Solid Density From Retort Analysis Mud Calculation

Retort analysis is the method to determine solid and liquid components in the drilling fluid. In this article, we will adapt mass balance and retort analysis data to determine solid density in the mud.


Mass balance for mud is listed below;

equation 1

We can rearrange the Euqation#1 in order to determine the solid density


equation 2

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Volume of Cutting Generated While Drilling

While drilling, cuttings are generated every footage drilled and this topic will demonstrate how to determine volume of cutting entering into the wellbore.

Figure 1 - Cutting Generated While Drilling

Figure 1 – Cutting Generated While Drilling

 The following formula is used to calculate cutting volume generated while drilling;

vc - bbl per hour


Vc is volume of cutting in bbl/hr.

Ø is formation porosity (%).

D is wellbore diameter in inch.

ROP is rate of penetration in feet per hour.

Vc can be presented in several unit as follows;

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Buoyancy Factor with Two Different Fluid Weights in The Well

Buoyancy Factor is the factor that is used to compensate loss of weight due to immersion in drilling fluid and you can find more information from this article > buoyancy factor calculation .  In that article, it demonstrates the buoyancy formula only for one fluid in the wellbore. However, this time, we will have the details about buoyancy factor when inside and outside fluid are different.

Buoyancy factor with different fluid inside and outside of tubular is listed below;

equation 1


Ao is an external area of the component.

Ai is an internal area of the component.

ρo is fluid density in the annulus at the component depth in the wellbore.

ρi is fluid density in the component depth in the wellbore.

ρs is steel weight density. Steel density is 65.4 ppg.

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How does the 0.052 constant come from?

In the hydro-static pressure formula, if you use an oil field unit, you must see the hydro-static formula like this

Pressure, psi = 0.052 x Mud Weight (ppg) x TVD (ft)

I got the question asking about how the constant 0.052 is figured out.

What is 0.052?

0.052 is a constant used for converting ppg-ft into pound per square inch (lb/in2)

Do you know how it comes from? Let’s get started

First of all, the unit conversions that you need to know are as follows:

1 gallon = 231 cubic inch (inch3)

1 ft = 12 inch

Convert density from ppg (pound per gallon) to lb per cubic inch

Basic hydrostatic pressure

The constant can be determined by substituting the unit conversion.

The constant is 0.051948 and if we round it up, it will be 0.052.