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5.1. Reservoir Engineering

Reservoir engineering is a branch of petroleum engineering, typically concerned with maximizing the economic recovery of hydrocarbons from the subsurface.

Of particular interest to reservoir engineering is monitoring of existing fields and optimization of production and injection rates. Other activities include production forecasting, well testing, well drilling and workover planning, economic modeling, PVT analysis of reservoir fluids and numerical reservoir modeling - simulation modeling, i.e. the conduct of reservoir simulation studies to determine optimal development plans for oil and gas reservoirs. Reservoir engineering typically uses analytical and empirical techniques to perform this work, including decline curve analysis, material balance modeling, and inflow/outflow analysis.

Activities

1.Прочитайте текст и выпишите все ключевые слова и словосочетания по теме «Reservoir Engineering».

2.Опираясь на ключевые слова, сделайте краткое устное сообщение о том, какие проблемы решают специалисты в области разработки нефтяных и газовых месторождений.

3.Найдите в тексте английские эквиваленты для следующих выражений: разработка месторождений газа и нефти, извлечение нефти,

скорость закачивания, прогноз производительности пласта, испытания скважины, бурение скважин, анализ зависимости: давление-объем-

температура, кривая падения добычи, пластовое моделирование.

4.Попросите вашего партнера ответить на вопросы.

1.What does reservoir engineering deal with?

2.What makes possible to determine optimal reservoir engineering?

3.What types of analyses are used in reservoir engineering?

5.Прочитайте текст и выполните учебный перевод.

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5.2. Work of Reservoir Engineers

Reservoir engineers work to optimize production of oil and gas via proper well placement, production levels, and enhanced oil recovery techniques. Reservoir engineers study the behaviour and characteristics of a petroleum reservoir to determine the course of future development and production that will maximise the profit.

They gather data from various sources to produce a development plan, using computer models to simulate production conditions. This enables them to identify risks and forecast the likely outcome of events and possible interventions, to maximise reservoir yields and performance.

Decisions on the numbers and sites of wells depend on these models, as do development programmes, such as commissioning additional wells or recommending the employment of enhanced recovery technologies (e.g. water injection to simulate flow). Reservoir engineers monitor and update the model as necessary during the life cycle of the reservoir.

Typical work activities include:

estimating the potential of a reservoir in order to determine its value and likely investment required;

simulating fluid flow (running computer models that simulate fluid flow through the field over time);

analysing the properties of fluid to predict fluid behaviour and various physical effects, and investigate gas cycling schemes;

liaising with laboratories to get oil and water measurements;

identifying in-fill well locations to maintain oil rate;

investigating enhanced oil recovery options, e.g. by using water injection;

providing economic data to evaluate various aspects of commercial potential;

working closely with operational staff, and with other professionals, such as geologists, geophysicists and petrophysicists.

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Reservoir engineers play a central role in field development planning, recommending appropriate and cost effective reservoir depletion schemes such as waterflooding or gas injection to maximize hydrocarbon recovery.

Activities

1.Прочитайте текст и скажите, отражена ли его главная тема в заголовке. Если да, то, какие лексические средства в тексте способствуют

еереализации.

2.Прочитайте текст и выпишите основные слова, характеризующие трудовую деятельность специалиста в области разработки нефтяных и газовых месторождений.

3.Изучите содержание текста и ответьте на вопросы:

1.What are the main tasks of reservoir engineers?

2.What technique do they use to enhance oil and gas production?

2.How do reservoir engineers forecast production level?

3.What is their development plan based on?

4.What decisions are taken to increase reservoir outcome?

5.What technique is involved to simulate fluid flow?

6.Why do reservoir engineers study properties of fluid?

7.What helps to maintain oil rate?

8.What schemes do the reservoir engineers develop to increase oil recovery?

4. Подтвердите или опровергните высказывания вашего партнера,

используя фразы: That’s right, you are right, to my mind, in my opinion, I agree with you, I think so, as is known, I can say that, I do not agree, on the contrary, I think you are wrong, according to the text.

Образец: Reservoir engineering is a branch of petroleum engineering. –

That’s right. As is known, it is a subset of petroleum engineering.

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1.Reservoir engineers evaluate underground geologic structures to find oil and gas fields.

2.Reservoir engineers deal with maximizing the economic recovery of hydrocarbons from the surface.

3.Computer simulation allows reservoir engineers to identify risks and enhance reservoir yields.

4.The model of a well can not be changed during the life cycle of the reservoir.

5.Typical work activity of a reservoir engineer includes mine planning and exploration for new ore reserve.

6.Reservoir engineers use water injections to estimate the potential of a reservoir.

