The Movement of Oil Initially Bypassed behind Stochastic Shale Barriers

Thomas, Jonathan Milo

doi:10.1007/978-94-009-0791-1_38

Cited by 10 publications

(6 citation statements)

References 3 publications

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“…However, the effect of these heterogeneities on two-phase fluid flow is not well-understood. During immiscible flooding, oil in the vicinity of isolated shale is initially bypassed by the displacing fluid, and subsequently drains from around the shale driven by viscous and gravitational forces (Richardson et al 1978;Davies and Haldorsen 1987;Thomas 1990;Jones et al 1994). The initial bypassing of the oil leads to the premature breakthrough of displacing fluids.…”

Section: Statement Of Problemmentioning

confidence: 97%

Characterizing the Role of Shale Geometry and Connate Water Saturation on Performance of Polymer Flooding in Heavy Oil Reservoirs: Experimental Observations and Numerical Simulations

2011

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Many heavy oil reservoirs contain discontinuous shales which act as barriers or baffles to flow. However, there is a lack of fundamental understanding about how the shale geometrical characteristics affect the reservoir performance, especially during polymer flooding of heavy oils. In this study, a series of polymer injection processes have been performed on five-spot glass micromodels with different shale geometrical characteristics that are initially saturated with the heavy oil. The available geological characteristics from one of the Iranian oilfields were considered for the construction of the flow patterns by using a controlled-laser technology. Oil recoveries as a function of pore volumes of injected fluid were determined from analysis of continuously recorded images during the experiments. We observed a clear bypassing of displacing fluid which results in premature breakthrough of injected fluid due to the shale streaks. Moreover, the results showed a decrease of oil recovery when shales' orientation, length, spacing, distance of the shale from production well, and density of shales increased. In contrast, an increase of shale discontinuity or distance of the shale streak from the injection well increased oil recovery. The obtained experimental data have also been used for developing and validating a numerical model where good matching performance has been observed between our experimental observations and simulation results. Finally, the role of connate water saturation during polymer flooding in systems containing flow barriers has been illustrated using pore level visualizations. The microscopic observations confirmed that besides the effect of shale streaks as heterogeneity in porous medium, when connate water is present, the trapped water demonstrates another source of disturbance and causes additional perturbations to the displacement interface leading to more irregular fingering patterns especially behind the shale streaks and also causes a reduction of ultimate oil recovery. This study reveals the application of glass micromodel experiments for studying the effects of barriers on oil recovery and flow patterns during EOR processes and also may provide a set of benchmark data for recovery of oil by immiscible polymer flood around discontinuous shales.

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Section: Statement Of Problemmentioning

confidence: 97%

Characterizing the Role of Shale Geometry and Connate Water Saturation on Performance of Polymer Flooding in Heavy Oil Reservoirs: Experimental Observations and Numerical Simulations

2011

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“…Previous studies of discontinuous shales have used either simple, 2D generic models, in which shales are located randomly within a homogeneous background, 2,3,[6][7][8]11,12 or detailed, 2D models of specific depositional environments derived directly from outcrop data or modern analogs. [13][14][15] We focused upon inclined and intersecting shales within sandbodies 16 ͑Fig.…”

Section: Shale Modelingmentioning

confidence: 99%

“…1b͒. 2,11,12 The initial bypassing of oil leads to early breakthrough of the displacing fluid, and if many shales are present, to disruption of the displacement front. However, if the timescale of oil drainage from around the shales is short compared to the timescale of reservoir production, the ultimate recovery of oil is unchanged.…”

Section: Introductionmentioning

confidence: 99%

“…These discontinuities may facilitate efficient sweep; 2D models generally overestimate the effect of heterogeneities. 13 The studies conducted to date have considered only a limited number of 2D shale realizations and flow regimes; for example, the generic studies of Richardson et al, 2 of Thomas, 11 and of Davies and Haldorsen 12 considered only horizontal shales and vertical displacements, in which the principal flow direction was always perpendicular to the shales, while the outcrop studies of White and Barton, 13 of Ciammetti et al, 14 and of Peihua 15 considered only a small number of specific 2D shale distributions. As yet, the effect on recovery of inclined shales, in which the principal flow direction is not perpendicular to the shales, and of variations in shale continuity in the third dimension, are poorly understood.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Discontinuous Shales on Reservoir Performance During Horizontal Waterflooding

Jackson

Muggeridge

2000

SPE Journal

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We investigate quantitatively the effect of inclined and intersecting discontinuous shales on horizontal waterfloods, using generic, dimensionless two-and three-dimensional models. We focus upon whether the shales alter the sweep efficiency. We find that they have a significant effect only if they are continuous over large areas of the bedding surfaces and are steeply inclined to the flow, or if the displacement is highly unfavorable. We also find that two-dimensional simulations can significantly overestimate the effect of intersecting shales, because they assume that the shales are entirely continuous in the third dimension. Flow Modeling The effect of a given heterogeneity on reservoir performance depends both upon the nature of that heterogeneity and upon the flow regime. 19,20 Given the variation in lengthscales ͑e.g., accretional surfaces vs. foreset surfaces͒ and timescales ͑flow rates͒ to

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“…However, the effect of these small‐scale flow barriers heterogeneities on two‐phase flow behaviour is not well‐understood. Several studies have suggested that during immiscible flooding, oil in the surrounding area of an isolated shale is initially bypassed by the displacing fluid (injected fluid) and subsequently drains from around the shale driven by viscous and gravitational forces. The initial bypassing of oil leads to early breakthrough of the displacing fluid, and if many shales are present, to disruption of the displacement front .…”

Section: Introductionmentioning

confidence: 99%

Effect of small scale flow barriers heterogeneities and connate water on displacement efficiency of polymer floods to heavy oil reservoirs

et al. 2013

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This work concerns a fundamental understanding of how heterogeneities induced by flow barriers and connate water affect the displacement efficiency of polymer floods, which has rarely been studied in the available literature. Here, a series of water/polymer injection experiments to heavy oil performed on five-spot glass micromodels containing randomly distributed shale structures is presented. It has been found that macroscopic efficiency of polymer flooding majorly depends on flow barriers distribution/configuration; shale content and geometrical characteristics; presence of connate water and wettability of medium. Microscopic pictures revealed that the main parts of connate water were trapped in some pores/throats near and especially behind the shale streaks; also, presence of connate water causes a reduction of sweep efficiency due to premature breakthrough of displacing fluid in an oil-wet media. In absence of connate water, polymer solution could linger and stick to the pore walls to delay the time for a polymer to channel to the production site. Results of this work disclose requirements for a detailed geologic study of barrier size and distribution for successful design of EOR processes in heterogeneous reservoirs.

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The Movement of Oil Initially Bypassed behind Stochastic Shale Barriers

Cited by 10 publications

References 3 publications

Characterizing the Role of Shale Geometry and Connate Water Saturation on Performance of Polymer Flooding in Heavy Oil Reservoirs: Experimental Observations and Numerical Simulations

Characterizing the Role of Shale Geometry and Connate Water Saturation on Performance of Polymer Flooding in Heavy Oil Reservoirs: Experimental Observations and Numerical Simulations

Effect of Discontinuous Shales on Reservoir Performance During Horizontal Waterflooding

Effect of small scale flow barriers heterogeneities and connate water on displacement efficiency of polymer floods to heavy oil reservoirs

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