Selection of drilling fluids for minimizing coalbed damage. Final report, December 1981-February 1983. [Effect on permeability of coal bed near the well]
The following conclusions have been drawn from work performed in this project: (1) both of the fluids tested (a KC1/CaCl2 brine and drilling mud filtrate) caused a loss in permeability when flowed through coal; (2) the damage mechanism for brine is undetermined, but the major part of the damage from mud filtrate appears to be related to particulate matter plugging flow channels; (3) a decrease in net confining pressure, caused by drilling overbalanced, can increase the risk of formation damage; and (4) an increase in net confining pressure, caused by drilling underbalanced, can also lead to permeability losses. The three potential formation damage mechanisms have been particulate plugging, clay swelling and/or migration, and relative permeability effects. Laboratory investigations have added a fourth - pressure effects.
- Research Organization:
- Institute of Gas Technology, Chicago, IL (USA)
- OSTI ID:
- 5206604
- Report Number(s):
- PB-84-132208; R-30553
- Country of Publication:
- United States
- Language:
- English
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