N470 AVO Reflectivity, Pre-stack Inversion and Quantitative Seismic Interpretation

Course Facts

Course Code:
N470
Duration:
3 days
Type:
Classroom
CEU:
2.4 Continuing Education Units
PDH:
24 Professional Development Hours
Certificate:
Certificate Issued Upon Completion

Summary

Utilization of AVO (Amplitude Versus Offset) reflectivity-based pre-stack elastic and anisotropic seismic inversion methods has increased in the last decade, thereby providing geoscientists and engineers with direct subsurface investigation methods to characterize reservoirs and plan drilling projects. During the same period, improvements in seismic reflection imaging and QI (quantitative interpretation) analysis have enabled more reliable predictions of reservoir lithology, porosity, and fluids while also yielding useful insights regarding fluid flow and hydro-fracture stimulation through detailed 3D mapping of reservoir inhomogeneities, stresses, and fractures.   This course provides geoscientists and engineers with the practical skills necessary to utilize seismic inversion methods and QI techniques to characterize reservoirs and plan drilling projects for both conventional and unconventional reservoirs.

Duration and Training Method

This is a 3-day classroom course containing lectures, exercises, workflow examples and case histories.  (Optional - Internal runs may substitute discussions of client data for some of the case history materials scheduled on day 3).

Participants will learn to:

  1. Apply fundamental principles of rock physics and seismic wave propagation to plan and execute effective seismic inversion projects.
  2. Utilize petrophysical models to calibrate seismic inversion products using well control.
  3. Characterize commonly utilized seismic inversion techniques and select appropriate methods to achieve project objectives.
  4. Create milestones and a list of deliverables with a multidisciplinary team to insure project goals are realized.
  5. Investigate the sources of computational error and validate inversion products to ensure that results are a reasonable representation of subsurface geology.

This course will demonstrate that seismic interpretation workflows combining AVO inversion products with petrophysical log analysis can provide profound geological and engineering insights from observed relationships between seismic data and elastic reservoir parameters such as Poisson’s Ratio (ν), Young’s Modulus (E), shear modulus (mu, or µ) and incompressibility (lambda, or λ) or bulk modulus (K). 

In the relatively recent paradigm of horizontal well hydro-fracture stimulation of fully charged tight unconventional reservoirs with low porosity, the application of AVO and Amplitude Variation with Azimuth (AVAZ) inversion methods can be simplified to extracting lithology and geo-mechanical properties from seismic data.  Consequently, this course will address the rock-mechanics and petrophysics workflows necessary to map tight shale lithology, porosity, OOIP/OGIP, closure stress, and brittleness to quantifiably characterize hydrocarbon reservoirs and to assist in wellbore design and hydro-fracture stimulation.

Furthermore, it will be demonstrated for conventional reservoirs that the Lamé impedances LambdaRho and MuRho (Rho represents density) derived from seismic data and well logs and utilized in petrophysical cross-plot analysis can be utilized effectively to map lithology changes and discriminate between types of pore fluids in a reservoir.  A case study, calibrated with walkaway VSP data, will be reviewed that demonstrates the potential of this workflow to distinguish between economic gas reservoirs and “wet” reservoirs containing low-saturation gas.

The aim of this course is to cover the basic principles of rock physics involved in seismic wave propagation and inversion through related case history examples of workflows designed to calibrate seismic data sets and produce reliable interpretation products for wellbore placement/design and reservoir modeling.

These topics will be addressed as follows:

Day 1

 AVO basics:

  • Brief overview of theory and methods from Hooke’s Law and moduli involved in AVO

Rock properties and seismic theory:

  • P-wave & S-wave velocities, mudrock line
  • P-wave, S-wave propagation and wave equations
  • P-wave, S-wave velocities AVO attributes and DHI’s

Seismic petrophysics:

  • Seismic log-based motivation for AVO: lambda, mu, LambdaRho, MuRho
  • Gassmann fluid replacement modeling and DHI’s

Borehole VSP/log petrophysical calibration:

  • Walkaway VSP AVO case study including Lamé parameters
  • Inversion of walkaway VSP, P-P & P-S “AVO gathers” and surface P-P seismic: Gas Sand Example
  • Quantitative comparison of P-, S-impedance and Vp/Vs ratio from walkaway VSP inversion to log sonic curves and surface seismic

AVO methods based on linearized reflectivity with offset equations:

  • Processing to preserve and enhance AVO response
  • AVO reflectivity equations, methods and Rp, Rs analysis including Lamé reflectivity
  • Examples of AVO inversion for elastic parameters from 3D data
  • Errors in reflectivity methods
  • Case study example of how AVO reflectivity methods reduced exploration drilling and delineation risk

Day 2

 AVO inversion:

  • AVO QI inversion equations and methods: Elastic Impedance (EI) and Lambda-Mu-Rho (LMR)
  • Resolution and sensitivity of QI inversion methods for elastic parameters
  • AVO/LMR examples: Alberta Land and Offshore West Africa
    with VTI anisotropy effects on AVO and log calibration
  • Errors in QI inversion methods (EI, LMR)
  • Case study examples of how AVO inversion methods did and did not reduced exploration drilling risk

Day 3

Seismic geomechanics: 

  • Brittleness vs. Geomechanics, Mohr-Coulomb, min closure stress, bound in-situ moduli/ratios
  • Seismic petrophysical log templates

 AVO inversion for unconventional plays:

  • Horn River NEBC: 3D AVO/LMR seismic attributes to predict completions performance and production
  • In-situ stress estimation from VTI and HTI anisotropy
  • Microseismic and 3D AVO/LMR attributes for Geomechanics, OGIP, minimum closure and stress anisotropy mapping
  • Microseismic combined with 4D: a better way to map stimulated reservoir volume
  • Tight Oil Case Study

 

 

Establishing project objectives with multidisciplinary teams

  • Integrated multi-disciplinary case histories
  • Characterization of shale and tight sand reservoirs

Review of Client data (Internals only)

Who should attend

Geoscientists and engineers having a basic understanding of rock physics and seismic imaging, and who would like to learn more about seismic inversion tools capable of improving their knowledge of conventional and unconventional reservoirs.

Prerequisites and linking courses

Attendees should have an understanding of the fundamentals of rock physics and seismic wave propagation, and also have some familiarity with seismic data processing.  Nautilus courses N004, N080, N085, N443, or equivalent training are recommended to provide an understanding of seismic fundamentals.  Attendees may also consider Course N032  “Professional Level Rock Physics and Seismic Amplitude Interpretation (AVO and Seismic Inversion)” which focuses on conventional reservoirs.  Course N284  “Seismic Attributes and Pre-Stack Inversion Tools for Characterizing Unconventional Reservoirs” provides an introduction to topics that are addressed in more detail in this course.

Click on a name to learn more about the instructor

Bill Goodway

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