Trip Tank
Trip Tank
Trip Tank
Not included in the mud recycling system, the design for trip tank is to protect
the inner wall of drilling hole when the drilling stem out and in the hole and
prevent the kick off. Trip Tank is always equipped with a level gauge so that the
operator could control the mud capacity on the operation board. To some
extent, trip tank is a independent tank from the mud cleaning system.
Trip Tank is a small metal tank with small capacity about 20-40 bbls with 1 bbl
divisions inside and it is used to monitor the well. There are several operations
that we can use the trip tank to monitor the well as follows;
Trip Out Of Hole (TOOH): While tripping out of hole, the trip tank is used to
track volume of mud replacing volume of drill string. The volume of mud
should be equal to displacement volume of any kind of tubular tripped out of
hole.
1. Trip In Hole (TIH): While tripping in hole, the drilling string (bit, BHA and
drill pipe) is ran back in the hole, the trip tank must be use to keep track
volume gain. The expected volume gain should be equal to the
displacement volume of whole string.
2. Flow check: The trip tank is utilized to determine well condition in order to
see if the well is still under static condition.
well control. For this reason, mud in trip tank must be filled into hole to
maintain hydrostatic pressure.
2. Kick Indicator: Volume of mud from the trip tank is pumped in the hole
can be an indicator that relates to a situation occurring in wellbore as
kick. If the volume of mud measured by trip tank is less than the
expected volume of drill pipe volume tripped out of hole, the suspect
problem is kick because volume of kick substitutes volume of mud.
I would like to show the circulation system while tripping out of hole therefore
you will be more understanding about how trip tank works.
While Tripping Out of Hole (TOH), a trip tank pump will circulate mud into a
bell nipple in order to keep the hole full all the time and the over-flow mud will
return back to the trip tank. Once every stand is pulled, the mud volume in the
well will decrease because the drill pipe is pulled out of hole. Since the trip
tank pump is always run while tripping, the annulus will be full all the time
(see figure below).
The diagram (Figure 2) below demonstrates how the trip tank is lined up.
Each trip tank has a pump which will suck the fluid from the tank and pump
into the well via the fill up line connected to a bell nipple under the rig floor.
The fluid return will flow back via a return line and back to the trip tank. The
float in the trip tank is connected to the wire and the position of the float will
represent the trip tank volume indicator. Whats more, nowadays several rigs
have installed the electronic instrumentation for the accurate volume
measurement. This will help personnel on the rig track what is going on the
well very quickly and accurately. As you can see, the complete system allows
personnel to monitor the well.
The trip tank must be maintained in order to avoid solid build up, pump and
valve failure, leakage, etc. Moreover, it is very critical to frequently check the
float and the electronic instrument to see if they are in good condition.
Stripping operation requires a separate trip tank which has very small capacity
of 3 to 4 bbl therefore it is not recommended to use the normal trip tank for
this operation. The small volume tank, called strip tank, has more accuracy
and suite for the operation.
How The Trip Tank Monitor The Well For Well Control
Trip Out of Hole
While pulling out of hole, each stand of drillstring pulled out must have the
same amount of drilling fluid to replace the drillstring volume. For instant,
each stand should take around 0.8 bbl. If you pull 10 stands out of hole, you
should see at least 8 bbl of mud volume decrease in the trip tank. If you see
the volume displacement less than what it should be, it indicates that the well
is swabbed in.
Trip In Hole
While tripping in hole, mud will be pushed out of the well to the trip tank
because steel displacement will replace the drilling fluid in the well. The
volume displacement should be the same as the steel displacement. If the
volume displacement is more than the steel displacement, the well may has
some unwanted kick in the well.
Flow Check
While flow checking, the volume in the trip tank should be at the same level.
There should not be any changes. Increasing volume in the trip tank means the
well is flowing. Conversely, if the volume decreases, the well has static loss.
Note:
Kick detection devices as flow show, Pit Volume Totalizer monitor, and
alarm must be tested properly and regularly.
Mud logger kick detection devices must also tested in the same way as rig
instrumentation to confirm an accuracy and readiness.
Set the trip tank gain/loss and the flow show at required level.
Use mud pit to monitor the well if larger casing is ran. Use a trip tank to
monitor the well if a smaller casing or tubing is ran. This depends on the rig
system.
Track volume displacement with two separate systems if possible (one
from the rig system and another one from mud logger system).
Verify all well control equipment is properly lined up to shut the well in.
Confirm the correct line up for well monitoring via a trip tank.
Confirm the correct line up from mud pumps to the rig floor.
Review shut in procedure while running casing or tubing.
Review any foreseeable issues with Tool pusher and Customer
Representative
Ensure correct casing or tubing tally while running in hole
Trip sheets must be recorded every stand of casing / tubing ran.
Assistant Driller has a responsibility to accurately fill a trip sheet while
running casing/tubing.
Trip sheets must be kept in a tool pusher office after tripping operation
completed.
While running casing/tubing, if the volume discrepancy is seen,
Assistant Driller must inform Driller, Tool Pusher and Company
Representative. The running casing/tubing operation must be stopped for
further evaluation and a Full Open Safety Valve must be installed.
Ensure shut in while running casing/tubing procedure is posted on the
rig floor closed to the driller console
While tripping, if the volume discrepancy is seen, Assistant Driller must
inform Driller, Tool Pusher and Company Representative. The tripping
operation must be stopped for further evaluation and a Full Open Safety
Valve must be installed.
available on the drill floor at all time. Driller must check this equipment. It
must leave in an opened position. It may be required to have cross over from
FOSV to drill string connection.
The Driller is responsible for well monitoring while tripping. The driller
has the right to shut the well in if there is an indicator of well control or any
doubt while tripping out.
