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Gold/Mining/Energy : Oil Sands and Related Stocks
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To: crumbs who wrote (9819)5/15/2006 1:01:04 AM
From: crumbs  Read Replies (1) of 25575
 
Regarding PBG and THAI.

I was not precise enough in expressing my interest in the THAI process. Yes I have read the material from the University of Bath regarding the principles of THAI - papers which are largely concerned with heat and mass balance. I have yet to see anything about the chemistry of the process - and we probably have to wait for the outcome of real trials.

So lets consider the differences between SAGD and THAI. With SAGD the bitumen is heated, it then softens and flows, thus relatively unmodified bitumen is extracted. With THAI some of the bitumen is burnt, some of the bitumen is 'cracked' such that the viscosity of the extracted bitumen is reduced, i.e. some long chain molecules are untangled and broken. Obvious the amount of oxygen that is introduced into the bitumen deep underground will determine the amount of heat released and the amount of material that can be turned into carbon monoxide, carbon dioxide and water. However the intense heat will also have an effect on the chemistry of the unburnt and partially burnt bitumen.
Consider the distillation of coal. when coal is heated in the absence of air it breaks down into a huge range of chemicals having various molecular weights and distillation temperatures. For example the wood preservative creasote was made in this way and its composition is characterised in terms of the proportion of the distillate (fractions) that comes over at various temperatures from approximately 200 to 350 degrees Centigrade. An oil refinery works in a similar manner: cracking and distilling of the desired fractions.

THAI is a bit like an underground refinery - except it is not a closed system, and there is imperfect, empirical control. It is the uncertain combination of oxygen-time-temperature from point to point within the bitumen field that will determine whether the bitumen at any particular point simply flows, or if it gets hot enough for long enough that it will be cracked. THAT IS THE ONLY WAY THE THAI PROCESS CAN RESULT IN A PERMANENT REDUCED VISCOSITY.

Being very simple, the bitumen closest to the oxygen down-pipe with burn, the bitumen next to the horizontal pipe will largely melt and be extracted. It is the stuff in between that presents the most interesting opportunity - it gets hot enough to be cracked - but not all will be extracted.

At the end of the process there must be some residue left underground - some will be unmodified and some will be modified.

The question that I posed could be rephrased "what are the consequences of leaving this chemically modified residue?" As I said, somewhere I thought I noted that the process will result in some phenols. It is possible that such materials will be mobile and of some environmental concern even in parts per million. I'm not saying there is a problem. I am asking whether anyone has information to share on this matter.
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