обсадиа колона, глибина спуску, обважнювач, важкий шпат, офлюсований агломерат, вологий стан, умовна в’язкість, водний розчин, тонка фракція.
§ Гranslate the following sentences into Ukrainian:
In the course of drilling the viscosity of the weighted drilling fluid gradually increases because of a higher concentration of the solid phase at the expense of fine fractions of the drilling breaks and due to coagulating action of salts. To bring down the viscosity the mud fluid is usually diluted with water and treated with a water-loss control agent and, since the density then diminishes a new portion of the weighting material is added to the mud. This results in that a large surplus of the weighted mud accumulate at the drill rig and the consumption of the weighting material and chemical agents greatly increases.
6 Give a summary of Text 1.
7 Speak about density of the drilling fluid and weighting materials.
Unit 13 Oil-Base Drilling Fluids
1 Learn the meaning of the following words, word-combinations and word groups:
adversely, specimen, contaminate, permeability filtrate, prone to, rigidity, crumble, collapse, intercalation, overhaul, closing-in, bitumen, surfactant, paraffin, naphtha, hydrocarbons, resinous, asphalt.ene, dilute, liberate, disintegrate, impair-, flush, curtail.
2 Read Text 1:
Text 1 Oil-Base Drilling Fluids
Mud fluids other than the water-base ones are intended largely for drilling in producing formations, when water-base muds act adversely on the productivity; in core-drill sampling, when there is a need for obtaining rock specimens uncontaminated with the filtrate (to determine the actual presence of oil, the content of connate water and permeability); in piercing argillites and schistous clays prone to lose their rigidity and to crumble (or collapse) under the effect produced by the water-base mud filtrate; in sinking high- temperature (hot) wells and, not infrequently, in cases of high coefficients of the formation pressures abnorma ity, when it becomes difficult to keep in good condition a water-base mud fluid; in drilling over chemogenic deposits, which are readily soluble in water-base drilling fluids. Fluids other than water-base ones may be also utilized in overhauling the wells and for temporary closing-in of the latter.
These fluids form complex multicomponent colloidal- chemical systems in which liquid petroleum products, most often diesel fuel, serve as dispersion medium. There exist numerous formulations for such fluids, significantly differing from one another.
Most promising are lime-bituminous muds which, apart from diesel fuel, contain highly oxidized bitumen, highly active calcium oxide, a stabilizing surfactant and a small amount of water.
The properties of the lime-bituminous drilling fluid are in a large measure dependent upon the composition of the diesel fuel, first of all as regards the proportions of paraffin and naphthene hydrocarbons therein, and on the composition of the bitumen that plays the part of the dispersion phase in the muds. Diesel fuel is a complex mixture of hydrocarbons of diverse classes with a small amount of resinous substances and naphthenic acids. Its chemical composition depends on the type of the initial petroleum and on the technology employed for its processing. The proportions of paraffin and naphthenic hydrocarbons in the diesel fuel are a factor determining the degree of coagulation of asphaltenes that are responsible for structurization in the lime- bituminous mud fluid.
In preparing lime-bituminous drilling fluid use is made of a highly oxidized bitumen whose softening point is not below 135-140 °C, while for hot wells this point should not be inferior to 145-150 °C.
The lime-bituminous drilling fluids are distinguished by their great stability, so long as the water content in them does not exceed approximately 20 per cent. To combine water entering the mud in the course of drilling, lime and, if needful, a surfactant are added to it. If the mud becomes too thick after addition of lime, the viscosity is reduced through diluting the mud with fresh oil-base mud. The density of the lime-bituminous drilling fluid can be regulated within a broad range, starting from 900 and up to 2500 kg/m3.
The preparation of the lime-bituminous drilling fluid entails certain difficulties. At an ordinary temperature the highly oxidized bitumen poorly dissolves in diesel fuel and therefore the latter has to be heated up to approximately 80 °C. Commonly, a bitumen concentrate is made ready preliminarily in a comparatively small volume of diesel fuel and it is only after this that drilling fluid is prepared with the concentrate. On interaction of CaO with water some heat is liberated, which contributes to a better dissolution of bitumen.
