Mixing During Single-Phase Flow in Reservoir Rocks: Models, Effects of Pore Structure and Interpretation of Experiments

Bretz, R.E.; Specter, Robert M.; Orr, Franklin M.

doi:10.1016/b978-0-12-434065-7.50024-1

Cited by 10 publications

(6 citation statements)

References 14 publications

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“…The contention that hydraulic conductivity variability predominates dispersive transport at the field scale in comparison to factors such as rate-limited sorption and local heterogeneities is supported by several analyses. Coats and Smith [1964], Warren and Skiba [1964], and Bretz et al [1986] investigated the relative contributions of local heterogeneities and field-scale hydraulic conductivity variability to solute transport. They found that the effect of local heterogeneity was significant at the scale of laboratory columns.…”

Section: Significance Of Individual Factorssupporting

confidence: 84%

Transport of reactive contaminants in heterogeneous porous media

Brusseau¹

1994

Reviews of Geophysics

137

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The potential for human activities to adversely affect the environment has become of increasing concern during the past two decades. Concomitantly, the transport and fate of contaminants in subsurface systems has become one of the major research areas in the environmental, hydrological, and Earth sciences. An understanding of how contaminants move in the subsurface is needed to evaluate the probability of contaminants associated with a chemical spill reaching an aquifer and contaminating groundwater. This knowledge is also required to develop and evaluate methods for cleaning up contaminated soils and aquifers. Just as importantly, knowledge of contaminant transport and fate is necessary to design “pollution prevention” strategies. A tremendous body of literature on contaminant transport has been generated in response to these needs. This literature consists primarily of results obtained by theoretical, experimental, and mathematical modeling based investigations and, to a much lesser extent, field experiments. This paper consists of a brief review of some of the major aspects associated with the transport of reactive contaminants in heterogeneous subsurface environments. It begins with a review of basic concepts related to contaminant transport, followed by a discussion of the results obtained from some of the few well‐controlled field experiments designed to investigate transport of reactive contaminants in the subsurface. Some of the major factors controlling contaminant transport will then be discussed, followed by a review of conceptual and mathematical approaches used to represent those factors in mathematical models. A brief overview of future needs and opportunities in contaminant transport will close the discussion.

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Section: Significance Of Individual Factorssupporting

confidence: 84%

Transport of reactive contaminants in heterogeneous porous media

Brusseau¹

1994

Reviews of Geophysics

137

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“…8 Effluent composition measurements were performed in an apparatus used to make similar measurements for reservoir core samples. 11 , 12 In those experiments, the model was filled with brine,and then a pulse of brine containing 0.4% sucrose as a tracer was injected. Effluent compositions were measured continuously with a differential refractometer.…”

Section: Methodsmentioning

confidence: 99%

Experimental Investigation of the Interaction of Phase Behavior With Microscopic Heterogeneity in a CO2 Flood

Bahralolom

Bretz

Orr³

1988

SPE Reservoir Engineering

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This paper reports results of an experimental investigation of the effects of microscopic heterogeneity on local displacement efficiency in a CO 2 flood. Flow-visualization experiments for first-contact miscible displacements are described and compared with effluent composition measurement for the same models. High-pressure flow-visualization experiments for multicontact miscible CO 2 floods are also described. The displacements were performed in two-dimensional (2D) etched glass models made from thin-sections of San Andres carbonate core from the Maljamar field. Techniques used in preparation of the models are described briefly.Observations of first-contact miscible displacements in heterogeneous models indicate that early breakthrough and a long transition zone occur when preferential flow paths exist in the pore structure. This behavior corresponds to a flowing fraction less than 1 in the Coats-Smith model. Because the 2D models contained no dead-end PV, the results presented indicate that a low flowing fraction can occur if flow velocities in different portions of the pore space differ significantly. Coats-Smith parameters obtained for models were comparable with values obtained in floods performed in reservoir samples.Visual observations of the CO 2 /crude-oil displacements indicate that there is an interaction between phase behavior and microscopic heterogeneity. Mixing of nearly pure CO 2 in the preferential flow path with oil in adjacent regions leads to a residual oil saturation (ROS) that forms in the preferential path after oil initially present has been displaced.

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“…In this situation, the flow contains a large amount of capacitance. 11,12 This will be evident in the results from the singlelayer case. For most of the cases described in this paper, the assumption of pure dispersion is valid.…”

Section: Estimation Of the Amount Of Dispersionmentioning

confidence: 71%

The Dispersive Effect of Variable Layer Lengths on Miscible Displacements in Layered Heterogeneous Porous Media

Kossack¹

1989

SPE Reservoir Engineering

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The effect of small-and intermediate-scale heterogeneities on miscible displacements is investigated by Monte Carlo simulations in a two-dimensional (2D) flow field containing random permeabilities and random layering. The effect of the variable layer lengths on the level of dispersion is calculated for various well-to-well distances. It was determined that the variable layer lengths add a significant amount of dispersion compared with constant layer lengths for well-to-well distances on the order of 1,000 ft [305 m] or less. IntroductionIn a reservoir engineering study of an oil field, an accurate, detailed description of the reservoir-i.e., permeabilities, porosities, and heterogeneities such as variations in permeabilities, porosities, layering, faults, fractures, and shale streaks-is required. In the past, reservoir descriptions used in simulations contained oversimplified geological models that in many cases described the reservoir as a vertical sequence of homogeneous layers or blocks that extended over very long distances, perhaps even over the entire flow field. This situation was created partially by the need to discretize the porous medium into a limited number of gridblocks for the numerical model and partially from a lack of understanding of the importance of various scales of heterogeneities on the oil recovery and displacement processes. In general, very large-scale features, such as faults and shale layers, would be incorporated in the numerical description, but most intermediate-and small-scale heterogeneities would be omitted. l In many cases, this approximation creates a large error source in the simulation results. The standard technique to reduce this error was to adjust the input data, permeabilities, porosities, relative permeabilities, and other data during history matching, provided that history exists. The trial-anderror history-matching process produces a nonunique reservoir description that has only a small likelihood of accurately predicting future production. The ability of the history-matched model to predict the future is highly dependent on the quality and quantity of the data in the reservoir description, on the detail of the numerical grid, and on the engineer's (who is doing the history match) understanding of the physics, fluid flow, and interactions involved in the particular oil recovery process.To reduce the errors created by simplified descriptions, researchers in the oil industry have recently been describing rock heterogeneities by measuring permeability variations in outcrops and thus attempting to understand reservoir heterogeneities and their effect on oil recovery. 2-4 The assumption is, of course, that the variations and patterns seen in outcrops maintain the same or similar relationships at depth (in oil reservoirs). The next step, after measuring the permeability variations in rock formations, is to determine what effects these descriptions would have on a displacement process. This can generally be accomplished by numerically simulating the displacement process th...

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Mixing During Single-Phase Flow in Reservoir Rocks: Models, Effects of Pore Structure and Interpretation of Experiments

Cited by 10 publications

References 14 publications

Transport of reactive contaminants in heterogeneous porous media

Transport of reactive contaminants in heterogeneous porous media

Experimental Investigation of the Interaction of Phase Behavior With Microscopic Heterogeneity in a CO2 Flood

The Dispersive Effect of Variable Layer Lengths on Miscible Displacements in Layered Heterogeneous Porous Media

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