Well Control: Soft Shut in Procedure



If any positive kick indication is noticed and the flow check has showed that the well is flowing, it should be shut in immediately. If there is any doubt about the kick, the safest procedure is to shut the well in the check for surface pressures. A small gain can quickly turn into an uncontrolled situation leading to a blowout. There are a level of hesitation to shut the well in due the fear of stuck pipe. In general, the stuck pipe is minimized if the well is closed early, the influx will be small and the wellbore pressures will be reduced and controlled. Other issues which can lead to hesitate to close the well is the possibility of breaking down the formation, especially at the casing shoe.

There are different methods to close the well for different rig type. In this article, the procedures for a fixed rig are presented:
- Shut in while drilling 
- Shut in while tripping

Soft shut in procedure

Circuit alignment during operations

During operations the circuit has to be aligned as follows:
- Manuel valve on choke line is opened
- Hydraulic valve on choke line has to be closed
- The choke on choke manifold has to be opened
- All the valves leading to the separator passing by the choke (downstream valves) have to be in open positions.
- Beside these valves, all the valves have to be in closed position. 


Fig 01- Circuit Alignment in Soft Procedure
 

Soft Shut in procedure while drilling

The procedure is performed as follows:
- if there is any kick indication, stop rotary, pick up off bottom and space out ( Tool joint one meter above rotary table to avoid getting the next tool joint on the pipe rams)
- Stop pumps, perform flow check. If the well is flowing then:
- Open choke line valve at the BOP stack ( Called HCR)
- Close annular BOP 
- Close Choke 
- Read and Record pressures and times. Check pit volume gain in order to prepare the kill sheet
- If the gas is migrating , control the wellbore pressures during the shut in 

Soft Shut in procedure while tripping 

If there is any kick indication, stop tripping immediately. Here, two different situations can be identified:

a) The well is flowing, then the shut in is proceeded as follows: 
- Set the string on the slips
- Install a fully opening safety valve in open position. Close the valve once is installed
- Open choke line valve at BOP stack (HCR valve)
- Close annular BOP
- Close choke. 
- Read and record pressures and times, check pit volumes
It depends on the situation to weather to start killing procedures or to strip back to the bottom.
- If the stripping is faced, then, Stab IBOP (Grey valve) 
- Open the fully opening safety valve
- Reduce the annular pressure and start stripping the string to the bottom

b) The well is not flowing:
- Set the string on the slips
- Install IBOP (grey valve or non-return valve)
- Run back in the hole with controlling the volumes, if any anomalies are noticed then proceed to the stripping. Once on bottom, circulate annular volume and evaluate the situation.




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