Oil-base mud fluids are, as a rule, not susceptible to filtration; even with a high pressure differential the dispersion medium either does not filter out at all into the permeable rock or the volume of filtrate does not exceed 1-3 cm3 in 30 minutes. The particles of drilled-out rocks, including the clayey ones, disintegrate in such fluids, while those of chemogenic rocks do not affect the quality of the muds. Oil-base muds carry no substances that could have impaired the permeability of reservoirs. They are sensitive to the effects of temperature; with rising temperature the filtration rate of the dispersion medium increases, the viscosity declines more noticeably than this is in the case with water-base muds, the density diminishes and at higher temperatures some fluids lose their stability. For this reason, the formulation of the drilling fluid is to be chosen by taking account of the geostatic bottom hole temperature in the well.
Oil-base mud fluids are prepared of comparatively expensive materials. The cost of 1 m3 of such drilling fluids is several times as high as the water-base ones. Since the properties of oil-base muds change but very little in the course of drilling and long-term storage, it is advisable that one and the same volume of the mud be utilized repeatedly in flushing several wells. Then the cost of the mud per well will be materially curtailed. The application of oil-base muds helps reduce friction forces between the drilling string and borehole walls, lengthen the service life of the roller bit legs, keep down bit consumption in drilling and cut down the time spent in making round trips. The cost of drilling may come to be much less than the cost of sinking a well by using an ordinary mud fluid.
3 Pick out Infinitive and Participle constructions from Text 1 and explain their use.
4 G ive English equi valents of the following words and use them in the sentences of your own:
продуктивний пласт, буріння з відбором керна, сланцювата глина, пластовий гиск, капітальний ремонт, вапняно-бітумний розчин (ВБР), дизельне паливо, поверхнево-активна речовина (ПАР), сира нафта, нафтенова кислота, розчин на нафтовій основі, проникна порода, проникність колектора, забійна геостатична температура, тривале зберігання.
5 Translate the following sentences into Ukrainian:
Oil-base mitd fluids are, as a rule, not susceptible to filtration; even wilh a high pressure differential the dispersion medium either does not filter out at all into the permeable rock or the volume of filtrate does not exceed 1-3 cm3 in 30 minutes. The particles of drilled-out rocks, including the clayey ones, disintegrate in such fluids, while those of chemogenic rocks do not affect the quality of the muds. Oil-base muds carry no substances that could have impaired the permeability of reservoirs. They are sensitive to the effects of temperature; with rising temperature the filtration rate of the dispersion medium increases, the viscosity declines more noticeably than this is in the case with water-base muds, the density diminishes and at higher temperatures some fluids lose their stability. For this reason, the formulation of the drilling fluid is to be chosen by taking account of the geostatic bottom hole temperature in the well.
6 Divide the text into logically complete parts and give each a subtitle. Put questions to the first part and retell it in English.
7 Speak about the properties of the lime-bitumious drilling fluid.
Unit 14 Emulsion Muds
1 Learn the meaning of the following words, word-combinations and word groups:
external, uniformly, globule, inverted, emulsifier, preclude, coalescence, adhesiveness, torque, pipe, axial, displacement, sticking, hazard, packer, solidify, release, shortcoming, inversion, elimination, facilitate, adjust, resistivity, logging, suffice.
2 Read Text 1:
Text 1
There are two types of emulsion muds in use:
1 Emulsion of the 1st kind or of the "oil in water" type, where it is water that acts as the part of the dispersion (external) medium, while oil or petroleum products form a dispersion phase uniformly distributed throughout the volume of the mud in the shape of minutest globules. Good emulsions are considered to be the ones in which oil drops are stabilized and have a diameter ranging from 0.1 to 0.6 mm. Muds of this type are commonly known by the name of oil emulsion drilling fluids.
2 Emulsions of the 2nd kind or inverted ones, of the type "water in oil", wherein oil or petroleum products play the part of external medium whereas water is dispersed in the form of minutest globules uniformly distributed throughout the mud volume.
