Drill collar size selection

Selection of the proper outside and inside diameter of drill collars is usually a difficult task. Perhaps the best way to select drill collar size is to study results obtained from offset wells previously drilled under similar conditions. 

The most important factors in selecting drill collar size are ... 

Being aware of standardized drill collar sizes, an 11 or 12-in. drill collar should be selected. To avoid such large drill collar OD, a stabilizer or a proper-sized square drill collar (or a combination of the two) should be placed above the... 

Selection drill collar size, Table 4-73, 7-J x 2- in., unit weight = 139 Ib/fi. Such drill collars can be caught with overshot or washed over with washpipe. 

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