Rock Physics Modelling of Organic-rich Chalk: The roles of porosity, organic content and maturation

O. Shitrit, Y. H. Hatzor, S. Feinstein, H. J. Vinegar

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Geophysical prospecting of organic-rich rocks usually combines petrophysical data with elastic properties, in order to estimate the acoustic velocities. We propose here a model designed for an organic-rich chalk based on porosity, density and TOC data. The model includes an extension for estimating bitumen and kerogen contents based on bitumen extraction measurements. Using the densities and volume fractions of each phase, the elastic moduli are calculated using the “HS kerogen” model which simulates a kerogen-supported rock and found suitable for the organic-rich chalk at its immature state. The model is used to create a rock physics template of the organic-rich chalk. We find that where the Vp/Vs ratio is plotted against the acoustic impedance (typical layout), the effects of organic content and maturity are unclear. By using a matrix-focused layout, in which the acoustic impedance is replaced by the product of solids density and S-wave velocity (ρs∙Vs), the changes associated with organic content and maturity level are much better pronounced. We believe this layout can be useful for all organic-rich rock types. As for the Ghareb-Mishash chalk studied here, we find that its elastic properties are strongly influenced by porosity and organic-content, while their dependence on maturity is somewhat smaller.

Original languageEnglish
Title of host publication80th EAGE Conference and Exhibition 2018
Subtitle of host publicationOpportunities Presented by the Energy Transition
PublisherEuropean Association of Geoscientists and Engineers, EAGE
ISBN (Electronic)9789462822542
DOIs
StatePublished - 1 Jan 2018
Event80th EAGE Conference and Exhibition 2018: Opportunities Presented by the Energy Transition - Copenhagen, Denmark
Duration: 11 Jun 201814 Jun 2018

Conference

Conference80th EAGE Conference and Exhibition 2018: Opportunities Presented by the Energy Transition
Country/TerritoryDenmark
CityCopenhagen
Period11/06/1814/06/18

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