To make the emulsion stable it is necessary to introduce the emulsifier. The emulsifier is a complex chemical compound, in which one part of the molecule is readily soluble in water and the other in the petroleum product. Because of this, the emulsifier reduces the surface tension and precludes the coalescence of the globules into separate large drops when they come in contact with one another. Moreover, each globule is enveloped by a thin compact film of sufficiently high mechanical strergth, which imparts additional stability to the globule.
The type of the resulting emulsion depends on the selected emulsifier. If at the water-emulsifier interface the surface tension
should prove weaker than at the petroleum product-emulsifier interface, the formation of an emulsion of the first type will result; the emulsion of the second type or inverted one will emerge if this tension is greater.
Oil emulsion drilling fluids find wide use in sinking of wells. They are prepared by adding 5-30 per cent (by volume) of oil or a petroleum product (usually diesel fuel) to an ordinary drilling fluid and pumping the whole through the circulating system during two- three cycles. More often than not the concentration of oil amounts to 8-15 per cent.
An addition of oil to a water-base drilling fluid tends to reduce the adhesiveness of filter cakes and, consequently, the torque required to impart rotational motion to the drilling string, to bring down the friction force between the drill pipes and the borehole walls during axial displacements of the drilling string and minimize sticking of the latter to the borehole walls. This, at the same time, materially lessens the hazard of formation of packers from drilled-out rock fragments on the bit and on outwardly projecting members of the drilling string, keeps down the filtration loss of the mud and considerably speeds up the drilling rate and the advance per bit run (footage per bit).
The use of saline oil emulsion drilling fluids in piercing chemogenic (sulphate) deposits helps to significantly economize on the consumption of barite and reagents and to reduce the total cost of the drilling fluid.
There are now available inverted emulsion muds carrying up to 80 per cent of water. Here, calcium soaps of fatty acids, especially the water-soluble ones (with ethylene oxide, amines, amides, sodium sulphonates) and other surfactants are utilized as emulsifiers. Like all other oil-base muds, such emulsions do not solidify at high temperatures, nor undergo any changes under the effect of salts and sulphate rocks, are indifferent with respect to clays and argillites. From a well-stabilized emulsion of the second type there are but insignificant amounts of petroleum products that are released in the form of a filtrate. The appearance of water in the filtrate is a sign pointing to an insufficient concentration of the emulsifier, or to a wrong selection of it.
One of the basic shortcomings of the emulsions of the second type is their tendency towards inversion of the phases and transformation into an oil ermilsion drilling fluid at temperatures above 50 °С, or the need to increase the solid phase content in order to raise the density beyond 1400 kg/m3. The elimination of this disadvantage is greatly facilitated by the application of hydrophobic amino compounds which are capable of being adsorbed on the surface of clayey particles.
The properties of inverted emulsions are adjusted by the selection of a proper type of the emulsifier, its concentration, introduction of clays treated with amines, fractional composition and concentration of the solid phase particles., or by a combination of these factors.
Inasmuch as in an inverted emulsion mud to the share of liquid petroleum products often fall not more than 20-30 per cent (by volume) of the total, it is much cheaper than any other oil- base mud, where the proportion of liquid petroleum products reaches 50 per cent.
In using oil-base muds, including also the inverted emulsions, there arise difficulties with the measurement of electric resistance of formations, for a high electric resistivity of the mud itself makes impossible electric logging and microsounding. Nonetheless, sufficiently abundant information can be obtained on rocks drilled in by the well with the aid of induction, neutron, acoustic, thermal, gamma and gamma-gamma loggings and nuclear magnetic resonance. Often the induction, neutron and gamma-gamma methods may suffi ce.
3 Pick out Infinitive Constructions from Text 1 and explain their use.
4 Give English equivalents of the following words and use them in the sentences of your own:
емульсійна промивальна рідина, нафтоемульсійна промивальна рідина, контакт вода-емульгатор, контакт нафтонродукт- емульгагор, осад після фільтрування, обертальний момент, бурильна колона, стінка свердловини, виступаючий назовні, проходження долота за рейс, кальцієве мило жирна кислота, питомий огіір, елекгрокаротаж, мікро зондування, ядерно- магнітний резонанс.
