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  1. Find in Text 1 five sentences with Passive Voice forms of the verb and translate the sentences into Ukrainian.

  2. Give English equivalents of the following:

реагент-понижувач в'язкості, окислені лігніни, вапняний розчин, гіпсовий розчин, понижувач водовіддачі, оптимальне значення, висококальцієвий розчин, зазнавати змін, у процесі обробки, тонкодисгіерсна твезда фаза, стежити, дисперсійне середовище, під впливом соле?:, зростання водовіддачі, вибирати спосіб інгібування, уламки вибурених порід.

  1. Translate the following sentences into English using the words and expressions from Text 1.

  1. Властивості промивальної рідини змінюються в процесі буріння.

  2. Хімічну обробку проводять багато разів, періодично додаючи в промивальну рідину нові порції реагентів.

  3. Оптимальне значення рН підтримують додаванням

лугу..

  1. ГІри виборі способу інгібування слід враховувати можливий економічний ефект, оскільки вартість деяких реагент ів висока, а витрати їх значні.

  2. ГІри деяких видах комбінованої хімічної обробки має значення послідовність введення реагентів.

    1. Make a plan to Text 1.

    2. Write ten questions to the text.

    3. Speak about the causes responsible for changes in the properties of the drilling fluid.

Unit 12

Density Adjustment of Water-Base Mud Fluids

      1. Learn the meaning of the following words, word-combinations and word groups:

shoe., avert, crumbling, caving-in, mill, admixture, sinter, slag, smelt, copper, lead, ore, humid, retard, preliminary, dilute, diminish, surplus, consumption, reclaim.

      1. Read Text 1:

Text 1 Density Adjustment of Water-Base Mud Fluids

To preclude the inflow of formation fluids into the well it is necessary that the pressure of the drilling fluid column be somewhat greater than the formation one. For this reason, the density of the mud fluid is chosen with due regard for the coefficients of abnormality in the horizons which will be drilled in the course of advancing along an interval from the shoe of the preceding rasing string to the landing depth of the subsequent casing string.

The density of the drilling fluid must sometimes be increased also in order to avert crumbling or caving-in of unstable rocks.

A more significant increase of the mud density is achieved by addition of special finely ground heavy minerals (weighting materials). Such minerals must have high density and should not be abrasive.

The best weighting material is the one containing barite, obtained through milling of the natural mineral - heavy spar (barium sulphate). The density of pure barium sulphate is as high as 4600 kg/m\ For the needs of drilling commercial grades of barite that contain various admixtures (silica, limestone, dolomite, etc.) are supplied.

Apart from barite wide use have found ferruginous weighting materials, and also slags remaining after smelting of copper and lead ores. These weighting materials are much more abrasive by comparison with barite. Their use is however, favoured by the higher density and, partially, is due to the shortage of barite weighting materials.

The weighting material is added to the drilling fluid in a humid state. To introduce dry weighting material is not recommendable, for air particles adsorbed on hard minerals tend to raise funnel, viscosity and to retard the growth of density. Inasmuch as on add tion of the weighting material funnel viscosity of the drilling fluid increases, it is advisable that the weighting material be preliminarily humidified with an aqueous solution of thinners and water-loss control agents. This enables it to achieve a more intensive rise of density with an insignificant increase of viscidity.

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.

The consumption of the weighting material and reagents, and also the cost of the treatment, may be significantly reduced if, as the surplus stocks of the mud pile up, the weighting material is being reclaimed therefrom.

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