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

Example of Real Gas Calculation This example will demonstrate how to calculate the compressibility of real gas in order to determine gas density and specific gravity at a specific co...
Increase Mud Weight by Adding Hematite You have learn how to weight up with Barite andCalcium Carbonate from previous posts. Sometimes, you may need to weight up to extremely high weight th...
Mobile Formation Causes Stuck Pipe Mobile formation is caused by overburdened pressure that squeezes shale and/or salt into a wellbore. The squeezed formations reduce wellbore diameter;...
What are gas show, connection gas and trip gas? You may have heard about gas show, connection gas and trip gas. What are differences of those term? Gas show: It is gas that appears in drilling ...
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.