Well Killing Methods (Driller's Method)
Well control is an essential aspect of drilling, minimizing the risk of uncontrolled flow of formation fluids. One of the most common well-killing techniques, the Driller's Method, requires circulating kill-weight mud on two separate occasions to displace the influx and do it safely. This can effectively keep a well under control while maintaining little pressure fluctuations and thus a decreased risk of blowouts.
This article explains the Driller’s
Method in detail, specifying its working steps, advantages, and crucial aspects
for successful well control techniques, kill mud density calculation, drilling
safety procedures, oil and gas well killing methods.
Driller’s Method – Brief Overview
Driller's Method: It uses a minimum
of two circulation cycles:
Primary cycle: The goal is to flow
the influx to the annulus using the original drilling fluid.
2nd Cycle — Pump kill-weight mud
down the wellbore to replace the original drilling mud. The kill mud of equal
density to the formation pressure.
This essentially provides this
method the major advantage of being able to kick the influx before the
kill-weight mud is introduced, thereby reducing the chances of massive pressure
development.
1. Driller’s Method: Stepwise Procedure
The Driller’s Method is a systematic
procedure to ensure safe well killing operations are performed. Here is how it
executes step by step:
Step 1: Shut-In and First
Calculations
In case of detection of an overflow
(kick), the well should be shut-in, according to the proper well control
procedures, at the earliest opportunity.
Log the following parameters:
Operation of Shut-In Drill Pipe
Pressure (SIDPP)
SICP (Shut-In Casing Pressure)
Pit gain or loss
Formation pressure based kill mud density
calculation
Use the recorded data to complete
the well kill sheet.
Step 2: First Cycle — out goes the
flow
Linearly return the pump to the well
kill rate;
Close choke valve to keep casing pressure
at SICP.
This will raise the standpipe
pressure to the original circulating pressure.
This is to ensure the standpipe
pressure constant.
Circulate until the influx and the
entire amount of contaminated drilling fluid are out of the annulus.
Halt the pump and seal the well. The
casing pressure accounts for the wellbore annulus volume plus the friction
along the pipe per the above relation and this should be equal to standpipe
pressure at this stage as indicated.
Step 3: Second Circulation Cycle -
Pump kill mud
Gradually restart pump and position
the choke valve to maintain steady casing pressure equal to SIDPP.
Maintain casing pressure as you ramp
the pump rate to the kill rate.
Therefore standpipe pressure at this
stage will be equal to ICP.
Circulate kill mud down to the bit
while keeping casing pressure constant.
When kill mud is at the bottom of
the work string, the stand pipe pressure should decrease from ICP to FCP (Final
Circulating Pressure).
Adjust choke valve to maintain
standpipe at FCP while kill mud circulates to surface.
2. Execution of the Well Killing Operation
After the pressures on both
standpipe and casing are at zero, shut pump.
Release the BOP and reinstate normal
circulation.
The well is now successfully
plugged.
Handling Pressure Anomalies
Stop the pump & if the stand
pipe & casing pressures are not zero, since you are also doing the kill mud
density calculation, do a second well kill.
Ensuring full well control and
eliminating the risk of a further influx.
Benefits of the Drillers Method
No Influx Removal Prior To Adding
Kill Mud
Minimizes risk of over pressure
spikes.
Constant Pressure Maintenance
—Ensures the integrity of
formations by avoiding fractures.
Improved Control of the Well
Pressure
Gradual circulation and safe killing
of the well.
Most Drilling Works Applicable
Regardless of mud density and well
conditions.
Minimizes Kick Intensity
Minimizes risk of damage to downhole
formations and equipment.
What You Need to Know for
Successfully Killing Wells
Kill mud density calculation offers
the ability to maintain pressure equilibrium.
Sets the choke properly to avoid
getting too high on the pressure spikes.
Control Portfolio Pressure (SIDPP, SICP,
ICP, and FCP)
Having trained personnel perform
procedures allows for smooth and proper operation of safe systems.
Regular well control drills improve response
time for unexpected kicks.
Conclusion
The Driller's Method is an
established and efficient technique for killing wells in oil and gas drilling
operations. It enables the safe circulation of the influx out of the well and
the replacement of the drilling fluid with kill-weight mud while maintaining
well control. Implementing the structured step process and continuous pressure
control risk & well control incidents are reduced with this method.
For drilling engineers, fields
related to drilling supervision and operations, it is of utmost importance to
get the Driller method accurately understood and applied at any point in time
to ensure safety and functioning. With accurate calculations, effective well
control equipment, and adherence to best practices, drilling teams can approach
well control scenarios with certainty.
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information regarding Oilfield drilling safety procedures, well control, and
advanced petroleum engineering techniques!
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