In September, 1966 the former Soviet Union suffered blowouts on five natural gas (methane) wells and despite their best efforts, including hydraulic fracturing, were unable to quench the flames.
The gas well accident in Urta-Bulak, about 80 kilometers from Bukhara, Uzbekistan in the former Soviet Union.
The Russian news agency Pravda said that after years of burning uncontrollably the Soviets were able to put out the fires.
The Soviets lowered a specially made 30 kiloton nuclear bomb into a 6 kilometres (20,000 ft) borehole drilled 25 to 50 metres (82 to 160 ft) away from the original (rapidly leaking) well.
A contained nuclear explosive was considered necessary because conventional explosive both lacked the necessary power and would also require a great deal more space underground.
When the nuclear bomb exploded, it crushed the original pipe and gas well from the deep reservoir to the surface and glassified the surrounding rock.
Within 23 seconds of the explosion, the leak and fire at the surface was finally put out.
Extinguishing Runaway Gas Well Fires
The Soviet Program for Peaceful Uses of Nuclear Explosions
by Milo D. Nordyke 1998
Formerly Director, Lawrence Livermore National Laboratory, Center for Studies of Security, Energy and Arms Control, Livermore, California.
Science & Global Security, 1998, Volume 7, pp. 1-117
from PrincetonUniversity Website
Shortly after the Soviet PNE Program was established, an urgent industrial problem was brought to the leaders of the program - could an underground nuclear explosion be used to put out a gas well fire that had been raging for some 3 years? (See section B.2, Appendix B.)
On December 1,1963, while drilling gas Well No. 11 in the Urtabulak gas field in Southern
Uzbekistan about 80 km southeast of Bukhara, control of the well was lost at a depth of 2450 m. This resulted in the loss of more than 12 million m3 of gas per day through an 8-inch
casing, enough gas to supply the needs of a large city, such as St. Petersburg. Formation pressures were about 270-300 atmospheres.
Over the next three years, many attempts were made using a variety of techniques to cap the well at the surface or to reduce the flow and extinguish the flames. However, because the
bottom 1,000 m of the casing had not yet been cemented, such attempts led to diversion of the gas into nearby wells and to serious personnel safety problems because of the high H2S content of the gas.
Underground attempts were hampered by the fact that the location of the lower portion of the hole had not been logged at the time control was lost.
Finally, in the fall of 1966, a decision was made to attempt closing the well with the use of a nuclear explosive. It was believed that a nuclear explosion would squeeze close any hole
located within 25-50 m of the explosion, depending on the yield. Two 44.5-cm (13.5 in) diameter slant wells, Holes No. 1c and 2c, were drilled simultaneously.
They were aimed to come as close as possible to Hole No. 11 at a depth of about 1,500 m in the middle of a 200-m-thick clay zone. This depth
was considered sufficient to contain the 300-atmosphere pressure in the gas formation below. A number of acoustic and electromagnetic techniques were used to estimate the distance
between Hole No 11 and inclined explosive emplacement hole at 1,450 m.
The final estimate for the closest distance between Hole No. 11 and Hole No. 1c was 35 ± 10 m.
The location for the explosive in Hole 1c was cooled to bring it down to a temperature the explosive could withstand. A special 30-kt
nuclear explosive developed by the Arzamas nuclear weapons laboratory for this event was emplaced in Hole 1c and stemmed. It was detonated on September 30, 1966.
Twenty-three seconds later the flame went out, and the well was sealed.
A few months after the closure of the Urtabulak
No. 11 hole, control was lost of another high-pressure well in a similar nearby field, Hole No. 2-R in the Pamuk gas field.
In this case, drilling had progressed to a depth of 2,748 m before the gas-containing horizon was
encountered, and gas pressures were significantly higher than those at Urtabulak (580 atm). A month and a half after the runaway
well started, it blocked itself at a depth of 800-1,000. Remedial work was done in the well and appeared to have resolved the problem when,
four months later, gas started coming to the surface through other holes and through the ground itself.
After several unsuccessful attempts to seal the well by hydraulic fracturing from a
slant-drilled well, it was decided to again use a nuclear explosive to pinch off the runaway
well. A new inclined hole, No. 10-N, was drilled to intersect Hole 2-R in the middle of a salt
formation that overlay the gas producing formation. Measurements after it had been
drilled indicated that the minimum separation distance at a depth of 2,440 m was 30 ± 5 m.
This time, a special explosive developed by the Chelyabinsk nuclear weapons laboratory was used,
one that had been designed and tested to withstand the high pressures and temperatures in
excess of 100°C expected in the emplacement hole. It also was designed to be only 24 cm in
diameter and about 3 m long to facilitate its use in conventional gas and oil field holes. Its yield was 47 kt.
The explosive was inserted into Hole 10-N and detonated on May 21, 1968, at a depth of 2,440 m. Because of the large amount of gas that had
infiltrated the overlying strata during the preceding two years, the flow continued for seven days before it finally died out and the seal was complete.
The second "success" gave Soviet scientists great confidence in the use of this new technique for rapidly and effectively controlling runaway gas and oil wells.
Crater and Fakel
Some four years later, two more opportunities arose for the use of nuclear explosions to extinguish runaway gas well fires.
The first, code-named "Crater," was in the Mayskii gas field about 30 km southeast of the
city of Mary in Central Asia. Control of the gas well was lost on May 11, 1970, and about 700,000
m3 of gas was lost per day. The producing horizon in this field was at the 3,000-m level.
No details have been made public about this application, except that on April 11, 1972, a
14-kt explosion at a depth of 1,720 m in an argillite formation was used to successfully seal the runaway well.
On July 7,1972, another runaway gas well in the Ukraine, about 20 north of the city of Krasnograd and 65 km southwest of Karkov, was
sealed with a nuclear explosion. The runaway well was in the Krestishche gas formation at a depth of over 3,000 m. No additional information has been made available except that for this
event, named "Fakel," a 3.8-kt explosion at a depth of 2,483 m in a salt formation, was used.
The small yield would indicate that the location of the runaway well was well known, and the explosive emplacement hole was drilled to be very close to it at shot depth.
The last attempt to use this application occurred in 1981 on a runaway well in the
Kumzhinskiy gas deposit in the northern coast of European Russia near the mouth of the Pechora River, 50 km north of the city of Nar'yan Mar.
Control of the well was lost on November 28, 1980, resulting in a loss of about 2,600,000 m3
of gas per day. On May 5, 1981, a 37.6-kt nuclear explosion, code-named "Pyrite," was detonated at a depth of 1,511 m in a sandstone-clay formation near the runaway well.
However, the nuclear explosion did not seal the well, perhaps because of poor data on the position of the runaway well.
No additional details have been published on the results of the nuclear attempt or of subsequent efforts to close the well by other means.
Of the Soviet attempts to extinguish runaway gas wells, MinAtom reports that all were completely
contained, and no radioactivity above background levels was detected at the surface of the ground during post-shot surveys.