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