Connecting assembly of SK type is applied in tool assemblies when performing works using coil tubing (CT) in tubing strings with a diameter of 73÷89 mm.
CA connecting assembly consists of the four units:
I – circulation diaphragm valve is designed to provide fluid circulation when pulling the downhole equipment as well as for emergency depressurization in CT, if necessary.
II – emergency disconnector is designed to release CT from the downhole equipment or object being pulled if the force generated by the injector is insufficient for releasing of stuck pipes.
III – back-pressure clappet valve is designed to prevent reverse fluid flowing in CT.
IV – connecting crossover is designed to connect CT with connecting assembly. Connecting assembly set may also include a matrix of MGT 38 type designed to prepare CT for connection with SK–54 case.
The connecting assemblies manufactured have 45 and 54 mm nominal diameters.
Basic parameters and dimensions:
| Parameter | Value | |
| SK–45 | SK-54 | |
| Rated string size, tubing string, mm | 60; 73; 89 | 73; 89 |
| Coil tubing nominal diameter, mm | 38.1 | |
| Working pressure, MPa | 10 | |
| Shear pressure of pins after positioning the ball in the seat of the disconnected section or circulation valve seat, MPa, not greater than | 15 | |
| Diaphragm fracture pressure (unit I), MPa, not greater than:
– inner choke No. 1 (with one screwdriver slot) o11 mm – inner choke No. 2 (with two screwdriver slots) o10.5 mm |
24–26
27–30 |
|
| Bore minimum diameter, mm, not less than | 12 | 15 |
| Connecting assembly length, mm, not greater than | 1,015 | 1,210 |
| Outer diameter, mm | 45 | 54 |
| Weight, kg, not greater than | 10 | 13.8 |
| Working fluid | Drilling fluid, oil, water | |
| Fluid temperature, °С, not greater than | 100 | |
| Connecting thread dimensions as per GOST 24705-81, 8724-81, 9150-81 | М х 42 | М х 42 |