Petroleum engineering. Нефтегазовая инженерия. Учебное пособие

READING

1. Read the text.

Modern Oil Well Drilling

The story of modern oil well drilling began at the start of the industrial revolution. The first modern oil well was drilled in Baku in 1848 to a depth of 69 feet (21 metres). In 1872 the Baku area had so many wells that it became known as the “Black City.” Now wells are drilled for various purposes, e.g. to explore for oil and gas, to appraise an earlier discovery, or to create a development well. Types of rigs have evolved along with the development of science and technology: cable-tool rigs drilled many wells in the past while rotary drilling rigs dominate the industry today. In other words, currently, rotary drilling is the standard oilwell drilling method, with almost all operations being performed by rotary drilling rigs. Depending on the location and geography of a reservoir a variety of rotary drilling rigs may be used. Generally, rotary rigs may be classified as either land rigs (which can be categorized as conventional and mobile) or marine rigs (drillships, semisubmersible rigs, jackup rigs, fixed platforms, etc.). According to the type of operations performed rigs can be broadly classified into exploratory, drilling and workover rigs.

As for drilling techniques, they vary from field to field. Conventional wells are drilled vertically from the surface straight down to the pay zone. However today most wells are drilled using such drilling techniques as horizontal drilling, extended reach drilling and multilateral drilling and which fall into the category of directional drilling techniques. The term directional drilling is a broad term that refers to all activities that are required to design and drill a wellbore to reach a target, or a number of targets, located at some horizontal distance from the top of the hole. In other words, the purpose of directional drilling is to connect the surface location with oil/gas reservoirs that are not located right below it.

Horizontal drilling uses technologies that allow making a turn and drilling horizontally along the pay zone. Extended reach drilling is a directional drilling of very long horizontal wells. Roughly speaking, it is drilling a well horizontally to at least twice its vertical depth. In multilateral drilling a schematic of wellbores (often several from the same drill site) resembles the roots of a plant, which allows operators to branch out3 from the main well to

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tap reserves at different depths. This drastically increases production from a well and reduces the number of wells drilled on the surface.

It should be noted that whatever directional drilling technique is used, it can be done for many reasons, e.g. when the bottomhole location (BHL) is under an obstruction such as a building or lake where rigging up over the required BHL is not possible, or when it is necessary to drill several wells from a fixed place, such as an offshore platform or an onshore drilling island to different BHLs. Some of the applications of directional drilling are:

reaching under a river or lake;

extinguishing an oil fire by drilling from a site some distance away and pumping in mud;

drilling under a city or other occupied place;

undersea drilling from the shore;

offshore drilling from a platform.

Today, drilling or workover rigs, iconic symbols of the oil field, are not always required for drilling, completions or maintenance operations. Increasingly, the coiled tubing technology is used for many well intervention operations and certain drilling applications. Coiled tubing refers to a continuous length of small-diameter steel pipe and related surface equipment as well as associated drilling, completion and workover techniques. Being initially developed for working on producing wells, coiled tubing oil field technology has more recently gained wider acceptance among operators for a wide variety of workover and drilling applications and for its ability to reduce costs.

Once the formation evaluation is done, the operator must decide if the well should be completed as a producing oil or gas well. If the well does not contain hydrocarbons, or not enough to pay for the completion, the well will be plugged and abandoned (P&A). In case a well is commercially viable, it must be completed to allow for the flow of oil or gas. The completion process involves strengthening of the well walls with casing and installing the appropriate equipment to control the flow of oil or gas from the well.

Nowadays drilling has become a specialized and technologically advanced business. The equipment used to drill a well is technically complex (for example, the navigation systems used in directional drilling are as sophisticated as those found on modern jet aircraft or spacecraft), and those who run the equipment must be well trained. Safety training is part of everyday life for all hands on a drilling rig. There are safety meetings at the

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beginning of every tour and before each new part of a job. Outside training, such as helicopter safety training for offshore crews, is also required for drilling personnel.

DEVELOPING PROFESSIONAL VOCABULARY WORKING OUT THE MEANING OF UNKNOWN WORDS

2. The following words in the box are all from the text above. Find them in the text.

rigging viable semi-submersible exploratory multilateral

3. For each word, read the sentence it occurs in and answer the questions.

a)Is the word positive, negative or neutral?

b)Is it a noun, adjective, adverb or verb?

c)Can you think of a word with a similar meaning (synonym) and one with an opposite meaning (antonym)?

READING COMPREHENSION

4. Answer the questions.

1.What are the reasons for drilling?

2.What is the oldest drilling technique?

3.What types of drilling rigs are mentioned in the text?

4.What techniques of well drilling do you know?

