Davorin Matanović

DRILLING LINE (ROPE) AND BLOCKS

DRILLING LINE (ROPE) AND BLOCKS

• The term – drilling line pertain to the wire rope made from steel wires.

• It is spooled onto the drum of the draw works hoist, strung on the crown and traveling block, anchored at the one end and fastened on the other.

• It supports the entire drilling assembly by means of pulley-style devices and grasping elements.– They are called the overhead tools and include:

• crown block – an arrangement of sheaves that is fixed to beams at the top of the derrick or mast;

• the traveling block, another sheaved device that moves up and down on the line;

• the hook, which is fastened to the traveling block; and• the elevators, which grip the pipes when coming in or out of hole.

DRILLING LINE (ROPE) AND BLOCKS

• The purpose of the system is to give the drilling line the effect of many lines in hoisting the heavy loads required in drilling.

Blocks/Sheaves

• A block is an assembly of large pulleys known as sheaves mounted on a common framework through which the drilling line is reeved.

• The function of the sheaves is to guide and support the drilling line as it passes through the blocks.

• The number of sheaves in block is determined by the weight to be supported.

• Two features of sheaves are of primary concern:

(1) the size or radius of groves in which the wire line runs on the sheaves, and

(2) the tread diameter, the diameter of the sheave measured from groove to groove bottom; to be sure that wire rope and sheave will work together well (bending radii).

Cross section of a typical sheave

A gauge to measure sheave groves

Grove radii for new and reconditioned sheave grooves

WIRE ROPE DIA., d už TOLERANCE * GROOVE ROOT RADIUS, Ru** mm (")

mm (") mm (") minimum maximum 9,53 (3/8) +0,794;-0 (+1/32;-0) 5,207 (0,205) 5,461 (0,215)

11,11 (7/16) +0,794;-0 (+1/32;-0) 5,969 (0,235) 6,223 (0,245) 12,70 (1/2) +0,794;-0 (+1/32;-0) 6,731 (0,265) 6,985 (0,275) 14,29 (9/16) +0,794;-0 (+1/32;-0) 7,62 (0,300) 7,874 (0,310) 15,88 (5/8) +0,794;-0 (+1/32;-0) 8,382 (0,330) 8,636 (0,340) 19,05 (3/4) +0,794;-0 (+1/32;-0) 9,906 (0,390) 10,16 (0,400) 22,23 (7/8) +1,19;-0 (+3/64;-0) 10,312 (0,460) 12,065 (0,475) 25,40 (1) +1,19;-0 (+3/64;-0) 13,335 (0,525) 13,716 (0,540)

28,58 (1 1/8) +1,19;-0 (+3/64;-0) 14,859 (0,585) 15,240 (0,600) 31,75 (1 1/4) +1,59;-0 (+1/16;-0) 16,637 (0,655) 17,018 (0,670) 34,93 (1 3/8) +1,59;-0 (+1/16;-0) 18,288 (0,720) 18,669 (0,735) 38,1 (1 1/2) +1,59;-0 (+1/16;-0) 19,812 (0,780) 20,193 (0,795) 41,28 (1 5/8) +2,38;-0 (+3/32;-0) 21,844 (0,860) 22,225 (0,875) 44,45 (1 3/4) +2,38;-0 (+3/32;-0) 23,495 (0,925) 23,876 (0,940)

Crown block• The crown block is an

assembly of sheaves mounted on beams at the top of the derrick.

• Some crown blocks are equipped with extra sheaves to accommodate a sand line, and a cat line.– The former is used for

retrieving special tools from the hole and

– the letter used for hoisting heavy equipment on the rig

Traveling block

• It moves between an up and down position on the line.

– It carries the hook that supports the drill string when drilling and the elevator bails that hold the elevators when tripping in or out of the hole.

• Cutaway view of a traveling block.

Hook

• The hook is a large joining device suspended from the traveling block to grasp the various pieces of equipment needed in drilling and in making trips.

• It rotates on bearings in its supporting housing and can be locked into as many as twelve different positions.

• A strong spring within it cushions the weight of the drill pipe so that tool joint threads are not damaged in making up or breaking out the pipe

• The hook has a safety latch for the swivel and locking arms or link ears at both sides for the elevator-bail attachments.

• Major parts of a hook

• A hook-block combination takes less space than the two used separately.

Elevators

• Elevators are clamps that grip a stand, or column of drill pipe, casing, tubing or sucker rods so that the stand can be raised from or lowered into the hole.

• They are attached to the hook by elevator links or bails.

• Most of the drill pipe that elevators have to fit has a taper of 18° on the tool-joint shoulder where it meets the pipe.

• Another type of pipe is that with square shoulder (90°) on the tool joint box.

Drilling line – wire rope

• In the making of wire rope, steel wires are made into strands and the strands into rope in an action similar to braiding.

• Outer strands are laid spirally around a central core.

• The spiral of strands in a wire rope either to the right or to the left when viewed from above is known as the lay of the rope. – Regular lay means that

the wires in each strand of the rope are twisted in a direction different from the strands themselves.

– Lang lay ropes have both the strand and the wires in each strand spiraling in the same direction.

– Right regular lay is generally referred in drilling process.

• A common arrangement of the wire rope refers to the core and six strands that consist of various wire numbers and layers.

• The core is the inner support of the strands.– It can be produced of fiber,

plastics or it can be an independent wire rope.

Sand and coring line

• Strand consists of one central a six more wires around.

