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dc.contributor.authorNarongsirikul, Sirikarn
dc.contributor.authorMondol, Nazmul Haque
dc.contributor.authorJahren, Jens
dc.date.accessioned2019-06-07T07:12:11Z
dc.date.available2019-06-07T07:12:11Z
dc.date.created2019-05-23T11:25:45Z
dc.date.issued2019
dc.identifier.citationGeophysical Prospecting. 2019, 67 804-824.nb_NO
dc.identifier.issn0016-8025
dc.identifier.urihttp://hdl.handle.net/11250/2600243
dc.description.abstractThis paper part one is set out to lay primary observations of experimental compaction measurements to form the basis for rock physics modelling in paper part two. P‐ and S‐wave velocities and corresponding petrophysical (porosity and density) properties of seven unconsolidated natural sands with different mineralogical compositions and textures are reported. The samples were compacted in a uniaxial strain configuration from 0.5 up to 30 MPa effective stresses. Each sand sample was subjected to three loading cycles to study the influence of stress reduction on acoustic velocities and rock physical properties with the key focus on simulating a complex burial history with periods of uplift. Results show significant differences in rock physical properties between normal compaction and overconsolidation (unloaded and reloaded). The differences observed for total porosity, density, and P‐ and S‐wave velocities are attributed to irrecoverable permanent deformation. Microtextural differences affect petrophysical, acoustic, elastic and mechanical properties, mostly during normal consolidation but are less significant during unloading and reloading. Different pre‐consolidation stress magnitudes, stress conditions (isotropic or uniaxial) and mineral compositions do not significantly affect the change in porosity and velocities during unloading as a similar steep velocity–porosity gradient is observed. The magnitude of change in the total porosity is low compared to the associated change in P‐ and S‐wave velocities during stress release. This can be explained by the different sensitivity of the porosity and acoustic properties (velocities) to the change in stress. Stress reduction during unloading yields maximum changes in the total porosity, P‐ and S‐wave velocities of 5%, 25%, and 50%, respectively. These proportions constitute the basis for the following empirical (approximation) correlations: Δϕ ∼ ±5 ΔVP and ΔVP ∼ ±2ΔVS. The patterns observed in the experiments are similar to well log data from the Barents Sea. Applications to rock physics modelling and reservoir monitoring are reported in a companion paper.
dc.language.isoengnb_NO
dc.titleAcoustic and petrophysical properties of mechanically compacted overconsolidated sands: part 1 – experimental resultsnb_NO
dc.typeJournal articlenb_NO
dc.typePeer reviewednb_NO
dc.description.versionacceptedVersion
dc.source.pagenumber804-824nb_NO
dc.source.volume67nb_NO
dc.source.journalGeophysical Prospectingnb_NO
dc.identifier.doi10.1111/1365-2478.12744
dc.identifier.cristin1699714
cristin.unitcode7452,4,5,0
cristin.unitnamePetroleumsgeomekanikk og geofysikk (PGG)
cristin.ispublishedtrue
cristin.fulltextpostprint
cristin.qualitycode1


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