Excerpt:
In the middle of 1966, a crisis in the gas industry suddenly offered an opportunity for a new application for peaceful nuclear explosions, the extinguishing of runaway gas wells. Successful closing several such wells in 1966 and 1967 gave growing confidence to the leaders of the program, and they began to think about a broad spectrum of new applications.
Urtabrdak
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 27@300 atmospheres.
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 1500 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 1450 m. The final estimate for the closest distance between Hole No. 11 and Hole No. lC 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.
Pamuk
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 2748 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 80&l 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 2440 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 10OC 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.s 1 The explosive was inserted into Hole 10-N and detonated on May 21, 1968, at a depth of 2440 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 tires. 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 3000-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 1720 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 3000 m. No additional information has been made available except that for this event, named Fakel, a 3.8-kt explosion at a depth of 2483 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.
Pyrite
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 Naryan 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 1511 m in a sandstone+ lay 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.