Ministry Of Energy To Set Up Special Local Content on Oil and Gas Sector

The Ministry of Energy and Minerals plans to set up a special local content on gas and oil unit to enable the public easily access information on various issues concerning the sector.

Senior Supplies Officer (Local Content) at the Ministry of Energy and Minerals, Ms Neema Lungangira made the revelation in Dar es Salaam during a seminar organised by Twaweza Organisation to present and discuss the report titled ‘Great Expectations On Gas Sector And Relevant Policies’.

“Government through the ministry is setting up various strategies to enable the citizens fully participate in the oil and gas sector and one of the strategies is the establishment of the special local content unit,” she said.

Among the issues to be tackled under the unit will include public awareness creation, providing knowledge of public participation in the sector.

The unit will be established under the local content policy and will focus on the providing information from the key document on the sector.

According to the report presented by Twaweza at the seminar, citizens do not have access to full information about Tanzania’s gas sector.

Presenting the report, Executive Director of Twaweza, Mr Aidan Eyakuze said that 53 per cent of citizens think that gas from the new offshore discoveries is already flowing with some thinking that both government and foreign companies are already earning revenues from the gas.

The report based on data from ‘Sauti za Wananchi’ Africa’s first nationally representative high frequency mobile survey also indicate that citizens expect four million jobs and 7.5m/- each from gas deposits.

The report which shows that citizens are significantly misinformed about the potential of the country’s deposits, show that 59 per cent of citizens think that natural gas deposits will improve their lives and a similar (58 per cent) expect government to invest gas revenue into public services.

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Tpdc has Awarded Ion A Contract For Seismic Survey in Ruvuma Delta Region

 ION Geophysical Corporation has announced that the TPDC has awarded ION a contract to acquire 4,058 km of 2D seismic, gravity and magnetic data over offshore blocks 4/1B and 4/1C in the Rovuma Delta region. The award follows an international tender, number PA/031/2014-15/W/06, for a 2D multi-client survey, to be known as 'TPDC Phase I 2015', that is planned to be acquired in fourth quarter 2015.

"We are very excited on the commencement of this program, which is part of a broader campaign aimed at adding value to all of TPDC assets, both onshore and offshore," Dr James Mataragio, Managing Director of TPDC, commented. "This survey and three other surveys carried onshore are 100% funded by TPDC. This marks an important step for TPDC, as a National Oil Company, to begin fully focusing on exploration, development and production. Blocks 4/1B and 4/1C are 100% owned and operated by TPDC, and this new seismic data will be used to assist TPDC with a competitive farmout process, details of which will be announced at a later date."

Joe Gagliardi, Senior Vice President of ION's Ventures group, added, "ION is delighted to have been awarded this contract, which represents a further phase of seismic acquisition, processing and interpretation services to be provided by ION in support of the government's hydrocarbon exploration strategy."

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Low Crude Price Will Lead To The Shortage of Talents In Many Petroleum Companies

Oil companies have been doing recruiting in  local university. Where by graduates from these Universities have received jobs offer prior to their graduation date. Forexample In Tanzania, graduates from University of Dar es Salaam and Dar es Salaam Institute of Technology have received these job offer from oil companies.

In order to cope with this low level price ,oil companies has been  giving up  to work with local universities  since june last year. The truth is, Many oil companies will have scarcity of talents  they used to find  from  local universities. And when I say talents, I mean from operators, geologist engineers ,accountants, human resources people  and all who have background unrelated with oil and gas industry

MY FINAL THOUGHT

  Currently I am very anxious about this low crude price.If this  downturn will be  long slump,probably  it could affect graduates jobs prospect and oil companies can’t find the talents they need. But if the slump will be short, petroleum companies could find the talents they need and this will give graduate future they are trying to seek for.

Dear readers we would love to hear your views on all of these

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One Simple thing to Keep in Your Mind and It will help You To Work In Petroleum Industry

 Petroleum industries require personnel with diverse academic background, It involve  both technical personnel (such as enigineers , land survey, geomatics) and non technical personnel ( such as Lawyer, human resources accounting marketing environmental and safety, banker, transportation, security insurance and so on.)

