Condition string

The condition part of the classifier is constructed from the ternary alphabet [o, l, ], so each of the following is a valid condition string ... 

Until downhole motors became available a whipstock (Fig. 3.15) which is a slightly asymmetric steel joint, was inserted in the drill string. The assembly is oriented downhole and a rathole is drilled which is then enlarged to full bore hole size. The technique is still used in wells where hole conditions e.g. high temperatures, are unsuitable for downhole motors (see below). 

One of the most sensitive situations for the TPG string is during emergency conditions. Because of the lower inertia of the three-body... 

Control acceleration of the string during an afterburn condition. The available energy of the string is increased as a result of higher inlet temperatures. 

This entire book is about the emergence, nature and cultivation of a new discipline, materials science and engineering. To draw together the strings of this story, it helps to be clear about what a scientific discipline actually is that, in turn, becomes clearer if one looks at the emergence of some earlier disciplines which have had more time to reach a condition of maturity. Comparisons can help in definition we can narrow a vague concept by examining what apparently diverse examples have in common. 

A stone dropped in a pond pushes the water downward, which is countered by elastic forces in the water that tend to restore the water to its initial condition. The movement of the water is up and down, but the crest of the wai c produced moves along the surface of the water. This type of wave is said to be transverse because the displacement of the water is perpendicular to the direction the wave moves. When the oscillations of the wave die out, there has been no net movement of water the pond is just as it was before the stone was dropped. Yet the wave has energy associated with it. A person has only to get in the path of a water wave crashing onto a beach to know that energy is involved. The stadium wave is a transverse wave, as is a wave in a guitar string. 

For dynamic conditions, find the total load on a derrick that is capable of lifting a 600,000-lb drill string with an 8-working line block and tackle. The crown... 

The drilling string got stuck after remaining motionless in the hole circulation can be broken and continued at normal pressure. Permeable formation is exposed above the bit. The borehole is clean and in good condition, see Diagnosis of stuck pipe as above as above... 

The drill string is defined here as a drill pipe with tool joints and drill collars. The drill stem consists of the drill string and other components of the drilling assembly that includes the kelly, subs, stabilizers, reamers as well as shock absorbers, and junk baskets or drilling jars used in certain drilling conditions. The drill stem (1) transmits power by rotary motion from the surface to a rock bit, (2) conveys drilling fluid to the rock bit, (3) produces the weight on bit for efficient rock destruction by the bit, and (4) provides control of borehole direction. 

To maintain the BSR at less than 5.5, the string of drill collars must frequently be composed of different sizes. For severe drilling conditions (hole enlargement, corrosive environment, hard formations), reduction of the BSR to 3.5 helps to reduce frequency of drill pipe failure. 

Design a drill string for conditions as specified below ... 

BHA — Change bottom hole assembly DMF — Down hole motor failure DSF — Drill string failure DST — Drill stem test DTF — Down hole tool failure LOG — Run logs CM — Condition mud CP — Core point DP — Drill plug FM — Formation change... 

Rotary Speed. Diamond bits can usually be rotated at up to 150 rpm without any problem when hole conditions and drill string design permit. Rotary speeds of 200 and 300 rpm can be used with stabilized drill strings in selected areas. Diamond bits have also operated very successfully with downhole motors at 600 to 900 rpm. The actual rotary speed limits are usually imposed by safety. 

Having stipulated this condition, the explicit scheme y f = y ) for the string vibration equation is stable for r/h < l/- /(l + s) (see Chapter... 

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