How are pressure and pit volume doing during the first circulation of the driller’s method?

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.

Let take a look at the equation

Bottom hole pressure constant = Casing Pressure (increase to compensate for loss hydrostatic pressure) + Hydrostatic Pressure (decrease due to gas expansion).

When the gas in the mud starts coming out on surface, the casing pressure will continually decrease. If the gas kick in the annulus is totally out of hole, casing pressure should be equal to Shut-In Drillpipe Pressure (SIDPP). Casing pressure sometimes may be slightly more than SIDPP due to safety factor that you add while circulating. In addition, pit volume will increase until gas reaches surface due to gas expansion. When gas reaches surface, the pit volume will start to decrease.

The plot below demonstrates pressure profile of both casing pressure and tubing pressure during 1st circulation of driller’s method.

 

first circulation profile driller method

Note: you need to understand that this article is based on the following assumptions;

• Water base mud

• Well bore influx (kick) = gas

Reference book: Well Control Books

Related Post

Surge Pressure, Swab Pressure and Trip Margin You may have heard about Surge Pressure, Swab Pressure and Trip margin in the drilling business. Today, I would like to share my knowledge about these...
Driller’s Method or Wait and Weight Method – What ... Driller’s method and wait and weight method (engineer’s method) are widely used to circulate wellbore influx while maintaining bottom hole pressure co...
Useful Well Control Handouts from Texas A&M U... Petroleum engineering department at Texas A&M University has a strong technical in every aspect of oilfield. This is the one of top petroleum ...
Gas Behavior with Constant Bottom Hole Pressure You have learned from 2 previous topics, gas behavior in shut in well and gas behavior with constant surface pressure. Both ways are not how you contr...
Share the joy
  • 3
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
    3
    Shares
Tagged , . Bookmark the permalink.

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.

2 Responses to How are pressure and pit volume doing during the first circulation of the driller’s method?

  1. Man says:

    Hi Rachain J.

    Hopefully you are doing great now.

    Could u help me with these two questions:

    1. What is flow check? How it is executed?

    2. I know the mud circulation system during drilling. But i am not sure about the circulation system during tripping ie the trip tank is connected to what etc? Appreciate if you give some comments on it.

    Regards

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.