§ Translate the following sentences into Ukrainian:
There are now available inverted emulsion muds carrying up to 80 per cent of water. Here, calcium soaps of fatty acids, especially the water-soluble ones (with ethylene oxide, amines, amides, sodium sulphonat.es) and other surfactants are utilized as emulsifiers. Like all other oil-base muds, such emulsions do not solidify at high temperatures, nor undergo any changes under the effect of salts and sulphate rocks, are indifferent with respect to clays and argillites. From a well-stabilized emulsion of the second type there are but insignificant amounts of petroleum products that are released in the form of a filtrate. The appearance of water in the filtrate is a sign pointing to an insufficient concentration of the emulsifier, or to a wrong selection of it.
6 Supply a heading for Text 1.
7 Read Text 1 again. Find, read and translate the sentences in Text 1 in which we learn about emulsion of the oil in water type, emulsion of the water in oil type, the emulsifier.
8 Look through Text 1 again. Give the main points of each passage of the text. Use: “deals with”.
9 Divide the text into logically complete parts and give each a subtitle. Put questions to the second part and retell it in English.
Unit 15
Gaseous Agents and Aerated Drilling Fluids
1 Learn the meaning of the following words, word-combinations and word groups:
pervious, secure, torque, strip, permafrost, surfactant, moderate, mobile, pulp, restore, explosion, reestablish, entail, devoid, unprofitable, shallow, disperse, bubble, slippage, blowing-out, avert.
Text 1 Gaseous Agents
In drilling over pervious rocks with low coefficients of the formation pressure abnormality (Ca < 1) and also when it is desired to increase the drilling and advance rates per bit in firm rocks it is better to make use of muds with density below 1000 kg/m. The density of the drilling fluid is reduced through addition of some gases to it (air, natural gases, sometimes exhaust gases of internal combustion engines). In this way the density can be regulated within a wide range, roughly from 1300 to 1000 kg/ml.
Gaseous agents are open to general use. When boring in a dry stratum they secure good cleaning of the bottom hole from drilled-out rock fragments and their removal to the ground surface, provide for satisfactory cooling of friction surfaces, including specially constructed bits, help improve all-round efficiency of the operation by comparison with the use of dropping liquids, lessen sticking of the drilling string to the borehole walls and reduce the magnitude of the torque needed to rotate the string. All this favours broad application of gaseous agents in drilling oil and gas wells, and also in stripping down minor boreholes in coal, ore mining and other industries.
Gaseous agents meet only some of the requirements that the drilling fluid has to satisfy. Therefore, their use is recommended mainly for drilling over of permafrost, dry stable rocks and also in dealing with formations with the low coefficient of abnormality (Ca <
1) and containing no clayey particles.
Surfactants are introduced into the stream of gas in the form of an aqueous solution. Their concentration in water is chosen in such a way as to keep the viscidity of the mud at a low level and the ratio of drilling breaks in the bottom hole (by mass) to the volume of water below a certain limit. Thus in drilling of argillaceous rocks with the use of sulphonate, this ratio should not go beyond 1: 2 and in traversing non-argillaceous rocks, 1:1. When employing oxyethylated polyphenols, the concentration of drilled-out argillaceous rocks should be kept within 1: 2 to 1: 5 and that of non-argillaceous rocks within 1:1 to 1:2.
With moderate water inflows (up to 8 m3/h) a mobile pulp forms on the bottom hole which is quite easily removed by an air current. Difficulties usually arise when attempts are made to restore circulation after a protracted period of standing idle. During the stand-by time a considerable volume of fluid amasses in the bottom hole; this calls for a significant increase in the compressor plant pressure in order to remove it. Hence, in these conditions higher capacity compressor units intended for a comparatively short time performance at sufficiently high pressures (3-6 MPa and more) are required for air drilling.
