Difference between True Vertical Depth (TVD) and Measured Depth (MD)

I have a question asked regarding what the differences between True Vertical Depth (TVD) and Measured Depth (MD). Today, I will describe both definitions and their importance for calculation in a drilling field.

True Vertical Depth (TVD) is measured vertically from the surface down to a certain target down hole.

Measured Depth (MD) is the total length of the wellbore measured along the actual well path.

See the following illustration for more understanding.

True Vertical Depth (TVD) is used for following calculations:

Hydrostatic Pressure Calculation

Hydrostatic Pressure (HP) Decrease When POOH

Formation Temperature Estimation

Drill pipe pulled to lose hydrostatic pressure 

Kill Weight Mud Calculation

Formation Pressure from Kick Analysis

Leak Off Test (LOT) Calculation 

Formation Integrity Test (FIT) Calculation

Equivalent Circulating Density (ECD) 

Surface Pressure During Drill Stem Test 

Measured Depth (MD) is used for following calculations:

Annular volume

Drill string and tubular volume 

Well control as stokes pump in the drill string and in the annulus, pressure schedule for wait and weight method well control.

Reference book: Drilling Formula BookFormulas and Calculations for Drilling, Production and Workover, Second Edition

Related Post

Pipe Line S-Lay Method S-lay method is the oldest and the most commonly used method for offshore pipeline installation. This is named as “S-lay” because the shape of the pip...
7 Ways to Strengthen a Wellbore Strengthen a wellbore while drilling is the most effective technique to do to the wellbore before bad losses will be happened. Techniques of wellbore-...
Fatality Drilling Rig Accident, Oilfield Worker wa... This is the oilfield incident resulting in our friend working on the rig got killed. It is very important that we need to heavily focus on the safety....
Top 10 Oil Companies Based On Oil/Gas Reserves We published the article regarding Top 10 International Oil Companies In The World and there are few people asking about what the big oil company base...
Share the joy
  • 7
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
    7
    Shares
Tagged , , , . Bookmark the permalink.

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.

2 Responses to Difference between True Vertical Depth (TVD) and Measured Depth (MD)

  1. Yousef Hasan says:

    Hi every one,
    what is the equation used to calculate TVD from MD??

    Any reference is highly appreciated

    Thanks in advance

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.