The role of hydrochlorofluorocarbon densifiers in the formation of clathrate hydrates in deep boreholes and subglacial environments

Title The role of hydrochlorofluorocarbon densifiers in the formation of clathrate hydrates in deep boreholes and subglacial environments
Publication Type
Journal Article
Year
2007
Author(s) M. Mangir Murshed , Sérgio H Faria, Werner F Kuhs, Sepp Kipfstuhl, Frank Wilhelms
Journal/ Publication
Annals of Glaciology
Volume
47
Pagination
109-114
Abstract

Clear evidence for the formation of mixed clathrate hydrates of air and hydrochlorofluorocarbon densifier (known as HCFC-141b, sometimes also called R-141b) is found by means of synchrotron X-ray diffraction and Raman spectroscopy on a sample recovered from the bottom of the EPICA Dronning Maud Land deep borehole in Antarctica. Subglacial water (SGW) appears to have reacted with the drilling liquid to build a large lump of clathrate hydrate. The hydrate growth may well have been accelerated by the stirring of the SGW–densifier mixture during drilling. Moreover, dissolved air in the SGW appears to have participated in the formation of mixed hydrates of air and HCFC-141b as evidenced by the concomitant appearance of Raman signals from both constituents. Our findings elucidate to some extent the meaning of earlier accounts of the formation of ‘heavy chips’ that may sink to the bottom of the borehole, possibly affecting or even impeding the drilling advance. These observations raise concerns with respect to the use of HCFC-141b densifiers in ice-core drilling liquids under warm ice conditions.

DOI
10.3189/172756407786857659
URL
Special Collections International Workshop on Ice Drilling Technology Series, 6th International Workshop on Ice Drilling Technology
Categories Deep Drilling, Drilling Fluids, Warm Ice
Citation M. Mangir Murshed , Sérgio H Faria, Werner F Kuhs, Sepp Kipfstuhl, Frank Wilhelms ( 2007 ) The role of hydrochlorofluorocarbon densifiers in the formation of clathrate hydrates in deep boreholes and subglacial environments. Annals of Glaciology , 47 , 109-114 . doi: 10.3189/172756407786857659
Lead Author
M. Mangir Murshed