Compactional behavior of fine-grained sediments — examples from Deep Sea Drilling Project cores

Abstract

ZusammenfassungDie Synthese experimenteller Labor&ten, statistischer Analysen yon Messungen an Kernen und theoretischer Modellierung der Kompaktion im Gleichgewicht mit der Auflast erm6glicht die Definition yon Typ-Kurven fiir das Kompaktionsverhalten yon verschiedenen Tiefsee-Sedimenten. Eine erweiterte und verbesserte Form der Athy'schen Gleicbung erlanbt zusammen mit Laborexperimenren, Sedimente entsprechend des Anteils an strukmrell gebundenem Porenwasser zu klassifizieren. Anhand yon Saugspannungsexperimenten k6nnen die Bindungskf~ifte zwischen Wasser and Partikeloberfl~ichen abgesch~itzt werden. Die untersuch-~:en Sedimente reichen yon ,,suspendierten K6rnern,, bis zu einem ,,kolloidalen System,,. Die notwendigen Methoden ,and Gleichungen zur Bestimmung der relevanten Parameter aus Bohrlochdaten und Laborexperimenten werden diskualert. AbstractLaboratory experiments, statistical analysis of field data and theoretical models are combined in the attempt to derive ,;tandard compaction curves for various deep-sea sediments which are in compaction equilibrium with the overburden. A revised and generalized version of Athy's law together with laboratory experiments allows the classification of ,;ediments in terms of the amount of porewater structurally bound to the particles' surfaces. Especially suction pressure experiments are useful in quantifying the forces that bind water on the particle surfaces. The sediments analyzed almost range from systems of ~,suspended grains,, to nearly perfect ,~colloidal systems,,. The methods and equations required to derive the relevant parameters are given for both, downhole porosity/density measurements and laboratory experiments. . Present address: GeologischPal~iontologisches Institut, UniversMt Basel, Bernoullistraf~e 32, CH-4056 Basel, Switzerland. R6sum6A partir d'une synth~se de r&ultats d'exp6riences de laboratoires, d'analyses statistiques de donn6es de terrain et d'une mod61isation th6orique, il est possible d'&ablir des courbes standard du processus de compaction pour divers types de s6diments de mer profonde, pour lesquels la compaction est en 6quilibre avec la charge. Une version revue et g6n&alis6e de la loi d'Athy permet, en accord avec les r6sultats exp&i-mentaux, de classer les s6diments selon la quantit6 d'eau intersticielle li6e structuralement ~ la surface des particules. Les s6diments analys6s correspondent ~i des syst~mes qui vont du type ~ ~,grains suspendus,, ~t des colloYdes presque parfaits. Les auteurs pr6sentent une discussion d6taill6e des m6thodes et des 6quations n6ssaires ~ l'obtention des param~tres significatifs rant ~ partir des exp6riences de laboratoire qu'~t partir des mesures de porositUdensit6 effectu6es dans les forages. Kpa'l~oe co,~epxanneHpOCMOTp aaHHbIX sm6opaTopm,~x Hccae~oBami~, CTa-THCTW-IecKa~ o6pa6oTKa ~anm, ix H3MepennfI Ha KepHax rI weopeTrmecKoe uo~earIposanrre ynaoTneHrt~ ce~nMeHTa npn ycYtosrLqx paBnOBeCn~t C HarpysKofi pa3pema~oT oxapaKwepn3oBawh THYIbI KpnBt, IX, OI~ChIBalO~rIX IIoBe~erme pa3ar~qrIblX ray6OKOBO~m, IX ce~nM...

Factors controlling the thermo-mechanical deformation of oil shales: Implications for compaction of mudstones and exploitation

“…Normally consolidated samples show ratios around 1 while higher values are due to overconsolidation (Bayer and Wetzel, 1989;Nyga˚rd et al, 2004). The apparent pre-consolidation stress (s 0 vmax ) represents the point at which a sharp change occurs during laboratory loading when plotting the volumetric strain or void ratio change against effective stress (Nyga˚rd et al, 2004).…”

“…The compaction of mudstones during burial and subsidence has major implications on fluid generation and transport in sedimentary systems. It has therefore been of wide interest in studies on the evolution and understanding of dynamic processes in sedimentary basins (Terzaghi, 1925;Athy, 1930;Weller, 1959;Perrier and Quiblier, 1974;Bayer and Wetzel, 1989;Broichhausen et al, 2005). Compaction proceeds with increasing stress and temperature in nature.…”

Mudstone compaction and its influence on overpressure generation, elucidated by a 3D case study in the North Sea

“…Marine and terrestrial sedimentary basins contain about 60-70% of finegrained mudstones and siltstones on average (Garrels and Meckenzie 1970). However, the compaction behaviour of mudstones is complex and differs from that of coarse-grained lithologies such as sandstones (Bayer 1989;Bayer and Wetzel 1989). For example, mudstones have a much higher initial porosity than other sedimentary rocks and are therefore most severely reduced in thickness during diagenesis.…”

Interpreting transient carbonate compensation depth changes by marine sediment core modeling

“…Sediment composition is plotted as a function of bulk CaCO 3 age relative to the time of release using the internal carbonate-tied chronology (Figure 3) and contrasted with the independently dated Walvis Ridge observations. By making this comparison in time rather than space (depth), compaction processes [Bayer and Wetzel, 1989], which become important at the 140 -336 m stratigraphic depth of the Paleocene-Eocene boundary in Walvis Ridge sediments need not be taken into account in the model. I find that 4500 Pg C, a quantity identified from previously global sediment modeling Zachos et al, 2005], drives only a rather weak depletion of carbonate regardless of whether the release is over 1 or 10 ka.…”