You as a Lawyaer or accountant you might  be interesting to join or make career change into oil  and gas industry or for those with engineering background unrelated to oil and gas industries or no field experience but you  would like  to join into this industry. To day I will share with you one thing in order to help you join into petroleum industry.

Lets go,

           Generally, company  would  hire you and train you,  even though the company need people, it does not mean they  would like to start  completely from scratch. This applies to both technical and non technical personnel. The Company would need some who having understanding of petroleum field.  You should have a basic knowledge of petroleum industry.To increase chances to get your dream  job  in petroleum industry you must having a basic understanging of terminology of oil field such as a word HYDROCARBON and so on.

What you have To do?

As we have already seen above, for those with courses unrelated to oil and gas industries like  electrical engineers and accounting, they must have basic understanding of this petroleum industries in order to join the industry. May be you ask yourself. “How  i would manage to know all of these basic concepts in oil and gas industry. The answer is very straight forward. A great way for you to satand out is would be to learn that on your own time.With these information age  you can learn any thing you want to learn, you can know any thing you want to know. Now days every thing is on the internet, you can learn millions of things simply by touch your mouse or mobile device.

MY FINAL WORDS

If you don’t know where to start and you are willing to learn the basic of petroleum industries, you should contact me through Boffuhussein@gmail.com, and i am going to show you the area where you will find those stuff

Dear readers, We would love to hear your views on all of these

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Mnazi Bay Gas Wells Deliver 1st Gas to Tanzania Pipeline

East Africa-focused junior producer Wentworth Resources announced Friday the first gas delivery from its Mnazi Bay Concession in southern Tanzania to the country's new transnational pipeline. Wentworth said that two wells are now producing, with the three remaining wells expected to be put on production in the coming months. Initial production volumes will be used for commissioning purposes and to fill the pipeline, with production rates expected to increase to 70 million cubic feet per day by October this year and 80 MMcf/d by the end of 2015. Wentworth added that the Mnazi Bay joint venture partners have agreed payment security terms with Tanzania Petroleum Development Corporation, the buyer of the gas, and various other parties. Wentworth Managing Director Geoff Bury commented in a company statement: "We are very pleased to announce that production from Mnazi Bay has now commenced and the Mnazi Bay joint venture is the first supplier to the new transnational pipeline in Tanzania. Concluding the payment guarantee and starting production in our Mnazi Bay gas fields are pivotal events for Wentworth and underpin the long-term viability of our operations in East Africa and our partnership with Maurel & Prom and TPDC. "Wentworth is well positioned to become a significant gas producer in Tanzania, where supply and demand dynamics offer an opportunity which we and our partners are uniquely placed to realize. We expect to exit 2015 in a strong financial position."

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Mnazi Bay Gas Wells Deliver 1st Gas to Tanzania Pipeline

East Africa-focused junior producer Wentworth Resources announced Friday the first gas delivery from its Mnazi Bay Concession in southern Tanzania to the country's new transnational pipeline.

Wentworth said that two wells are now producing, with the three remaining wells expected to be put on production in the coming months. Initial production volumes will be used for commissioning purposes and to fill the pipeline, with production rates expected to increase to 70 million cubic feet per day by October this year and 80 MMcf/d by the end of 2015.

Wentworth added that the Mnazi Bay joint venture partners have agreed payment security terms with Tanzania Petroleum Development Corporation, the buyer of the gas, and various other parties.

Wentworth Managing Director Geoff Bury commented in a company statement:

"We are very pleased to announce that production from Mnazi Bay has now commenced and the Mnazi Bay joint venture is the first supplier to the new transnational pipeline in Tanzania. Concluding the payment guarantee and starting production in our Mnazi Bay gas fields are pivotal events for Wentworth and underpin the long-term viability of our operations in East Africa and our partnership with Maurel & Prom and TPDC.

"Wentworth is well positioned to become a significant gas producer in Tanzania, where supply and demand dynamics offer an opportunity which we and our partners are uniquely placed to realize. We expect to exit 2015 in a strong financial position."

