Detonation work in boreholes
A) Perforation of the string casing
This kind of operation is carried out by cumulative charges, which are placed in special covers. After the perforator is detonated the string casing is perforated and the contact with the reservoir horizon is obtained. The perforators are lowered into the hole either by the tubing ( TCP perforating) or on the logging cable with the aid of the logging truck. We are able to carry out this operation up to the pressure of 179 MPa and the temperature of 230°C in the 4 ½” to 9 5/8”diameter casing. . We can use cumulative charges with the weight from 13 to 61 grams according to customers’ demands and the environment in the hole. This determines the power of the casing perforator. The charge frequency is from 16,5 to 39 charges/m.
B) Perforation made under pressure in completed wells
It is used for the casings perforation by lowering the perforator hung on the cable into the tubing through the lubricator head and the cable preventer. The perforators are able to withstand the pressure of 100 MPa and the temperature of 205°C. The individual cumulative charges with the weight of 8 or 13 grams can be aimed at the angle of 60° or 90° (link Perforating Systems) or they can all aim at the same direction (Strip Perforating Systems).
It is used for demolition of casing or tubing in the boreholes. This procedure takes advantage of the effect created by special explosives placed in the sealed or unsealed blasts, which are lowered to the wanted position by the logging cable.
D) Casing cutters
They are used for cutting off the casing and tubing in the boreholes by the effect of explosives. The 2 7/8” to 9 5/8” diameter cutters can withstand the pressure of 140 MPa and the temperature of 200°C.
E) Disposal of jammed equipment
This operation is used for the string release after the precise location of the jammed equipment. It is done by shaking or uncoupling as well as using the effect of sealed or unsealed blasts.