Gas hydrate investigations are converging on a suite of common techniques for hydrate
observation and quantification. Samples retrieved and analyzed at full in situ pressures are the
”gold standard” with which the physical and chemical analysis of conventional cores, as well as
the interpretation of geophysical data, are calibrated and groundtruthed. Methane mass balance
calculations from depressurization of pressure cores provide the benchmark for gas hydrate
concentration assessment. Nondestructive measurements of pressure cores have removed errors in
the estimation of pore volume, making this methane mass balance technique accurate and robust.
Data from methane mass balance used to confirm chlorinity baselines makes porewater
freshening analysis more accurate. High-resolution nondestructive analysis of gas-hydratebearing
cores at in situ pressures and temperatures also provides detailed information on the in
situ nature and morphology of gas hydrate in sediments, allowing better interpretation of
conventional core thermal images as well as downhole electrical resistivity logs. The detailed
profiles of density and Vp, together with spot measurements of Vs, electrical resistivity, and
hardness, provide background data essential for modeling the behavior of the formation on a
larger scale. X-ray images show the detailed hydrate morphology, which provides clues to the
mechanism of deposit formation and data for modeling the kinetics of deposit dissociation. Gashydrate-
bearing pressure cores subjected to X-ray tomographic reconstruction provide evidence
that gas hydrate morphology in many natural sedimentary environments is particularly complex
and impossible to replicate in the laboratory. Even when only a small percentage of the sediment
column is sampled with pressure cores, these detailed measurements greatly enhance the
understanding and interpretation of the more continuous data sets collected by conventional
coring and downhole logging. Pressure core analysis has become the keystone that links these
data sets together and is an essential component of modern gas hydrate investigations.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/1200 |
| Date | 07 1900 |
| Creators | Schultheiss, Peter, Holland, Melanie, Roberts, John, Humphrey, Gary |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Rights | Schultheiss, Peter |
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