Pressure Profile of Drillpipe and Casing Pressure while killing a well with wait and weight method

This topic will cover about pressure profile both drill pipe and casing pressure while kill a well with wait and weight method.


Drill Pipe Pressure

Firstly, we will take a look at the drillpipe pressure. When kill weight mud is displaced in the well, drill pipe pressure drops as per the drill pipe schedule. Once kill weight mud is to the bit, drill pipe pressure is maintained until the well is killed. A pressure profile will look like the following chart.

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Drill Pipe Pressure Schedule Calculation for Wait and Weight Well Control Method

This example demonstrates how to determine drill pipe pressure schedule for wait and weight method.


Well Information

Current mud weight = 9.5 ppg

Pump output = 0.1 bbl/stroke

Well depth = 9000’MD/9000’TVD

Drill string capacity = 0.0178 bbl/ft

Surface line volume = 15 bbl.

Shut in casing pressure = 700 psi

Shut in drill pipe pressure = 500 psi

ICP = 1600 psi at 30 spm as kill rate

Please follow steps below to determine the drill pipe pressure schedule (step down chart).

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Formulas for Wait and Weight Well Control Method

There are some well control formulas that you need to know for wait and weight method.


1. Kill Weight Mud

KWM = OMW + [SIDPP ÷ (0.052 x TVD)]


KWM is kill weight mud in ppg.

OMW is original mud weight in ppg.

SIDPP is shut in drill pipe pressure in psi.

TVD is true vertical depth of the well in ft.

Note: Read more about it>> Kill Weight Mud

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Wait and Weight Well Control Method (Engineer’s Method)

I will give you overview about the wait and weight method on this blog post and some basic concepts and calculations will be described later.

Wait and Weight Well Control Method or someone calls Engineer’s Method is a method to control well with one circulation. Kill weight mud is displaced into drill string and kick (wellbore influx) is removed while displacing a wellbore.

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