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;
We can rearrange the Euqation#1 in order to determine the solid density
Coring is a special process to recover wellbore rock in the well.
Figure 1 – Core from the well. Credit – Wikipedia
This article will demonstrate how to calculate coring cost per footage recovered.
Coring cost per footage recovered is expressed below;
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
The following formula is used to calculate cutting volume generated while drilling;
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;
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;
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.
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.