Evaluation of EL836 explosive stimulation of Devonian gas shale
This report presents an evaluation of EL836, an explosive developed at E.I. duPont de Nemours and Company Laboratories, in stimulating gas shale. EL836 is a water gel type explosive with a high aluminum content. The computational evaluation of EL836 involved four one-dimensional cyclindrical geometry calculations to assess the influence of two equation-of-state descriptios of EL836, the effect or rock yielding and the effect of internal crack pressurization. Results of a computational evaluation of the EL836 explosive in stimulating Devonian gas shale suggest the following: Extensive plastic yielding will occur in a region immediate to the borehole. Extensive tensile fracture will occur in a region that begins at the outer boundary of plastic deformation and terminates at more than 100 borehole radii. Without a mechanism of ;near-wellbore fracture, such as crushing or pre-cracking during drilling or intentional borehole grooving, the plastic flow that occurs adjacent to the wellbore causes stress redistributions which prohibit early-time (less than a millisecond) tensile fracture immediate to the wellbore and thus prohibits gas penetration from the wellbore into the crack system. The barrier that the near-wellbore plastic zone presents to gas flow from the wellbore is reduced in radial dimension as time increases. Natural fractures in the wellbore wall or cataclysmic deformation and fracture adjacent to the wellbore, as a result of the explosive detonation, will likely assist in breaking down the barrier to gas flow. Very significatn enhancement is achieved in the EL836 stimulation treatment when gases penetrate the stress-wave induced radial cracks. Only minor differences were observed in the EL836 stimulation effects when comparison is made between two different explosive equations-of-state. 33 figures, 2 tables.
- Research Organization:
- Science Applications, Inc., Fort Collins, CO (USA)
- DOE Contract Number:
- AM21-78MC08216
- OSTI ID:
- 6398827
- Report Number(s):
- DOE/MC/08216-1352; ON: DE83007141
- Resource Relation:
- Other Information: Portions are illegible in microfiche products. Original copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
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04 OIL SHALES AND TAR SANDS
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BLACK SHALES
EXPLOSIVE FRACTURING
CHEMICAL EXPLOSIVES
EVALUATION
NATURAL GAS WELLS
CRACKS
DEVONIAN PERIOD
EQUATIONS OF STATE
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHATTANOOGA FORMATION
COMMINUTION
ENERGY SOURCES
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EXPLOSIVES
FOSSIL FUELS
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FUELS
GEOLOGIC AGES
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PALEOZOIC ERA
WELLS
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