1. Making Connections During Fast Drilling: "Late Pump Stop, Early Pump Start"
When drilling fast with a high rate of penetration (ROP), cuttings accumulation is a major risk. The recommended practice is to stop the pump late and start it early when making a connection. This minimizes the time drilling fluid is static, preventing settled cuttings from causing a stuck pipe incident.
2. Judging a Locked Cone in a Tricone Bit
A locked cone is a serious downhole failure. Key indicators include a sudden increase in torque, manifested as:
- Increased load on the rotary table.
- Periodic bouncing or jerking of the kelly.
- Fluctuations in engine sound.
- The rotary table reversing after being disengaged.
If these signs are observed, combined with the bit's service hours and formation conditions, a locked cone is likely. The immediate action is to circulate and pull out of the hole.
3. Hazards of High-Speed Tripping Out (POOH)
Tripping out too quickly poses multiple risks:
- Overloading the rig equipment.
- Increasing the risk of sticking the pipe if wellbore issues exist.
- Potential crown-out accidents if the brake system fails.
- Generating excessive swab pressure, which can induce kicks, wellbore influx, or formation collapse.
4. Hazards of High-Speed Tripping In (RIH)
Running in the hole too fast is equally dangerous:
- Causes abnormal wear on brakes, brake drums, and drilling lines.
- Risks pipe failure, sticking, or drill string dropping if sudden resistance is encountered.
- Generates high surge pressure, potentially leading to lost circulation or wellbore collapse.
- Can damage the bit by colliding with the wellbore.
- May force cuttings into the bit nozzles, causing plugging when circulation is started.
5. Emergency Response: Brake Failure While Lowering Drill String
If brakes fail while lowering the string, the priority is to immediately engage the low-speed clutch to slow the descent. Personnel on the rig floor must quickly set slips or latch the elevator, and all personnel should evacuate the area immediately.
6. Wireline Twisting During Tripping: Causes & Solutions
- Causes: New wireline with residual twist; severe pipe rotation during tripping; unlathed elevator bail.
- Solutions: Release the live end of the wireline to remove twist; control tripping speed to minimize rotation; if the bail is unlathed, set the slips and rotate the traveling block to release the lock.
7. Importance of Unlatching the Elevator Bail
Unlatching the bail during tripping is standard practice to prevent wireline twisting when making or breaking connections. It also allows the pipe to rotate freely (e.g., when stabilizers are in the hole) and facilitates safer operation for the derrickman and floorman.
8. Reasons for Circulating Drilling Mud Mid-Trip
Circulating mud while running in the hole is a preventive measure for several scenarios:
- To prevent degraded mud properties or excessive settled cuttings that could make starting circulation difficult.
- When wellbore instability (collapse) is suspected.
- After mud contamination (e.g., from saltwater or gypsum).
- In cases of minor fluid loss.
- In complex wellbores with a history of circulation problems.
- In long, deep open-hole sections or when drilling through high-pressure zones.
Safe and efficient drilling relies on vigilant monitoring of downhole indicators, strict control of tripping speeds, adherence to standard procedures (like unlatching the bail), and executing preventive measures (like mid-trip circulation) based on well conditions. For more detailed information, please don't hesitate to contact Vigor team for more detailed product information.
