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Book Chapter

Production-Induced Diagenesis During Thermal Heavy Oil Recovery: Grain SİZe as a Predictor of Reservoir Alteration

By
Mary L. Barrett
Mary L. Barrett
Department of Geology and Geography, Cenlenary College, Shreveport, Louisiana 71134
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Richard W. Mathias
Richard W. Mathias
GeoGraphix, Denver, Colorado 80202
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Published:
January 01, 1996

Abstract

Terrigenous clastic alteration during thermal heavy oil recovery processes has been documented in whole core and laboratory tests from four California fields. Sediments are subjected to either steam/hot water processes (up to 200°C) or in-situ combustion processes (up to 500°C) or both. Consideration of original and altered mineral compositions do not fully describe reservoir changes. Fabric and permeability changes can be understood in a predictive sense by comparison to original grain size and sorting.

Sand-size constituents are plagioclase feldspar and quartz, with lesser amounts of mica, volcanic rock fragments and volcanic glass. Original matrix is dominated by smectite, biogenic opal, zeolites and mica/illite. During hot water/steam alteration, primarily the fine-grained matrix is altered. Sediments with either finer grain sizes or increased original matrix have the highest magnitude of permeability decrease as compared to coarser, better sorted material. This pronounced permeability decrease is due to: (1) additional smectite and zeolite growth as the expense of original matrix components and (2) the dispersion, migration and pore-throat blockage by the matrix. The finer-grained sediments, characlerized by smAller pore throats, are subjected to extensive pore blockage as unstable silt- and clay-size particles move (fines migration).

Sediment reaction during in-situ combustion follows the alteration pattern above. Fine-grained matrix continues to alter, with some smectite transforming to illite. Calcite and oil reaction rims form in the burn stage. The overAll fabric is a lightly-consolidated sandstone. Only in the near-wellbore area of an combustion injector have partiAlly-melted fabrics been recognized.

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SEPM Special Publication

Siliciclastic Diagenesis and Fluid Flow: Concepts and Applications

Laura J. Crossey
Laura J. Crossey
University of New Mexico Albuquerque NM
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Robert Loucks
Robert Loucks
ARCO Exploration Production Technology Piano TX
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Matthew W. Totten
Matthew W. Totten
University of New Orleans New Orleans LA
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Peter A Scholle
Peter A Scholle
Editor of Special Publications Special Publication No 55
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SEPM Society for Sedimentary Geology
Volume
55
ISBN electronic:
9781565761780
Publication date:
January 01, 1996

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