Category Archives: Drilling Engineering Calculations

How Much Force Applied to a Rig Tong To Get The Right Torque at The Connection

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One application of the rig tong is to use to make up connection. The question is asked about how to get the right torque value to the connection if you use the rig tong because you will not see the torque value on the gauge. This article will describe how to determine the correct force applied to get the correct torque value when you use the rig tong to make up the connection.

 

This formula below is used to determine force at required make up torque value.

rig-tong

Oilfield Unit

Force = Torque ÷ Length of the tong

Where;

Torque in ft-lb

Force in lb

Length of the tong in ft

Force is perpendicular to the tong length.

The illustration above demonstrates the direction of force.

Metric Unit

Force = Torque ÷ Length of the tong

Where;

Torque in N-m

Force in N 

Length of the tong in m

Force is perpendicular to the tong length.

Example:

Connection 4-1/2” IF – required make up torque = 30,700 ft-lb.

Tong length is 4 ft

rig-tong-example

How much pulling force do you require to achieve the required make up torque?

Force = Torque ÷ Length of the tong

Force = 30,700 ÷ 4.0

Force = 7,675 lb

Answer: 7,675 lb pulling force is applied to 4-ft tong in order to get the torque at connection at 30,700 ft-lb.

You can download the spreadsheet from the  download link.

Ref books: 

Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.

Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.

Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.

Rig Derrick Load Calculation

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The drilling line is reeved over a set of crow block and down to another set of sheaves known as travelling block. The hook connected to travelling block is used to suspend the drilling load. One end of drilling line is wound onto the drawworks and this line is called “Fast Line”. Other end of the drilling line is tied into an anchor point on the rig floor and this line is named as “Dead Line”. The drilling line is reeved around the blocks several times in order to meet required load.

derrick Load Calculation 1

According to the diagram above, we can use basic physic to determine derrick load.

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Drillstring Elongation Due To a Tensile Load

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When a tensile load is applied into a drillstring, it results in elongation of the drillstring.

Drillstring elongation due to tensile load 1

The formula to determine pipe elongation is listed below;

Oilfield unit

e = (L x T) ÷ (735,000 x W)

Where;

e = elongation, inch

L = length of drill string, ft

T = tensile load, lb

W = drill string weight, lb/ft

Metric (SI) unit

e = (L x T) ÷ (26.7 x W)

Where;

e = elongation, mm

L = length of drill string, metres

T = tensile load, kN

W = drill string weight, kg/m

Note: The equations are taken from API RP 7G 16th Edition, August 1998.

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Directional Drilling Handout from Texas AM

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I would like to share very useful Power Point slide in the topic of directional drilling which is belong to Texas A&M university, USA.

Directional Drilling –

When is it used?

Type I Wells (build and hold)

Type II Wells (build, hold and drop)

Type III Wells (build)

Directional Well Planning & Design

Survey Calculation Methods

Download here => 

Survey Calculation Methods –

Radius of Curvature

Balanced Tangential

Minimum Curvature

Kicking Off from Vertical

Controlling Hole Angle (Inclination)

Download here=> 

Directional Drilling  Continued

 Tool-Face Angle

Ouija Board

Dogleg Severity

Reverse Torque of Mud Motor

Download here=>

The Wellbore Trajectory Control –

Bent Motor and Bent Sub

Examples

Directional Drilling Measurements

Single Shot and Multishot

Magnetic and Gyro

Steering Tools

MWD tools

Download here=>

Pressure Drop Across a Bit

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Pressure across a bit occurs when the drilling mud passing through the jet nozzles. This pressure drop is important for drilling hydraulic optimization (maximum hydraulic horse power or impact force) and hole cleaning. The pressure drop at the nozzle area is a function of total flow area of the bit, flow rate and mud density.

Pressure drop across the bit can be determined by the following equation:

Oilfield Unit

Pb = (Q²×W) ÷ (12031 × A²)

 

Where:

Pb = pressure drop across a bit, psi

Q = flow rate, gpm

W = mud weight, ppg

A = total flow area, square inch

Please use the following information to determine pressure drop across a bit

Flow rate = 800 gpm

Mud weight = 9.0 ppg

Total Flow Area = 0.3728 square inch

Pb = (800²×9.0) ÷ (12031 × 0.3728²)

Pb = 3,446 psi

Metric Unit

Pb = (Q²×W) ÷ (7.191 × A²)

Where:

Pb = pressure drop across a bit, KPa

Q = flow rate, lpm

W = mud weight, kg/m³

A = total flow area, mm²

Please use the following information to determine pressure drop across a bit

Flow rate = 3,000 l/m

Mud weight = 1,100 kg/m³

Total Flow Area = 240 mm²

Pb = (3,000²×1,100) ÷ (7.191 × 240²)

Pb = 23,901  KPa

The new version of spreadsheet can be downloaded by clicking the image below. 

Ref books: 

Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.

Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.

Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.