These are some general rules for the tripping operations. They can be changed from a company to another company according to its policy.
Tripping Instructions
The assistant driller and the derrick man should check that the following points are carried out:
- Check that all the valves are fully closed or opened according to the situation
- Trip tank fill up
- Return flow is lined up from the mud box to the pits passing by the shakers
- Lined up the mud pump when necessary
The driller has to check the correct hole depth. He has to use the BHA tally and write on it the total number of stands and any double or single.
Some precautions have to be taken to avoid stuck pipe (Read about Stuck Pipe here )
- Note the pick up and the slack off weight on trips in order to recognize any abnormal over pull or set of weight.
- It any doubt about tight spot, the overpull has to be increased in 10000 lbs increments to the allowable overpull which depends on the drill pipe grades (safety margin has to be considered). If the maximum is reached, the top drive has to be connected and work on that interval.
For the trip in or out of the hole, the trip tank has to be used. The hole has to be maintained full of mud if possible. In order to get an accurate volume usage, adequate timing has to be given to fill or empty the trip tank.
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| Fig 01- Alignment when tripping |
If any total losses is faced, the string has not to be tripped out of the hole until getting a stable fluid level. Depending on the company policy, if a severe total loss is faced, the string has to be pulled with filling twice steel volume. (Click Here)
The trip sheet has to be used with all the information in it. The expected and actual volumes have to be compared. Any deviation from theoretical volumes, a flow check has to be performed.
The flow check has to be made at these following points:
- When the bit is just pulled off the bottom prior to tripping out
- When the drill bit is at the last casing shoe
- When the top of BHA is at the BOP level
- When getting a difference between the theoretical filling volume and the actual filling volumes which is checked using the trip tank
The flow check is conducted before dropping any survey instruments or slugging the drill pipe. In case of oil based mud, 15 minutes is required for the flow check and in the case of water based, 5 minutes can be enough for the flow check. ( Read about Kick behavior in drilling fluids here )
Tripping speed is chosen according to the swab or surge pressures to keep them below the critical values. The driller has pull the stands smoothly.
Kick drills has to be carried out with the bit inside the casing when drilling is performed through the reservoir.
The driller has to apply correct make up torque to all connections. The recommended torque for all components such as bit, drill collar, drill pipes should be available for the driller. The tong torque gauge has to be checked and calibrated for function.
The tool joints should be positioned at the right height above the slips to avoid pipe bending.
Drilling jars have to be handled carefully. The safety clamps will be installed and removed strictly as per the specification of the manufacturer. (Presentation about Drilling Jars here )
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| Fig 02- Jars Safety Clamps |
The maximum permissible tensile load has to be determined.
The drill collars should be racked in such a way that the drill pipe can be run first in to the hole without any delay.
In order to prevent any junk from falling when the drill string is out of the hole, the well cover plate has to be set and the blind rams has to be closed.
The trip tank has to be monitored closely when the string is out of the hole in case when the blind rams are in open position.
Two safety valves with proper connections have to be on the rig floor.
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| Fig 03- (a) Safety valve (b) Grey Valve |
The drill sting has to be filled frequently to avoid any pipe collapse. Filling each 10 stands can be a good practice.
In order to pull dry trip a weighted slug can be pumped which has 2 ppg heavier than the mud in hole.
In case when large amounts of gas is expected to be circulated, some techniques are recommended:
Tripping in the hole
- When reaching the bottom, start circulating a bottom up until getting to 600 m from surface
- Close the BOP's and circulate through the choke ( in fully open position) and through the mud gas separator until circulating the expected gas
- Open the BOP and continue operations
Tripping out of the hole
- Circulate bottom up before starting to pull out of the hole
- If any increase in pit level or any indicative of gas is noticed close the BOP and continue circulation through the mud gas separator passing by fully opened choke until circulating any possible gas.
- Open the BOP and perform the flow check
- When pulling out of the hole any the well is not taking the right filling volume and if the conditions allow, go back to the bottom and circulate till the hole indicators are favorable for the tripping.
Thanks for sharing this guide.
ReplyDeleteThe expected and actual volumes have to be compared. Any deviation from theoretical volumes, a flow check has to be performed.
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ReplyDelete