Abstract
The research presented herein is a new design and development of a special methodology to delineate the nature of clay fabric in natural sediments under in situ downhole pressure conditions using pressurized core barrel samples obtained from the Mississippi Delta. The fabric was compared with that of samples prepared under ambient atmospheric conditions. To attack this problem, a special apparatus - a "pressure vessel" for replacing interstitial water with intermediate fluid before critical point-drying under equivalent in situ downhole pressure - has been designed and employed. The newly developed special methodology allows drying of the clay specimen under equivalent in situ downhole pressure conditions, thus preventing any possible fabric disturbance due to the removal of downhole pressure and degassing of the sample. Grain size, bulk mineralogy, and clay mineralogy analyses showed the constituents of the silty clay sediments obtained from the Mississippi Delta are essentially the same throughout the studied core sections. These samples appear to have been subjected to very similar geologic conditions. Results of detailed investigations and semi-quantitative analyses of nearly one thousand electron micrographs obtained by transmission electron microscopy and scanning electron microscopy not only reveal detailed in situ clay fabric microfeatures but also demonstrate the degassing effect on clay fabric configurations. The clay fabric of shallow gassy deltaic silty clays was controlled by different sample dehydration techniques. Clay fabric of sediments prepared by the new techniques developed in this research is characterized by well oriented clay particles and domains. In contrast, clay fabric of the same sediment prepared by the conventional method is composed of relatively non-oriented and highly randomly arranged clay particles. Some interesting clay fabrics or other microfeatures have also been pointed out. These microfeatures may play important roles in understanding the clay fabric, the depositional environment, and post-depositional history of a sediment...
Chiou, Wen-An (1981). Clay fabric of gassy submarine sediments. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -647089.