Well Killing Methods (Driller's Method)

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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