Full Record

New Search | Similar Records

Author
Title Pore-scale controls of fluid flow laws and the cappillary trapping of CO₂
URL
Publication Date
Date Accessioned
Degree PhD
Discipline/Department Geological Sciences
Degree Level doctoral
University/Publisher University of Texas – Austin
Abstract A pore-scale understanding of fluid flow underpins the constitutive laws of continuum-scale porous media flow. Porous media flow laws are founded on simplified pore structure such as the classical capillary tube model or the pore-network model, both of which do not include diverging-converging pore geometry in the direction of flow. Therefore, modifications in the fluid flow field due to different pore geometries are not well understood. Thus this may translate to uncertainties on how flow in porous media is predicted in practical applications such as geological sequestration of carbon dioxide, petroleum recovery, and contaminant’s fate in aquifers. To fill this gap, we have investigated the role of a spectrum of diverging-converging pore geometries likely formed due to different grain shapes which may be due to a variety of processes such as weathering, sediment transport, and diagenesis. Our findings describe the physical mechanisms for the failure of Darcy’s Law and the characteristics of Forchheimer Law at increasing Reynolds Number flows. Through fundamental fluid physics, we determined the forces which are most responsible for the continuum-scale porous media hydraulic conductivity (K) or permeability. We show that the pore geometry and the eddies associated therein significantly modify the flow field and the boundary stresses. This has important implications on mineral precipitation-dissolution and microbial growth. We present a new non-dimensional geometric factor β, a metric for diverging-converging pore geometry, which can be used to predict K. This model for K based on β generalizes the original and now widely-used Kozeny (1927) model which was based on straight capillary tubes. Further, in order to better quantify the feasibility of geological CO2 sequestration, we have conducted laboratory fluid flow experiments at reservoir conditions to investigate the controls of media wettability and grain shapes on pore-scale capillary trapping. We present experimental evidence for the snap-off or formation of trapped CO2 ganglion. The total trapping potential is found to be 15% of porosity for a water-wet media. We show that at the pore-scale media wettability and viscous-fingering play a critical role in transport and trapping of CO2. Our investigations clearly show that that in single-phase flow pore geometry significantly modifies pore-scale stresses and impacts continuum-scale flow laws. In two-phase flows, while the media wettability plays a vital role, the mobility ratio of CO2 - brine system significantly controls the CO2 capillary trapping potential- a result which should be taken into consideration while managing CO2 sequestration projects.
Subjects/Keywords Non-Darcy law; Forchheimer law; Eddies; CO₂ trapping; CO₂ sequestration; Pore geometry; Fluid flow; Grain shape; Wettability
Contributors Cardenas, Meinhard Bayani, 1977- (advisor); Bennett, Philip C. (Philip Charles), 1959- (advisor)
Language en
Country of Publication us
Record ID handle:2152/22083
Repository texas
Date Retrieved
Date Indexed 2019-09-12
Grantor The University of Texas at Austin
Note [] text; [department] Geological Sciences;

Sample Search Hits | Sample Images | Cited Works

Forchheimer flow characteristics ................................................22 2.5 Results and discussion from straight diverging-converging pore ...........25 2.5.1 Persistent eddies at Re << 1 ........................................................27…

…30 2.5.4 Forchheimer flow characteristics ................................................32 2.6 Summary .................................................................................................34 Chapter 3: Pore geometry effects on intra…

…54  3.3.6 The distribution of friction drag ..................................................58  3.3.7 Pore geometry and the failure of Darcy’s Law ...........................60  3.3.8 Pore geometry and characteristics of Forchheimer flow

…where Darcy’s law is valid and Zone II marks the emergence of the Forchheimer flow regime. ..............................................................................................18  Figure 2.3: Ratio of growth in eddies  [-] is directly…

…Characteristics of Forchheimer flow in Zone II and Zone III as shown by dependence of: (a) specific flux q [m/s], (b) apparent hydraulic conductivity Ka [m/s], (c) rate of change in apparent hydraulic conductivity…

…drag Fτ' [N] at increasing hydraulic gradient i [-]. Zone I shows where Darcy’s law is valid and Zone II marks the emergence of the Forchheimer flow regime…

…31 xiii Figure 2.9: Characteristics of Forchheimer flow in Zone II and Zone III as shown by dependence of: (a) specific flux q [m/s], (b) apparent hydraulic conductivity Ka [m/s], (c) rate of…

…53  Figure 3.6: Average net drag forces, (a) total drag FD [N], (b) friction drag Fτ [N] and form drag FN [N], from pore boundaries during Darcy to Forchheimer flow regimes…

.