Shut In Well Procedures

When any of the positive indications of a kick are observed and a check shows that well is flowing, it should be shut in well immediately. However, If surface casing alone has been set the flow should be diverted rather than attempting a shut-in which might endanger a the rig. Diverter procedures are discussed later in this section. Where a good casing seat exists it cannot be over-emphasised that early detection and early shut-in of well kicks minimises the hazards and simplifies the kill process. If there is doubt as to whether or not the well is flowing, the safest policy is to shut-in and check pressures. A small flow can rapidly turn into a full flow and blow out. Occasionally, fear of stuck pipe has caused hesitation in shutting in wells. In general, stuck pipe problems are minimised by closing in the well early, with a small influx to remove and lower the well bore pressures being exerted.

The possibility of breaking down the formation – especially at the shoe may also cause hesitation in shutting the well in. Here if the well is allowed to flow, eventually it will be necessary to shut the well in, with higher pressures and a greater likelihood of causing damage.

There are several different shut in well procedures for different types of rigs  and for different drilling operations. These are:

  • Shut-in well while drilling, fixed platform
  • Shut-in well while tripping, fixed platform
  • Shut-in well while drilling, floating rig
  • Shut-in well while tripping, floating rig
  • Shut -in well while out of hole.

Floating Vessel

It should be noted that the shut-in procedure on a floating vessel differs from that of a fixed rig. In general, the differences are:

  1. The floating rig tends to move.
  2. The BOP stack is remotely located – usually on the sea floor.
  3. The string can be hung off during a kill, with a tool joint lowered onto closed pipe rams, and string weight hung on these rams.
  4. A space distance, to prevent a tool joint being opposite the BOP rams must be calculated and available immediately to the driller. Where necessary allowance for tidal range must be made.

The alternative procedure for those previously mentioned is diverter operation. The procedures which follow are generalised suggestions, not necessarily applicable in detail to any specific rig.

 

Shut In Well Shut In Well Procedures

Fixed Rig Example of Line Up

Soft Shut In Procedure While Drilling – Fixed Rig

Proceed as follows

  1. When a possible indication is observed, stop rotary, pick-up off bottom until spaced out.
  2. STOP pumps. Check for Flow. If positive, then;
  3. OPEN choke line valve at the BOP stack (often called HCR valve or ‘F’ type valves.)
  4. CLOSE annular BOP.
  5. CLOSE choke. If this choke is NOT a positive shut off type, it is necessary to close a valve (ideally just downstream of the choke) in order to read well pressures.
  6. Alert supervisors. Read and record pressures and times. Check pit volume gain.
  7. If necessary, control well bore pressures during the shut in period, for example due to gas migration.

Soft Shut In Well Procedure While Tripping – Fixed Rig

Proceed as follows:

  1. When a possible sign is observed, set top tool joint in the slips.
  2. Install a full opening Safety valve on the drill pipe. Close the valve once it is installed.
  3. Pick pipe up, check for flow. Check trip volumes.
  4. OPEN choke line valve at Bop stack. (HCR valve).
  5. CLOSE annular BOP.
  6. CLOSE choke. If this is not a positive shut-off type, it is necessary to close a valve just downstream of the choke in order to read well pressures.
  7. Alert supervisors.
  8. Stab IBOP (Grey Valve) and open full opening safety valve.
  9. Read and record pressures and times. Check pit volumes.
  10. The operators representative will have to decide whether to kill in situ, or strip back to bottom.

Hard Procedure While Drilling  Fixed Rig

  1. When any indication is observed while drilling that the well maybe flowing, stop rotating the drill string, raise the drill with pumps on until spaced out.
  2. Stop pumping and check for flow, if positive;
  3. Close annular or pipe rams.
  4. Open choke line HCR valve.
  5. Call supervisor and commence plotting a graph of shut in well drill pipe pressure. Check pit volume again.
  6. Refer to API RP 53 for advantages and disadvantages of the hard shut-in.

NOTE:       Choke in closed position while drilling.

After shut in well. In any shut-in procedure it is prudent to line up the annulus to the trip tank above the annular or rams. This will assist in double-checking to see if they are leaking. Double check that the well is lined up through the choke manifold prior to circulating kick out

Diverter Procedure While Drilling Fixed Rig

1.    Where shallow casing strings or conductor pipe are set, fracture gradients will be low. It may be impossible to close the BOP on a shallow gas kick without breaking down the formation at the shoe. If a shallow gas kick is taken while drilling top hole then the kick should be diverted. Drilling shallow sand too fast can result in large volumes of gas cut mud in the annulus and cause the well to flow, also fast drilling can load up the annulus increasing the mud density leading to lost circulation and the level in annulus drops far enough then well may flow. When drilling top hole a diverter should be installed and it is good practice to leave the diverter installed until 133/8’’ casing has run. An automatic diverter system should first:

  • Open an alternative flow path to overboard lines.
  • Close shaker valve and trip tank valve.
  • Close diverter annular around drill pipe.
  • If there are two overboard lines then the upwind valve should be manually closed.

2.    If any indication of flow is observed while drilling top hole, close diverter immediately as the gas will reach surface in a very short time and it is inadvisable to attempt a flow check.

