dpt1 - 01 - rig sizing and selection

8/11/2019 DPT1 - 01 - Rig Sizing and Selection

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Rig Sizing and SelectionRig Sizing and SelectionRig Sizing and SelectionRig Sizing and Selection

DPT1


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At the end of this lecture YOU will be able to:

Select a rig for a given well

Rig Sizing & Selection - Objectives


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1. Types of rigs

2. Hoisting system

Loads: hook, fastline and deadline Drawworks sizing

Drilling line Sizing, Ton-Miles, Slip & Cut

Derrick, Rig Floor & Substructure

3. Rotating System

4. Circulating System

5. BOP System

6. Power System7. Group exercise: Select a Rig for a 30000ft well

Rig Sizing & Selection - Agenda


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There are a number of considerations that are fundamental to the design of the wellprogram and selection of the drilling equipment that will be used.

Territory in which to operate

Ranges of well depths and hole sizes to be drilled

Casing loads expected, Drill string components weights and sizes

Range of rotary speeds and torque required

Mud system, tanks and manifolding, solids control equipment

Auxiliary services and power required

Substructure height - clearances

Blowout prevention equipment

Rig Sizing - Introduction


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Rig Sizing - Introduction

A drilling rig is made of many individual pieces of equipment which togetherform a unit to construct wells. Without this unit wells could not be drilled andcased.

The correct procedure for selecting and sizing a drilling rig is as follows:

1) Design the well.

2) Establish the various maximum loads to be expected during drillingand all other operations to be done with the rig (Testing, Completions)

3) Find rigs available in the area that match the requirements

4) Discuss availability with Rig Contractors.

5) Issue tenders and select rig based on cost, capability and availability


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Rig Types:

Land rig

Offshore rigs:

Floating rigs:

Semisubmersible

Drillships

Bottom-supported rigs:

Jack-up

Platform

Barge

Rig Sizing


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Land Rig


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Mobile Land rigs


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Jack-up Rigs


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Rig Move - Rowan Gorilla


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Submersible Rigs/Barges

Submersibles can be anchored when used in water depths

of up to 175ft, or can rest on the seabed when working inwater depths from 5 to 20 ft. Swamp barges are typically

used to drill wells in shallow water depths of up to 20ft ininland waterways and swamps.


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Semi-submersible Rigs


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Semi-submersible Rigs


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Drillship


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Drillship


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Rig Types - Summary


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Rig Components

The major rig components that need to be reviewed for

capability are:

Hoisting system

Derrick capacity and substructure

Rotating equipment

Circulating system

Pressure control

Power requirements

Tubular goods


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Hoisting System

The hoisting system consists of:

1. The Supporting Structure:

Derrick

Rig Floor

Substructure

2. The Hoisting Equipment

Drawworks

Crown block

Traveling block

Hook

Drilling line


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Hoisting System - Drawworks

This is an assembly of a rotating drum, a series of shafts, clutches,chains and gears for changing speed and for reversing. It alsocontains the main brake stopping the drilling line.

The drilling line is wound a number of times around the drum andpasses to the crown and traveling blocks

The Drum


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Hoisting System - Drawworks


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A block located at the top of derrick

It contains a number of sheaves onwhich the drilling line is wound.

The crown block provides a meansof taking the drilling line fromthe hoisting drum to thetraveling block

The crown block is stationary and isfirmly fastened to the top of thederrick

Each sheave inside the crownblock acts as an individualpulley

Hoisting System Crown Block


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Hoisting System - Sheaves


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A diamond-shapedblock containing anumber of sheaveswhich is always lessthan those in the crownblock.

The hook and bailshang below the TB tofacilitate drilling with

the swivel andrunning pipe.

Hoisting System Travelling Block


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Connects the Kellyor Top Drive with

the travelling Block.

The hook carriesthe entire drillingload

Hoisting System - Hook


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Hoisting System - Swivel


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The Dead Line Anchor anchors the last line coming from thecrown block and allows new line to be fed from the reel inwhich it is stored. New lengths of line can be fed into thesystem. The used line is cut off at the drum side.

Hoisting System - Deadline Anchor


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The drilling line is wound continuously on the Crown and TravelingBlocks, with two outside ends being wound on the hoisting drum andattached to the deadline anchor respectively.

The block and tackle is a term used to refer to the arrangement of crownblock, drilling line and traveling block.

Hoisting System - Block & Tackle

Fastline


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Hoisting System Wire Rope

Wire rope differs in the number of strands and pattern of wiresin the strand. Most wire rope constructions are grouped intofour standard classifications, based on the number of strandsand wires per strand as shown in the following table taken fromthe IADC Drilling Manual:


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The strands can be placed in a right or left direction and the wires in thestrand can be placed such that they appear to be parallel to the rope axis(Regular) or to the axis of the strands (Lang).

