Technology associated with hole volume calculations in petroleum well drilling

Hello friends and technology lovers and all those who make life in steemit.

In this opportunity I want to share with all of you how the technology is related to the various forms in the calculation of volumes of an oil well while drilling.

The pipes used in the drilling of a well are diverse in relation to the material with which they are constructed so that they can withstand all the efforts, friction and temperature at the bottom of the hole, which is why the technology is constantly evolving developing drill pipes of different diameters and can have a technology that provides strength and durability in the work of drilling.

This technological evolution has an impact on the way in which the volumes are calculated at the bottom of the hole, because the larger the diameter with which the pipes are built, the more space they occupy in the well, and therefore the space where the drilling fluid has to circulate ends up being a very small space, so the volume calculations for the annular space have to be constantly calculating and evaluating, thanks to engineering and science we have all the equations involved in the calculation of such volumes, which is the main objective of this post.

What happens if the well is cased and cemented?

As it is well known, an oil well must be cased to cover the walls of the hole with cement and thus meet certain requirements or functions of the construction of the hole, once the well is cased and at the same time the drill pipe is inside the hole, there will be an annular space between the drill pipe and the internal walls of the casing, logically this space will have a much smaller volumetric capacity than the one between the walls of the hole and the drill pipe, due to the space occupied by the casing and the cement that supports them.

Why talk about volumetric capacity in the drilled hole?

We can conceptualize the volumetric capacity of the hole as that capacity to hold a volume of fluid for each foot of depth, which means that if for example the volume is measured in barrels (bls), the volumetric capacity will be measured in barrels/ft (bls/ft).

The volume that the well will occupy will depend on its geometry, logically we could talk about a cylinder, however this geometry is not perfect, since the hole is not built with a perfect geometry, the other thing to consider is that the space where the drilling fluid will circulate is a space shared by multiple spaces, where there may be a section of the hole without drill pipe, there may be a section of the hole with pipe inside the hole and a bare hole (without casing), there may be a section of pipe without drill pipe but where the diameter to be considered is not the diameter of the hole but the internal diameter of the casing, there may be another space between the drill pipe and the internal walls of the drill pipe.

Example of calculation of volumetric capacity between the walls of the hole and the drill pipe
Suppose an oil well is being drilled to a depth of 8500 feet, you have 7000 feet of 5 inch outside diameter drill pipe, the diameter of the hole is 12-1/4 inches.

Calculate the total volume in barrels of drilling fluid that can circulate in the well.

The first important thing is to divide the hole geometry into two sections:

There is a section of the hole from the surface to the depth of 7000 feet where the drill pipe is submerged, so this is going to be a very different volume than the rest of the 1500 feet more depth that exists to reach the total 8500 feet of the well, this is a space called annular space between pipe -hole and we can calculate it with the following equation:

Volumetric capacity of the annulus (space: drill pipe - hole) (Bls/pie):

Volumetric capacity of the annulus (space: drill pipe - hole) (Bls/pie):

Volumetric capacity of the annulus (space: drill pipe - hole) (Bls/pie):

To calculate the volume of this part of the well that can be occupied by drilling fluid, we must multiply the volumetric capacity of 0.14577 barrels/foot by 1500 feet, which is the depth between 7000 feet and 8500 feet, which is the section where there is no drill pipe, therefore it is calculated as follows:

Volume (barrels): Volumetric capacity x depth

Volume (barrels):

Volume (hole spacing - drill pipe) (barrels): 850,43 barrels.

The other section of the well in which we must calculate a second volumetric capacity is the section of the hole where there is no drill pipe, which is calculated as follows:

Annular capacity (hole):

Annular capacity (hole):

Annular capacity (hole):

To calculate the volume of this part of the well that can be occupied by drilling fluid, we must multiply the volumetric capacity of 0.14577 barrels/foot by 1500 feet, which is the depth between 7000 feet and 8500 feet, which is the section where there is no drill pipe, therefore it is calculated as follows:

Hole volume (bls):

Hole volume (bls): 218,66 Bls.

Conclusion

The total volume of drilling fluid that will fit in the well is 850.43 barrels + 218.66 barrels, for a total of 1069.09 barrels.

If the objective is to be able to know what volume of drilling fluid must be prepared to cover the 8500 feet deep section of the well, to those 1069.09 barrels must be added the internal volume of the drill pipe plus the volume of the hoses and accessories through which the drilling fluid will circulate including the active tanks and mud pumps, however, being able to calculate the volume of the well helps us to have a fairly estimated calculation of the volume that we will need to prepare, of course taking into account the importance of the calculations of volumetric capacities within the various existing spaces in the hole.

The volume calculations allow us to adjust the amount of drilling fluid volumes that fit in the well using the latest technological tools regarding drill pipes and other essential tools.

Bibliography consulted and recommended

• Well Control Manual. Well Control School (WCS). Harvey Louisiana. Year 2003.

Spanish version of: Volumetric capacity in the drilling of an oil well.

Note: All equations used in this post were developed by the author using Microsoft Word equation insertion and design tools.