Influence of microporosity distribution on the mechanical behavior of oolithic carbonate rocks

Regnet, Jean-Baptiste; David, Christian; Fortin, Jérôme; Robion, Philippe; Makhloufi, Yasin; Collin, Pierre‐Yves

doi:10.1016/j.gete.2015.07.002

Cited by 35 publications

(23 citation statements)

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“…Fortin et al () observed a continuous decrease of the P wave velocity during hydrostatic compaction of Chauvigny limestone (17% porosity) without any significant change at the hydrostatic yielding point P *. More recently, Regnet et al () also reported a decrease of V P during compaction of an oolithic carbonate rock (16% porosity), but significant variations only occurred beyond the onset of cataclastic pore collapse C *. Our new triaxial data showed a similar behavior (Figures ).…”

Section: Discussionmentioning

confidence: 94%

Inelastic Compaction in High‐Porosity Limestone Monitored Using Acoustic Emissions

et al. 2017

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We performed a systematic investigation of mechanical compaction and strain localization in Saint‐Maximin limestone, a quartz‐rich, high‐porosity (37%) limestone from France. Our new data show that the presence of a significant proportion of secondary mineral (i.e., quartz) did not impact the mechanical strength of the limestone in both the brittle faulting and cataclastic flow regimes, but that the presence of water exerted a significant weakening effect. In contrast to previously published studies on deformation in limestones, inelastic compaction in Saint‐Maximin limestone was accompanied by abundant acoustic emission (AE) activity. The location of AE hypocenters during triaxial experiments revealed the presence of compaction localization. Two failure modes were identified in agreement with microstructural analysis and X‐ray computed tomography imaging: compactive shear bands developed at low confinement and complex diffuse compaction bands formed at higher confinement. Microstructural observations on deformed samples suggest that the recorded AE activity associated with inelastic compaction, unusual for a porous limestone, could have been due to microcracking at the quartz grain interfaces. Similar to published data on high‐porosity macroporous limestones, the crushing of calcite grains was the dominant micromechanism of inelastic compaction in Saint‐Maximin limestone. New P wave velocity data show that the effect of microcracking was dominant near the yield point and resulted in a decrease in P wave velocity, while porosity reduction resulted in a significant increase in P wave velocity beyond a few percent of plastic volumetric strain. These new data highlight the complex interplay between mineralogy, rock microstructure, and strain localization in porous rocks.

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Section: Discussionmentioning

confidence: 94%

Inelastic Compaction in High‐Porosity Limestone Monitored Using Acoustic Emissions

et al. 2017

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“…It showed dilatancy and failed by brittle faulting, that was accompanied by permeability reduction (Table ). Regnet et al () presented permeability data for two Oolithe Blanche limestones samples, triaxially compressed at confining and pore pressures of 28 and 5 MPa, respectively. In each sample the permeability showed a very slight increase from the onset of dilatancy C ′ to near the peak stress (Table ).…”

Section: Discussionmentioning

confidence: 99%

The Effect of Stress on Limestone Permeability and Effective Stress Behavior of Damaged Samples

Meng

Baud

et al. 2019

JGR Solid Earth

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The evolution of permeability and its effective stress behavior is related to inelastic deformation and failure mode. This was systematically investigated in Indiana and Purbeck limestones with porosities of 16% and 14%, respectively. High-pressure compression tests were conducted at room temperature on water-saturated samples. At relatively high confinement shear-enhanced compaction was observed to initiate at a critical stress, accompanied by significant permeability reduction of up to a factor of~3. Overall, the permeability reduction due to inelastic compaction in our limestones is smaller than that observed in sandstones. At relatively low confinement, dilatant failure was observed, which was accompanied by a decrease and increase of permeability in Indiana and Purbeck limestones, respectively. There seems to be a trend for the correlation between porosity and permeability changes to switch from positive to negative with increasing porosity. The void space of both limestones has significant proportions of macropores and micropores. The effective stress behavior of such a limestone with dual porosity has been documented to be different from the prediction for a microscopically homogeneous assemblage, in that its effective stress coefficients for permeability and pore volume change may attain values significantly >1. In contrast, our investigation of damaged samples consistently showed effective stress coefficients for both permeability and pore volume change with values <1. This suggests that the behavior in the damaged samples is akin to that of a microscopically homogeneous assemblage, possibly due to pervasive collapse of macropores that would effectively homogenize the initially bimodal pore size distribution.

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“…Porosity, fabrics and pore types being the main contrai factors of elastic velocity in carbonate rocks (Eberli et al, 2003;Baechle et al, 2008;Verwer et al, 2008), it seems natural to seek to link elastic properties and diagenesis. However, only a few studies tackle the key issue of relating sedimentological and diagenetic features to physical properties measured at the sample scale and extrapolating the obtained results at the formation scale to derive global evolution laws (Brigaud, 201 O;Regnet et al, 2015aRegnet et al, , 2015bMatonti et al, 2015Matonti et al, , 2016. Numerous acoustic of 0.02) to the reference pores.…”

Section: Introductionmentioning

confidence: 99%

Effective medium modeling of diagenesis impact on the petroacoustic properties of carbonate rocks

et al. 2019

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1Carbonate formations are heterogeneous and their velocity -porosity relationships are mainly controlled by microstructural parameters. As diagenesis is responsible for important changes in the microstructure of carbonate rocks, we propose here to extend the classic effective medium approach to mode! the impact of diagenesis on carbonate elastic properties through a step by step effective medium modeling. Two different carbonate formations are considered. The first key step is the characterization of the diagenesis which affected the studied carbonate series.An effective medium mode! integrating ail the geological information accessible from thin section analysis is then built. The evolution of the micro structural parameters during diagenesis is thoroughly constrained based on an extensive experimental dataset, including XRD analysis, various porosimetry techniques and ultrasonic velocities measurements. Finally, direct calculations with the mode! provide elastic wave velocities representative of the different diagenetic stages. An extrapolation to permeability evolution is also introduced. This approach allows the identification of the acoustic signature of specific diagenetic events, such as dolomitization, dissolution or cementation, and the assessment of their impact on the flow properties of carbonate formations.

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Influence of microporosity distribution on the mechanical behavior of oolithic carbonate rocks

Cited by 35 publications

References 50 publications

Inelastic Compaction in High‐Porosity Limestone Monitored Using Acoustic Emissions

Inelastic Compaction in High‐Porosity Limestone Monitored Using Acoustic Emissions

The Effect of Stress on Limestone Permeability and Effective Stress Behavior of Damaged Samples

Effective medium modeling of diagenesis impact on the petroacoustic properties of carbonate rocks

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