a blasting operation performed in boreholes using special charges called torpedoes. Shooting is done during or after the drilling of deep wells for exploration and extraction of useful minerals, such as petroleum, natural gas, and water. Shooting of wells was first used in the late 19th century in the state of Oklahoma and in Baku, Russia.
During drilling, shooting of wells is used to prevent the tool from becoming trapped in the well, to break up damaged metal (primarily using shaped-charge axial torpedoes), to loosen stuck drilling pipe at a particular point and free it by “shaking” (using a torpedo made from a detonating cord), and to break and cut off pipes using high-explosive torpedoes and shaped-charge pipe cutters, respectively. In operating wells, with wire and mesh filters, primarily those drilled for water, shooting is used to clean clay out of the filter immediately after drilling or to remove sediment deposited on the filter during operation (a detonating-cord torpedo). The blast and the accompanying pulsation of the explosion products and movement of liquid in the area completely remove sediment from the filter, thus increasing the yield of the well. Shooting may be used to open a horizon; this is usually done by torpedoes with cartridges of explosives.
Large charges containing up to several tons of explosives are used to increase the yield of wells whose productive horizons contain hard rocks. In some cases, a liquid or paste explosive is forced into the horizon or cracks in the horizon for this purpose. The blast is often set off by fuses with delays of up to ten days, and the shaft is protected by installing cement bridges above the torpedo that are reopened by drilling after the blast. For example, in shallow water wells (to 0.2–0.5 km), this is done using relatively small torpedoes weighing from 3–5 kg to a few dozen kilograms, and the blast is set off without protection of the shaft.
The temperature and pressure in the well are very important for selecting the charge and design of the torpedo. Torpedoes suitable for use at pressures up to 150 meganewtons per sq m and temperatures up to 250°C have been developed (1975). Special heat-resistant explosives and fuses are used in such torpedoes.
S. A. LOVLIA