Question

Problem 5 A vertical well is drilled to point A (L-30ft) at constant angular velocity, the bottom end of drill pipe encounters a torsional resistance TA 30 kip ft. Also, the friction along the sides of the pipe creates a linear distribution of torque per unit length, varying from zero at the surface B to ta at location A. Known that the shear modulus of the drill pipe G = 1 . 1 x 1 Oksi and tA-10kip . ft / f. The outer diameter and inner diameter of the drill pipe are 6.625 in and 5.9 in, respectively. TB TA 1) Determine the minimum torque T, that must be supplied by the drive unit to overcome the resisting torques Determine the maximum shear stress in the pipe Assume C is arbitrary location between A and B, and depth of C is z (0szsL), try to express the relationship between the torque at C and the depth z. Determine the angle of twist of A with respect to B 2) 3) 4)

Answer 1

CnS- 乙- o. ③ do =G1625 in Tr 9灴'T8-180eq.ft =1104081矧 6,625

3 3 Te 120-J (刀, 2-360わ 230 360 50X12 3601 613 67 | 18;02-乙2 7360 43200. 66251-5) 32-