cattermole ◽  
Tony Martin ◽  
Stuart Fairhead
Keyword(s):  
Seismic Data ◽  
Model Building ◽  
Large Population ◽  
Waveform Inversion ◽  
Structural Complexity ◽  
Velocity Model ◽  
Near Surface ◽  
Field Development ◽  
The North ◽  
The Right

Evaluating, planning, and forecasting are integral parts of asset development and continue throughout the life cycle of a producing field. The right decisions are required to lower risk and maximize economic recovery in challenging environments. The Claymore Complex is located in the North Sea and was discovered in 1977. A number of geologic challenges affect the imaging and hence field development including a system of shallow interweaving Quaternary channels, numerous high-contrast layers of varying composition, overburden structural complexity, and a sequence of tilted fault blocks containing the main reservoir systems. Historically, seismic processing over the area has not fully solved these challenges, resulting in significant imaging uncertainty. The Claymore Complex has an abundance of data including a large population of well information and interpretation. As part of a data revitalization process, geostatistical integration of these auxiliary data into a velocity model building sequence using full-waveform inversion and wavelet shift tomography enabled the generation of an accurate high-resolution velocity model. Access to a recent 3D survey acquired obliquely to existing data improved subsurface illumination for both the model building and imaging phases. Near-surface imaging effects and their impact on reservoir positioning and clarity were improved using the upgraded velocity model and dual-azimuth data. Shallow imaging challenges were mitigated by utilizing the additional illumination and angular diversity contained within the multiple reverberations. The revitalization of the Claymore area seismic data has challenged the current understanding of the geologic framework. Confidence has been improved by solving depth conversion problems and increasing the understanding of fault positioning and reservoir connectivity, which are invaluable for future field development.

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