Category Archives: Applied Drilling Calculations

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].

Do you have too much slug in the well?

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Slug is heavy drilling mud that is used to pump when you want to pull pipe dry. However, excessive volume of slug in the well can create higher mud weight and cause the problem. Today I would like to share my experience regarding slug in the well.

The situation happened on the drilling rig like this.

The well was TD with 13.0 ppg mud and circulation was conducted until the shale shakers. After that we pull 10 stands wet and pumped 40 bbl of 15.0 ppg slug and came out of hole without any problem. Then we run the logging and we got stuck. We picked the fishing gear and grabbed the fish. We pulled out 10 stands wet and hole was taking proper fill. We pumped same amount of slug 40 bbl of 15.0 ppg and came out of hole. The decision was made by town to trip in hole to do the wiper trip.

Tripping was done with caution and break circulation was conducted every 3000 ft to break the gel. Prior to TD 100 ft, we made up top drive and slowly washed down to TD. While we were circulating, the mud weight out was varied from 13.2 ppg to 14.2 ppg. Additionally, we start losing mud while circulating.

Do you know what went wrong?

The two slugs in the well cause us trouble.

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Total Bit Revolution in When Running A Drilling Mud Motor and Rotating At Surface

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I’ve got an email asking me about how to figure out the total bit revolution (RPM) at down hole when the mud motor is used in the drill string  and the rotating at surface is also conducted.

There are two components contributing in the total revolution of downhole drilling bit using mud motor.

1. The rotor RPM of drilling mud motor– each drilling mud motor has its specific performance data which will tell you how many revolutions per flow rate flowing through it.

For example (see the image below), it shows Rev/Gal which means the rotor will turn 0.147 turn/min per one gallon/min of drilling mud passing thought.

2. The rotary speed from top drive or rotary table.

The total drilling bit revolution downhole:

The total drilling bit revolution is equal to summation of the rotor RPM at specific flow rate and the rotary speed on surface.

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How To Determine Hole Size By Fluid Caliper

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This article will demonstrate you how to determine hole size by fluid caliper. First of all, you need to know what is the fluid caliper is. The fluid caliper is one simple way to calculate hole diameter. The concept is based on hole volume, annular capacity, and inner capacity. You pump any substance and when you seen it on surface, you back calculate the hole size based on strokes pumped. It is quite tricky to explain so I would like you to see the example below which it will make you clear about what I say.

116 How To Determine Hole Size Based On Carbide

Assumption for the calculation: No losses

 

7” casing shoe is set at 5000’MD/4500’TVD

7” casing 23 ppf, ID 6.33 inch

4” drill pipe is used to drill the well and its ID is 3.34 inch.

4-3/4” drill collar is used as BHA and its ID is 2.5 inch. The length of drill collar is 500 ft.

This hole section is used water based mud and the bit size is 6-1/8”

Drill to section TD at 10,000’MD/9,000’TVD then drop carbide once TD is reached.

Pump output is 0.1 bbl/stroke.

Surface line from pumps to rig floor is 20 bbl.

Carbide is detected by a gas sensor on surface after 4,000 strokes pump.

With the given information, determine what is the hole size of the open hole section.

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Cutting Carrying Index – Simple Tool To Determine Hole Cleaning

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To get the good idea on how good of the hole cleaning is, the another method called Cutting Carrying Index (CCI) is utilized. The CCI is an empirical relationship from real data and the equation is below:

CCI = (K × AV × MW )÷(400,000) — Equation 1

Where;

AV is annular velocity in ft/min.

MW is mud weight in ppg.

K is a Power Law Constant.

The Power Law constant (K) can be calculated from the equation below:

Where;

PV is plastic viscosity in centipoises.

YP is yield point in lb/100sqft

n is flow behavior index.

The flow behavior index (n) can be determined by the following equation:

Where;

PV is plastic viscosity in centipoises.

YP is yield point in lb/100sqft

How will the CCI tell you about hole cleaning?

If CCI is equal to 0.5 or less, the hole cleaning is poor and the hole problem may be seen.

If CCI is equal to 1.0 or greater, it indicates that the hole cleaning is good.

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