The Retrievable Drop-in Check Valve (RDCV) is used to control back flow from high pressure formations into the well and through the drill string back to the surface. It also allows for downward fluid circulation within the drill string. When the back flow is under control, the Drop-in Check Valve can be retrieved using a wire line.
If a kick or back flow starts while tripping out the pipes, it can be controlled with a drill pipe Safety Valve orKelly Cock to close the flow through the drill pipe before reconnecting the Kelly and for pumping the RDCV down to its landing sub.
By design, the Check Valve is equipped with a self-locking (under down hole pressure) feature.
Landing Sub OD ranging from 3-3/8” to 8-1/2"
Check Valve OD sizes ranging from 1-9/32” to 3-7/64”
Check Valve ID sizes ranging from 3/8” to 1-11/16”
10,000 or 15,000 PSI working pressure (testing pressure 15,000 or 22,500 PSI respectively)
Supplied with API or proprietary connections
Other configurations available upon request, subject to engineering department approval.
The RDCV product range has 8 Valve series corresponding to different Check Valve outside diameters (OD):
CHECK VALVE OD (IN)
One Piece Kelly Cock Valve
Figure 1 Landing Sub
Figure 2 Landing Sub
Figure 3 Check Valve
Figure 4 Check Valve
Figure 5 Overshot
Figure 5 Overshot
Each RDCV is hydraulically bench tested according to API spec 7-1 (latest edition) and delivered with its individual pressure test records. The tests are carried out in two steps:
SHELL TESTING during which the valve is pressurized to the test pressure for 3 minutes, then depressurized and pressurized again for at least 10 minutes.
SEAT TESTING during which the valve is pressurized from the pin end to its working pressure for at least 5 minutes.
During the pressure-holding period, timing shall start when pressure stabilization is achieved. No visually detectable leakage is permitted during the test time period and the pressure drop shall be no greater than maximum 1% of the pressure test value with a zero leak rate.
In case the Check Valve has to be dropped into the drill string, the compatibility of Check Valve OD and Kelly Cock Valve free ID passage is a critical factor. The table to the right shows the compatibility between KC2S Kelly Cock Valves and Retrievable Drop-in Check Valves:
RDCVs body and internal parts are made of high grade heat treated steel. Sealing is achieved through a metal to metal contact between a ball and a seat.
Two RDCV versions exist to suit all drilling environments:
The standard version which is suitable for normal drilling conditions.
The H2S trim version which has been designed for H2S environments in which the internal parts are made of corrosion resistant materials matching the NACE MR0175 standard (latest edition), fitted in a standard steel landing sub.