5.What is the advantage of multilateral drilling?

6.When are wells completed?

7.What operations does completion involve?

8.When are wells plugged and abandoned?

9.Why is safety training a must for all hands on a drilling rig? How often is it done?

10.How do feet and meters correlate?

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5. Choose the right option.

1.The first modern oil well was drilled in Baku in a) 1848.

b)1746.

c)1946.

2.Today, the most common types of rigs are

a)rotary rigs.

b)cable-tool rigs.

c)both rotary and cable-tool rigs.

3.Conventional wells are drilled using a) vertical drilling

b) horizontal drilling

c) extended-reach drilling

4.Well completion is the

a)first stage of drilling operations

b)intermediate stage of drilling operations

c)final stage of drilling operations

6.Say whether the following statements are true or false. Correct the false ones.

1.Drilling engineers are well paid.

2.Cable-tool drilling is older than rotary drilling.

3.Onshore and offshore rigs do not differ in design.

4.Vertical drilling has developed from horizontal drilling.

5.Horizontal drilling is considered a conventional drilling technology.

6.Directional drilling is the most commonly used drilling technology.

7.Coiled tubing technology is not used offshore.

8.If a well is commercially viable, it is to be completed.

9.Completion process involves strengthening the well with casing.

10.Today, drilling is a much more technologically advanced business than it used to be.

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7. Match the words with their meanings.

8. Fill in the gaps in the sentences with the words given below. evolved whatever tapped strengthened hand personnel continuous conventional run untapped

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1.The new director is likely to make major changes in … .

2.The company has … over the years into a multi-million dollar organization.

3.I joined the firm as a factory … and gradually worked my way up to the top.

4.… oil and gas refers to petroleum, or crude oil, and raw natural gas extracted from the ground by conventional means and methods.

5.Do you know how to … this sort of machinery?

6.Yesterday the pound … against the dollar.

7.Western and central China will experience increasing energy development because they hold many … and fewer … oil and gas fields.

8.She was in … employment until the age of sixty-five.

9.The personnel may take … action if needed.

9. Choose the best option.

1.A producing well / An exploratory well is a well drilled in a proven producing area for the production of oil or gas.

2.An appraisal well / An injection well is an exploratory well drilled to establish the extent and size of a petroleum deposit that has already been discovered by a wildcat well.

3.Cable-tool / Rotary drilling was the first method used to drill a bore

hole.

4.Pay zone / Drill site refers to the rock in which oil and gas are found in exploitable quantities.

5.Rotary rigs / Cable-tool rigs drill the vast majority of wells today, including all medium and deep wells.

6.Jack-up rigs / Semisubmersibles are offshore rigs with retractable steel legs that can be placed on the ocean floor and raise the rig above the water line.

7.Vertical drilling / Horizontal drilling is a conventional type of drill-

ing.

8.Horizontal drilling / Vertical drilling starts with a vertical well that turns horizontal within the reservoir rock.

9.If the well is commercially viable, it is completed / plugged and abandoned.

10.The purpose of safety training / guidance systems is to provide the knowledge necessary to perform job safely.

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WORD BUILDING

10.Form verbs with an opposite meaning adding the prefix disand translate them.

Example:

to agree – соглашаться

to disagree – не соглашаться

1.to cover

2.to appear

3.to place

4.to continue

5.to approve

6.to charge

7.to connect

8.to close

9.to arrange

10.to assemble

11.to mount

12.to join

TRANSLATION

11. Translate the sentences from English into Russian.

1.The National Petroleum Corporation should promote petroleum exploration activities and to appraise existing petroleum discoveries.

2.The small company has evolved into a major chemical producer.

3.The cost of semisubmersibles is generally higher than that of a jackup.

4.Fixed off-shore platforms are best suitable for depths up to about

500 m.

5.A workover is a service on an oil or gas well, requiring interventions in the wellbore itself to correct a problem with the well.

6.Drilling rigs have bigger and taller derricks than workover rigs.

7.Oil industries and governments across the globe are investing in unconventional oil sources due to the increasing scarcity of conventional oil reserves.

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8.Pay zone (or pay, or pay sand) is a reservoir or portion of a reservoir that contains economically producible hydrocarbons. The term derives from the fact that it is capable of “paying” an income.

9.The overall interval in which pay sections occur is the gross pay; the smaller portions of the gross pay that meet local criteria for pay (such as minimum porosity,permeability and hydrocarbon saturation) are net pay.

10.Engineers often use directional-drilling techniques for drilling under rivers, highways, and other obstacles.

11.  Hydrates resemble snowflakes and can clump together (образовывать комки) to form plugs in pipes.

12.  There are many oil reserves around the globe that remain untapped, and explorers continue to discover new fields deep beneath the earth's surface.

