## Vibration Mechanisms In Drillstring by SperrySun

Vibration in drillstring is one of major downtime associated with drilling operation. Therefore, it is very important to learn and understand what each vibration mechanism is. This VDO created by Sperry Drilling Services well explains various of vibration modes that is happened downhole with the drillstring. You can watch the VDO here and we also provide full VDO transcription to help learns get more understanding about the content if the learners cannot catch all wordings from this VDO.

## Using Combined Load Chart For Stuck Pipe Situation

When the drill string get stuck, there are several ways to free the string as using Jar (up and/or down), straight pull, working torque down, etc. Pulling stuck pipe with torque in the drill string is one of those technique which often utilize to free the stuck drill string. However, there are some concerns that you should know before doing this because torque in the string will reduce a tensile capacity of tubular. This is very important to read and understand the combined load chart (Torque‐Tension Graph) in order to determine the limitation before pulling the pipe.

For this example, we use 5” DP, S-135, NC50 (4-1/2” IF connection) to be a reference figure.

Pipe information

• Pipe Size and Weight: 5.000″ 19.50ppf 0.362″ wall IEU
• Range: 2
• Tool Joint: 6.625″ X 3.250″ NC50
• Tool Joint 120,000 psi Material Yield Strength

## Basic of Drillpipe Tensile Capacity and Its Calculation

This article demonstrates basic knowledge understanding of tensile capacity of the drill pipe and some calculation. First of all we need to know basic of material strength and for our case is strength of metal.

There are few simple terminologies which we would like to explain.

## Stress (σ)

Stress (σ) equals to force divided by cross sectional area of the material (F/A). For our case, we will discuss about only stress in tensile because the drill pipe is almost always designed to work in a tensile condition.

### Stress (σ) = F/A

Figure 1 – Stress (σ) = F/A

## Drill String Components – VDO Training

This is a great VDO Training about drill  string components. We also added the detailed transcripts so you can learn from the VDO effectively.

Please give us comments if you think this is useful for you.

Transcription of Drill String Components

There are many components that make up the drill string as shown in this graphic. Drill pipe is a strong but relatively lightweight pipe. Crew members attach it to a top drive or Kelly. Drill pipe forms the upper part of the drill string. Usually the drill pipe rotates which also rotates the bit. Each section of pipe is called a joint. Crew members screw together or make up several joints and put them in to the hole as the bit drills.

## Why Does Drillstring Fail? Basic Understanding of Drill String Failure

In drilling industry, it is common that drill string will fail while drilling. Two main factors causing drillstring failure are stresses and corrosion.

### Stress Affects on Drillstring

Drillstring is exposed to the following stresses:

Tension – Suspended weight of drillstring sometimes can be several thousand pounds. Additionally, overpull weight while pulling out can be over drill string limit resulting failure (see Figure 1).

Figure 1 – Drillstring in Tensile