Introduction To Underbalanced Drilling VDO Training

by DrillingFormulas.Com on August 17, 2014

Underbalanced drilling becomes very famous in several places of the world because there are some advantages over normal drilling operations. Today we would like to share the basic underbalanced drilling 101 for everybody who is interested in this topic. It is presented by Shell and we also add full VDO transcript for anybody who cannot catch the information from this presentation.

Underbalanced Drilling 101 Full VDO Transcript

This presentation introduces the concept and equipment used in underbalanced drilling operations. The key differences between underbalanced drilling and conventional overbalanced drilling are at both the conceptual and the technical level. At the conceptual level the subsurface drilling conditions needs to be investigated further, the rotating drill bit cuts away rock to deepen the well. The drill cuttings are lifted to the surface by the circulating drilling fluid.

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Can Women Work in the Oilfield (Oil and Gas Industry)?

by DrillingFormulas.Com on August 14, 2014

Women nowadays are dominating the world of men especially when it comes to jobs. They work side by side with males in a man’s industry, which is considered as a great achievement. Back in the days, women should stay at home, serve her husband, cook for the family, care for the children and do the household chores. This happened for many decades until some brave ladies stood up and fought for women’s rights. They showed that women can do almost anything and they can perform the work of a man. In fact, there are women who work in the oilfield, which is a tough job. People, mostly men and unbelievably some women, don’t want to accept that Eve’s daughters can work hard and do laborious jobs too.


Good thing these days men have embraced this fact and offer wider opportunities to the ladies. There are several male jobs that are now handled by women. These jobs include being a CEO, lawyer, doctor, rescuer, military work, police, a taxi driver, a construction worker, an electrician, a race car driver, engineer, oilfield worker and the list goes on. Some of these jobs were once performed by men and are not allowed for women.

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Fracture Gradient Reduction Due to Water Depth

by DrillingFormulas.Com on August 10, 2014

Fracture gradient is one of the critical information which drilling engineers need to know in order to design drilling programs. For the well control stand point, the fracture gradient directly affects on how much influx volume can be successfully contained in the wellbore. If the wellbore pressure is over the fracture pressure, formations would be broken down and this situation will result in loss of drilling fluid into formations. Additionally, it might lead to well control situation because of loss of hydrostatic pressure. Fracture gradient is quite straight forward for land operation because it will not be reduce due to water column. However, the fracture gradient will be reduced in deepwater environment. In this article, we will discuss why water depth can cause the reduction in fracture gradient.

Fracture Gradient Reduction Due to Water Depth

Basically, the fracture gradient is related to fluids occupying in pore spaces of rock and weight of rock which are called overburden pressure. Generally, the overburden of a typical sedimentary is about 1.0 psi/ft (19.2 ppg). Rocks will be fractured when the wellbore pressure exceeds the confining stresses acting on it. If we make a general assumption that the overburden pressure causes the minimum confining stress of the rock. Then the formation fracture gradient will not be 1.0 psi/ft if the location is offshore.

Note: this assumption is made in order to help you get more understanding on how and why water depth can decrease the formation fracture gradient.

Why does the water depth reduce fracture gradient?

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Ekofisk Bravo Blowout Oilfield Incidents

by DrillingFormulas.Com on August 6, 2014

Ekofisk Bravo blowout incident happened when performing workover operation. If you study in the oilfield industry about well control incidents, there are several cases when the well was unable to control during workover operation. This is what personnel working in this industry needs to learn and fully aware of the hazard which could be occurred and this can affect lives, environment, etc. This is one of the reason why we always emphasize the important of well control in every operation.

The Ekofisk Bravo Platform Blowout

The Ekofisk Bravo Platform is located towards Ekofisk field’s north and is one of the two prime wellhead production facilities of Ekofisk. However, on April 22nd, 1977, it went through a major blowout which is regarded as the biggest oil spills till date at the North Sea.

Ekofisk Bravo 1

The Ekofisk B blowout took place when workover was being carried out at B-14 production well where they were busy pulling about 10,000 feet of production tubing. Before the task, the production Christmas tree valve stack was removed. Besides, the BOP was not installed. However, the well kicked and wrongly installed while the downhole safety valve failed, which caused immediate blow out of the well with wild release of gas & oil. However, fortunately the crew onboard was evacuated safely through lifeboats and was later transferred to the supply vessel. Miraculously, no one was injured.

This event led to wastage of approximately 28,000 barrel/day, later resulting into overall discharge of 202,380 bbls. Around 30-40% oil was assumed to be evaporated and the overall spill estimate by the Norwegian Petroleum Directorate was to be considered around 80,000 bbls & 126,000 bbls.

Ekofisk Bravo 2

Finally, after 7 days, the well was capped in April 30th, 1977. However, higher air temperature & rough seas helped the break-up of the most of the oil. Further investigations concluded that there was no major damage to the environment & shoreline pollution. Besides, there was no major damage to the platform.

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Free Cross Over Generator Excel Spreadsheet for Oilfield Use

by DrillingFormulas.Com on August 4, 2014

You may have a problem regarding ordering the cross over to use on the rig because there are so many threads used for the operation. For example if you have just only three threads (3-1/2” IF, 4-1/2” IF, 7” BTC) for the operation. These are a total of 18 the possible crossovers that you may need as listed below.

