Mud Weight and Its Importance in Drilling

Mud weight or mud density is a weight of mud per unit volume. It is one of the most important drilling fluid properties because it controls formation pressure and it also helps wellbore stability. Mud weight is measured and reported in pounds per gallon (PPG), pounds per cubic feet (lb/ft3), or grams per milliliter (b/ml).
Mud weight is normally measured by a conventional mud balance; however, if you have some air inside a fluid phase, reading from the conventional mud balance will give you an inaccurate number. Therefore, the most accurate method to measure the mud weight is with a pressurized mud balance.

conventional mud balance

Conventional Mud Balance

Pressurized Mud Balance

Pressurized Mud Balance

The pressurized mud balance looks like the convention one, but it has a pressurized sample cup. When you press a mud sample into the cup, any gas in a fluid phase is compressed to a very small volume so the mud weight measurement is more accurate. Continue reading

Increase In Mud Weight Due To Cutting

Cutting generated while drilling will increase drilling fluid density and it will finally affect equivalent circulating density while drilling. In this topic, we will talk about how to determine mud weight increase due to cutting.

 Figure 1 - Cutting Increases Mud Density

Figure 1 – Cutting Increases Mud Density


Effective mud density due to cuttings in the hole can be determined by the empirical equation below;

euqation pm

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