3.    Suggested diverting procedure in the event of shallow gas kick.

  • Maintain maximum pump rate and commence pumping kill mud if available.
  • Space out so that the lower safety valve is above the drill floor.
  • With diverter line open close shaker valve and diverter packer.
  • Shut down all non-essential equipment; if there is an indication of gas on rig floor or cellar area then activate deluge systems.
  • On jack-up and platform rigs monitor sea for evidence of gas breaking out around conductor.
  • If mud reserves run out then continue pumping with seawater.
  • While drilling top hole a float should be run. This will prevent gas entering drill string if a kick is taken while making a connection. It will also stop back flow through the drill string on connection.
Shut In Floating Rig Example of Line Up Shut In Well Procedures

Floating Rig Example

Hard Shut In Procedure Floating Rig

  1. When any indication is observed while drilling that the well maybe flowing, stop rotating the drill string with pumps running and space out for hang off rams.
  2. Stop pumps and check for flow, if positive:
  3. With compensator at mid-stroke close annular or pipe rams.
  4. Open fail-safe valves on the choke line.
  5. Call supervisors and commence plotting a graph of shut in drill pipe pressure. Check pit volume again.
  6. If rams have been closed then reduce manifold pressure, slack off on drill string and land tool joint on rams. Increase manifold pressure to 1500 psi close wedge locks; adjust compensator to support drill string weight to BOP plus 20,000 lbs.
  7. Refer to API 53 for advantages and disadvantages of the hard shut-in.

 

NOTE:        Choke in closed position while drilling.

Soft Shut In Procedure While Drilling Floating Vessel

Proceed as follows:

  1. When a possible indication is observed, stop rotary and pick up string to the predetermined height required for spacing out.
  2. TOP pumps. Check for flow. If positive.
  3. OPEN failsafe valve on BOP stack (valve on the choke line).
  4. CLOSE annular BOP.
  5. CLOSE choke. If this choke is not a positive shut-off type, it is necessary to close a valve (ideally just downstream of the choke) in order to read well pressures.
  6. Alert supervisors. Check pit gain. Read and record pressures and times. If pipe is to be hung off, some companies prefer to exchange the Kelly for a circulating head first. In this case:
    • Set slips. CLOSE lower Kelly cock. Bleed off pressure in Kelly. Remove Kelly, above lower Kelly cock.
    • Make up and install circulating head. OPEN lower Kelly cock. Remove slips.
  7. CLOSE top pipe rams.
  8. Reduce the pressure on annular preventer and lower the drill pipe until it hangs off on top pipe ram. Note that it may be necessary to bleed off mud while lowering pipe, to prevent wel pressure increase due to the extra volume of string being lowered into the hole. Bleed of mud to hold annulus pressure constant during this time.
  9. OPEN annular BOP.

Soft Shut In Procedure White Triping Floating Vessel

Proceed as follows:

  1. When a possible sign is observed, set top tool joint in the slips.
  2. Install a full opening, fully opened safety valve in the drill pipe. CLOSE the valve once installed.
  3. Remove slips and pick pipe up to predetermined height for space out and check for flow and check trip volumes.
  4. OPEN choke line valve at BOP stack (failsafe valve).
  5. CLOSE annular BOP.
  6. CLOSE choke. If this is not a positive shut off type, it is necessary to close valve just downstream of the choke in order to read well pressures.
  7. Alert supervisors.
  8. Stab IBOP (Grey Valve) open safety Valve.
  9. Read and record pressures and times. Check pit gain.
  10. CLOSE upper pipe rams.
  11. Reduce pressure on annular preventer and lower the drill pipe until it hangs off on a pipe ram. Note that it may be necessary to bleed off mud while lowering pipe, to prevent well pressure increase due to the extra volume of string being lowered into the hole. Bleed off mud to hold annular pressure constant during this time.
  12. OPEN annular BOP

Shut In Procedure While Out Of The Hole

Proceed as follows:

  1. Detect flow. Note that monitoring equipment should always be in use when the hole is open.
  2. OPEN choke line valve. (failsafe or HCR valve)
  3. CLOSE blind rams.
  4. CLOSE choke. If not a positive shut off, then close a downstream valve to record pressure.
  5. Alert supervisor. Read and record casing pressure and times. Check pit and trip volumes for pit gain.

The operators representative shall decide what steps to make from this point. The main options available are:

  • Stripping into the hole.
  • Bull heading down the kill line.
  • Volumetric method.

Diverter Procedure While Drilling

  1. When a possible indication is observed, STOP the rotary, pick up until spaced out.
  2. Shut down pumps and check for flow. If positive;
  3. OPEN diverter line valves- check that flow will be diverted to downwind side of rig.
  4. CLOSE flowline valves.
  5. CLOSE diverter annular BOP.
  6. Start pumps – ideally to pump water at maximum possible rate, for lubrication.
  7. Alert supervisors.

NOTE:       On many rigs, there is a mechanical interconnection to prevent the diverter annular closing, until the diverter line valves are opened. This is to prevent an inadvertent close in, and is a legal requirement in some countries.

There has been no regulatory definition of when diverters should be used instead of normal shut in procedures in the UK.  Accepted good practice is to run a diverter system until 133/8” casing or its equivalent is set, typically at depths between 4,000 – 5,000 feet true vertical.

Surface & Subsea BOPS While Wireline Logging

  • Direct the wireline loggers to cease operations and close the well on the upper annular.
  • Open kill line valves and begin to record shut in pressure and pit gain.
  • Pass word to the OIL COMPANY REPRESENTATIVE and SENIOR DRILLING CONTRACTOR REPRESENTATIVE of the well condition.
  • Decide on kill programme.

NOTE:       If at all possible the wireline should be pulled or stripped out of the hole.  If the line needs to be cut and dropped, a surface hydraulic cable cutter should be used.  The shear rams should be considered as a last resort and used only if the annular(s) fail to secure the well.

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