Lay used for Drilling Lines:Right Regular Lay (RRL)

Strands are preformed to give them the helical shape they will take when

they are placed on the wire: preformed strands (PRF)

Patterns used in drilling line: Filler Wire, Seale, Combined patterns

Hoisting System Wire Rope Strands


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The primary purpose of the core in wire rope is to provide foundation or supportfor the strands. There are 3 types of core:

Fiber Core (FC), Strand Core, Independent Wire Rope Core (IWRC)

The strands provide the whole of the tensile strength of a FC rope but with aIWRC rope, the core contributes to the nominal strength. For example in a 6strand rope with IWRC, 7.5% of the nominal strength is attributed to the core.

Wire rope used for Drilling Lines has IWRC

Hoisting System Wire Rope Core & Grade

All rotary drilling lines are of 2 grades: Improved Plow Steel (IPS) or Extra

Improved Plow Steel (EIPS)

A standard 6 strand EIPS rope within the same classification have a nominalstrength 15 % higher than IPS ropes.


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The correct diameter of a wire rope is the diameter of a circumscribed circle

that will enclose all the strands. It is the largest cross-sectional measurement.

Measurements should be carefully made with calipers.

Hoisting System Wire Rope Size

The size of most Drilling Lines varies from 1/2 to 2


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The table below taken from the SPE ADE textbookshows the nominal breaking strength for 6X19 wire rope.

Hoisting System Wire Rope Strength


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1 = Diameter of line5000 = Length of line

6 = Number of Strands per Line19 = Number of Wires per Strand

S = Seale PatternPRF = Preformed StrandsRRL = Right Regular Lay

IPS = Improved Plow SteelIWRC = Independent Wire Rope Core

Strength = 89800 lbs

Hoisting System - Wire Rope

What does the following description of a rotary drilling line mean?What is its nominal strength?

1 X 5000 6 X 19 S PRF RRL IPS IWRC


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Design Considerations

1. Determine the deepest hole to be drilled

2. Determine the maximum drilling loads or casing loads

3. Use these values and compare to the derrick capacities on

available rigs

Elements for Calculation

1. Static Derrick Loading

2. Efficiency Factor3. Dynamic Crown Load

Hoisting System Design


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Exercise RIG 00 - Hoisting System

Line Tension and Derrick Load Under Static Conditions:

Crown Block

Fixedsheaves

Deadline

Hook

W

Drawworks

Fastline

WWWW4444 WWWW

4444

WWWW4444

WWWW4444 WWWW

4444

WWWW4444

n

WF

L =

n

)n(*WF

D

2+=Derrick Load =Line Tension =

Where: W = hookload and n = number of lines


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For dynamic conditions friction between the line and sheaves has to beaccounted for:

For roller bearings which are the normal type of bearings in a block & tackle

system, the Friction Factor is K=1.04.

Hoisting System Dynamic Loading

Efficiency Factor of the Hoisting System: (API RP9B)

)K(N*K

KEF

S

N

1

1

=

Where: N = the number of lines and S = the number of sheavesNote: For the general configuration of a block and tackle system of a rotary drilling rig S = N.


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Exercise RIG 01: Efficiency Factor

Calculate the efficiency factor for a hoisting systememploying 8 string lines.


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Dynamic Fast-Line Load:

Dynamic Deadline -Load is given by:

n*EF

WFFL =

n*EF

)K/(*WF

n

DL

1=

Hoisting System Dynamic Loads

What is the total derrick load under dynamic conditions ?

DLFLDT FFWF ++=


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1. The Total Derrick Load should not exceed 80% of the minimum

hoisting system rating

2. If the breaking strength of the drilling line is known, then a designfactor, DF, may be calculated as follows:

DF = Nominal strength of wire rope (lb) / Fast-line Load (lb)

Min Design Factors;

Drilling / Tripping : 3

Casing Running : 2

Hoisting System - Design

H i i S D k P


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Hoisting System Drawworks Power

Power developed at hook: P = W x Vhk

Power consumed at the drum: P = FFL x Vf

P = W x Vhk/ EF

Drum output (horsepower) = W x Vhk / (EFx33,000)

Vf = Velocity of fast-line load (Vf)

Vhk= Velocity of traveling block

Vf = N x Vhk

As a rule of thumb, the drawworks should have 1 HP for every 10 ft to be

drilled. Hence for 20,000 ft well, the drawworks should have 2000 HP.