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Paragon Offshore appoints ISS to drill in Tanzania Songo Songo Island

Paragon M826 can drill to depths of 20,000 ft

US company Paragon Offshore has appointed Inchcape Shipping Services (ISS) to provide marine and logistic services for a new drilling campaign off the Songo Songo Islands, Tanzania.

The Songo Songo project is the first new commercial drilling operation in Tanzania in a number of years. Paragon Offshore has been contracted by Tanzania’s first natural gas producer, PanAfrican Energy on a nine-month campaign.

“We are delighted by our first appointment by Paragon Offshore in East Africa,” said TS Mahesh, General Manager, ISS Tanzania.

“The opportunity to support this drilling campaign takes ISS to the next level in the oil and gas support service sector in Tanzania and boosts our future growth plans.”

The services ISS is providing for Paragon Offshore include full husbandry, crew logistics, visa assistance as well as arranging marine and air charters.

Paragon Offshore, a leading provider of standard specification offshore drilling services, is deploying jack-up rig M826, which was delivered to the field on board semi-submersible vessel, OHT Falcon, to be floated off and pinned to the drilling location.

M826 is expected to clear actively producing wells to enhance output and drill several new wells in the same field
.

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Efforts to Build Oil,Gas Local Content.

 

The  African Capacity Building Foundation(ACBF) has hailed current government efforts to build  a strong local content legal and policy framework to guide the oil and  gas sector.

Prof  Emmanuel Nnadozie  the Executive Secretary said the local content policies and legislations would ensure the local populace are active in the oil and gas value chain.

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Petroleum Industry's Local Impact

Tanzaniapetroleum's  core objectives include the acquisition of latest information on  Tanzania's exploration and production activities,gain exposure to     the latest trends and development in the East African market and  to keep abreast of geopolitical,industrial and technological developments.
Articles 10 and 109 of  2010  mining Act Stipulate that exploration firms must make provisions for local ownership in areas where they are active.
Therefore  as active players in the industry we are committed to act as a check and balance against other players as we move closer to commercial production.
Some of the prevalent concerns include,transparency in revenue management,sharing of royalties with local communities,access  to information,environmental degradation  and lack of consultation with communities  in oil-rich regions.
Lastly  is to highlight  the  secrecy in public sharing contracts that the government has with oil,gas and mining companies.
    The writer is an oil and gas analyst.Member of Tanzania Petroleum

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Gas pipeline to be complete next month

TRANSPORTATION of natural gas from Madimba in Mtwara to Kinyerezi I Power Plant in Dar es Salaam will start early next month after completion of the construction of the 542-kilometre natural gas pipeline project.

According to the Minister for Energy and Minerals, Mr George Simbachawene, the transportation of natural gas will save over 1 1.6tri/- per year currently spent on importation of fuel for electricity generation.

The pipeline will have an installed capacity of transporting 784 million standard cubic feet daily, a volume which can generate over 2,000 megawatts (MW) of electricity, including the 300MW plant at Mnazi Bay.

Mr Simbachawene noted that upon completion of the infrastructures, the project would see the country getting reliable electricity supply, expansion and increase of industrial production, cleaner environment and employment creation.

The Minister made his remarks yesterday in Dar es Salaam after he visited Kinyerezi 1 Power Plant to inspect the progress of the implementation of the project carried out by contractors, TANESCO as well as Tanzania Petroleum Development Corporation (TPDC).

He urged Tanzanians to be patient as TANESCO will cut off electricity where repairs will be done so as to ensure the availability of gas electricity in most parts of the country.

He stressed that the availability of natural gas will help reduce the use of water where in some of the hydroelectric dams that have slowed down production due to climate change and environmental degradation.

Kinyerezi I Power Plant, Eng John Mageni noted that two out of four machines are complete and will produce 220Kv of electricity.

“The machines are currently on a test run and within two weeks will be complete,” said Eng Mageni adding that by early September this year, natural gas from Mtwara will be available at the plant ready to be distributed to various sub stations including the national grid.

In a related development, TANESCO Managing Director, Eng Felchesmi Mramba said when Kinyerezi 1 Power Plant kicks off, the company would significantly reduce the cost of power supply.