In boring with air flushing the well is to be invariably filled with dropping mud fluid. Drilling with air circulation is, sometimes, attended by explosions in the well. These occur due to the formation of an explosive mixture of air with hydrocarbons entering the well from a hori2r.on. The mixture becomes susceptible to explosion when concentration of methane in the air reaches 6.5-12.8 per cent by volume. To lessen the hazard of explosions it is recommended that a certain amount of an aqueous solution containing frothing surfactants be added to the air stream. If it becomes possible for crude oil or condensate to accumulate in the well during stand-by period, it is then advisable to pump into the well separate portions of water and foam before the air circulation is re-estabiished.
Drilling with natural gas circulation entails the risk of a fire. Such a fire is put down, first of all, by stopping the delivery of gas and pumping instead a water-base drilling fluid into the well.
Note is to be taken of the fact that in using gaseous agents the wear-out of drill pipes gets more intensive. This is caused both by the abrasive effect of drilling breaks moving in the ascending stream of gas at a hi gher speed than would be the case in flushing the well with dropping mud fluid, and also by friction of the drill string against the borehole walls devoid of the filter cake. Here we may also speak about the influence of higher stresses in the column, since the ejecting force of the gas is rather insignificant by comparison with the buoyancy force of the dropping liquid.
3 Write ten questions to the text and answer them.
4 Make a plan to Text 1.
5 Reproduce Text 1 in your own words according to the plan.
Text 2 Aerated Drilling Fluids
In the event of abundant inflows of water, drilling with air flushing becomes unprofitable, for this steeply increases the required capacity of the compressor plant. When Ca < 1, it is better to make use of aerated drilling fluids. Such fluids are obtained through mixing up of water or a water-base mud with a preset volume of air forced by compressors into a mixer, built into the delivery line of slush pumps, or by adding a foaming surfactant (sulphanol, for example) to the drilling fluid. The latter method is commonly employed in traversing comparatively shallow horizons (down to 500 m).
Aeration influences only the density and funnel viscosity of the drilling fluid (the viscosity of muds increases with aeration). To disperse better air bubbles and to lessen their slippage with respect to the liquid phase, it is recommended that surfactants (anion-active ones, for instance) be added to the aerated mud fluid, while in drilling in oil reservoirs they should be non- ionogenic. Such additions improve evacuation of drilling breaks, reduce contamination of producing formations, visibly lower consumption of air and, consequently, keep down the required capacity of compressors.
Boring accompanied by blowing-out or flushing with an aerated mud fluid, particularly a saline one, materially adds to corrosion of the equipment. To avert corrosion of steel parts (drill pipes, for example), it is advisable to introduce calcium hydroxide as an inhibitor in the air current and thus maintain pH of the drilling fluid filtrate in the well at not less than 10.
7 Pick out of Text 1 and Text 2 five sentences containing Passive Voice Constructions and translate them into Ukrainian.
8 Give English equivalents of the following words and use them in the sentences of your own:
газоподібний агент, аерована промивальна рідина, підвищення швидкості, двигун внутрішнього згорання, сухий розріз, краплинна рідин, розробляти відкритим способом, суха стійка порода, поверхнево-активна речовина, вибурена частинка, тривалий період, простій, компресор підвищеної потужності, буріння з продуванням повітрям, ціноутворюючий ПАР, буріння з продуванням природним газом, висхідний потік, сила виштовхування (Архімеда),