• It is also possible that strand consists of 12, 14, 19, 30etc. wires.

• Instead of three there can also be ropes with more strands; 4, 5, 7, 8, 16 and more.

Seale design

• The number of inner wires in each strand is the same as the number of outer wires.

• The diameter of the inner wires is smaller than that of the outer.

• API Spec. 9A defines the conditions for wires and ropes according to construction type.

• Approved constructions are: 6x7, 6x19, 6x21, 6x25, 6x26, 6x31, 6x36, 6x41, 6x46, 6x57, 6x61, 6x91, 6x103; and for special purposes: 8x19, 8x25, 18x7, 19x7; and with triangle strand construction: 6x25 type B, 6x27 type H, 6x30 type G and 6x31 type V.

Warrington/Seale construction (6x26)

• Combination of wires with different diameter in central layer enables to position wires closely.

• The lay of all layers is the same.

• Filler Wire rope differs from other in that the space between wires is filled with wires of small diameter. – Such wires do not

contribute in calculating the metal area of the rope.

• Triangle shaped strands enable the maximum metal area of the rope according the diameter.

(6x25 style B)

(6x25 style H)

Dimensions and characteristics, according to

the rope diameterBREAKING FORCE

NOMINAL DIAMETER

MASS OF THE UNIT LENGTH STEEL

ENHANCED STEEL

EXTRA ENHANCED

STEEL mm (in.) kg/m kN kN kN 13 (1/2) 0,63 83,2 95,2 105

14,5 (9/16) 0,79 106 120 132 16 (5/8) 0,98 129 149 163 19 (3/4) 1,41 184 212 233 22 (7/8) 1,92 249 286 315 26 (1) 2,50 324 372 409

29 (1 1/8) 3,17 407 468 514 32 (1 1/4) 3,91 500 575 632 35 (1 3/8) 4,73 - 691 760 38 (1 1/2) 5,63 - 818 898 42 (1 5/8) 6,61 - 952 1050 45 (1 3/4) 7,66 - 1100 1220 48 (1 7/8) 8,80 - 1250 1390

52 (2) 10,00 - 1420 1560

• The often mistake is in wrong way of wire rope measuring.

Measuring

Possible rope position in the sheave groove

Typical sizes and constructions of wire rope for

oil field services (API RP 9B)

WELL TYPE WIRE ROPE DIAMETER

(in) mm WIRE ROPE DESCRIPTION

SAND LINES AND SHALOW, INTERMEDIA AND DEEP

WELLSWELLS

(7/8 to 1) 22,23 to 25,4

(1 to 1 1/8) 25.4 to 28.58

6x19 Seal or 6x25 FW PS or IPS, PF or NPF, RL, IWCR

orFC 6x19 Seal or 6x25 FW, EIPS, PF,

RL or IWRC

DRILLING LINES, LARGE ROTARY RIGS, SHALLOW AND INTERMEDIA WELLS

DEEP WELLS

(1 to 1 1/8) 25.4 to 28.58 (1 1/8 to 1 1/4) 25.58 to 31,75

(1 1/4 to 2) 31,75 to 50,80

6x19 Seal or 6x21 FW PS or IPS,

PF or NPF, RL, IWRC or FC

6x19 Seal or 6x21 FW, EIPS, PF, RL, IWRC

MAST RAISING LINES (1 3/8 and less) 34,93 and less

(1 1/2" and greater) 38,1and greater 6x25 FW, IPS or FPS, PF, IWRC

6x37 IPS or EIPS, PF, IWRC

FW – filler wire construction,

PS – plow steel (rope wire having a breaking strength from 1570�106 Pa to 1760�106 Pa),

IPS – improved plow steel (rope wire having a breaking strength from 1770�106 Pa to 1960�106 Pa),

EIPS – extra improved plow steel (rope wire having a breaking strength from 1970�106 Pa to 2150�106 Pa),

NPF – non-performed,

RL – right lay,

LL – left lay,

FC – fiber core,

IWCR – independent wire rope core,

• The wire rope is with one end attached in the clamp inside the breaking crest.

• Also enough dead wraps should be wind to protect the clamp.

• Deadline anchoring system.

• After making a proper number of wraps, the line is threaded through the deadline anchor and fastened in clamp.

• The most common reeving pattern is left-hand reeving with the deadline anchor located to the left of the derrick vee.

• The flat angle isimportant in preventing rope wear.– It should be held to a

minimum – less than 1,5 degrees for grooved drums.

• Total stress in the wire rope is:

• Stress due the axial force is:

svu σσσ +=

Where:

σu – total stress in the rope, Pa

σv – axial stress, Pa

σs – stress due bending, Pa

už

maksv A

P .=σ

Where:

Pmaks. – maximum force in the rope, N

Auž – rope cross section area, m2

• Stress due bending:

kol

žsrBachs D

ECδσ ⋅⋅=

Where:

CBach – Bach’s coefficient (due thedifferences in wire area); 0,375

E – Young’s modulus of elasticity, Pa

δžsr – mean wire diameter, m

Dkol – sheave diameter, m

u

dmσσ

=

Where:

m – rope coefficient of security (for drilling ropes 3 to 5)

σd – material yield point, Pa

• Coefficient of security:

• Carrying or metal rope area (Auž) is the

sum of all the wire areas in the rope:

...44

22

2

21

1 +⋅⋅+⋅⋅= ππ žžuž

dn

dnA

Where:

n1,2- number of wires of same diameter

dž1,2 – wire diameter, m