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Rock Physics and Inversion (Q.I.)

For successful prospect identification it is imperative to tie together well and seismic information to understand how this data responds to variation in physical properties and fluid content.

Our Quantitative Interpretation service supplies a full suite of rock physics indicator logs describing the in-situ physical properties in each well (e.g. porosity, saturation). Fluid Replacement Modelling (FRM) is applied to these to learn how each property changes when pore fluid type and content varies. The impact on seismic response can then be modelled from synthetics and AVO classes identified. Fluid identification is aided further by deriving for each fluid case elastic properties (Lambda-Mu-Rho) and extended elastic impedances (EEI). 

Seismic inversion integrates the rock physics and elastic log information with seismic data to produce geologically meaningful attribute volumes that highlight key geological and fluid induced seismic effects. A full range of attribute volumes are generated to match the log rock physics and elastic properties.

To maximise the benefits of inversion we recommend our AVO/AVA compliant depth migrations.

Nelson, Forties Sand, U.K.


Kirchhoff Lambda-Rho

Kirchhoff depth migration is unable to provide accurate angles of incidence that show the polarity reversal associated with oil. As a result, two of the wells appear to be dry.


GRT Lambda-Rho

Inversion performed by SIP using GRT depth migration as input provides accurate angle gathers with polarity reversal resulting from oil. Lambda-Rho correctly relates to known oil wells.

AVO Machine Learning


EEI Fluid Projection

Extended Elastic Impedance (EEI) projection for maximum fluid, derived after GRT depth migration. West of Shetlands area.


AVO Identification from Gathers

Class II/III AVO identified directly from angle gathers using SIP's machine learning algorithm. Direct analysis gives a good match to EEI. The result is more discrete and a better measure of where AVO is cleanest and strongest.

Our QI Services


  • Rock Physics Indicators

  • Fluid Replacement Modelling

  • EI / EEI logs

  • Single and Multi-well Analysis

  • Synthetic CMP Modelling

  • Wedge Modelling


  • Simultaneous Pre-stack Inversion

  • P-, S-impedance, Density

  • Vp/Vs, Poisson's Ratio

  • Lambda-Mu-Rho

  • Geomechanical Attributes


  • Coloured Inversion

  • EEI projections (Chi, Psi)

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