13.“Bottom-hole location” means the subsurface point at the greatest measured penetration of a well or a well branch.

14.Rigging up is placing and assembling the various parts of equipment that make up the rig, and preparing the rig for drilling.

12. Translate the text from English into Russian.

Slant Drilling

Slant drilling is a non-vertical form of well drilling typically used in natural gas and oil production. This form of drilling is generally for extracting oil or gas resources that cannot be accessed through traditional vertical drilling. Slant drilling is also employed as a means of protecting sensitive areas of the environment such as wetlands and oceans. This directional drilling also helps to reduce the number of wells and equipment. In some cases, slant drilling provides pressure relief when a vertical well malfunctions.

Natural gas and oil reservoirs are sometimes located beneath inaccessible areas such as lakes, mountains, glaciers, or residential areas. Rather than disturbing the existing landscape, a well is drilled at a 30-45 degree angle to tap into the reservoir from another location. Vertical well production of underground reservoirs can sometimes be very difficult due to their shape. In these instances, slant drilling is required for more efficient removal of oil and natural gas.

Slant drilling also provides many environmental benefits by allowing natural gas and oil production to take place away from delicate ecosystems. This

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type of drilling is especially important in protecting the marine environment near offshore reservoirs. Slant drilling can allow a single offshore drilling rig to gain access to more than 20 wells. This production arrangement reduces the total number of drilling rigs operating in a single body of water and can minimize the risk to the marine environment.

13. Translate the text from English into Russian.

Unconventional Reservoirs

Unconventional reservoirs form in completely different ways to conventional reservoirs, the main difference being that they do not have "traps". This type of reservoir can be driven in a unique way as well, as buoyancy might not be the driving force for oil and gas accumulation in such reservoirs. This is analogous to saying that the oil which can be extracted forms within the source rock itself, as opposed to accumulating under a cap rock. Oil sands are an example of an unconventional oil reservoir.

Unconventional reservoirs and their associated unconventional oil are always changing in their definitions, as they encompass a broad spectrum of petroleum extraction and refinement techniques, as well as many different sources.

Due to how the oil is contained within the source rock, unconventional reservoirs require that the extracting entity function as a mining operation rather than drilling and pumping like a conventional reservoir. This has tradeoffs, with higher post-production costs associated with complete and clean extraction of oil being a factor of consideration for a company interested in pursuing a reservoir. Tailings are also left behind, increasing cleanup costs. Despite these tradeoffs, unconventional oil is being pursued at a higher rate due to the scarcity of conventional reservoirs around the world.

Estimating reserves

After the discovery of a reservoir, a petroleum engineer will seek to build a better picture of the accumulation. In a simple textbook example of a uniform reservoir, the first stage is to conduct a seismic survey to determine the possible size of the trap. Appraisal wells can be used to determine the location of oil-water contact and with it the height of the oil bearing sands. Often coupled with seismic data, it is possible to estimate the volume of an oil-bearing reservoir.

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The next step is to use information from appraisal wells to estimate the porosity of the rock. The porosity, or the percentage of the total volume that contains fluids rather than solid rock, is 20–35% or less. It can give information on the actual capacity. Laboratory testing can determine the characteristics of the reservoir fluids, particularly the expansion factor of the oil, or how much the oil expands when brought from the high pressure and high temperature of the reservoir to a "stock tank" at the surface.

With such information, it is possible to estimate how many "stock tank" barrels of oil are located in the reservoir. Such oil is called the stock tank oil initially in place (STOIIP). As a result of studying factors such as the permeability of the rock (how easily fluids can flow through the rock) and possible drive mechanisms, it is possible to estimate the recovery factor, or what proportion of oil in place can be reasonably expected to be produced. The recovery factor is commonly 30–35%, giving a value for the recoverable resources.

The difficulty is that reservoirs are not uniform. They have variable porosities and permeabilities and may be compartmentalized, with fractures and faults breaking them up and complicating fluid flow. For this reason, computer modeling of economically viable reservoirs is often carried out. Geologists, geophysicists, and reservoir engineers work together to build a model that allows simulation of the flow of fluids in the reservoir, leading to an improved estimate of the recoverable resources.

Reserves are only the part of those recoverable resources that will be developed through identified and approved development projects. Because the evaluation of "Reserves" has a direct impact on the company or the asset value, it usually follows a strict set of rules or guidelines (even though loopholes are commonly used by companies to inflate their own share price). The most common guidelines are the SPE PRMS guidelines, the SEC Rules, or the COGE Handbook. Government may also have their own systems, making it more complicated for investors to compare one company with another.

14. Make the glossary to the text.

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