Before starting 1st circulation of driller’s method, you have this following information
Original Shut in Drill Pipe Pressure = 500 psi
Shut in casing pressure = 800 psi
After complete the 1st circulation, you shut down pumps and you see the drill pipe pressure and the casing pressure as this figure below
What do you think about this well?
Let’s take another quiz regarding driller’s method.
Before start the first circulating, you have the following information
Original Shut in Drill Pipe Pressure = 500 psi
Initial Circulating Pressure (ICP) = 1500 psi
After end of 1st circulation of Driller’s Method, the drillpipe pressure gauge and the casing pressure gauge shows that the circulating drill pipe pressure = 1500 psi and casing pressure = 500 psi (see the figure below).
What do you think about this well?
In order to get more understanding about driller’s method, there are some quizzes that will help you get clear picture of it.
1st example –
Before start circulating, you have the following information
Original Shut in Drill Pipe Pressure = 500 psi
Initial Circulating Pressure (ICP) = 1500 psi
After end of 1st circulation of Driller’s Method, the drillpipe pressure gauge and the casing pressure gauge shows that the circulating drill pipe pressure = 1500 psi and casing pressure = 650 psi (see the figure below).
Do you think what is happening with the well?
When we perform the first circulation of driller’s method, the casing pressure will increase due to gas expansion and the maximum casing pressure will be observed when the gas influx reaches surface.
When gas is moved upward during circulation, the gas will expand due to pressure decrease (refer to Boyle’s gas law P1V1 = P2V2). The higher gas is moved up inside annulus, the higher expansion will be. Therefore, the system hydrostatic pressure will be decreased. For this reason, the casing pressure will increase in order to maintain constant bottom hole pressure.
The mud pumps can be shut down after the total volume of the well has been displaced with kill mud. Practically, you need to check mud weight out several times to ensure that the mud weight out equates to the kill weight mud. Otherwise you may have misinterpretation once the well is shut in and flow checked.
Once shutting down the mud pumps, the choke should be gradually closed in order to hold casing pressure constant. The drill pipe pressure will be slowly dropped to zero as the pump speed is reduced. Please always remember every time that you either bring the pumps up to speed or slow down pump speed, you must hold casing pressure constant.
