Geophysics - Seismic Acquisition

Advanced Seismic Data Acquisition and Processing

 

Instructor

  Dr Jaap C. Mondt (Breakaway, Netherlands)

Duration

  5 days

Disciplines

  Geophysics – Seismic Acquisition and Processing

Level

  Advanced

Languages

  English, Dutch

EurGeol

  25 CPD points

 

Course description

The course deals with advanced methods of seismic acquisition and processing. It will be taught not only by explaining the methods, but above all by applying the theory in mainly Excel based assignments.

Seismic data is one of the main sources of information on the subsurface. We not only need to obtain the structure that could contain hydrocarbons, but also the rock properties so we can decide on whether we are dealing with reservoir rocks (sandstone, carbonates, even shales), sealing rocks (shales, salt) or source rocks (shales, coal). It is not only important to know what type of rock is present, but also what its porosity and permeability is: how easy do the hydrocarbons flow through the rocks. To obtain the best image of the subsurface we first need optimum acquisition. Optimum means fit for purpose. There are several criteria that need to be satisfied. First of all, the area covered during acquisition should be the prospect area extended sufficiently to provide fold-fold and fully migrated data. An acquisition principle that should be adhered to as much as possible is symmetric sampling, which means equal shot and receiver spacing and equal in-line and cross-line distances (for a 3D). A noise spread (trial acquisition with closely spaced receivers and shots) is acquired in each new area to determine the needed shot and receiver intervals, the bandwidth, etc. The shot and receiver station spacing should be such that no spatial aliasing of the data occurs. Surface and subsurface diagrams are useful to see what CMP spacing and offsets in each CMP gather result from the surface geometry of shots and receivers. The data recorded is the ground motion which gives a continuous (analogue) signal in time which needs to be digitized for the processing. This digitization needs to be done so that neither temporal nor spatial aliasing occurs. Namely, by aliasing information will be lost. Hence, the complete wave-field which arrives at the surface must be faithfully represented by the discrete/digital data.

Although all the information is present in the so-called shot or field records, processing is needed to make them accessible for interpretation. In interpretation, we try to obtain a true image of the “geology” of the subsurface. Processing can be divided into a) signal processing steps and b) wave propagation based processing steps. Signal processing steps are, for example, static corrections, removal of shot-generated noise by velocity filtering, shortening of the wavelet by de-convolution, NMO correction, etc. The wave-propagation part consists of migration or imaging. For wave propagation we need, in principle, to use equations describing full elastic wave propagation in an inhomogeneous, anisotropic, visco-elastic earth (as that is what really happens in the subsurface). However, these equations would lead to very complicated and computer intensive processing algorithms. So, we usually simplify our description of the wave propagation. What we do is to use, as phrased by Ian Jones and others, "appropriate approximations". The one most commonly used is the one-way acoustic wave equation which describes only a single reflection per reflection ray-path and ignores density. It only uses a velocity depth model and only considers P-wave propagation. This will provide us, for example, with migration algorithms/operators (for time- as well as depth migration) that will still do a reasonably correct summation of acquired data. It will give a migration output that still shows, maybe not correctly, the results of anisotropy, attenuation, wave conversions, shear velocities, etc. Despite the use of this acoustic approximation in our processing, amplitudes can be used (can they?) to determine pore-fluids and pre-stack migrated data that can be used in AVA analysis for deriving shear wave properties. But note that if we model, as in inversion, a synthetic geophysical quantity, say related to amplitudes, such as the reflection coefficient we need (do we?) to include densities across the interface and for AVA we need to include density and shear velocity to interpret the pre-stack seismic amplitudes (as the effect of these properties is contained in the observed data).

All of this will be treated in this course.

 

Course objectives

At the end of the course participants will have a good understanding of what information seismic data can give and for what purposes in Exploration and Production it can be used. This will enable them to specify the requirements for a survey, either done by themselves of by a special service provider.

Other benefits include:

  • Place and value geophysical activities in a multi-disciplinary context
  • Judge the merits of various seismic geophysical techniques
  • Better liaise and collaborate with staff in related disciplines
  • Recognise artefacts and direct hydrocarbon indications on seismic
  • Value novel developments such as time lapse methods for hydrocarbon reservoir monitoring

 

Course outline

  • Part 1: The role of seismic in the Exploration and Production of Hydrocarbons
  • Part 2: Seismic Acquisition Strategies
  • Part 3: Seismic processing Strategies
  • Part 4: Time-to-Depth conversion, Direct Hydrocarbon Indicators
  • Part 5: Value of Information: How much to spend on new acquisition and/or new processing

 

Participants' profile

The course is designed for geophysicists involved in designing and supervising seismic acquisition and processing, and for those involved in specifying/supervising the acquisition and processing done by service companies.

