Line drilling

Finished wire rope, unless otherwise specified, shall be shipped on substantial round-head reels. Reels on which sand lines, drilling lines, or casing lines are shipped shall have round arbor holes of 5 in. (127 mm) to 5-J-in. (146-mm) diameter. When reel is full of rope, there shall be a clearance of not less than 2 in. (51 mm) between the full reel and the outside diameter of the flange. 

I. Controlled Blasting, described in Chap 28 of Ref 63, includes Line Drilling, Cushion Blasting and Pre-shearing, One can use "Trimtex and "Trimtex Z , which are modified DuPont Ammonia Dynamites (Ref 63, p43)... 

Safety clothing and gloves Stack and duct coatings Tank linings Drill bit seals V-ring packers... 

Wire-line drilling is performed using thin-walled drill rods through which an inner tube can be lowered into position within the outer core barrel to receive the core as it is cut by the bit. After completion of the coring, the inner tube (containing the core samples) is disconnected so that it may be retrieved by hoisting to the collar of the hole the drill rods, outer barrel, and bit remain in the hole until they need to be withdrawn to, say, replace a dull bit. 

In many excavations, it is important to keep overbreak to a minimum. Apart from the cost of its replacement with concrete, damage to the rock forming the walls or floor may lower its strength and necessitate further excavation. What is more, smooth faces allow excavation closer to the payline and are more stable. There are two basic methods that can be used for this purpose, namely, line drilling and presplitting. 

Line drilling is the method most commonly used to Improve the peripheral shaping of excavations. It consists of drilling alternate holes between the main blastholes forming the edge of the excavation. The quantity of explosive placed in each line hole is significantly smaller and indeed if these holes are closely spaced, from 150 to 250 mm, then explosive may be placed... 

The problems after most chapters will be divided into two or three groups (a) up to the single line drill on basic ideas and operations (b) from the single to the double line more advanced or more complex situations (c) after the double line applications to special fields, not necessarily more difficult than sets (a) or (b). 

At 2130 the pumps were shut off to investigate an unexpected pressure difference between the drill-pipe and the kill line. Drill-pipe pressure increased by 550 pounds per square inch over the next five and a half minutes - while the kill line pressure remained significantly lower. (Remember, low pressure in the kill line had been taken as the reason for confirming the negative pressure test was satisfactory. With hindsight, therefore, it looks like the kill line was blocked.) This was now clear evidence of a kick, but no further action was taken. 

Semi-submersible rigs are often referred to as semis , and are a floating type of rig. Like the jack-up, a semi is self contained. The structure is supported by large pontoons which are ballasted with water to provide the required stability and height. The rig is held in position by anchors and mooring lines or dynamically positioned by thrusters. A large diameter steel pipe ( riser ) is connected to the sea-bed and serves as a conduit for the drill string. The blowout preventer (BOP) is also located at the sea-bed ( sub sea stack ). 

If a situation arises whereby formation fluid or gas enters the bore bole the driller will notice an increase in the total volume of mud. Other indications such as a sudden increase in penetration rate and a decrease in pump pressure may also indicate an influx. Much depends on a quick response of the driller to close in the well before substantial volumes of formation fluid have entered the borehole. Onoe the BOP is closed, the new mud gradient required to restore balance to the system can be calculated. The heavier mud is then circulated in through the kill line and the lighter mud and influx is circulated out through the choke line. Once overbalance is restored, the BOP can be opened again and drilling operations continue. 

Once the production potential of the producing wells is insufficient to maintain the plateau rate, the decline periodbegins. For an individual well in depletion drive, this commences as soon as production starts, and a plateau for the field can only be maintained by drilling more wells. Well performance during the decline period can be estimated by decline curve analysis which assumes that the decline can be described by a mathematical formula. Examples of this would be to assume an exponential decline with 10% decline per annum, or a straight line relationship between the cumulative oil production and the logarithm of the water cut. These assumptions become more robust when based on a fit to measured production data. 

Oil and Petrochemicals. There are a variety of uses for defoamers in oil recovery. They are used in some of the materials used in oil extraction, such as in drilling muds and cement lining, and also directly with the cmde oil itself. In its natural state cmde oil contains dissolved gases held by high reservoir pressure. When this Hve cmde oil is extracted and passed into the low pressure environment of a gas-oil separator, the dissolved gases are... 

A simple way to measure the resistivity of soil is a four-pin method in which four probes are drilled into the ground along a straight line at equal distances a and depth b. Then a voltage V is applied to the two inner probes and a current, T, is measured in the two outer probes (Figure 22.16). This test can also be conducted with the help of a ground icster as discussed in Section 22.3, which normally also has a provision for ihis test. 

Further cell currents flow between the wells as a result of electrical connections established between them by the flow lines and of the different free corrosion potentials, thereby allowing them to behave as anode or cathode. The currents can amount to a few amps so that considerable corrosion damage can arise. The action of these cells can be prevented by building in insulators between the drilling and the field cable. 

Seismic studies are very useful when information is lacking on subsurface stratigraphy, or when the depth to bedrock, the water table, a particular bed or formation, or some other layer in the subsurface must be determined without drilling. Seismic lines can be set up to produce stratigraphic cross sections and they can be a very useful "non-invasive" inves-... 

Before allowing welding or similar operations on a pipeline that has or could have contained flammable gas or liquid, (1) sweep out the line with steam or nitrogen from end to end, and (2) test at the point at which welding will be carried out. If necessary, a hole may have to be drilled in the pipeline. 

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