Abstract:
Fine-grained sediments, or “fines,” are nearly ubiquitous in natural sediments, even in the predominantly coarse-grained sediments that host gas hydrates. Fines within these sandy sediments can be mobilized and subsequently clog flow pathways while methane is being extracted from gas hydrate as an energy resource. Using two-dimensional (2D) micromodels to test the conditions in which clogging occurs provides insights for choosing production operation parameters that optimize methane recovery in the field. During methane extraction, several processes can alter the mobility and clogging potential of fines: (1) fluid flow as the formation is depressurized to release methane from gas hydrate, (2) shifting pore-fluid chemistry as pore-fluid brine freshens as a result of pure water released from dissociating gas hydrate, and (3) the migration of gas/water interfaces, which are created as gas evolves from dissociating gas hydrate. In this study, 2D micromodel experiments were conducted on a selection of pure fines, natural sediments, pore-fluids, and micromodel pore-throat sizes to evaluate fines migration and changes in clogging behavior resulting from methane gas production and pore-water freshening during hydrate dissociation. Additionally, tests were run with and without an invading gas phase (carbon dioxide) to test the importance of a moving meniscus on fines mobility and clogging. The endmember fine particles chosen for this research included silica silt, mica, calcium carbonate, diatoms, kaolinite, illite, and bentonite (primarily made of montmorillonite). The pore fluids included deionized water, sodium chloride brine (2 molar concentration), and carbon dioxide gas. The microfluidic pore models, used as porous media analogs, were fabricated with pore-throat widths of 20, 40, 60 and 100 micrometers to cover the range of anticipated pore throat sizes sampled during NGHP-02. This dataset provides a clogging diagram showing how grain size, fines concentration, pore fluid chemistry and mobile interfaces define the clogging behavior of the pure fines. This fundamental properties diagram helps interpret the clogging behavior of three natural samples also tested for this dataset. The natural samples were collected during NGHP-02. This research shows that in addition to the expected dependence of clogging on the ratio of particle-to-pore-throat size, pore-fluid chemistry is also an important factor because the interaction between a particular type of fine and pore fluid influences that fine’s capacity to cluster, clump together, and thereby increase the effective particle size relative to the pore-throat width. The presence of a moving gas/fluid meniscus increases the clogging potential regardless of fine type because the advancing meniscus tends to gather and concentrate the fines.
Purpose:
This dataset provides a comprehensive relationship between the minimum concentration of fines (concentration = mass of fines divided by the mass of fluid) required to clog two-dimensional micromodel pore throats of various sizes. The clogging dependence is captured in terms of the sediment type, the ratio of the mean particle size to the pore throat size, the pore fluid chemistry (fresh water or brine) and whether or not there is a gas/water meniscus. Each of these parameters provides information required for estimating the clogging potential of fines in natural settings, such as in sediments where gas hydrates are being destabilized to extract the methane as an energy resource.
Supplemental_Information:
Time_Period_Information:
Multiple_Dates/Times:
Single_Date/Time:
Calendar_Date: 20150522
Single_Date/Time:
Calendar_Date: 20150618
Currentness_Reference:
These are the dates the NGHP-02 specimens were collected from Sites NGHP-02-16 (20150522) and NGHP-02-09 (20150618). Data were also collected for pure, endmember sediment types that were purchased rather than collected.
Theme:
Theme_Keyword_Thesaurus: USGS Metadata Identifier
Theme_Keyword: USGS:5b0da47ce4b0c39c934b0775
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword:
Louisiana State University, Department of Civil and Environmental Engineering
Theme_Keyword:
Woods Hole Coastal and Marine Science Center, U.S. Geological Survey
Theme_Keyword: fine-grained sediment
Theme_Keyword: bentonite
Theme_Keyword: calcium carbonate
Theme_Keyword: diatoms
Theme_Keyword: illite
Theme_Keyword: kaolin
Theme_Keyword: mica
Theme_Keyword: silica silt
Theme_Keyword: deionized water
Theme_Keyword: brine
Theme_Keyword: 2D micromodel
Theme_Keyword: clogging
Theme_Keyword: NGHP-02
Theme_Keyword: NGHP-02-09
Theme_Keyword: NGHP-02-16
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: earth material properties
Theme_Keyword: soil sciences
Theme_Keyword: laboratory experiments
Theme_Keyword: image analysis
Theme_Keyword: optical microscopy
Theme_Keyword: permeability
Theme_Keyword: natural resource extraction
Theme_Keyword: gas hydrate resources
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Laboratory
Place_Keyword: Louisiana State University
Place_Keyword: Department of Civil and Environmental Engineering
Place_Keyword: Indian Ocean
Place_Keyword: Bay of Bengal
Place_Keyword: Krishna-Godavari Basin
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the Louisiana State University as the originator of the dataset.