He added that 150MW are expected to be produced after the completion of the construction of Kinyerezi 1 Electricity Power Plant, a step towards the execution of the government’s aim of adding electricity capacity on the national grid.

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See Where does Petroleum Come from

We are going to talk Origin of petroleum

But First  I will talk about the origin of the world itself, Rock outcrop at the surface of the earth have been producing oil for century and this oil was known as rock oil, Because at that period oil was seeping out the rock, But at the middle of 19 century some body called the word Petroleum, Petro is greak word meaning rock and leum is latin word meaning oil and they combine these two word called petroleum. Then become popular word and eventually the word adopted by industry itself and now is known as petroleum industry

 Where does petroleum come from?

 There are two theory about where petroleum come from

·         Organic theory :State that oil was developed over millions of years from organic materials from remains of animals and plants that were once alive, the proteins life floaded in the sea like plankton and algae then die and fed to the bottom of the ocean.

·         Inorganic theory In this teory the source of oil is from chemical reactions between minerals, In the laboratory scientists have been able to make methane gas by applying heat under high pressure to minerals even though a very small percentage of oil today may have developed from in organic chemical reactions between minerals the source of most our oil appear to be the result of organic decomposition.

These decomposition is the decay of the remains of animals and plants that died millions of years ago

                When am talking about animals that was died and generate oil am talking about tiny microscopic animals that live in the sea eg plankton and algae

    These animals die under special circumstances, and what do I mean by that?

         As you know when most animals die other animals and bacteria arrive to consumes the remains living nothing. In the shallow water where these animal live, sweep current come on and push these down to where there is no enough oxygen to live and so they die. These animals went from an aerobic environment where there is plenty of oxygen to an anaerobic environment where there is little oxygen where all die at the same time.

In an anaerobic there also not enough oxgen for most animals microbs or bacteria to come along and eat the remains of planktons and algae so the just lie there until the get buried by particles of silt and sand.

Over period of millions of years these layers of remains in sand and silt particles are buried and curved by more layer until first layer become very deep. All the way of these layer to press down and squeezed caused increased in pressure and temperature until the sedimentary layers are formed into shale, sediment change into rock, and little dead microbs get cooked into hydrocarbon.

These is the theory of how petroleum and coal is made.

Oil is made from animal like plankton

Coal is made from vegetation like plants

Gas is made from deeper formation where microbes are cooked longer

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CAG TO AUDIT OIL AND GAS COMPANIES

Dar es Salaam: The Controller and Auditor (CAG) will carry a special audit on oil and gas industry.

CAG Mussa Assad said citizens from areas with gas and oil should benefit from companies operating in their locales.

“This sector [oil and gas] is very crucial,” he said, adding “we will make sure they are controlled accordingly to give to the society what it really deserves.”
Assad said his office might fail to compete auditing in some offices following budget deficit.

Despite receive less from treasury; the CAG remains adamant that his office will execute its duties.

“With the little we have we will make sure we implement fruitful projects which will benefit citizen but we will not be able to finish all of projects.”

For this fiscal year the CAG office were scheduled to receive TZS 86 billion but only received TZS 76 an amount which will not be enough for all projects set for this year.

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Components of Production Sharing Contract in Kenya

Licensing of petroleum exploration blocks, is governed by the Petroleum (Exploration and Production) Act Chapter 308 of the Laws of Kenya. All contracts are based on a Model Production Sharing Contract (PSC) issued as a schedule to the Regulations issued under Section 6 of the Act.

The signed Production Sharing Contracts have the following key component:

a) Signature Bonus: This is a one-off fee payable to the Government by the Company upon signing of an oil exploration contract. It depends on the area of the Block and previous data acquired on the Block. Signature Bonus negotiation came into effect in 2009. In block 12B for example the signature bonus paid was $300,000 according to JV partner Australian Swala Energy. In block L27 operated by CAMAC Energy the signature bonus paid was $310,000 according to the PSC available on this website.