 

Prerequisites

Participants should have a basic understanding of seismic acquisition and processing and general knowledge of the role of seismic in exploration and production of hydrocarbons.

 

About the instructor

Jaap MondtDr Jaap C. Mondt obtained a Bachelors degree in Geology at the University of Leiden followed by a Masters degree in Theoretical Geophysics and a PhD on “Full wave theory and the structure of the lower mantle” at the University of Utrecht. Dr Mondt then joined Shell Research in The Netherlands to develop methods to predict lithology and pore-fluid based on seismic, petrophysical and geological data. Subsequently he worked at Shell Expro in London to interpret seismic data from the Central North Sea Graben. After his return to The Netherlands, he headed a team for the development of 3D interpretation methods using multi-attribute statistical and pattern recognition analysis on workstations. After a period of Quality Assurance of “Contractor” software for seismic processing, he became responsible for Geophysics in the Shell Learning Centre. During that time he was in addition part-time professor in Applied Geophysics at the University of Utrecht. From 2001 till 2005 he worked on the development of Potential Field Methods (Gravity, Magnetics) and EM methods (CSEM) for detecting oil and gas. After his retirement from Shell, he founded his own company (Breakaway), specialised in courses on acquisition, processing and interpretation of geophysical data (seismic, gravity, magnetic and electromagnetic data). In addition to providing support to the Shell Learning Centre, he gives his own courses to International as well as National energy companies.

 

Recommended readings

  • An Introduction to Geophysical Exploration, Keary, Brooks & Hill, ISBN-0-632-04929-4
  • Looking into the Earth, Mussett & Aftab Khan, ISBN-0-521-78574-X
  • Fundamentals of Geophysics, Lowrie, ISBN-978-0-521-67596-3
  • The Art of Being a Scientist, Snieder & Larner, ISBN-978-0-521-74352-5
  • 52 Things you should know about Geophysics, Hall & Bianco, ISBN-978-0-9879594-0-9

 

 

                    Learning Geoscience Logo

 

Explore other courses under this discipline:

 

Advanced Marine Seismic Acquisition Techniques

Instructor: Dr Mike Branston (WesternGeco)

The course is designed to familiarize the student with the latest developments in Marine Seismic Acquisition including Wide-Azimuth with its many geometry variants, Broadband techniques (boosting the high and low frequencies), seabed receivers for both P-wave and Converted-wave recording, simultaneous source acquisition, and methodologies to improve efficiency. The course starts with an overview of conventional 3D towed streamer seismic acquisition and then concentrates on recent advances that have enabled dramatic improvements in seismic data quality and interpretability.

More information

Integrated Seismic Acquisition and Processing

Instructor: Mr Jack Bouska (Independent Consultant)

This course covers modern techniques in 3D seismic acquisition, from the perspective of seismic as an integrated system comprising: acquisition design, field operations, data processing, imaging, and interpretation. This one day course will review the basics of 3D survey design, with emphasis on how practical aspects of interpretation, data processing, imaging and/or field operations can either constrain.

More information

Seismic Acquisition Project Essentials: from Concept to Completion and Beyond

Instructor: Mr Jan de Bruin (Project Manager - Seismic Acquisition)

Existing courses and books with the title `seismic acquisition' typically deal with designing seismic surveys. Although I treat design in a somewhat less conventional way, it is an important part of this course too, but other equally important subjects receive equal attention. These are: Clients, Finance, Procurement, Scouting, Communities, Execution, Equipment, HSE and Project Management. Any serious flaws in either of these can make a seismic survey less successful or fail altogether. Although these elements have nothing to do with Geophysics, they are essential ingredients of Seismic Acquisition. The course will look at all this from the perspective of seismic companies as well as oil companies

More information

The Benefit of Broadband Technology for Reservoir Characterization and Imaging – the End-User Value

Instructor: Dr Cyrille Reiser (Petroleum Geo-Services)

The main aim of this course is to provide a very accessible overview of the many concepts behind broadband seismic (primarily offshore) and its implication for the reservoir focused asset based geoscientist. This will be done through the a very comprehensive set of case study material from all regions of the world and for various stages of the exploration, appraisal and development asset life cycle. The course aims to objectively discuss the various broadband seismic technologies and commercial offerings available today and their respective merits with regards to quantitative reservoir characterization and reservoir imaging using real world application examples. The course will further attempt to identify possible pitfalls and issues with regards to the treatment of broadband data that might lead to flawed or erroneous QI.

