Category Archives: Applied Drilling Calculations

How to Select a Scientific Calculator for Oilfield Personnel

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Working in the oilfield, you need a scientific calculator to help you solve problems with complex formulas. As you learn from this website, drillingformulas.com, you really need a scientific calculator to help you.

How-to-Select-a-Scientific-Calculator-for-Oilfield-Personnel

There are different brand companies that design scientific calculators. However, the difference in brand names might not alter the similarity in functions and programming. When you are choosing a small scientific calculator, there are a number of factors that you should consider. These factors include; functionality and efficiency, portability and durability.

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Cement Transition Period in The Oil Well Can Cause Well Control Situation

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When cement is in transition period (forming the bond), you will lose some hydrostatic pressure because cement becomes solid phase, therefore only water in the cement will provide hydrostatic pressure. In many cases happened, there is no issue while performing the cement job, however; once the cement is set after period of time, there is a casing pressure indicating that there is hydrocarbon in the annulus.

This example will demonstrate you why the well is in underbalance condition while waiting on cement.

Well information: Previous 9-5/8” casing shoe at 4000’ ft.

The vertical well (8.5” hole) is drilled to TD at 10,000ft with 12.1 ppg mud and the pay zone is at 9,800’ TVD with reservoir pressure of 11.6 ppg. The cement is planned to cover 3,500 ft in the annulus above the casing shoe. Water used to mix cement is 8.3 ppg weight.

 cement Transition Period

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Equivalent Circulating Density (ECD) Using Yield Point for MW More than 13 ppg

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Another equation to determine equivalent circulating density is to use yield point.

This formula below is used to calculate the ECD and it is good for mud weight more than to 13.0 ppg

Where:

ECD is equivalent circulating density in ppg.

MW is mud weight in ppg.

Hold ID is inside diameter of hole in inch.

Pipe OD is outside diameter of pipe in inch.

YP is mud yield point.

YP can be calculated by these following equations.

YP = Reading at 300 rpm – PV

PV = Reading at 600 rpm – Reading at 300 rpm

AV is annular velocity in ft/min

AV can be determined by the following equation.

AV in ft/min = (24.5 x Q) ÷ (Dh2 – Dp2)

where

Q = flow rate in gpm

Dh = inside diameter of casing or hole size in inch

Dp = outside diameter of drill pipe, drill collars, or tubing in inch

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Equivalent Circulating Density (ECD) Using Yield Point for MW less than 13 ppg

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Another way to determine equivalent circulating density (ECD) is to use yield point.

This formula below is used to calculate the ECD and it is good for mud weight less than or equal to 13.0 ppg.

Where:

ECD is equivalent circulating density in ppg

MW is mud weight in ppg

Hold ID is inside diameter of hole in inch

Pipe OD is outside diameter of pipe in inch

YP is mud yield point

YP can be calculated by these following equations

YP = Reading at 300 rpm – PV

PV = Reading at 600 rpm – Reading at 300 rpm

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Useful Kill Sheets from IWCF (International Well Control Forum)

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IWCF  (International Well Control Forum) is the world class organization in well control which many people know about. A lot of people working on the rig are required to have well control certificates and IWCF certificates are accepted world wide.

iwcf-kill-sheet

 

IWCF also shares excellent kill sheets used for well control situation to everybody. There are both surface and sub sea BOP version. Additionally, IWCF provides the files in several units. There are a total of 16 kill sheets  and please download the IWCF well control kill sheet from the following links:

Surface BOP Stack Version

Surface BOP Stack (http://pirtekasia.com, 2017)

Surface BOP Stack Operations API – Deviated Well Kill Sheet

Surface BOP Stack Operations API – Vertical Well Kill Sheet

Surface BOP Stack Operations BL 0.0981- Deviated Well Kill Sheet

Surface BOP Stack Operations BL 0.0981- Vertical Well Kill Sheet

Surface BOP Stack Operations BL 10.2- Deviated Well Kill Sheet

Surface BOP Stack Operations BL 10.2- Vertical Well Kill Sheet

Surface BOP Stack Operations SI – Deviated Well Kill Sheet

Surface BOP Stack Operations SI – Vertical Well Kill Sheet

IWCF Kill Sheet for Surface Stack (XLS)

Subsea BOP Stack Version

Subsea BOP Stack Operations API – Deviated Well Kill Sheet

Subsea BOP Stack Operations API – Vertical Well Kill Sheet

Subsea BOP Stack Operations BL 0.0981- Deviated Well Kill Sheet

Subsea BOP Stack Operations BL 0.0981- Vertical Well Kill Sheet

Subsea BOP Stack Operations BL 10.2- Deviated Well Kill Sheet

Subsea BOP Stack Operations BL 10.2- Vertical Well Kill Sheet

Subsea BOP Stack Operations SI – Vertical Well Kill Sheet

Subsea BOP Stack Operations SI- Deviated Well Kill Sheet

If you think this is useful for your friends/colleagues, please feel free to share 🙂

References 

Pirtekasia.com. (2018). Off-Shore Equipment Service. [online] Available at: http://pirtekasia.com/services-old/off-shore-equipment-service/ [Accessed 22 Apr. 2018].

IWCF Well Control Exam Downloads (2018) | Study Materials | IWCF. [online] Iwcf.org. Available at: http://www.iwcf.org/training-qualifications/useful-downloads [Accessed 22 Apr. 2018].