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Services >Mud Logging
Services >Drilling Realtime Monitoring Services |
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Drilling
Realtime Monitoring Services |
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During
drilling, it is very important to record drilling and circulating
parameters for drilling safety. Engineers can analyze
all kinds of drilling statuses through these data. The
detailed specifications of some important parameters
are as follows:
-
The Mud Pit Level Monitors:
The pit level sensors are installed in or at all
mud pits in order to monitor their volume and
the change of volume.
-
Mud Flow In/Out: This sensor
is a kind of back-up for the mud pit sensors.
An increase in mud flow indicates a kick, a decrease
in mud flow (out) may indicate lost circulation.
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-
Mud Resistivity: The resistivity
of the drilling mud can be measured in the mud pits
or ¨C better - at the shaker feeder tank (possum
belly). It can be displayed as resistivity (units
ohm.m) or its inverse, conductivity (unit mmho/cm).
A change in mud resistivity indicates that the mud
is mixed with other matter. It may also be that
a different type of shale is drilled and incorporated
into the mud system or the conductivity of the mud
has changed due to mud additives such as KCl. It
may also indicate that water is entering the bore
hole and mixing with the mud.
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- Mud Temperature: The temperature of the mud flow
into, and out of the hole is monitored. The temperature
increases with drilling time or due to the circulation as
the increasingly warmer mud of the active system is recycled
into the wellbore. If water is added to the mud system,
for example to dilute the mud, the differential temperature
will behave erraticly tending towards lower temperatures.
- Mud Density: A change in mud density, in particular
a decrease of mud density indicates that the mud is
diluted. This may be at the surface when the drilling
people reduce the mud weight for one reason or another.
A more severe situation is given when the
mud is diluted with formation waters. This means also
that the formation pressure exceeds the hydrostatic
pressure of the mud column; in other words, the
well is not in balance. This is an alarm situation
that must be reported immediately to the company man.
- The Pump Stroke Counters: This is a mechanical switch
type sensor on every mud pump (that is one sensor
per pump, typically three mud pumps on the rig).
- Hook Load Sensor: The hook load gives a value for
the load on the drilling draw works. The units are
kilo-pounds (kips) or tons in a metric environment.
-
Kelly Height Indicator (ROP
System): The kelly height indicator is a simple device
that indicates how high the kelly is above the rotary
table. Two methods are used: 1) The mechanical (steel)
line connected to a wheel and sensor and 2) the
hydrostatic method using the principle of connected
U-shaped pipes. When drilling, i.e. when making
progress, the kelly is increasingly lowered to compensate
for the progress of the new hole. The drilling progress or
rate of penetration (ROP) is calculated either in
feet per hour or minutes per meter.
-
Rotary Table Speed (RPM):
Displays the rotary speed of the rotary table.
Again, check and compare with the driller's
display on the rig floor. The RPM is of secondary
importance for geological purposes. On computerized
logging units it is used to calculate the Dx
exponent10, number of revolutions over the bit
life and other drilling parameters.
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- Standpipe Pressure: The standpipe pressure is of
high interest to the driller but relatively unimportant
for the geologist. 1) A change of standpipe pressure
can indicate washouts in the drill pipe, plugged bit
nozzles, condition of the downhole motor (if used),
etc. The standpipe pressure is recorded continuously
on strip chart and - on modern logging units - on
computer. This parameter is used to calculate several
hydraulic parameters used to optimize drilling. There
is little relevance in the standpipe pressure for
the geological interpretation. 2) When coring or when
drilling with a downhole motor or turbine, the standpipe
pressure gives an indication as to whether the downhole gear
is performing properly. 3) Compare the read-out in
the mud logging unit with the gauge on the rig floor.
Accuracy should be better than 5% and precision should
allow the detection of pressure changes ¡À25 psi.
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