Relationship between Azimuths of Flood Anisotropy and Local Earth Stresses in Oil Reservoirs

Heffer, Kes; Dowokpor, A. B.

doi:10.1007/978-94-009-0791-1_21

Cited by 27 publications

(13 citation statements)

References 18 publications

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“…-Reservoir flow performance, i.e. how stresses and stress alterations affect preferred flow directions (Heffer and Dowokpor, 1990) and reservoir permeability (e.g. Holt, 1990;Ruistuen and Hanssen, 1996;Boutéca et al, 2000), and the coupling of fluid flow simulation to geomechanical models (e.g.…”

Section: Introductionmentioning

confidence: 99%

Particle Scale Reservoir Mechanics

2002

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Mécanique du réservoir à l'échelle des grains -Cet article résume quelques déve-loppements et applications de la modélisation par particules discrètes, basés sur le code commercial PFC (Particle Flow Code). Nous décrivons ci-après les exemples ayant un rapport avec le comportement géomécanique du réservoir : -Des résultats de simulations numériques et d'expériences sont présentés, illustrant une évolution nonlinéaire de la compaction induite par déplétion et du chemin de contrainte pour des simulations de roches de réservoir, c'est-à-dire des matériaux formés sous contrainte. Cette non-linéarité est souvent perdue dans les mesures effectuées sur carotte, et cela est dû au relâchement de contrainte intervenant après carottage (dommage de carottage). -Des superparticules anguleuses et fissurables ont été implémentées dans le modèle particulaire et utilisées pour simuler la formation de bandes de compaction à forts niveaux de contrainte. Le modèle est aussi utilisé pour étudier la formation de bandes de cisaillement à des niveaux de confinement inférieurs. -Un schéma numérique permettant un couplage fluide à été développé, aussi bien pour des modèles 2D que 3D, et appliqué à l'étude de la dépendance de la perméabilité au niveau de contrainte. -La dépendance des propriétés acoustiques par rapport au niveau de contrainte dans un assemblage de particules soudées a été étudiée. Les résultats préliminaires des simulations avec divers développements montrent un accord qualitatif mais aussi quantitatif avec les expériences. Cela démontre la faisabilité de l'application d'une modélisation par particules discrètes comme laboratoire numérique pour l'étude de la mécanique du réservoir à l'échelle des grains. Abstract -Particle Scale Reservoir Mechanics -This paper summarizes some developments and applications of discrete particle modelling based on the commercial code PFC (Particle Flow Code

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Section: Introductionmentioning

confidence: 99%

Particle Scale Reservoir Mechanics

2002

Oil & Gas Science and Technology - Rev. IFP

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“…Conversely, the minimum horizontal stress will have been across the fractures, and they could therefore have acted as conduits for fluid flow. Support for preferential fluid flow parallel to S hmax is provided by borehole breakout observations (Linjordet & Skarpnes 1992) and field water-flood studies (Heffer & Dowokpor 1990), while direct evidence of open, hydrocarbon-conducting NW-SE fractures on the NEAM is found in the Clair Field, West of Shetlands (Coney et al 1993). The NW-SE lineaments may therefore have provided a mechanism for breaching and vertical remigration from deep traps, and for regional migration from basin axes to basin flanks.…”

Section: Charging From Deeply Buried Sourcementioning

confidence: 97%

The NE Atlantic margin; implications of late Mesozoic and Cenozoic events for hydrocarbon prospectivity

Doré¹,

Lundin²,

Birkeland³

et al. 1997

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The study takes in the entire NE Atlantic margin (NEAM) but emphasizes the sparsely drilled Møre and Vøring Basins. A network of PermoTriassic and Jurassic basins was strongly overprinted by younger extensional episodes. At least three phases are probable -early Cretaceous, mid-Cretaceous and latest Cretaceous-early Eocene -between the late Jurassic and break-up. Substantial thicknesses of Cretaceous and Cenozoic strata along the margin have focused exploration interest on the late Cretaceous and Paleocene intervals as easily drillable targets. Reservoirs within these intervals were deposited as gravity-driven sand incursions into an overwhelmingly mud-prone environment. Sand pulses of AlbianConiacian, Santonian-early Campanian and Paleocene age occur widely, and can be tied to the tectonic episodes. Vertical migration of hydrocarbons from known Jurassic source rocks is proven west of Shetlands, but in many parts of the margin remigration from intermediate reservoirs would be required to charge the shallower plays. Failing this, prospectivity will hinge on the presence of frontier source rocks, with best possibilities at Barremian, Aptian-Albian, Cenomanian-Turonian and Paleocene levels. Potential hydrocarbon traps were formed by pre-breakup extensional faulting and by post-breakup compression.

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“…A further independent set of observations that provides a test for the models presented here is that of directionalities in flooding schemes (Heffer & Dowokpor 1990;Heffer & Lean 1993). In a set of more than 80 fields worldwide of many different descriptions (and including none of the six North Sea fields providing data to the flowrate correlation analyses), those studies found that the preferred directions of breakthrough of injected fluids were strongly biased towards the local major horizontal principal stress axes.…”

Section: Consistency With Observations Of Directionality In Flooding mentioning

confidence: 99%

“…Heffer & Dowokpor (1990) and Heffer & Lean (1993) analysed the preferred directions taken by injected fluids between injection and production wells in over 80 fields, and found them to be strongly biased towards the local major horizontal principal stress axis (Shmax). Heffer et al (1995) observed that the correlations in flowrate fluctuations between injection and production wells (i.e.…”

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confidence: 99%

Geomechanical mechanisms involving faults and fractures for observed correlations between fluctuations in flowrates at wells in North Sea oilfields

Heffer¹

2012

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The hydraulic conductivities of faults and fractures in reservoirs can be influenced by geomechanical perturbations due to production operations. It is anticipated that such dynamic permeabilities will be manifest as changes in flowrates at production and injection wells. Statistical correlations in flowrate fluctuations between wells from fields in the North Sea appear to bear out this expectation; they are characterized by high correlations over very large separation distances between wells, and appear to be stress-related and fault-related. This paper discusses possible geomechanical mechanisms that might explain orientational characteristics of correlations relative to stress state: (1) creation of new Andersonian, bimodal faults; (2) shear slip on preexisting structural features according to slip tendencies; (3) polymodal faulting more consistent with three-dimensional strain; and (4) dilatation or compaction of aligned compliant (micro-)fractures at near-critical densities arranged in en echelon patterns. Mechanism 4 is currently preferred in that it is consistent with: (a) established theory of the nucleation of shear failure; (b) interpretations of widespread microfractures in the lithosphere from observations of shear-wave splitting; (c) (as shown in this paper) the observed frequencies of directionalities in oilfield flooding schemes, an independent empirical feature of production data.

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Relationship between Azimuths of Flood Anisotropy and Local Earth Stresses in Oil Reservoirs

Cited by 27 publications

References 18 publications

Particle Scale Reservoir Mechanics

Particle Scale Reservoir Mechanics

The NE Atlantic margin; implications of late Mesozoic and Cenozoic events for hydrocarbon prospectivity

Geomechanical mechanisms involving faults and fractures for observed correlations between fluctuations in flowrates at wells in North Sea oilfields

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