Using a vibrator truck

• A vibrator truck acts as the source of sound energy for a land-based seismic survey.

• A group of detectors called geophones is placed in a line or other pattern.

• Several groups of receivers are often used to form a spread.

• A cable is laid between the geophones and a recording truck where the data is recorded.

• The vibrator truck is driven to the shot point, where the sound impulses will be emitted.

• The correct position for the truck is where the angle of incidence equals the angle of reflection).

• A pad or base-plate is lowered from the truck to the surface of the ground until it carries the weight of the truck.

• The hydraulic motors are then activated to enable the weight of the truck to shake the ground.

• This continues for a period of between ten and twenty seconds, and is known as a sweep.

• Both unwanted noise, such as from traffic or wind, and the wanted signal, are picked up by the geophone. The two must be distinguished in the recording truck.

• Explosives, or a thumper truck, can also be used as a seismic source on land.

• At sea, obviously, a vibrator truck cannot be used. The most common alternative is an array of air guns towed behind a seismic ship.

• The signals are received by hydrophones connected to a cable, the streamer.

Task 5. Read and translate the following passage:

Задание 5. Прочитайте и переведите следующий отрывок:

Principles of seismology

Seismology is based on the mathematical principles of acoustics. A sound wave is emitted through a rock formation.

When it reaches a particular boundary in the formation, it is reflected, and the total time it takes to reach the receiver is measured. This is called its travel time. The amplitude of the seismic echo off the top of a surface depends primarily on the contrast in acoustic impedance (sound velocity multiplied by density) between the upper and lower rock layers that form the surface. The greater the contrast, the larger the reflection. The percentage of seismic energy reflected is called the reflection coefficient. Typical sedimentary layers have a reflection coefficient of between 2 and 4%. Gas has a very slow velocity and, if the layer is overlain by a seal, the acoustic impedance contrast will produce an echo of about 16% of the seismic energy, called a bright spot. This is often an indicator of the presence of hydrocarbons. Another type of direct hydrocarbon indicator is a flat spot, which is a level, flat seismic reflector in a petroleum trap produced by rock layers that are not flat, such as an anticline.

Task 6. The following sentences contain a number of factual mistakes. Amend or rewrite the sentences in the spaces provided so that they make sense:

Задание 6. Следующие предложения содержат смысловые ошибки. Исправьте и перепишите предложения так, чтобы они имели смысл:

1) The greater the impedance of the formation, the shorter the travel time of the sound wave.

2) Acoustic impedance is calculated by dividing sound velocity by density.

3) The smaller the contrast in acoustic impedance, the greater the reflection.

4) Typical sedimentary layers normally have a very high reflection coefficient.

5) Gas increases the velocity of sound passing through it.

6) It is easier to tell the difference between oil and rock than between gas and rock.

7) A bright spot is where the contrast in impedance is very low.

8) A flat spot shows a petroleum trap in a flat layer of rock.

Task 7. Speak on seismic exploration.

Задание 7. Расскажите о сейсморазведке на английском языке.

Практическое занятие 22

Mud Logging

Анализ проб бурового раствора

mud loggin g анализ проб бурового раствора

well log каротажная диаграмма

rate of penetration механическая скорость бурения

lithology литология

chromotograph хроматограф

plotting нанесение данных на карту или график

pixler ratios показатель, коэффициент

instrumentation контрольно-измерительная аппаратура

submit представлять

lag интервал, время

cased-hole logging каротаж в обсаженном стволе скважины

openhole logging каротаж необсаженной скважины

core батолит, буровая колонка

rock sample образец горной породы

sonde зонд

wireline well log каротаж с применением талевого каната

Task 1. Read and translate the text:

Задание 1. Прочитайте и переведите текст:

Mud log diagram

The ROP (rate of penetration) is represented by the black line on the left side of the log. The further to the left the line goes, the faster the rate of penetration. On this mud log, ROP is measured in feet per hour, but on some older, hand-drawn mud logs, it is measured in minutes per foot. Faster rates are an indication of softer rock formations.

The porosity is represented by the blue line furthest to the left of the log. It indicates the pore space within the rock structure. Notice how far to the left the porosity goes where all the sand (in yellow) is. This indicates that the sand has good porosity. Porosity is not a direct or physical measurement of the pore space, but rather an extrapolation from other drilling parameters and therefore not always reliable.

The lithology is represented by the cyan, grey/black and yellow blocks of color. Grey/black = shale and yellow = sand. More yellow represents more sand identified at that depth.

The lithology is measured as a percentage of the total sample, as visually inspected under a microscope. These are only a fraction of the different types of formations that might be encountered.

The gas is represented by the green line and is measured in units of ppm (parts per million) such as the quantity of total gas, but does not represent the actual quantity of oil or gas the reservoir contains. The squared-off dash-dot lines just to the right of the sand (in yellow) and left of the gas (in green) represents the heavy hydrocarbons detected.

Task 2. Read the extract from a mud logging company's website promoting their Data Acquisition System. Underline the key elements of the digital recording service described on the website:

Задание 2. Прочитайте информацию о новой системе сбора данных, предложенную на сайте компании, которая занимается анализом проб бурового раствора. Подчеркните ключевые элементы цифровой обработки данных:

Alternative systems

We have developed one of the most dependable and accurate Computer Data Acquisition Systems in the industry. Depth, Rate of Penetration, Total Gas and Chromatograph component gases are all read and plotted by the computer. Plotting of component gases by the computer is a revolutionary development that gives an accurate depiction of Show zone character and provides a tremendous database to utilize Pixler Ratios to evaluate re wellbore.

For further information the DAS, visit http://www.pmles.com/live-well-data-247

Task 3. Here are two extracts from a company website advertising their mud logging services. Fill in the blanks using the words in the box:

Задание 2. Прочитайте рекламу услуг компании по анализу проб бурового раствора. Заполните пропуски словами, данными в рамочке:

compatibility, cuttings, instrumentation, interpretations, loggers, manned, remotely, reports, submitted, tours, trailer, zone of interest