Unit 8 Part II
UNIT 8
Part II
Words to the text “Well logging”
cuttings n. / буровой шлам, обломки выбуренной породыsample n. / образец
I’d like to see some samples of your work.
integral adj. / неотъемлемый, существенный
Vegetables are an integral part of our diet.
saturation n. / насыщение, насыщенность
water saturation, saturation point
aid v. / помогать, способствовать
This technique aids in geophysical interpretation
complete v. / заканчивать, завершать
The building took two years to complete
complete adj. / полный, завершенный
a complete edition of Shakespeare’s plays
procedure n. / процедура
A test is a procedure intended to establish the quality, performance or reliability of something.
wireline n. / проволочный кабель
integrate v. / объединять (в единое целое)
Transport planning should be integrated with energy policy.
drill string / бурильная колонна
retrieve v. / брать, вернуть обратно; извлекать информацию
to retrieve information from a computer
infer v. / заключать, делать вывод
A lot can be inferred from these statistics.
quantify v. / определять количество
The damage caused in the industry is difficult to quantify.
curve n. / кривая (диаграмма)
The curve illustrates cost growth.
case v.
casing n. / крепить (скважину) обсадными трубами
a cased well
обсадная колонна
Casing is a steel pipe.
resolution n. / разрешающая способность
Resolution is a power of a tool to give a clear picture.
advance n. / продвижение, прогресс
advances of science.
The country has made great advances.
Ex.1. Read the text “Well logging” and find English equivalents of the following word combinations:
возможное существование углеводородов; внимательно следит; эксплуатация скважин; показания снимаются; скважинные исследования во время бурения; многожильный кабель; разработка пласта; межскважинная корреляция.
Well logging
If all the surface and subsurface information indicates a strong hydrocarbon potential an exploration well may be drilled. As drilling progresses, a geologist keeps a watchful eye on the underground rock and fluids it contains by cutting examination, core samples, well logs, and test results.
A well log is a graphical presentation of physicochemical characteristic of the formation measured in a borehole as a function of depth.
Well logging is an integral part of formation evaluation. Borehole measurements provide the largest source of data. These are used with core and fluid data to determine reservoir depth and thickness, porosity, lithology, hydrocarbon saturation, and permeability. Logging information also aids in drilling, completion, and operation of wells; geological and geophysical exploration; and development of reservoir models for efficient production.
The procedure for each log is basically the same. It consists of lowering a “logging tool”(sonde) on the end of a wireline into a well to measure the rock and fluid properties of the formation. The readings are taken at the surface. In LWD (logging while drilling) instead of sensors being lowered at the end of wileline cable, they are integrated into the drill string. The measurements are made while the well is being drilled. Data are recorded downwhole and retrieved when the drill string is removed from the hole. As well logging methods usually do not measure directly the primary rock properties needed for reservoir engineering purposes (porosity, permeability, fluid saturation, fluid mobility, etc.), these are to be inferred from borehole measurements of electromagnetic, acoustic and nuclear properties. An interpretation of these measurements is then made to locate and quantify potential depth zones containing oil and gas. Among the most common wireline logs are electric, radioactivity and acoustic logs.
The first well log – electrical log – was designed in 1927 by the Shlumberger brothers. At that time only a single resistivity (the property related to porosity and permeability) curve was obtained in each well, but it is very useful for well-to-well correlation.
Today wireline logging of high resolution is cheaper, faster, and more accurate than ever due to advances in technology over the past decades. Logging techniques are useful not only for evaluating exploration wells but also for planning the best way to produce the oil or gas in a development well.
Ex.2. Match synonyms in A and B.
A B
1. indicate / 1.progress2. potential / 2.define
3. exploratory well / 3.estimation
4. characteristic / 4.show
5. a well / 5.extract
6. evaluation / 6.uncased well
7. determine / 7.property
8. aid / 8.aim
9. complete (v.) / 9.possible
10. wireline / 10.borehole
11. purpose / 11.tool
12. subdivide / 12.wild cat
13. accurate / 13.fulfil
14. advance / 14.help
15. technique / 15.precise
16. produce / 16.classify
17. open hole / 17.cable
Ex.3. Say which word doesn’t match.
1. estimate –evaluate – assess- evolution
2. well – boring – wellbore – borehole
3. enable – help – hope – aid
4. progress – operation – process – procedure
5. similar – identical - some – same
6. pore – hole – void – voice
7. purpose – objective – object – aim
8. layer – stratum – bed – lower
9. investment – investigation – survey – study
10. exact – account – precise – accurate
Ex.4. Match A and B.
A B
1.development well / 1.an instrument that automatically transmits information about its surroundings underground, in the atmosphere, etc.2.core / 2.a well that produces oil
3.well logging / 3.a steel pipe placed in a well to prevent the wall of the hole from caving in, to prevent seepage of fluids.
4.borehole / 4.a wellbore in which casing has been run.
5.formation evaluation / 5.a cylindrical sample of rock.
6.permeability / 6.recording of information about subsurface
geologic formations.
7.well completion / 7.a hole drilled by a bit.
8.sonde / 8.determination of the ability of a borehole to produce petroleum.
9.casing / 9.activities and methods of preparing a well for the production.
10.cased hole / 10.a measure of the ease with which a fluid flows through the connecting pore space of a rock.
Ex.5. Explain the meaning of the following terms.
1. uncased well
2. logging tool
3. wireline measurements
4. drill cuttings
5. electric logging
6. radioactivity logging
7. acoustic logging
8. exploratory well
9. well log
Ex.6. Translate the following sentences into Russian.
