Prediction of Abrupt Reservoir Compaction and Surface Subsidence Caused By Pore Collapse in Carbonates

Smits, R.M.M.; Waal, J.A. de; Kooten, J.F.C. van

doi:10.2118/15642-pa

Cited by 41 publications

(23 citation statements)

References 6 publications

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“…The interfossil porosity vs. depth curves for the Site 803 samples fall along a single trend, as predicted for a uniform sediment type by Smits et al (1988). The more scattered picture for the Site 807 samples probably reflects problems with the determination of the intrafossil porosity in material with variable microfossil abundance.…”

Section: Discussionmentioning

confidence: 57%

“…They noted the presence of calcite overgrowth on discoasters and the dissolution of nannofossils in Site 586 samples from a depth of 150 mbsf, and the transition from soft ooze to stiff ooze and chalk at roughly 250 mbsf. Smits et al (1988) performed compaction experiments on moldic limestone as well as three different chalks. They established that subsequent to pore collapse, samples of similar lithology but different initial porosity tend to follow the same curve relating porosity to vertical effective stress.…”

Section: Introductionmentioning

confidence: 99%

“…Loading rate 1000 br/hr. After Smits et al (1988). direction of the samples, if the pore pressure rose as a consequence of loading, and if the liquid pressure exceeded the effective vertical stress.…”

Section: Introductionmentioning

confidence: 99%

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Loading Experiments on Carbonate Ooze and Chalk from Leg 130, Ontong Java Plateau

Lind¹

1993

Proceedings of the Ocean Drilling Program

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Consolidation experiments, in which the pore water is slowly squeezed from a sample, as well as undrained loading tests, where pore water under a high pressure is prevented from leaving a sample, have been conducted on samples of Ontong Java Plateau ooze and chalk. Hole 8O3D was sampled down to 519 mbsf and Holes 807 A and 807C down to 945 mbsf. Consolidation curves relating uniaxial stress to matrix porosity fall along a single trend for the Site 803 samples. The matrix porosity was determined from the bulk porosity by subtracting the intramicrofossil porosity, obtained by electron microscopy and image analysis of polished surfaces. No difference in the compaction trend was found between ooze and chalk, and no obvious indication of chemical compaction could be deduced from the compaction curves. Undrained loading leads to fracturing in the chalk samples, whereas ooze samples remain unfractured under these conditions.

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Section: Discussionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

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Loading Experiments on Carbonate Ooze and Chalk from Leg 130, Ontong Java Plateau

Lind¹

1993

Proceedings of the Ocean Drilling Program

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“…For very porous or weakly consolidated reservoirs, the increase in effective stress may be sufficient to cause inelastic deformation of the reservoir rock (e.g., Jones and Leddra, 1989;Goldsmith, 1989). The consequences of such inelastic compaction can be economically severe and include surface subsidence and various production problems (e.g., Smits et al, 1988;Fredrich et al, 1998). Significant reduction of permeability may also accompany the compaction (Zhu and Wong, 1997b).…”

Section: Introductionmentioning

confidence: 99%

Mechanical Compaction of Porous Sandstone

Wong

Baud

1999

Oil & Gas Science and Technology - Rev. IFP

102

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Résumé -Compaction mécanique des grès poreux -Pour de nombreux problèmes de tectonique et d'ingénierie de réservoir, la capacité à prévoir à la fois la fréquence, l'ampleur de la déformation inélas-tique et les ruptures repose sur une compréhension fondamentale de la phénoménologie et de la micromé-canique de compaction dans les roches-réservoirs. Cet article présente les résultats de recherches récentes sur la compaction mécanique des grès poreux. On insiste plus particulièrement sur la synthèse des données de laboratoire, la caractérisation microstructurale quantitative de l'endommagement, ainsi que sur les modèles théoriques basés sur un contact élastique et sur la mécanique de la rupture. Les attributs méca-niques de la compaction sur des échantillons initialement secs et saturés ont été étudiés sous des chargements hydrostatiques et non hydrostatiques dans une large gamme de pression. Les sujets spécifiques étu-diés ici incluent : la comparaison des données d'émission acoustique et mécanique avec une théorie de la plasticité ; le contrôle microstructural du début et du développement de la compaction ; l'écrouissage et l'évolution spatiale de l'endommagement lors de la compaction ; enfin, l'effet affaiblissant de l'eau sur le seuil de compaction et l'évolution de la porosité.Mots-clés : essais triaxiaux, porosité, émissions acoustiques, endommagement microstructural, compaction, dilatance. Abstract -Mechanical Compaction of Porous Sandstone -In many reservoir engineering and tectonic problems, the ability to predict both the occurrence and extent of inelastic deformation and failure hinges upon a fundamental understanding of the phenomenology and micromechanics of compaction in

