VII. Render the text about natural gas in the oral form. Unit 3 Oil well

I. Study and learn the vocabulary list:

percussively ударами

cable-tool drilling ударно-канатное бурение

lithology литология

casing обсадные трубы, обсадная колонна || крепление (скважины) обсадными трубами

drilled wellbore пробуренная скважина

drilling fluid буровой раствор; промывочная жидкость

perforation перфорация; перфорационное отверстие

abandonment закрытие; ликвидация скважины (по техническим причинам)

appraisal well оценочная скважина, параметрическая скважина

wildcat well скважина, заложенная без предварительного геолого-геофизического обоснования; опорно-геологическая скважина; разведочная скважина

oil terminal базисный склад, перевалочный склад для нефти и нефтепродуктов

workover rig установка для капитального ремонта скважин

II. Look at the title and the picture and say what information the text gives. Read the text attentively for the details and be ready to discuss it with your groupmates.

(Fig. 3. Oil well.)

A. The history of an oil well

An oil well is a term for any perforation through the Earth's surface designed to find and release both petroleum oil and gas hydrocarbons.

The earliest oil wells were drilled percussively (cable-tool drilling), that is, holes were drilled simply by hammering at the earth. Very soon, the limited depths, which this method could attain, meant that rotary drilling was introduced. Modern wells drilled using rotary drills can achieve lengths of over 12,000 meters / 38,000 feet.

Until the 1970s, most oil wells were vertical (or, more specifically, were supposed to be vertical — deviations introduced by different lithology and mechanical imperfections meant that most wells were at least slightly deviated). However, modern technologies (directional drilling) allow strongly deviated wells which can, given sufficient depth, actually become horizontal. This is of great value as the reservoir rocks which contain hydrocarbons are usually horizontal, or sub-horizontal. A well, therefore, which passes along a reservoir (rather than through it, as a vertical well must) can tap a larger volume with a much larger surface area (and thus a correspondingly higher production rate). Using deviated and horizontal drilling, it has also become possible to reach reservoirs several kilometers away from the drilling place, allowing to produce hydrocarbons from underneath environmentally sensitive areas or offshore close to the coast line.

B. Life of a well

The creation and life of a well can be divided up into four segments: 1) drilling; 2) completion; 3) production; 4)abandonment.

1. Drilling

The well is created by drilling a hole (5 to 30 inches wide) into the earth with an oil rig turning a drill bit. After the hole is drilled, a metal pipe slightly smaller than the hole size (called a “casing”) is run into the hole. The outside of the casing is then bonded and secured to the hole with cement. The casing provides structural integrity to the newly drilled wellbore in addition to isolating potentially dangerous high pressure zones from each other and from the surface.

With these zones safely isolated and the formation protected by the casing, the well can be drilled deeper (into potentially more-unstable and violent formations) with a smaller bit, and also cased with a smaller size casing. Modern wells often have 2-5 sets of subsequently smaller hole sizes drilled inside one another, each cemented with casing.

To start drilling, the drill bit, aided by rotary torque and the compressive weight of drill collars above it, breaks up the earth. Then drilling fluid is pumped down the inside of the drill pipe and exits at the drill bit and aids to break up the rock, as well as clean, cool and lubricate the bit. The generated rock "cuttings" are swept up by the drilling fluid as it circulates back to surface outside the drill pipe. The pipe or drill string to which the bit is attached is gradually lengthened as the well gets deeper by screwing in several 30' joints of pipe at surface.

This process is all facilitated by a drilling rig which contains all necessary equipment to circulate the drilling fluid, hoist and turn the pipe, control downhole pressures, remove cuttings from the drilling fluid, and generate onsite power for these operations.