Title: How does the connectivity of open-framework conglomerates within multi-scale hierarchical fluvial architecture affect oil-sweep efficiency in waterflooding?

Abstract

Understanding multi-phase fluid flow and transport processes within aquifers, candidate reservoirs for CO₂ sequestration, and petroleum reservoirs requires understanding a diverse set of geologic properties of the aquifer or reservoir, over a wide range of spatial and temporal scales. We focus on multiphase flow dynamics with wetting (e.g., water) and non-wetting (e.g., gas or oil) fluids, with one invading another. This problem is of general interest in a number of fields and is illustrated here by considering the sweep efficiency of oil during a waterflood. Using a relatively fine-resolution grid throughout a relatively large domain in these simulations and probing the results with advanced scientific visualization tools (Reservoir Visualization Analysis [RVA]/ ParaView software) promote a better understanding of how smaller-scale features affect the aggregate behavior at larger scales. We studied the effects on oil-sweep efficiency of the proportion, hierarchical organization, and connectivity of high-permeability open-framework conglomerate (OFC) cross-sets within the multi-scale stratal architecture found in fluvial deposits. We further analyzed oil production rate, water breakthrough time, and spatial and temporal distribution of residual oil saturation. As expected, the effective permeability of the reservoir exhibits large-scale anisotropy created by the organization of OFC cross-sets within unit bars, and the organization ofmore » unit bars within compound- bars. As a result, oil-sweep efficiency critically depends on the direction of the pressure gradient. However, contrary to expectations, the total amount of trapped oil due to the effect of capillary trapping does not depend on the magnitude of the pressure gradient within the examined range. Hence the pressure difference between production and injection wells does not affect sweep efficiency; although the spatial distribution of oil remaining in the reservoir depends on this value. Whether or not clusters of connected OFC span the domain affects only the absolute rate of oil production—not sweep efficiency.« less

Authors:

Gershenzon, Naum I. ^[1]; Soltanian, Mohamad Reza ^[1]; Ritzi, Robert W. ^[1]; Dominic, David F. ^[1]; Keefer, Don ^[2]; Shaffer, Eric ^[3]; Storsved, Brynne ^[3]

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+ Show Author Affiliations

1. Wright State Univ., Dayton, OH (United States). Dept. of Earth and Environmental Sciences
2. Univ. of Illinois at Urbana-Champaign, IL (United States). Illinois State Geological Survey
3. Univ. of Illinois at Urbana-Champaign, IL (United States). Dept. of Computer Science

Publication Date:

Fri Oct 23 00:00:00 EDT 2015

Research Org.:

Univ. of Illinois at Urbana-Champaign, IL (United States); National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE); Schlumberger Limited, Houston, TX (United States); Ohio Supercomputer Center (OSC), Columbus, OH (United States)

OSTI Identifier:

1438478

Grant/Contract Number:  

FE0005961

Resource Type:

Accepted Manuscript

Journal Name:

Geosphere

Additional Journal Information:

Journal Volume: 11; Journal Issue: 6; Journal ID: ISSN 1553-040X

Publisher:

Geological Society of America

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; 97 MATHEMATICS AND COMPUTING; anisotropy; aquifers; capillarity; carbon dioxide; carbon sequestration; clastic rocks; conglomerate; connectivity; data processing; fluid phase; ground water; imagery; lithofacies; lithostatic pressure; migration; movement; permeability; petroleum; petroleum exploration; recovery; reservoir properties; reservoir rocks; saturation; sedimentary rocks; simulation; textures; transport; traps; visualization; waterflooding; wettability