Rig Derrick Load Calculation

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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Pipe Light Calculation

Pipe light (figure 1) describes the condition of the well which well head pressure and buoyancy acting upward against a cross sectional area of pipe is greater than weight of the string. If the light pipe condition is happened and the string is not controlled by the snubbing unit, the string will be pushed out of the well.

Figure 1 - Diagram for Pipe Light Condition

Figure 1 – Diagram for Pipe Light Condition

You may see these videos showing the pipe light condition. These videos below clearly demonstrate when the pipe is in “Pipe Light” condition. You can see that the tubing string is  hydraulically pushed out of the hole by wellbore pressure.

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Kick Tolerance Concept and Calculation for Well Design

Kick tolerance is the maximum gas volume for a given degree of underbalance which the circulation can be performed without exceeding the weakest formation in the wellbore. This article is the extended version of Kick Tolerance Calculation  which will explain more on this topic. It is very critical that drilling personnel understand its importance to well design and drilling operation.


There are two important factors used for determining the kick tolerance

• Kick Intensity – It is the different between the maximum anticipated formation pressure and planned mud weight. For example, the planned mud weight is 13.0 ppg and the possible kick pressure is 13.5 ppg. Therefore, the kick intensity is 0.5 ppg (13.5 – 13.0).

A zero kick intensity (swabbed kick scenario) should be used for a know area where you have less uncertainty about an overpressure zone.

 • Kick Volume – It is a gas influx entering into the wellbore from the formation. Gas kick is always used for well control calculation because it is the worst case scenario. The kick volume should be realistic figure which personal can detect the influx on the rig. In a larger hole, it allows bigger influx volume than a small hole.

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How to Select a Scientific Calculator for Oilfield Personnel

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.


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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