A surface fee is also payable and is calculated on the basis of the surface area of the Contract Area on the date those payments are due. In Block L27 the amount set is $5 per square kilometre per annum during the Initial Exploration Period, $10 per square kilometre per annum during the first Exploration Period, $15 per square kilometre per annum during the second Exploration Period and $100.00 per square kilometre per annum during the Development and Production Periods

b) Work programme and expenditure: The contractor guarantees the agreed work programme and minimum expenditure. Initially this was pegged at 15% bank guarantee and 85% parent company guarantee. However, the Ministry has improved this and now the newly licensed companies are required to provide a 50% bank guarantee and 50% parent company guarantee.

This is to make sure that the companies proceed with their work progamme expeditiously as agreed with the Government and that incase of non-performance, the Government can liquidate the guarantees more easily. For small companies (based on their annual turnover criteria), they are required to post 100% bank guarantee. It is important to note that upstream petroleum operations are capital intensive and the Government entirely relies on the oil companies to invest their risk capital in the operations.

In addition, this risk capital is raised through equity. This is contrary to investment in mid stream and downstream petroleum segments which can be funded by debt

c) Cost oil: This is usually the negotiated percentage of total crude produced for recouping of investment costs incurred by the contractor in exploration and production of oil in a given field. It is normally up to 60% of all the oil produced in a field for about five years.

d) Profit oil: This is the remaining oil after deducting cost oil and is shared between the Government and the contractor. For example, when a field is small the Government take is 50%. As the production increases, the Government take can increase up to 78% of the total profit oil.

e) Windfall profit: Where oil prices are higher than the negotiated threshold, the Government creams off contractors take above the threshold crude oil prices by 26%.

f) Exploration phases – there are three exploration phases of two years each, the initial period, first additional period and second additional period. For ultra deep offshore blocks, the initial period is extended to three years due to extra logistical challenges in the deep water acreage.

g) Relinquishment – is 25% of the area of the block for each period

The PSC also has the license rental fee and training fee included. In Block 12B for example the license rental fee is set at $40,000 during the first year (2012-2013) and $80,000 during the second year, training fee is $100,000 per annum. During the first production phase the training fee is set at a minimum of $200,000 in Block 1 PSC with Lion Petroleum.

Check out PSC’s for the various East African countries namely Kenya, Uganda, Tanzania, Mozambique available on our website.

Additional Source: Ministry of Energy & Petroleum Website

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Oil prices 'could fall further'

Oil prices may have further to fall despite stabilising in recent months - and even beginning to rise modestly - because of a massive oversupply the International Energy Agency (IEA) has said.

The IEA said lower oil prices were likely to last well into 2016.

The agency added the world oil market was unable to absorb the huge volumes of oil now being produced.

It follows the massive drop in prices which started last summer.

The price of Brent crude fell sharply last year from $115 a barrel in June to $45 a barrel in January.

The current price of Brent crude is $59 a barrel.

The fall in prices has led oil firms to cut back investment in exploration, while North Sea oil has come under significant pressure.

All seven major global oil firms have also reported a year-on-year declines as a result of lower oil prices.

'Oversupply'

Only last month the Office for Budget Responsibility (OBR) forecast North Sea oil and gas revenues would fall to below 0.1% of GDP over the coming decades.

It said the tax take from North Sea oil and gas had already fallen by 80% in the last three years.

"The oil market was massively oversupplied in the second quarter of 2015, and remains so today," the IEA said in its monthly report.

"It is equally clear that the market's ability to absorb that oversupply is unlikely to last. Onshore storage space is limited," it said, adding: "Something has to give."

"The bottom of the market may still be ahead."

Core members of the Organisation of Petroleum Exporting Countries (Opec) have continued to produce the same level of oil in the past year despite falling oil prices in an attempt to regain market share.

US oil production has also soared in recent years, as fracking - or the process of extracting oil from shale rock by injecting fluids into the ground - has revolutionised oil production in the country.

Opec's response to the fall in prices was to refuse to cut production. Many Opec nations are able to tolerate a lower oil price despite losing money.

Record

For other nations such as Russia the lower oil price is doing substantial harm to economic growth

Last month, official figures showed the impact of international sanctions over Russia's continued involvement in east Ukraine and the lower oil prices had led to a 4.9% contraction in the Russian economy in the 12 months to May.

