Author Archives: DrillingFormulas.Com

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Working in the oil field and loving to share knowledge.

Casing Shoe Pressure While Circulating Influx in Well Control Situation

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Many people ask us a lot of questions regarding shoe pressure while circulating kick (wellbore influx) out of the wellbore. Pressure acting at casing shoe is different depending on where the kick is in the well therefore we will summarize all the scenarios to help you get clearer picture. There are a total of three cases which we will separately discuss as per the details below.

 

Note: All the calculations and scenarios are based on water based mud and gas kick. This assumption is used because it is the worst case scenario. The casing shoe will have less pressure if the influx is oil or gas kick.

casing-shoe-presure

 First Scenario – Top of Gas Kick Below Casing Shoe

 

Figure 1 - Top of Gas Kick Below Casing Shoe

Figure 1 – Top of Gas Kick Below Casing Shoe

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What is Closing Ratio in Blow Out Preventer (BOP)?

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People asked me about what the closing ratio is and what it tells us. Closing ratio is defined as the cross sectional area of the ram piston (cylinder) divided by the cross sectional area of the ram shaft. The closing ratio is used to determine Ram closing pressure which will overcome wellbore pressure acting to Ram body. The closing ratio formula is below;

Closing Ratio = Ram Piston Cylinder Area ÷ Ram Shaft Area

Before going into the detailed calculation, we would like to show you where the cylinder and the ram shaft are in BOP. In Figure 1 (Shaffer SL-Ram BOP), the yellow shaded parts demonstrate these two areas which will be used to calculate the closing ratio.

Figure 1 - Shaffer SL-Ram BOP

Figure 1 – Shaffer SL-Ram BOP

 

Detailed Formulas are as follows;

Ram Piston Cylinder Area  (square inch) = ( π× Ram Piston Cylinder Diameter2 ) ÷ 4

Ram Shaft Area  (square inch) = ( π× Ram Shaft Diameter2 ) ÷ 4

Closing Ratio = Ram Piston Cylinder Area ÷ Ram Shaft Area  

Figure 2 - Diagram of Closing Ratio Calculation

Figure 2 – Diagram of Closing Ratio Calculation

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Free Useful Well Control Spreadsheet – All Important Well Control Formulas For Oilfield Personnel

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There are a lot of people who are interested in well control and we would like to help them learn and make their life easier by sharing the well control spread sheet. The image (Figure 1) below is the screen shot of the spread sheet.

Version 1.3 updated on 28-Jan-19.

In this version (1.3), the spreadsheet is updated into .xlxs file which is the newest Excel Version. Moreover, all formulas are unlocked so you can modify to suit for you needs too.

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Basic Knowledge of Mud Pumps VDO Training

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Mud pump is one of the most critical equipment on the rig; therefore personnel on the rig must have good understanding about it. We’ve tried to find the good training about it but it is very difficult to find until we’ve seen this VDO training and it is a fantastic VDO training about the basic of mud pumps used in the oilfield. Total length of this VDO is about thirteen minutes and it is worth to watch it. You will learn about it so quickly. Additionally, we also add the full detailed transcripts which will acceleate the learning curve of learners.

Please feel free to share with anyone : )

Transcript for this VDO for learning purposes

Powerful mud pumps pick up mud from the suction tank and circulate the mud down hole, out the bit and back to the surface. Although rigs usually have two mud pumps and sometimes three or four, normally they use only one at a time. The others are mainly used as backup just in case one fails. Sometimes however the rig crew may compound the pumps, that is, they may use three or four pumps at the same time to move large volumes of mud when required.

Basic Knowledge of Mud Pumps VDO Training

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Basic of Drillpipe Tensile Capacity and Its Calculation

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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.

 Basic of Drillpipe Tensile Capacity and Its Calculation

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

Figure 1 – Stress (σ) = F/A

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