1. Most rock is completely saturated with water.
2. Cased wells or opened holes with all types of fluid can be logged without difficulty with radioactive logging.
3. Velocity logs must be run in open hole only, and the hole must contain a liquid.
4. A geologist can test the cuttings to determine whether they contain hydrocarbons.
5. Well logs not only indicate the presence of oil, they also aid to quantify the reservoir.
6. Water saturation is the fraction of the pore space occupied by water.
7. In petroleum production completion is the process of making a well ready for production or injection.
8. The simulation model computes the saturation change of three phases and pressure of each phase.
9. In cased holes completion involves running casing down through the production zone, and cementing it in place.
10. An operator probably would not decide to complete or abandon a well using only information from cuttings.
11. Exploration geophysics is the applied branch of geophysics which uses surface methods to measure the physical properties of the subsurface to detect or infer the presence and position of ore minerals, hydrocarbons, geothermal reservoirs, ground water reservoirs, and other geological structures.
12. Careful examination of cuttings can indicate whether the well is likely to produce.
13. Formation evaluation is the process of interpreting a combination of measurements taken inside a wellbore to detect and quantify oil and gas reserves in the rock adjacent to the well.
14. Gas content data are sufficiently accurate to be used as a tool to make exploratory and well completion decisions.
15. The same procedures were followed in all core sample examinations.
16. Detection of gases in the mud is essential for complete evaluation of the hydrocarbon potential in the formation and for improved drilling safety.
17. The well-site geologist’s prime objective is to identify the hydrocarbon-bearing zones and determine their characteristics.
18. The shale measurements are indicated versus (в зависимости, по отношению) depth.
Ex.7. Translate the sentences into English.
1. В настоящее время насчитывается более 30 методов ГИС.
2. ГИС – комплекс физических методов, используемых для изучения горных пород в околосвкажинном и межскважинном пространстве.
3. ГИС – измерение некоторых величин (свойств) горных пород, пересеченных скважиной.
4. В задачу ГИС входит корреляция разрезов скважины, определение литологии и глубины залегания пройденных скважиной пород; выделение и оценка запасов; контроль за разработкой месторождений.
5. Методы ГИС позволяют определить остаточную (residual) и текущую нефтегазонасыщенность продуктивных горизонтов.
6. ГИС дает возможность по всей длине скважины определить литологический состав, мощность пород, выделить интервалы залегания продуктивных горизонтов, установить коллекторские свойства в горных породах.
7. Существуют различные виды зондов – установок для измерения электрических свойств, сопротивления, проводимости.
8. Геофизические датчики опускаются в скважину на кабеле, и их сигналы передаются на поверхность и регистрируются наземной аппаратурой.
9. Электрический каротаж – способ измерения удельного сопротивления пород.
10. ГИС в открытом стволе включает в себя скважинную сейсморазведку, замер пластового давления, отбор проб (керноотбор), а также оценку пласта.
11. ГИС в обсаженной скважине – комплекс работ для оценки фильтрационных свойств пласта, контроль качества цемента и комплекс радиоактивных методов.
12. Сервисные компании (service companies) нефтегазовой отрасли предлагают программные продукты для геологоразведки и добычи, а также услуги по созданию и поддержке информационной инфраструктуры и управлению информацией.
Ex.8. Answer the following questions.
1. How does a geologist (geophysicist) control the underground rock and fluids?
2. What is a well log?
3. What information does a well logging provide?
4. Why is logging information of vital importance?
5. What is well logging procedure?
6. Where are measurements made and taken?
7. How do you understand LWD?
8. What are the most common logging methods?
9. Do logging methods provide direct measurements of rock properties?
10. How can logging methods be subdivided?
11. How can you characterize wireline logging?
Ex.9. Read the text and make a summary.
The Spirit of Log Interpretation
Log interpretation began as soon as logs were systematically run, in the late1920s. Soon afterwards, research work in the USSR and by western oil companies developed the all-important relationships between resistivity, porosity and saturation. By the 1950s, interpretation experts had developed the science and art of log interpretation to a high degree of sophistication.
In that precomputer age, the log analyst would scan a few resistivity curves, perhaps also a microlog, a gamma ray curve and one of the first so-called porosity logs – and rapidly “interpret” the data into oil, gas and water zones. Later, the combination of shallow and deep resistivity lgging data and the addition of compensated density and neutron logs allowed easier detection of gas zones. Seen through the eye of an expert analyst, the logs would first guide attention to zones of interest, and then prompt basic quantitative interpretation at a few depths.
This art was not to be radically affected by the first generation computers. True, the machines allowed more accurate algorithms, but they could not replace the eyes of the log expert. Quality interpretation remained dependent on the selection of parameters made by the log analyst.
Computers especially could not resolve outstanding interpretation issues in complex, heterogeneous formations, thinly laminated turbidites or fractured formations. That took new downhole measurement technology. In 1967, the borehole televiewer provided a radically new direction by providing the first acoustic images of the borehole wall. But not until the 1980s was reliable measurement technology developed – first for resistivity images and most recently for ultrasonic images.
Borehole images created a revolution in log interpretation. Previously invisible fractures, voids, heterogeneities and thin beds could at last be seen and therefore better interpreted using existing logs. Other innovations, possibly just as important, are coming. Interpretation needs both computer power and new technology. But let us not forget its true spirit. The truth lies with the measurements and deep understanding of what they may imply.
Ex.10. Agree or disagree with the following statements and give your reasoning.
1. Borehole measurements provide the most complete subsurface information.
2. The procedure for each logging method is different.
3. Well logging provides direct measurements of porosity, permeability, saturation, etc.
4. Well logging is run only in open holes.
5. Logging aids to evaluate exploration wells.
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Petroleum Geology