Tripping operations in drilling are critical phases where the drill string is either pulled out of the well (tripping out) or run back into the well (tripping in). These operations require good planning and execution to maintain well control and prevent issues such as kicks or swabbing. This article outlines essential tripping considerations for effective tripping, focusing on trip tanks, slugs, pumping out, tripping-in techniques, and breaking circulation.
The Role of Trip Tanks
A trip tank is a specialized vessel used to monitor the volume of drilling fluid during tripping operations. Typically holding between 20 to 50 barrels, its design allows for precise detection of fluid volume changes, which is vital for maintaining well control. The trip tank continuously circulates fluid to keep the well filled, compensating for the volume occupied by the drill string. Accurate monitoring through the trip tank helps detect potential issues such as swabbing or influxes of formation fluids.
During tripping out, it is crucial to ensure that every stand of drill string removed is replaced with an equivalent volume of drilling fluid. For instance, if ten stands are pulled out, there should be a corresponding decrease of approximately eight barrels in the trip tank. Any discrepancy may indicate that formation fluids have entered the wellbore, necessitating immediate corrective actions.
Slugs: Enhancing Efficiency
Slugs are large volumes of drilling fluid pumped into the well to facilitate pulling the pipe dry whenever feasible. The slug’s volume and weight should remain consistent across trips to ensure reliable measurements1. Monitoring the pressure-volume-temperature (PVT) data during slugging operations allows for accurate assessment of returns while the slug is pumped and falls. This practice not only enhances operational efficiency but also minimizes risks associated with unexpected pressure changes.
Pumping Out Techniques
In certain hole conditions, it may be necessary to pump the drill pipe out of the hole to a predetermined depth, such as the casing shoe or liner top. This technique helps minimize swab pressures that could lead to well control issues. Developing a rig-specific procedure for this operation ensures consistency and accuracy in monitoring and fingerprinting12. By adhering to these protocols, crews can effectively manage pressure dynamics during tripping operations.
Tripping-In: Managing Running Speeds
When tripping in, careful attention must be paid to running speeds to prevent excessive surges that can induce high surge pressures. Surge pressures can occur when initiating circulation or during pipe movement. To mitigate these risks, operators should aim for controlled descent rates and be vigilant about monitoring pressure fluctuations throughout the process.
Breaking Circulation: Challenges and Solutions
Breaking circulation can lead to very high surge pressures, especially if mud conditions are poor or gel strengths are elevated. In such scenarios, staging within the hole can be beneficial when breaking circulation. This technique involves temporarily halting operations at predetermined depths to allow for pressure stabilization before resuming full circulation4. It is essential to monitor mud properties closely during this phase to ensure optimal performance and prevent complications.
Conclusion
Effective management of tripping operations is paramount in drilling activities. Utilizing trip tanks accurately monitors fluid levels and prevents potential well control issues during tripping out and in. Additionally, employing slugs enhances operational efficiency while minimizing risks associated with pressure fluctuations. By developing specific procedures for pumping out and carefully managing running speeds during tripping-in operations, crews can significantly improve safety and performance outcomes.
References
Cormack, D. (2007). An introduction to well control calculations for drilling operations. 1st ed. Texas: Springer.
Crumpton, H. (2010). Well Control for Completions and Interventions. 1st ed. Texas: Gulf Publishing.
Grace, R. (2003). Blowout and well control handbook [recurso electrónico]. 1st ed. Paises Bajos: Gulf Professional Pub.