5. Прочитайте текст и скажите, в какой части можно поместить данную ниже дополнительную информацию:

Reservoir engineers determine the fluid and pressure distributions throughout the reservoir, the natural energy sources available, and the methods most useful in recovering the maximum amount of oil or gas from the reservoir. The reservoir engineer may develop complex computer-based mathematical programs to model the fluid flow and formation pressures. Reservoir engineers are responsible for estimating the amount of oil or gas that can be recovered from a reservoir. Making good estimates of recoverable resources is crucial to a company’s financial position since future recovery is a measure often used by bankers and financial analysts of a company's borrowing power and future worth.

6. Изучите внимательно текст дополнительной информации и выпишите новые слова, описывающие характер работы специалиста в области разработки нефтяных и газовых месторождений.

7. Опираясь на записи заданий 2 и 6, сделайте краткое сообщение о должностных обязанностях разработчика нефтяных и газовых месторождений.

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5.3. Technology of Petroleum Reservoir Engineering

The technology concerns the prediction of the optimum economic recovery of oil or gas from hydrocarbon-bearing reservoirs. It is an eclectic technology requiring coordinated application of many disciplines: physics, chemistry, mathematics, geology, and chemical engineering.

Originally, the role of reservoir engineering was exclusively that of counting oil and natural gas reserves. The reserves - the amount of oil or gas that can be economically recovered from the reservoir - are a measure of the wealth available to the owner and operator. It is also necessary to know the reserves in order to make proper decisions concerning the viability of downstream pipeline, refining, and marketing facilities that will rely on the production as feedstocks.

The scope of reservoir engineering has broadened to include the analysis of optimum ways for recovering oil and natural gas, and the study and implementation of enhanced recovery techniques for increasing the recovery above that which can be expected from the use of conventional technology.

The amount of oil in a reservoir can be estimated volumetrically or by material balance techniques. A reservoir is sampled only at the points at which wells penetrate it. By using logging techniques and core analysis, the porosity, oilsaturated interval and the average oil saturation for the interval can be estimated in the immediate vicinity of the well. The oil-saturated interval observed at one location is not identical to that at another because of the inherent heterogeneity of a sedimentary layer.

It is therefore necessary to use statistical averaging techniques in order to define the average oil content of the reservoir (usually expressed in barrels per net acre-foot) and the average net pay. The areal extent of the reservoir is inferred from the extrapolation of geology and fluid content as well as the drilling of dry holes beyond the productive limits of the reservoir. The definition of reservoir boundaries can be heightened by study of seismic surveys, particularly 3-D surveys, and analysis of pressure buildups in wells after they have been brought on production.

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The overall recovery of crude oil from a reservoir is a function of the production mechanism, the reservoir and fluid parameters, and the implementation of supplementary recovery techniques. In general, recovery efficiency is not dependent upon the rate of production except for those reservoirs where gravity segregation is sufficient to permit segregation of the gas, oil, and water. Where gravity drainage is the producing mechanism, which occurs when the oil column in the reservoir is quite thick and the vertical permeability is high and a gas cap is initially present or is developed on producing, the reservoir will also show a significant effect of rate on the production efficiency. Reservoir engineering expertise, together with geological and petrophysical engineering expertise, is being used to make very detailed studies of the production performance of crude oil reservoirs in an effort to delineate the distribution of residual oil and gas in the reservoir, and to develop the necessary technology to enhance the recovery.

Well testing broadly refers to the diagnostic tests run on wells in petroleum reservoirs to determine well and reservoir properties. The most important well tests are called pressure transient tests and are conducted by changing the rate of a well in a prescribed way and recording the resulting change in pressure with time.

The information obtained from pressure transient tests includes estimates of

(1) unaltered formation permeability to the fluid(s) produced in the well; (2) altered (usually reduced) permeability near the well caused by drilling and completion practices; (3) altered (increased) permeability near the well created by deliberately stimulating the well by injecting either an acid that dissolves some of the formation or a high-pressure fluid that creates fractures in the formation; (4) distances to flow barriers located in the area drained by the well; and (5) average pressure in the area drained by the well. In addition, some testing programs may confirm hypothesized models of the reservoir, including important variations of formation properties with distance or location of gas/oil, oil/water, or other fluid/fluid contacts.

Pressure transient tests are usually interpreted by comparing the observed pressure-time response to the predicted response by a mathematical model of the

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well/reservoir system. Graphical techniques are used to calculate permeability. More sophisticated graphical techniques involve matching changes in pressure to preplotted analytical solutions (type-curve matching). Regression analysis is used to match observed pressure-time data to mathematical models. Although analytical solutions are being found for more and more complex reservoir models each year, many reservoirs are still so complex that their behavior cannot be described accurately by analytical solutions. In such cases, finite-difference approximations to the governing flow equations can be used in commercial reservoir simulators, the reservoir properties treated as unknowns, and properties found that fit the observed data well.

