Reacting to a Warning Sign
When a blowout preventer (BOP) is in place, the immediate reaction to a warning sign is to perform a flow check. This test determines whether the well is flowing without the pumps running, signaling a kick (a positive indicator).
Conducting a Flow Check
To conduct a flow check, operations must be paused to allow enough time for observation. The flow check duration typically ranges from 10 to 15 minutes, though it may take up to 30 minutes depending on factors like mud type, formation permeability, and other conditions.
Flow Check Procedure
While the specific procedure may vary by rig, the general steps are:
- Pause Drilling: Stop drilling or other rig activities.
- Space Out the Tool Joint: Position the tool joint so that neither it nor its upsets are aligned with the pipe rams. A diagram for spacing out the tool joint should be displayed in the dog house.
- Stop the Pumps: Turn off the pumps. Stopping the rotary is optional.
- Align to the Trip Tank: Line up the well with the trip tank for monitoring.
- Record Flow Data: Observe and document the flow-back volume and the time taken for flow to stop. Compare these values with previous flow check data.
- Analyze Flow Status:
- If there is no flow or the flow-back is consistent with previous checks (fingerprinting), continue with operations.
- If the flow exceeds the normal range, sound the alarm and immediately shut in the well. Do not wait for a second opinion or delay.
- Confirm Well Security: After securing the well, notify the supervisor.
Flow Check During Drilling
When drilling, the flow check procedure is slightly modified:
- Lift the Bit: Pick the bit up off the bottom and space out the tool joint in the stack.
- Stop Rotary (optional): You may choose to stop the rotary.
- Stop the Pump: Make sure the booster valve is closed.
- Line Up to the Trip Tank: Prepare the return flow to the trip tank.
- Monitor the Well for Flow: Observe for any signs of flow.
- Shut in if Flow is Detected: If the well is flowing, shut the appropriate BOP and open the HCR (C & K line) valves.
- Monitor for BOP Leaks: Watch the trip tank for any BOP leaks. If a leak is detected, close a preventer below the leak to prevent escalation to a blowout.
- Record Pressure Readings: Document the SIDPP, SICP, Kill Line Pressure, and pit gain.
- Prepare for Further Actions: On a floater, set the compensator as needed.
When to Stop Pumping
It’s best practice to keep the mud pump(s) running until the tool joint is properly positioned. This helps retain the extra annular pressure acting on the wellbore, minimizing the risk of a kick.
Warning Signs During Tripping
While tripping, warning signs like the well not taking the expected amount of fluid, increased drag, or increased string weight suggest the possibility of a kick or losses, both of which could lead to underbalance.
If the trip sheet indicates deviations from expected hole fill volumes:
- Flow Check:
- If the well is taking less fluid than calculated, perform a flow check. If no flow is detected, return to bottom and circulate out the swabbed fluids. If flow is detected, shut in and strip to bottom if possible.
- If the well is taking more fluid than expected, top-fill the hole with a lighter fluid.
Flow Check While Tripping
- Position the Tool Joint: Place the tool joint at a working level on the rig floor and set the slips.
- Install and Close FOSV: Tighten the FOSV (DPSV) in the open position and close it to seal any back flow up the tubulars.
- Line Up to Trip Tank: Prepare the well for a flow check by lining it up to the trip tank.
- Monitor for Flow: Observe the well for flow. If flowing, remove the slips, space out the tool joint, and prepare the rig for further action.
- Close BOP and Open HCR Valves: Shut in the BOP and open the HCR valves if necessary.
- Check for Leaks: Monitor for any BOP leaks, closing a preventer below if any are detected. Inform the supervisor if a leak is found.
- Prepare for Further Drilling: Read and record SIDPP, SICP, and pit gain. Install an IBOP on top of the FOSV, and prepare for further operations.
Importance of Quick Response
When a kick is detected, shut in the well immediately to minimize the influx volume. Larger influx volumes lead to higher casing shoe pressures, which can result in lost circulation and make controlling the well more difficult.
Transitional Zone
While warning signs are important indicators of a possible developing well control issue, they may not always be present, and you may experience a well control incident in the absence of any pre-warnings! It is the responsibility of the entire crew to remain vigilent at all times and not rely on having warning signs.
For more information about warning signs and other well control subjects, please see my information-packed Well Control Manual at: Well Control Manual V2.6 by Edwin Ritchie