9 Translate Text 2 iinto Ukrainian..
10 Give the main points of each passage of Text 1. Use: “deals with”.
CONTROL TASKS
1 Answer the questions:
1 What are the functions of the drilling fluid?
2 What are the types of the drill ing fluid?
3 Why isn't water a universal drilling fluid?
4 What type of drilling fluid is used in piercing chemogenic strata, intersaline and subsaline deposits?
5 What special chemical substances are added to the mud fluid to protect it against the coagulative action of salts?
6 How should;an effective froth breaker be chosen to suit conditions prevailing at a concrete well?
7 How is the method of adjusting or stabilizing the properties of the mud fluid chosen?
8 What are the causes responsible for changes in the properties of the drilling fluid?
9 What are the types of emulsion muds?
10 What does dril ling with natural gas circulation entail?
2 Giive English equivalents of ithe following:
|
1 carboxymethyl cellulose | a) serve to bind calcium and magnesium ions and to improve the wettability of clays |
2 caustic soda | b) reduce the coefficient of friction and keep down the intensity of the rock-breaking tools wearout |
3 soda ash | c) a high-molecular powder- like agent of a white or cream colour, readily soluble in water |
4 soluble glass | d) a colourless crystalline mass, readily soluble in water |
5 phosphates | e) a white-coloured powder, difficultly soluble in cold water, bu: with rising temperature its solubility improves |
6 lubricating additives | f) a vitreous mass of an unstable composition, readily soluble in water |
4 Tell whether each of the following statements is true or false according to the text. Correct the false statements to make them true:
1 The drilling fluid transmits power from mud pumps installed on the ground surface to the bottom drive engine in turbodrilling and also to the face of the bottom hole.
2 Water cools the bit and friction surfaces of the drilling shaft worse than other liquids.
3 Water is a universal drilling fluid.
4 Caustic soda doesn’t cause bums on the body surface and blindness when it gets into eyes.
5 The properties of the mud fluid undergo changes in the course of drilling.
5 Make a written translation of the following:
Mud fluids other than the water-base ones are intended largely for drilling in producing formations, when water-base muds act adversely on the productivity; in core-drill sampling, when there is a need for obtaining rock specimens uncontaminated with the filtrate (to determine the actual presence of oil, the content of connate water and permeability); in piercing argillites and schistous clays prone to lose their rigidity and to crumble (or collapse) under the effect produced by the water-base mud filtrate; in sinking high- temperature (hot) wells and, not infrequently, in cases of high coefficients of the formation pressures abnormality, when it becomes difficult to keep in good condition a water-base mud fluid; in drilling over chemogenic deposits, which are readily soluble in water-base drilling fluids. Fluids other than water-base ones may be also utilized in overhauling the wells and for temporary closing-in of the latter.
PART 4 DRILLING METHODS AND DRILLING EQUIPMENT
Unit 16 Methods of Drilling
1 Learn the meaning of the following words, word-conibinations and word groups:
well head, inch, oil string, proceed, caving, encounter, exclude, casing, screw, socket, joint, segregate, seal off, cement, fitting, valve, cosing- in, attach, key hole, exploratory well, wild cat, producing well, fracture, abrade, penetrate, loosen.
2 Read and translate Text 1: Text 1 Description of an Oil Well
In general, an oil well is similar to any other borehole drilled for the purpose of producing water or other fluids.
The well bore length exceeds many times its diameter. The opening of the well bore at the surface is called the well head, and its lower part the bottom hole. The depth of an oil well is controlled by the depth at which oil is found.
The diameter of a well varies. A deep well has a diameter at the surface of about 16-18 inches, which diameter is reduced progressively to about 6 inches at the bottom. The diameter of the oil string depends on the expected productivity of the well.
As drilling proceeds, subsurface waters or formations of a caving nature are often encountered. To exclude such water from the well and to hold back the caving formations, the well is lined with steel tubes known as casing.
The number of strings of casing and their diameter is controlled by local conditions and by the depth to which the well is to be drilled.
Oil-well casing is usually made of solid drawn tubes with screwed and socketed joints. There may be within the well bore several strings of casing: the surface casing, the intermediate or protective string and the oil string.
In cases where the oil is struck at high pressures or where it is essential that all upper water shows, must be permanently sealed off or segregated from each other, each string of casing is cemented in place.
The necessary valves and fittings, known as the “Christmas Tree” for closing-in or controlling the production, are attached to the inner or oil string of casing.
There are different kinds of oil wells depending on the purpose for which they are drilled, such as: key holes, exploratory wells, wild cats, producing wells or producers, seismic wells and etc.
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