Stage-by-stage RIH of liners appeared firstly as a practical solution for the problem of
casing strings running into wells with intensive curvature and (or) long horizontal section
thus there is always a risk not to reach the target depth while running in a liner. Secondly
it appeared as a possibility to perform a liner collar cementing at a given interval by cementing its second section.
The stage-by-stage-casing (liners) running tool USSK is intended for running in of a liner
first (lower) section on drill pipes without its cementing with further running in, leaktight
connection of the liner second section followed by cementing of the second section. USSK
is threaded onto the upper pipe of the liner first section and is RIH on drill pipes.
USSK consists of two principal units: hydraulic disconnection unit to disconnect the liner
from a transport string and mechanical disconnection (back off) unit to disconnect the liner
from a transport string implemented in a single tool. After liner running into the adjusted
depth and a ball is dropped into the transport string and pumped until setting down a seat.
Pumping screws are cut by the pressure build-up to 14 MPa and the liner hydraulic disconnection unit is actuated. If there is no possibility for the internal overpressure build-up, the
disconnection is performed by rotating (20 rotations) of the transport string to the right.
The stage-by-stage-casing (liners) running tool with packer sealing USSKP.
The USSKP consists of three principal tools: hydraulic inflatable packer unit, hydraulic
disconnection unit to disconnect the liner from the transport string and mechanical disconnection (back off) unit to disconnect the liner from the transport string implemented
in a single tool.