More information

Understanding Ocean Bottom Seismic

Instructor: Mr Mark Thompson (Statoil)

The use of Ocean Bottom Seismic (OBS) is increasingly more utilised. The placement of receivers on the sea floor, allows for measurement of both pressure and shear waves, while the decoupling of source effort from receiver effort allows for full azimuth imaging. The characteristics of OBS creates challenges, which need to be addressed in survey design, acquisition, processing, imaging and interpretation. Through examples, successful use of this technology will be demonstrated.

More information

Broadband Technology

Instructor: Dr Robert Soubaras (CGG)

This one-day course is intended to explain how, by combining advances in equipment, acquisition design and processing, the bandwidth of marine seismic images has been increased recently from 3 to 6 octaves. The course starts with a theoretical part that provides a unified framework allowing to cover the theory of the various marine broadband methods that are currently used (over-under, dual sensor, variable-depth), with the aid of synthetic examples as well as real data results based on the variable-depth streamer method. After the specific receiver deghostings are addressed, other processing steps that have to be adapted to broadband data are described.

More information

Time-Lapse Seismic: A Multidisciplinary Tool for Effective Reservoir Management

Instructor: Mr Cedric Fayemendy (Statoil)

Geophysical Reservoir Monitoring (GRM) of reservoirs relies on frequent time-lapse observations with high-survey repeatability. This technology is a key enabler for maximizing the oil recovery of oil and gas fields. The GRM technology aims at understanding and updating the knowledge of producing reservoirs. This is achieved through mapping the movement of fluid and pressure fronts and fluid contacts during production and injection. The combination of production monitoring with repeated seismic acquisition and geological and reservoir information provides reliable estimates of static and dynamic reservoir parameters. The lecture will first review the geophysical reservoir monitoring history at Statoil. We will share our experience with 4D processes, resources allocation and the overall monitoring strategy. The lecture will also cover challenges in understanding the 4D responses and value creation. Finally, we will look at how we push the GRM technology towards higher use of quantitative results.

More information

4D Seismic for Reservoir Management

Instructor: Mr Ian Jack (Independent Consultant)

After a short perspective on the development of 4D seismic from the 1980s to its routine use in mature areas, the course covers the basics of rock and fluid physics. It moves on to describe current best practice and the technical and operational requirements for successful implementation of time-lapse technology whether for hydrocarbon extraction or for CO2 injection.

More information

Land Seismic on New Technological Level

Instructor: Dr Anatoly Cherepovskiy (Independent Consultant)

This course will provide information related to recent trends and advances in land seismic data acquisition technology, equipment and the methodologies that are being utilized to improve seismic imaging quality and productivity of 3D acquisition with an emphasize on the high-end surveys as performed in open areas. The course will not cover the fundamentals of 3D and multicomponent seismic survey design, although there will be a section that will give a review of recent survey design approaches and principles.

More information

Land Integrated Survey Design

Instructor: Mr Paul Ras (SD2I Geophysical Consulting)

This course presents an integrated approach to modern land 3D survey design as it has a key role in the seismic value chain going from acquisition to processing, imaging and inversion and characterization. It describes the main technology advances in land acquisition: high-channel count single sensor (point receiver), simultaneous source high-productivity vibroseis, broadband and wireless nodal systems. New acquisition technology has in turn inspired progress in processing, imaging and inversion and characterization. Survey designs have changed accordingly; wide azimuth high-density surveys are now the norm in many environments. And the survey design workflow now includes single sensor, single source, simultaneous source, broadband, symmetric sampling, cross-spreads, spatial continuity and more powerful 5D interpolation methods. It has also become more integrated, with requirements from inversion and characterization, imaging and processing feeding back to the design and hence acquisition.

More information

Basic Geophysical Data Acquisition and Processing

Instructor: Dr Jaap C. Mondt (Breakaway, Netherlands)

This course presents various geophysical methods from gravity to magnetics, electrical, electro-magnetic, refraction and reflection seismic.

More information

Advanced Seismic Data Acquisition and Processing

Instructor: Dr Jaap C. Mondt (Breakaway, Netherlands)

The course deals with advanced methods of seismic acquisition and processing. It will be taught not only by explaining the methods, but above all by applying the theory in mainly Excel based assignments.

More information

--