About this Training Course
Traditionally, reflection seismic is used for its kinematic attributes, i.e. reflection traveltimes. However, we can also use reflection seismic for its dynamic attributes, i.e. reflection amplitudes, specifically, the behaviour of these amplitudes versus angle of incidence: AVA = amplitude versus angle, or, equivalently, AVO = amplitude versus offset.
AVO attributes are used as independent evidence for the occurrence of hydrocarbons (in addition to structural evidence), as a hydrocarbon discriminator and as a lithology indicator. This course starts with a discussion of new developments in seismic data acquisition that have an impact on the accuracy of the AVO attributes, e.g. long offsets, wide-azimuth geometries and broadband data acquisition. It deals with elastic constants, wave propagation, boundary conditions, rock physics, and fluid substitution algorithms. It gives an overview of the factors that affect seismic amplitudes and of proper ways to process the seismic data such that amplitude information is preserved, which is then followed by the extraction of the relevant attributes and their interpretation. All aspects that are related with seismic inversion are dealt with, theoretical as well as practical. An AVO workshop will be part of the course.
Seismic inversion is the process of converting seismic reflectivity data into (a) models of elastic properties of the subsurface, or into (b) a quantitative rock-property description of a reservoir.
Seismic inversion may be pre-stack or post-stack, deterministic or geostatistical, and typically includes other reservoir measurements such as well logs and cores. Using the Bayesian approach, in which all available information can be reconciled, a statistical assessment of the desired reservoir properties can be obtained.
The choice for a specific seismic inversion techniques depends on the stage of development:
- Reconnaissance with no well control within the seismic
- Exploration and appraisal with well control within the seismic
- Focused reservoir characterization with well control and key reservoir parameters with their uncertainties.
The course consists of the following four chapters:
- Rock physics: elasticity theory and the Gassmann equation
- AVO: formulation, processing and derivation of attributes
- Geostatistics: estimation of variables, probability theory and Bayesian statistics
- Seismic inversion: elastic and lithologic and deterministic and stochastic
The course will deal with all aspects of deterministic and stochastic inversion.
By the end of this course, participants will able to
- Get a full understanding and appreciation of the theory and practicalities of AVO analysis
- Understand the interpretation of AVO attributes, the various methods of seismic inversion and the statistical assessment of inversion results.
- Anyone who deals with seismic and acts as a member of a multi-disciplinary team will benefit of this course.
- Geophysicists, interpreters/geologists, petrophysicists and reservoir engineers who want to familiarize themselves with all aspects AVO (= amplitude versus offset) and Seismic Inversion, i.e., anyone who wants to enhance structural interpretation with QI = quantitative interpretation.
- The theory is based on first principles; the applications exploit the latest developments in acquisition and processing and demonstrates how multi-disciplinary teams can share information in a meaningful way.