The IEA said Opec crude oil production rose 340,000 barrels per day (BPD) in June to 31.7 million barrel as day, a three-year high, led by record output from Iraq, Saudi Arabia and the United Arab Emirates.

It said Saudi Arabian crude oil supply rose 50,000 barrels per day to a record high of 10.35 million BPD in June, while Iraq crude oil output surged 270,000 BPD in June to its highest-ever rate of 4.12 million BPD.

However, increases in production have come just as demand for oil in economies across the world from Europe to China - the world's second-largest consumer of oil - has slowed.

The IEA trimmed its forecast for global oil demand growth this year slightly to 1.39 million BPD and said it expected global demand growth to slow to 1.2 million BPD in 2016.

The agency added non-Opec supply growth was expected to grind to a halt in 2016 as lower oil prices and spending cuts take their toll. It forecast zero growth in non-Opec oil supply in 2016 after an increase of 1 million bpd in 2015.

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The Ministry of Energy & Mineral Development has announced that the “Uganda International Oil & Gas Summit” (UIOGS) will be held in Kampala on 16-17 September 2015.
With a first-class conference programme led by Government, Public Sector and Private Sector industry leaders; the Summit marks an important point on the global calendar.
UIOGS is held under the Patronage of Eng. Irene Muloni,Minister of Energy and Mineral Development; and will be used by the Ministry as its official platform for meeting international companies and presentation of the multitude of energy projects presently ongoing or planned for in Uganda.
Uganda has much to offer the global oil and gas community and 2015 is an exciting year as the country moves towards commercial production. Uganda is blessed with its natural resources and now has an estimated 6.5 billion barrels of oil in place, a high drilling success rate of 85%, advanced refinery plans, vast acreage of underexplored areas rich in hydrocarbons and much to look forward to with the new licensing rounds.
The UOGS programme will provide an invaluable insight into all the major issues, challenges and opportunities including:

• Focus on the licensing rounds and new opportunities
• Update on existing fields and exploration success
• Financial and regulatory frameworks
• Uganda’s Refinery Project – 60,000 bpd by 2020
• Move to commercial production
• Supporting the oil and gas industry through a skilled workforce and local content
• Infrastructure developments to support oil & gas
• How can a successful oil industry support our drive towards rural electrification

The Ministry of Energy & Mineral Development will be using the UIOGS platform to actively engage with allits partners and suppliers from around the world. The services of the renowned market leaders for oil & gas conferences; Global Event Partners have been engaged to work alongside domestic experts Image Care to ensure that UIOGS is a first-class event that puts Uganda firmly on the global map.
UIOGS is a two day conference that will be held at the Kampala Serena Hotel on 16-17 September 2015. The programme will be opened by Hon. Eng Irene Muloni and will feature more than 30 Government officials, Company leaders and Industry experts gathered from Uganda, the region and throughout the world to give Uganda a truly global platform.

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This is How To Drill Oil and Gas Well

          Now, during this lesson, we will see how to drill them.
1. First of all, let’s see how to describe the subsurface characteristics, in order to plan the design of the future well and to define the phases of the drilling job.
2. Then, we’ll describe the drilling system, and how the driller can manage the drilling process safely.
During the exploration phase a well is needed to confirm the presence of oil or gas in the reservoir.
Some appraisal wells are needed for the delineation process.
Moreover, at the end of the reservoir strategy study, a reservoir model defines how to develop the field, and, more particularly, where to drill the wells and the contribution of each of them to the production plateau.
The role of the driller is to build these wells required for the field development.
A well is an expensive item. It must be carefully studied and planned before being drilled. The well preparation phase involves coordinated work between geoscience engineers and drilling/completion engineers.
How to design a well?
In order to set up the drilling program, the driller needs to know the location of the rig, where the well has to enter the reservoir, the trajectory of the well in the reservoir for a good connection between the well and the reservoir, and the formations to be drilled. Let’s detail the description of the subsurface.
For each formation to be drilled, there are 2 characteristics that need to be known accurately:
1. the pore pressure
2. and the fracture pressure.
The pore pressure is the pressure of the fluid within the grains of the rock. It depends on the depth of the formation and on its nature (sandstone, shale, …).
The fracture pressure corresponds to the minimum pressure to be applied on the rock to generate a fracture.
When the formation is drilled, the well is full of a fluid: the drilling mud, which is directly in contact with the rock, and applies a pressure on it: Pmud.
The mud pressure depends on the depth. One of the roles of the mud is to maintain the interstitial fluid within the rock, in order to avoid a kick.