3-1/2″ IF PIN X 4-1/2″ IF BOX

3-1/2″ IF PIN X 7″ BTC BOX

4-1/2″ IF PIN X 3-1/2″ IF BOX

4-1/2″ IF PIN X 7″ BTC BOX

7″ BTC PIN X 3-1/2″ IF BOX

7″ BTC PIN X 4-1/2″ IF BOX

3-1/2″ IF PIN X 3-1/2″ IF PIN

3-1/2″ IF PIN X 4-1/2″ IF PIN

3-1/2″ IF PIN X 7″ BTC PIN

4-1/2″ IF PIN X 4-1/2″ IF PIN

4-1/2″ IF PIN X 7″ BTC PIN


3-1/2″ IF BOX X 3-1/2″ IF BOX

3-1/2″ IF BOX X 4-1/2″ IF BOX

3-1/2″ IF BOX X 7″ BTC BOX

4-1/2″ IF BOX X 4-1/2″ IF BOX

4-1/2″ IF BOX X 7″ BTC BOX


You will get lost easily, won’t you??


As you can see, it is quite tricky to determine all possible required cross over especially when you have a lot of connections. Therefore we create an Excel file to help you do this task. We call this file as “Cross Over Generator”.


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Block and Drilling Line Calculation

by DrillingFormulas.Com on July 29, 2014

This article will focus on block and drilling line calculations as block efficiency, drilling power input/output, etc. Additionally, there are some examples which will help you understand how the formulas work.


Block and drilling line efficiency formula is described below;

Block and Drilling Line Calculation 1

Power Output (Po) = Fh x Vtb

Power Output (Pi) = Ff x Vf

Block and Drilling Line Calculation 2

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Oil & Gas Well Cementing VDO Training

by DrillingFormulas.Com on July 21, 2014

Cementing is very critical step of well construction. Bad cement job can lead to bad situations as well control, low productivity, gas channeling in annulus, etc. Therefore personnel in oilfield should learn and understand this topic. It is quite hard to find very good vdo training in the topic of oil well cementing but we finally find it. This VDO training is very excellent because it teaches all the basic with animations which absolutely helps learners fully understand this topic. Additionally, we add full VDO transcript so it will help some people who cannot catch all the wording in the VDO training. Please feel free to add comments and/or suggestions and we wish you would enjoy learning from this post.

  Full VDO Transcript


Here is an overview of casing cemented in a well called primary cementing. The cement’s main jobs are to completely isolate or totally seal off all the oil, gas and water zones from the well bore and to bond the casing firmly to the wall of the whole. Here the crew has drilled the well to the casing point, the depth at which they will set and cement casing. The driller circulates drilling mud to clean the hole and to make sure the mud is in good condition. Then the crew pulls the drill string out of the hole. The next step in primary cementing is for the casing crew to run the casing into the well, one joint at the time. Notice at the bottom of the casing, the guide shoe and float collar. Also notice the centralizers and scratchers. The guide shoe guides the first joint of casing into the well bore. A valve in the float color lets the crew float the casing into the well to lessen the load on the rig’s hoisting system.
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How Does 1029.4 Come From?

by DrillingFormulas.Com on July 16, 2014

1029.4 is used in several calculations in the oilfield and we’ve been asked about what is 1029.4, how it comes from, why it needs to be this figure so in this article, we will show you how 1029.4 comes from.


First of all, we would like to give someone about the background of this figure. The 1029.4 is widely used for capacity calculations. The following equations utilizing 1029.4 are listed below; [click to continue…]


Sedco 135F – IXTOC I Blowout and Oil Spill

by DrillingFormulas.Com on July 9, 2014

We learn from the past in order to prevent the bad incidents to be happened. This time we would like to discuss about Sedco 135F – IXTOC I Blowout and Oil Spill.  The Sedco 135F was perforating and drilling the IXTOC I well in 1979 for PEMEX, which is a petroleum company in Mexico owned by the state at the time when the well underwent an eruption. Through a drilling, the well had been dug up to 3.6 km with the 9-5/8″ casing set at 3.6 km. It has been vindicated by various studies that there was a failure in mud circulation (essentially mud is a massive and heavy weighted drilling fluid which is utilized as a lubricant for the drill bit, helps in cleaning the drilled rock from hole and present a column of hydrostatic pressure as a prevention from influxes), hence a consensus was reached that it is the best to pull the drill string & plug the well. The absence of mud column’s hydrostatic pressure triggered an unconstrained and liberal circulation of oil & gas to the surface, and this was what happened when the crew was working with drillstring’s lower part. The BOP was shut on the pipe however it was unable to chop the chunky drill collars, permitting oil and gas to come up to the surface where it burned and inflamed the Sedco 135F. The rig broke down and drowned on top of the wellhead space on the seabed, cluttering the seabed with debris like the rig’s derrick & 3000m of pipe.


Sedco 135F – IXTOC I Blowout

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Rig Engine Power Consumption and Engine Efficiency

by DrillingFormulas.Com on July 7, 2014

In this article, we will focus on the rig engine power consumption and overall engine efficiency and there are few examples for you to get more understand on how to use the formulas as well.



Input Power of Engine

The formula is listed below;

input power


Pi = input power in horse power (hp)

H = fuel heating value in BTU/lb

Qf = fuel consumption rate in lbm/hr

Fuel Consumption

The formula is listed below;

Fuel Consumption formula

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