3. Give English equivalents of the following:

порода продуктивного пласта, забруднююча дія промивальної рідини, вдаватись до додаткових способів стимулюючої дії, обробка кислотою, вібровплив, гідророзрив, допускати грубі помилки, інтерпретація геофізичних даних, швидкість буріння свердловини, витрати часу на освоєння свердловини.

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

   1. Вплив промивальної рідини на породу продуктивного пласта є індивідуальний і залежить від багатьох чинників.

   2. У розвідувальних свердловинах допускаються грубі помилки при інтерпретації геофізичних даних, деякі продуктивні горизонти класифікуються як непродуктивні, і тому їх не опробовують.

   3. Ступінь збитків від забруднення пласта промивальною рідиною і її фільтратом істотно залежить від тривалості їх дії: чим довша дія, тим більші збитки.

   4. Зменшувати забруднення продуктивного пласта можна, правильно підбираючи мінералогічний і гранулометричний склад твердої фази промивальної рідини.

   5. Великий вплив на властивості колекторів при- стовбурової зони продуктивного пласта мають поверхнево- активні речовини, використані для обробки промивальної рідини.

5. Pick out from Text 1 all the sentences with modal verbs and translate them.

6. Supply a heading for Text 1.

7. Make a plan to Text 1 and retell it.

8. Write a summary of Text 1.

Unit 26 Choosing a Metltiod for Opening-up a Reservoir-Bed and an Arrangement of the Area in and around the Hole Face in Producing Wells

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

area in, area around, producing well, case off, formation pressure, streak, homogeneous, saturate, permeability, casing shoe, suspend, packer., gas holder, production casing, overlap, slit, mill, back of the bed, competent rock, pierce, gas cap, tap, inrush, accelerated expenditure, feed, formation energy, advance, collar, deflect, side hole, fit out.

2. Read and translate Text 1:

Text 1

By the openir g-up of a reservoir is understood a complex set of operations associated with drilling in, securing the strength and stability of the area in and giround the bottom hole of the well and also with establishing communication between the production string and the reservoir after the well bore has been cased off. The choice of the opening-up method is largely dependent upon the structure of the bed (reservoir), its properties as an oil collector, the composition of fluids and gases contained in it, the number of productive oil streaks, and on the abnormality factor of formation pressures.

If the pay bed is homogeneous, made up of a strong, competent rock, saturated with a single fluid, and the permeability across the thickness of the bed varies but little, then the well bore opposite such a bed need not be reinforced with a casing. In open holes the casing shoe is placed in the roof (top) of the oil reservoir. With such a casing program of the well the type and properties of the drilling fluid may be chosen by taking account of features specific only for the oil reservoir. In this case it is possible to completely avoid any pollution of the reservoir.

If the pay bed is homogeneous, saturated with but a single fluid, and the permeability across the thickness of the reservoir varies insignificantly, but the reservoir rock is not stable enough, then the well bore opposite such a bed has to be rainforced and the collecting sands protected against destruction. Then, the production casing is lowered down to the roof of the bed, whereas the borehole walls amidst the bed itself are reinforced with a special filter, usually suspended in the casing from a packer.

Both methods of opening-up are widely used in the development of gas and gas-condensate deposits and also in dealing with underground gas holders and less frequently in oil deposits, mainly due to the fact that homogeneous oil reservoirs are of rare occurrence.

Most popular has become the method of opening up oil reservoirs when the production casing is run into a well sunk down to the pre-assigned depth and then cemented. Once the cement paste has solidified, the casing is perforated, e.g. a certain number of holes are made along its specified sections and in this way a communication between it and an oil-and-gas-saturated area is established.

The method has also a number of shortcomings. First, the composition and properties of the mud fluid must be selected by taking into consideration the properties not only of the pay bed, but also of all other overlying beds and the ones not overlapped by the preceding casing.

Second, the oil reservoir can be heavily polluted during cementation. The pollution of the pay bed with the cement slurry and its filtrates can be averted if the bottom part of the production string is made up of pipes with perforated holes, or slits milled in advance, with cementation involving merely the top portion of the string, starting from the back of the bed. This method, may, however, be applied only in opening up a comparatively homogeneous pay bed, composed of sufficiently competent rocks and saturated with a single fluid.

The complete opening-up of the productive series saturated with a single fluid depends on the thickness of impervious rocks separating them from a deeper-lying pervious area. If the thickncss is great enough, the well is sunk down to the floor of the bed, or somewhat deeper.

If the productive stratum contains two fluids (crude oil, water, or gas, water), or three fluids (gas, crude oil, water) it is opportune to have the bottom hole of a producing well positioned much higher above the surface of the water-oil (gas-water) contact, so as to avoid opening up the water-bearing portion of the bed.

When perforating casings in producing wells, the lower holes are pierced as far above the water-oil (gas-oil) contact as possible. With an oil well tapping a gas cap, the upper holes are then made as far below the gas-oil contact as possible, so as to minimize the danger of a gas inrush into the well and an accelerated expenditure of the formation energy.

Calculations and practical experience prove that the output of a well can be roughly doubled if the total length of side holes reaches 10-20 per cent of the drainage radius, i.e. the radius of the area feeding the given well.

The technology of advancing horizontal or nearly horizontal side holes involves the following operations. The main hole (well bore) is sunk first and the productive stratum is drilled in, if possible, throughout its entire thickness. Next, by employing different methods and appliances, the lowermost side hole is collared and this is forcibly deflected with the maximally possible intensity, seeking to make it run horizontally according to a preset azimuth. If the rocks of the collecting basin are firm enough, then, having bored one hole, the worn out bit is replaced and second side hole is advanced in the pre- assigned direction somewhat above the first one. But if the collecting basin is composed of insuffic iently stable rocks, a filter made up of case pipes with slits milled in their walls is lowered into the first hole, and only then is the second side hole collared. There maybe several (up to ten and more) such side holes. The length of each side hole ordinarily equals advance per run of bit. Sometimes, however, the length of a single hole is as great as several hundred metres.

It should be rioted that owing to the complexity of specific operations involved in sinking a well with a large zenith angle, the discussed method finds application on comparatively rare occasions, being used chiefly when other methods of intensifying the recovery of oil (gas) are thought to be ineffective.

If the pay sand is made up of insufficiently stable rocks, the lower part of the well is then fi tted out with a special filter so as to minimize the risk of the collecting basin to collapse.