During the drilling process, the mud is in contact with the rock, which contains a fluid within the grains.
A fluid always flows from high pressure to a lower pressure. If the mud pressure is higher than the pore pressure, the formation fluid cannot enter the well. It remains in the formation and there is no risk of blowout.
During the drilling process, the mud is in contact with the rock, which contains a fluid within the grains.
The mud pressure has to be lower than the frac pressure, in order to avoid the rock being fractured. To conclude, keep in mind that the mud has to be designed so that the mud pressure belongs to the interval between the pore pressure and the frac pressure. This interval is called the mud window.
Both Ppore, in red, and Pfrac, in blue, can be plotted on a (pressure/depth) graph.
The mud pressure has to be in the yellow zone, which is called the mud window. For each lithology to be drilled, the mud has to be well adapted to its characteristics. The well is therefore drilled in different phases, each phase corresponding to a new mud to be used.
At the end of a phase, a casing is installed and cemented to protect the well from the formation already drilled and to finalize the well walls.

The definition of each of these phases is called the well design.
A typical well design is as follows:
1. The first tubular is the conductor pipe installed by the civil engineer before the rig
arrives on site.
2. The next phases are drilled using the rotary drilling technique.
3. The surface casing maintains the unconsolidated surface formations and protects the groundwater.
4. The intermediate casing protects the well from the formations or fluid which could prevent the drilling process from continuing.
5. The last casing is the production casing which allows the reservoir to be isolated.
6. During the last phase the well enters the reservoir.
When a well is an exploration well, designing is much more difficult , due to a lack of measurements and information to describe the subsurface. The mud window is not accurately known. Such uncertainties have to be taken into consideration in the drilling process.
When a well has to be drilled in a new region, there are many uncertainties about the data, including that related to the pore and frac pressure profiles. On the contrary, when a development well is planned, it benefits from data from the surrounding wells already drilled. In this case, the pressure profiles are well known, and the uncertainties are lower.
Let’s mention that the trajectory of a well can be vertical, deviated, or horizontal. The choice of the trajectory depends on the location of the rig, the location of the target of the well when it enters the reservoir, and the trajectory of the drain in the reservoir itself. These two last data are defined and given by the reservoir engineer to the driller.

How a well is drilled in practice? Mechanically, a vertical force applied on the drilling bit (the weight on bit), together with a movement of rotation, generates down to the bit the power necessary to destroy the rock. A hook hangs up the drill string, which is composed of several tubulars screwed together, and, at the bottom, there is a drilling bit.
Both the weight on bit and the rotation per minute, which is given by the rotary table located at the rig floor, are controlled by the driller to maximize the rate of penetration of the bit.
Their optimization depends on several parameters, including the kind of rock to be drilled: the regulation of the hook height controls the part of the total weight of the drillstring applied on the bit, the rotation is often given by a rotary table located at the rig floor.
The mud circuit is combined to the mechanical part of the system.
Firstly, the pump sends the mud at high pressure through the discharge line, the stand pipe, the rotary hose and the top drive, into the pipes.
The mud flows in the drill string down to the bit and catches the small pieces of broken rock, the cuttings, to transport them up to the surface in the space between the drill string and the well walls.

At the surface, the cuttings, the sand and the silt are removed from the mud through shale shakers and other systems.
The mud can be sent to the tanks in order to be re-injected.
In order to control the well in case of blowout, a Blow Out Preventer is installed between the top of the well and the rig floor. This BOP stack is composed of an annular BOP and different rams able to close the well in case of emergency. The size of the BOP is adapted to the maximum pressure that can be encountered during the drilling process.

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