Extent of pervasive fracturing around underground nuclear explosions

Borg, I.Y.

doi:10.1016/0148-9062(73)90056-9

Cited by 14 publications

(7 citation statements)

References 7 publications

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“…This indicates that the chimney height is 83.8 m above the working point. This coincides very well with the shear failure limit calculated based on rock properties of 80.2 m (Borg, 1973). The extent of the increased permeability zone around the test was a fitting parameter in two separate analyses of the Rulison gas production tests.…”

Section: Explosive Phenomenology Of the Rulison Nuclear Testsupporting

confidence: 61%

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Tritium Transport at the Rulison Site, a Nuclear-stimulated Low-permeability Natural Gas Reservoir

Cooper¹,

Ye²,

Chapman³

2008

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EXECUTIVE SUMMARYThe U.S. Department of Energy (DOE) and its predecessor agencies conducted a program in the 1960s and 1970s that evaluated technology for the nuclear stimulation of lowpermeability natural gas reservoirs. The second project in the program, Project Rulison, was located in west-central Colorado. A 40-kiltoton nuclear device was detonated 2,568 m below the land surface in the Williams Fork Formation on September 10, 1969. The natural gas reservoirs in the Williams Fork Formation occur in low permeability, fractured sandstone lenses interbedded with shale. Radionuclides derived from residual fuel products, nuclear reactions, and activation products were generated as a result of the detonation. Most of the radionuclides are contained in a cooled, solidified melt glass phase created from vaporized and melted rock that re-condensed after the test. Of the mobile gas-phase radionuclides released, tritium ( 3 H or T) migration is of most concern. The other gas-phase radionuclides ( 85 Kr, 14 C) were largely removed during production testing in 1969 and 1970 and are no longer present in appreciable amounts. Substantial tritium remained because it is part of the water molecule, which is present in both the gas and liquid (aqueous) phases.The objectives of this work are to calculate the nature and extent of tritium contamination in the subsurface from the Rulison test from the time of the test to present day (2007), and to evaluate tritium migration under natural-gas production conditions to a hypothetical gas production well in the most vulnerable location outside the DOE drilling restriction. The natural-gas production scenario involves a hypothetical production well located 258 m horizontally away from the detonation point, outside the edge of the current drilling exclusion area. The production interval in the hypothetical well is at the same elevation as the nuclear chimney created by the detonation, in order to evaluate the location most vulnerable to tritium migration.A three-dimensional geologic model was developed of the local Williams Fork Formation at the Rulison site that includes a sequence of sandstone and shale lenses conditioned on observations at two site wells. The dominant flow and transport direction is east-west, in agreement with the direction of regional fractures in the area. The average sandstone lens length is approximately 161 m, and mean thickness is 7.5 m. The sandstone lenses are characterized by very low intrinsic permeability in core measurements (on the order of 10 -18 m 2 ), while reservoir tests often indicate higher permeabilities (up to 10 -16 m 2 ) presumably as a result of fractures encountered at the field scale. Porosity of Williams Fork sandstone units is generally reported as being between 0.01 and 0.1. Shale units are considered barriers to flow, with intrinsic permeability of 10 -20 m 2 .A conceptual flow and transport model for the area around the emplacement well (where the nuclear device was located) was developed to investigate the rates of tritium transport in...

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Section: Explosive Phenomenology Of the Rulison Nuclear Testsupporting

confidence: 61%

“…Beyond this, tensile fractures may have occurred, but would be widely spaced and would not contribute to an increase in overall permeability. Comparison of horizontal fracture radii with the limit of shear failure indicates that horizontal fracture radii are consistently smaller (Borg, 1973).…”

Section: Explosive Phenomenology Of the Rulison Nuclear Testmentioning

confidence: 99%

Tritium Transport at the Rulison Site, a Nuclear-stimulated Low-permeability Natural Gas Reservoir

Cooper¹,

Ye²,

Chapman³

2008

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“…The distance to the lava is consistent with an evaluation of cable termination data for tests on Pahute Mesa, which suggests subsurface collapse ranges between 5.5 and 7.5 cavity radii (Olsen, 1993). A calculated chimney height of 1091 m places the top of the chimney near the top of the lava at 311 m depth (Borg, 1973). It seems reasonable that collapse terminated near or within this lava.…”

Section: 2 Collapsementioning

confidence: 99%

“…Based on observations by Borg (1973), Toman (1975) and Butkovitch and Hearst (1976), permeability of the shock damaged region should be higher than the pre-test setting. Because the material has been mechanically failed in place, it will have lower permeability than the bulked rubblized regions.…”

Section: Permeabilitymentioning

confidence: 99%