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“…Dolomitic samples ranged from 33 to 47 MPa. Smits et al (11) reported a pore collapse vertical effective stress of 20 MPa to 50 MPa for mouldic limestone with porosity in the range of 27 to 39%. They also concluded that, for Danian and Maastrichtian chalk samples, there was a failure stress of 18 MPa to 60 MPa that were in a range of 35 to 50% porosity.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Investigation of Effective Stresses' Influence on Petrophysical Properties of Sandstone Reservoirs During Depletion

Belhaj

Islam

2009

Journal of Canadian Petroleum Technology

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An increase in effective stresses takes place in reservoirs as a consequence of fluid production, a well-known phenomenon in both shallow and deep reservoirs. It may seem reasonable to assume that permeability and porosity decrease as pore pressure declines, since both effective radial and axial stresses become intensified during reservoir depletion. However, laboratory results show that this is not always the case. Porosity certainly decreases as a result of the compaction process, which allows the breakage of grain-to-grain cement bonds. Grain particles will become more compacted as both lateral and axial effective stresses increase. On the other hand, permeability shows no definite trend. In this paper, a series of delicate experimental procedures were conducted to reveal some of the most intriguing phenomena in pore collapse and their impact on permeability. Sandstone samples were tested using a triaxial set-up. Based on the experimental results of this study, in weak reservoir formations, pore collapse does not occur suddenly. Rather, rocks gradually compact as grain-to-grain cement bonds break down. It was found that permeability indeed changes as effective stresses increase. However, the pathway to permeability was found to be much more complex than previously stipulated. It was discovered that enhancement or damage to permeability is not a function of pore collapse alone. Other factors, such as stress path, initial porosity, particle size, particle shape and particle distribution play a major role in determining what type of alteration in permeability occurs and to what magnitude that alteration would be. Introduction Traditionally, petrophysical properties data are very crucial for reserves assessment and fluid flow characterization of petroleum reservoirs. A great deal of money and effort are usually allocated in order to accurately estimate these properties. Permeability and porosity are among those properties and are by far the most important. Porosity is the key for reserves estimates while permeability is the main parameter to predict flow rates, design drawdown and, therefore, wellbore completion. Until recently, the common belief was that, once determined, these properties remain constant throughout the production life of the reservoir. Studies(1–3), including this paper, showed that this is not a realistic assumption. During the pressure depletion process, as production from the reservoir continues, effective stresses within the reservoir increase. It is understood that the effect of reservoir stresses on porosity and permeability of the reservoir is more severe when porosity and permeability are high, although some experimental studies like Hubbert and Willis(4), Voight and St. Pierre(5) and Rosepiler(6) showed this effect is still significant, even at low porosity and permeability. It is also understood that stress paths have a large influence on horizontal and vertical permeability, and also on porosity. The elastic uniaxial strain model is mostly used in reservoir engineering to describe production-induced changes in horizontal stress due to pore pressure decline (pressure depletion). It predicts the total horizontal stress by using overburden stress, reservoir pressure decrease and material mechanical parameters. The principal assumption in this model is that there is no lateral deformation (zero horizontal strain condition) during the depletion process.

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Prediction of Abrupt Reservoir Compaction and Surface Subsidence Caused By Pore Collapse in Carbonates

Cited by 41 publications

References 6 publications

Loading Experiments on Carbonate Ooze and Chalk from Leg 130, Ontong Java Plateau

Loading Experiments on Carbonate Ooze and Chalk from Leg 130, Ontong Java Plateau

Mechanical Compaction of Porous Sandstone

Laboratory Investigation of Effective Stresses' Influence on Petrophysical Properties of Sandstone Reservoirs During Depletion

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