Experimental compression of loose sands: relevance to porosity reduction during burial in sedimentary basins

Abstract

This study examines the one-dimensional stress–strain behaviour of sand at effective stresses as high as 50 MPa. Experiments were performed on 22 sands (approx. 150 tests) with different grain size, uniformity coefficient, angularity, density, grain mineralogy, and clay content. The results show that minor grain corner crushing starts at stresses of 2–8 MPa. The point of maximum curvature (yield point) in the porosity (n) versus logarithm of vertical effective stress (σ'v) curve defines the initiation of marked particle crushing. The stress at the yield point varies between 3 and 31 MPa depending on sand characteristics. A low yield stress is indicative of high porosity loss in the interval of intermediate stress (5–25 MPa). The yield stress is low when the grain size is large, grains are angular, grain strength is low, and uniformity coefficient is low. The lowest yield stress value occurs in the coarser carbonate sand, and the highest in the chert-rich sands. The sands rich in clays are highly compressible up to 25 MPa. At stresses higher than ~10 MPa, the coarser biogenic carbonate sands maintain higher porosities than the other sands. This can be explained by the fact that coarser biogenic carbonate sands have low yield stresses due to high angularity and low grain strength and initially there is local grain crushing at grain contacts. This increases the area of the grain contacts, so the coarser carbonate sands become less compressible at higher stresses. Within the high stress range (25–50 MPa) the porosity loss differences related to grain size, grain shape, grain mineralogy, and sand uniformity coefficient are significantly reduced. Hence the greater compressibility of lithic and carbonate sands becomes less evident in the high-stress interval as the grain size increases.Key words: sand, grain crushing, grain size, high stress, compression.

Overpressure preventing quartz cementation? - A reply

“…We agree with Maast (2016) that pore fluid overpressure and low VES is known to prevent extensive grain fracturing in rigid-grained sandstones (Chuhan et al, 2003(Chuhan et al, , 2002. However, we don't see why Maast (2016) raised this point, as the reservoir conditions (i.e., applied stresses) are throughout the entire burial history below reported stresses for grain fracturing (Chuhan et al, 2003(Chuhan et al, , 2002) (see Figure 4; Stricker et al, 2016b).…”

“…However, we don't see why Maast (2016) raised this point, as the reservoir conditions (i.e., applied stresses) are throughout the entire burial history below reported stresses for grain fracturing (Chuhan et al, 2003(Chuhan et al, , 2002) (see Figure 4; Stricker et al, 2016b). Experimental work focusing on high-pressure testing of compaction of sand shows that the yield strength relates to the onset of grain crushing and varies largely with sand properties (Chuhan et al, 2003;Mesri and Vardhanabhuti, 2009). The Triassic reservoir sandstones of the Heron Cluster fields are very fine grained to fine grained sandstones, show high yield strength, and are less prone to grain fracturing (e.g.…”

Creep of simulated reservoir sands and coupled chemical‐mechanical effects of CO2 injection

“…[49] Pure grain rearrangement, through sliding and rolling of particles until a "locked" aggregate is created, generally produces small strains (a few percentage) which depend on the starting porosity of the aggregate [Brzesowsky, 1995;Chester et al, 2007;Chuhan et al, 2003]. However, our quartz experiments showed instantaneous strains (e v 0 ) of ∼10% with no systematic dependence on starting porosity 8 0 (see Table 2).…”

Failure behavior of single sand grains: Theory versus experiment

“…Grain-scale fracture and rearrangement are believed to be mechanisms of importance in controlling the porosity and permeability evolution of sedimentary rocks in rapidly subsiding basin settings [Chuhan et al, 2002[Chuhan et al, , 2003Donaldson et al, 1995]. They may also be of importance in controlling production-related compaction of hydrocarbon reservoir rocks, as a result of rapidly changing effective stresses, leading to surface subsidence [Doornhof et al, 2006;Hettema et al, 2002;Schutjens et al, 1994;Zoback and Byerlee, 1976].…”

“…Experimental studies on time-independent compaction of porous sandstones and sands at room temperature have shown irrecoverable porosity reduction during loading, which increases significantly beyond a specific critical effective pressure (P cr ) [Borg et al, 1960;Chuhan et al, 2003;Dunn et al, 1973;Karner et al, 2003Karner et al, , 2005Lambe and Whitman, 1969;Lee and Farhoomand, 1967;McDowell and Humphreys, 2002;Nakata et al, 2001;Vesíc and Clough, 1968;Wissler and Simmons, 1985;Wong and Baud, 1999;Zhang et al, 1990;Zoback and Byerlee, 1976]. Experiments on sand aggregates and sandstones have shown that the amount of compaction obtained at a given effective pressure generally increases with increasing porosity (8) and increasing grain size (d) [Borg et al, 1960;Chuhan et al, 2002Chuhan et al, , 2003Dunn et al, 1973;Hangx et al, 2010;Karner et al, 2005;Lambe and Whitman, 1969;Lee and Farhoomand, 1967;McDowell and Humphreys, 2002;Nakata et al, 1999;Vesíc and Clough, 1968;Zhang et al, 1990]. This is in accordance with the observation that with increasing porosity and grain size, the critical pressure for grain crushing P cr decreases, i.e., the rock becomes weaker [Karner et al, 2005;Wong and Baud, 1999;Zhang et al, 1990].…”