Geophysics

Extended Elastic Impedance and its Relation to AVO Crossplotting and Vp/Vs
Extended Elastic Impedance (EEI) has proved to be a highly convenient framework for seismic AVO studies. The directness of the EEI method is one of its strengths, making it unnecessary to perform intermediate steps such as examining conventional AVO attributes (eg intercepts and gradients). This paper, presented by Graham Hicks and Ashley Francis at the EAGE 68th Conference & Exhibition, Vienna, Austria, 12 - 15 June 2006, explains some of the parallels between conventional AVO and EEI analysis and introduces a new AVO attribute for estimating background Vs/Vp ratio.

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Download PDF document: EAGE_ExtendedAbstract.pdf (0.7 Mb)

Technical Note: Ardmore Field Extended Elastic Impedance Study
This Technical note is a case study describing deterministic inversion work undertaken by Earthworks on the Ardmore Field, UKCS. In addition it serves as a briefing document on our methods of applying Extended Elastic Impedance to predict reservoir properties. A short version was presented by Ashley Francis and Graham Hicks at the EAGE 68th Conference & Exhibition, Vienna, Austria, 12 - 15 June 2006.
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Download PDF document: EAGE_ExtendedAbstract.pdf (2.2 Mb)

Download PDF document: ArdmoreFieldTechnicalNote.pdf (11.1 Mb)

How Uncertain is your Seismic Inversion?
Our ultraFast stochastic seismic inversion technology is still being improved. To understand the uncertainty in seismic inversion please see our Deterministic and Stochastic Comparison

Technical Note: Extended Elastic Impedance Theory
This new technical note is intended to provide summary of the Extended Elastic Impedance (EEI) methodology. Earthworks make extensive use of EEI as part of its partial pre-stack seismic inversion methodology

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Technical Note: Coloured, Deterministic and Stochastic Inversion
This technical note is intended to provide information on Earthwork's capabilities to undertake seismic inversion. In addition, it also serves as a briefing document on our ultra-FAST stochastic inversion technology with which we can perform stochastic inversion studies on a routine basis

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Download PDF document: StochasticInversionTechnicalNote.pdf (1.8 Mb)

PETEX 2002: Deterministic Inversion - Overdue for Retirement?
Seismic inversion tools designed to estimate impedance have been available to Geophysicists for over twenty years. Most of the available methods are based on minimising the difference between the seismic trace and forward convolution of the solution with the estimated wavelet. Methods based on minimisation are commonly referred to as "deterministic". This paper explores the limitiations of deterministic inversion, discusses the benefits of stochastic inversion and then presents an example using the new, ultra-fast stochastic inversion method developed by Earthworks.

On-line: First slide

Download PDF document: petex2002expandedabstract.pdf (0.8 Mb)

Download PDF of slides: petex2002presentation.pdf (3.0 Mb)

Improving a Well Tie with Backus Upscaling
Earthworks has a number of techniques available to condition data. Backus upscaling is a method of modifying well log data according to physical principles based on the work of Backus and others to correct for thin bed coupling effects. At Earthworks we NEVER apply arbitrary stretch and squeeze to well logs. Stretch and squeeze tends to reinforce initial phase assumptions and causes noise to be propagated into the wavelet estimation, degrading the result and giving rise to inconsistencies between wavelets estimated at different wells.

On-line show: First slide

Download PDF of slides: BackusUpscaling.pdf (0.4 Mb)

Real and Relict Direct Hydrocarbon Indicators in the East Irish Sea Basin
A. Francis, M. Millwood Hargrave, P. Mulholland and D. Williams. Published in Meadows, N.S., Trueblood, S.P., Hardman, M & Cowan, G. (eds), 1997, Petroleum Geology of the Irish Sea and Adjacent Areas, Geological Society Special Publication No. 124, pp 185-194

Download PDF document: eisb_paper.pdf (0.5 Mb)

Application of Relative Acoustic Impedance Inversion to Constrain Extent of E Sand Reservoir on Kadanwari Field
A. Francis and F. H. Syed. Presented at SPE & PAPG Annual Technical Conference, 7-8 November 2001, Islamabad, Pakistan

Download PDF document: kadanwari_paper.pdf (0.6 Mb)

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