Shut In Procedure While Tripping for Well Control Situation must be
posted in the driller cabin where the driller can see it easily at all time.
Kick detection devices as flow show, Pit Volume Totalizer monitor, and
alarm must be tested properly and regularly.
Mud logger kick detection devices must also tested in the same way as rig
instrumentation to confirm an accuracy and readiness.
Set the trip tank gain/loss and the flow show at required level.
Track volume displacement with two separate systems if possible (one
from the rig system and another one from mud logger system).
Verify all well control equipment is properly lined up to shut the well in.
Confirm the correct line up for well monitoring via a trip tank.
Confirm the correct line up from mud pumps to the rig floor.
Review shut in procedure while tripping.
At the following events, flow checks must be performed;
At the bottom of the well prior to tripping out.
o
At the deepest casing shoe.
o
Anytime that there is any doubt in the well condition.
o
Anytime that the hole displacement is not correct.
o
Prior to pulling HWDP or Drill Collars through the BOPs.
o
If the monitoring or circulating system does not work properly.
o
Review any foreseeable issues with Toolpusher and Customer
Representative
Check and maintain accurate pipe tally
Do not trip when filling up a trip tank
Perform trip drill with crew every trip if possible
Toolpusher should be on rig floor for at least first 10 stands to monitor
the operation.
Trip sheets must be recorded every stand of drill pipe pulled. Assistant
Driller has a responsibility to accurately fill a trip sheet while tripping.
Trip sheets must be kept in a tool pusher office after tripping operation
completed.
While tripping, if the volume discrepancy is seen, Assistant Driller must
inform Driller, Tool Pusher and Company Representative. The tripping
operation must be stopped for further evaluation and a Full Open Safety
Valve must be installed.
Ensure shut in while tripping procedure is posted on the rig floor closed
to the driller console
Record pick up weight and maintain a trend in a data sheet to observe
any hole issue.
Do not attempt to pull if you see abnormal drag 30 Klb over a current
pick up weight.
Any abnormal dram must be informed to Toolpusher and Customer
Representative.
If a slug is planned to pump, driller must determine volume gain from
slug.
The U-Tube effect must be discussed with team prior to pumping slug.
Ensure the well condition before pumping slug. Inform Toolpusher and
Customer Representative before pumping slug.
After pumping slug, it is required to wait until the well is stable prior to
continuing the tripping operation.
Increase drag and torque Increasing in drilling torque and drag are usually
noticed while drilling into overpressured shale formation because underbalanc
hydrostatic pressure exerted by drilling fluid column cannot to hold back the
formation intrusion into wellbore. Shale normally has low permeability so
formation fluid will not come into wellbore. Anyway, if we drill ahead pass high
shale pressure into overpressured high permeability zones such as sand or
carbonate, the formation fluid will flow into wellbore resulting in kick. This is
very important to record frequently drilling torque and drag because it could be
your well control indicator.
Decrease in Shale Density Typically, shale density will increase as we drill
deeper. If we see decrease in shale density, it may indicate that your well is in
underbalance condition because high pressure zones (abnormal pressure)
develop within large shale section. Practically, density of shale must be
measured frequency and plot against drilling depth. You can see from a chart if
there is any deviation in trend that could be an indication of change in pore
pressure.
Increase in cutting size and shape Pieces of formation may break apart and
fall into wellbore because of underbalance situation. Because rocks pieces
broken by underbalance condition are not ruined by bit, they will be more
angular and bigger than normal cutting. Larger of cutting size will be result in
difficulty to circulate them out of wellbore, hence, there will be more hole fill
and torque and drag will increase. In addition, without a proportional increase
in ROP (rate of penetration), cutting volume coming over shale shakers will
increased noticeably.
Wellbore geometry
Circulating rate
Cooling effect when drilling fluid flows through a long riser (deep water
consideration).
detecting change in pit level is easily accomplished at the rig site. However,
visually check the pit level is importance as well for double checking figure
from the sensors. Sometimes, change in pit level may be detected after the
increase in flow show because it takes more time to accumulate volume enough
to be able to detect by pit sensors.
Continue flowing while the pumps are off When pumps are turned off, bottom
hole pressure will decrease due to loss of equivalent circulating density (ECD).
If there is any flow coming after pumps off, it indicates formation influx into
wellbore.
personnel and mud logger. If volume in trip tank increases, personnel must
confirm flow check and prepare to shut the well in.
The Driller has a responsibility to check all well control equipment and
record into the sheet at the beginning of tour.
The Driller must review the schematic for line up and ensure the correct
line up for required operation.
A drilling parameter trend sheet will be updated every hour during
drilling operations. The parameters are as follows; RPM, active pit volume, %
return flow, Rate Of Penetration (ROP), drilling torque, off bottom torque,
pickup weight / slack-off weight, mud density, gas units or percentages,
pumping pressure, Equivalent Circulating Density (ECD), etc.
The driller must monitor any drilling break and inform Tool pusher and
Customer Representative if there is drilling break.
Kick detection devices as flow show, Pit Volume Totalizer monitor, and
alarm must be tested properly and regularly.
Mud logger kick detection devices must also tested in the same way as rig
instrumentation to confirm an accuracy and readiness.
Set the PVT gain/loss and the flow show at required level.
Discuss with pump man, shaker man, centrifuge engineer and mud
engineer to have a proper communication prior to transferring any drilling
fluid. Driller and mud logger must be informed prior to making any changes
in the mud pit level. Any changes in centrifuge parameters must be also
informed a driller and a mud logger.
A full opening safety valve and a closing handle with correction bottom
connections that fit with of drill string which is being used must be
available on the drill floor at all time. It must leave in an opened position.
Driller must check this equipment.
The driller must confirm a current space out diagram and ensure the
correct height.