It seems that tripping in or out of the hole is a simple operation, It can be true if no difficulties are encountered. Missing any detail can lead to complicated problems like well control situation or stuck pipe which can generate a non-productive time. In this article some guidelines of tripping are mentioned below as a check list before, during and after the tripping.
- Prior to pulling out of the hole, the wellbore has to be circulated for at least a bottoms up volume. During this circulation, no mud losses have to be recorded, otherwise the losses have to be cured before the tripping. Also, if any influx is noticed, it has to be circulated out.
- According to the companies policies, a high viscosity pills can be pumped down before starting the circulation to improve the hole cleaning
- The cleaning pill depends on the type of well: vertical, deviated or horizontal. In some cases, two pills are pumped for example a low viscosity pill followed with a high density pill to optimize the hole cleaning.
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| Fig 1 : Pipe and Slips |
- If there are any doubt about the hole cleaning which can be confirmed when getting the pill on the shale shakers, a decision can be made to pump another pill till getting clean shakers.
- A flow check has to be performed right before pulling out of the bottom and at the lowest casing shoe.
- The drill pipe should be slugged with a high density pill. This pill volume is related to the mud weight existing in the hole, mud rheology, capacity of the drill pipe and the hole depth.
- In some cases, it is not recommended to pump high density slugs like when drilling through reservoirs to do not damage them or through weak formation to avoid inducing mud losses.
- On the drilling floor, make sure that the rotary slips are inspected and fitted with good inserts.
- The wiper rubber can be used to prevent object to fall into the well.
- When pulling out of the hole, the two or three first stands have to be pulled carefully and preferably with back reaming. Usually the drill bit loses its gauge at the last feet which can generate under gauge hole.
- Trip tank should be used during tripping to monitor if the wellbore is taking or giving the accurate volume of drilling fluid. When noticing any discrepancy, the well must be flow checked.
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| Fig 2: Trip Tank Circuit |
- In general manner, if the well is not taking the right volume when pulling out of the hole, the drill string should be run back to the bottom then well has to be circulated at least for bottoms up volume.
- Trip sheet should be prepared and used during the tripping.
- The safety valves have to be on the rig floor in the open position with the adequate closing/opening wrench. Also, the handling device should be on the rig floor for the immediate use.
- If the tripping is stopped for any reason, the safety valve should be placed and hand tight installed.
- In some cases when tripping is ceased for long time, circulation and rotation should be established through top drive or rotary circulating head with the rotary table to avoid stuck pipe mechanically or deferentially.
- The running or the pulling speed should be controlled to avoid surging or swabbing effects.
- When pulling through restrictions, avoid to over pull more than third of the drill string weight( as a rule of thumb, it could be less). It is recommended to use back reaming. Also when running, do not insist to pass through these restrictions use the top drive or the Kelly system to ream down.
- When pulling or running through restrictions, monitor the torque and do not continue tripping till getting stable torque, avoid to run or pull with torque fluctuations, it is an indication about hole geometry problem.
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| Fig 3: Cutting bed |
- Work on those tight spots till getting steady torque.
- Avoid to push the drilling bit through restrictions when reaming down. No weight should be applied on the drilling bit, this can lead to sidetrack the original well bore.
- Make sure that all the connections are torqued with the required torque.
- Record and note all the over pull points to avoid any incident when running the next BHA
- When getting all the stabilizers and the drilling bit on the surface, gauge them and check for any damages.
- The blind or shear rams must be closed when getting the drilling bit out of the hole to avoid falling any objects in the well bore.
- Prepare for the next run
Appreciate this post. Let me try it out.
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