Reservoir behavior can be simulated using models that have been constructed to have properties similar either to an ideal geometric shape of constant properties or to the shape and varying properties of a real (nonideal) oil or gas reservoir.

For application to petroleum reservoirs, it is necessary to predict the simultaneous flow behavior of more than one fluid phase having different properties (water, gas, and crude oil). The permeability, the relative permeability, and the density and viscosity of each phase constitute its transport properties for calculating its flow. The relative permeability is a factor for each phase (oil, water, gas) which, when multiplied by the permeability for a single phase such as water, will give the permeability for the given phase. It varies with the volume fraction of the pore space occupied by the phase, called the saturation of the given phase. Generally, the relative permeability of the water phase depends only on its own saturation, and likewise for the gas phase. The relative permeability of the oil phase is a function of the saturations of both gas and water phases.

Activities

1. Прочитайте текст и выберите группу слов и словосочетаний,

отражающих тему «Technology of Petroleum Reservoir Engineering».

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2. Выпишите из текста все возможные словосочетания со словом

reservoir.

3. Прочитайте текст и выпишите из каждого абзаца ключевые слова.

Опираясь на записи, озаглавьте каждый абзац.

4. Найдите соответствия английских и русских словосочетаний:

5.Прочитайте текст и скажите, почему технологию разработки месторождений нефти и газа называют эклектической. Приведите аргументы.

6.Прочитайте текст и сделайте краткое сообщение о том, как со временем менялись задачи, выполняемые разработчиками нефтяных и газовых месторождений.

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7.Найдите в тексте абзацы, в которых описывается процесс испытания скважин с переменным давлением. Зафиксируйте в форме тезисов, с какой целью проводятся такие испытания и в чем заключается их суть.

8.Попросите вашего партнера ответить на вопросы.

1.What does the technology of petroleum reservoir engineering deal with?

2.Why is it called an eclectic technology?

3.What was reservoir engineering originally aimed at?

4.Why are the reserves required to be well studied?

5.What additional tasks does reservoir engineering involve?

6.What techniques are used to estimate the amount of oil in a reservoir?

7.What is the average oil content measured in?

8.What does the areal extent of the reservoir depend on?

9.What techniques are used to determine the reservoir boundaries?

10.What is general oil recovery governed by?

11.When does the reservoir show high production efficiency?

12.What is necessary for a detailed study of crude oil reservoirs?

13.What is the study of the production performance aimed at?

14.What are the wells tested for?

15.How are the pressure transient tests carried out?

16.What do the pressure transient tests inform about?

17.What comparison is a pressure transient test based on?

18.What are graphical techniques used for?

19.What are mathematical models of reservoir aimed at?

20.What characteristics are used in simulation of reservoir behavior?

21.What types of fluids are studied to predict the simultaneous flow behavior?

22.What determines transport properties of various fluids?

23.What is a relative permeability calculated for?

24.What does a relative permeability depend on?

25.What is the relative permeability of oil phase based on?

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9. Прочитайте интервью с Беном Стоун,

инженером компании BHB Billiton, отвечающим за разработку месторождений нефти и газа. Компания

BHB Billiton успешно осуществляет свою деятельность в течение многих лет благодаря высокой компетентности и большому опыту работающих в ней специалистов.

Why did you choose this profession?

There are some reasons I chose to become a reservoir engineer.

Firstly, I have always been interested in technical stuff. Secondly, working for an international company provides possibility to travel or even live abroad for some years. The third reason is above average starting salaries for graduates. And the fourth, a complex problem-solving which requires integration of many different disciplines - a great way of using technical skills in a commercial context.

Do find your specialization prospective?

Sure, there are great job prospects for a reservoir engineer. A large percentage of reservoir engineers are approaching retirement age, and graduate numbers are generally low.

Could you describe your job?

My job has nothing to do with building water reservoirs! Oil reservoirs are areas of porous rocks which contain oil - so reservoir engineers take data from geoscientists and other engineers to plan how to develop oil reservoirs by calculating or simulating how oil flows in those porous rocks towards wells.

What related specialists do you work with?

Reservoir engineering is the link between drilling engineers (drill wells), petroleum engineers (look after wells – how the oil comes up the well to surface facilities/pipelines), geologists (look at the reservoir rock, make geological computer models of the reservoir), geophysicists (evaluate seismic and other measurements to determine rock properties and structures) and commercial analysts (transfer predicted oil profiles into profit predictions).

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