Influence of effective stress coefficient on mechanical failure of chalk

Mohammad Monzurul Alam, Ida Lykke Fabricius, M.L. Hjuler, H.F. Christensen

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The Effective stress coefficient is a measure of how chalk grains are connected with each other. The stiffness of chalk may decrease if the amount of contact cements between the grains decreases, which may lead to an increase of the effective stress coefficient. We performed CO2 injection in chalk, as this process could affect the grain contact cement. If this happens, the effective stress at the grain contacts in a reservoir will change according to the effective stress principle of Biot. In a p′-q space for failure analysis, we observed that a higher effective stress coefficient reduces the elastic region and vice versa. However, as the effective stress working on the rock decreases with increased effective stress coefficient, the reduction of elastic region will have less effect on pore collapse strength if we consider the change in the effective stress coefficient. This finding will help estimate a more precise failure strength of chalk during changed stress state and under the influence of chemically reactive fluids during production of hydrocarbon and geological storage CO2.
Original languageEnglish
Title of host publicationProceedings of the 46th US Rock Mechanics / Geomechanics Symposium
Number of pages8
Publication date2012
Publication statusPublished - 2012
Eventthe 46th US Rock Mechanics / Geomechanics Symposium - Chicago, United States
Duration: 24 Jun 201227 Jun 2012
Conference number: 46


Conferencethe 46th US Rock Mechanics / Geomechanics Symposium
Country/TerritoryUnited States


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