E i RIG 02 D k P


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Exercise RIG 02 Drawworks Power

The following data refer to an Oilwell block-and-tackle system:

Number of lines = 10 with EF = 0.81,

Maximum expected hook load = 500,000 lbf,

Hook load speed = 120 ft/min,Hoisting drum diameter = 32,

Mechanical efficiency of drawworks = 0.88

Calculate:

1) The power at the drawworks

2) The motor power required

3) The fast line speed.4) The RPM of the drawworks drum.

E i RIG 03 D illi Li L d


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Exercise RIG 03 Drilling Line Loads

Consider a travelling block with 10 lines of 1.5 EIPS wire rope of strength 228klbs

Hole depth(MD) = 10,500 ftDP = 4000 ft 5 - 19.5 lb/ft (S-135-NC 50) 22.61 approx #

= 5700 ft 5 19.5 lb/ft (E-75-NC 50) 20.85 approx #

Drill collars = 800 ft, 8 x 2.825, 150 lb/ftMud weight = 10 ppgSheave bearing type = Roller Bearing (K=1.04)Travelling Block Weight = 23,500 lbs

Calculate:

1) Weight of drill string in air and in mud

2) Hook load.

3) Dynamic deadline and fast-line loads.

4) Dynamic crown load5) Wirerope Design Factor during drilling

6) Design Factor when running 7 in casing of 29 lb/ft

D illi Li Sli & C t


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Fig. M4-1 of the IADC Drilling Manual Illustrates thecritical wear points of drilling line.

Drilling Line Slip & Cut


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Sli & C t T Mil g l


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Drum

Diameter 1" 1 1/8" 1 1/4" 1 3/8" 1 1/2" 1 5/8"

18" 6.0 9.0

19" 6.0 9.020" 7.0 9.0

21" 7.0 10.0

22" 7.0 10.0

23" 8.0 10.0 13.0

24" 8.0 11.0 13.0 17.0

25" 8.0 11.0 14.0 17.0

26" 9.0 11.0 14.0 17.0

27" 9.0 12.0 15.0 18.0

28" 12.0 15.0 18.0

29" 12.0 15.0 18.0

30" 13.0 16.0 19.0

31" 16.0 19.0

32" 17.0 20.0

33" 17.0 20.0

34" 18.0 21.0 24.0

35" 21.0 25.0

36" 22.0 25.0 26.0

TON MILE PER FOOT CUT GOAL FOR RIGS HAVING NO PAST

PERFORMANCE RECORDS

The table below from the IADC manual shows the starting goal of ton miles per ft.

for a rig without previous records. Depending on results the goal can be increasedor decreased.It should be noticed that the goal changes with rope diameter and drum diameter

of the drawworks.

Slip & Cut Ton-Mile goal

Slip & Cut Cutting Length


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The idea is to prevent the rope to be passed from one critical point to another

one. The following table prevents this from occurring; however, other lengthscan be used.

Slip & Cut Cutting Length

Slip & Cut Practice Ton Miles


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Grand total of work done by the drilling line is the sum ofton-Miles done during:

1. Drilling

2. Coring

3. Tripping

4. Setting casing

Slip & Cut Practice Ton Miles

Slip & Cut Round Trips Work


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Work done in round trip operations (TR) ton-miles

M = mass of traveling block assembly (lb),Ls = length of each stand (ft),D = hole depth (ft),We = effective weight per foot of DP in mud,C = (L x Wdc- L x Wdp) x BF,

Wdc = weight of DC in airWdp = weight of DP in air,L = length of DCs.

00064022

00056010 ,,

)C

M(D

,,W)DL(*DT esR

+

++

=

Slip & Cut Round Trips Work

Slip & Cut Drilling Coring Casing


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Slip & Cut Drilling, Coring, Casing

When drilling from depth D1 to depth D2, the work done is:

When coring from D1 to D2, the work done is:

T1= Round trip at depth D1 where drilling/coring startedT2 = Round trip at depth D2 where drilling/coring stopped before POOH

When setting Casing at depth D, the work done is:

Wcs = effective weight per unit length of casing in mudLs = length of 1 Casing joint

+

+=

000640200056010

21

,,

DM

,,

W)DL(D/T

csss

[ ]123 TTxTd =

[ ]122 TTxTc =

Exercise RIG 04 Ton Miles Evaluation


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Exercise RIG 04 Ton Miles Evaluation

Using the data given in Exercise RIG 03, determine;

1) Round trip ton-miles at 10,000 ft;

2) Casing ton-miles if one joint of casing = 40 ft ;

3) Design Factor of the drilling line when the 7 inch casing is

run to 10,000 ft;

4) Ton-Miles when coring from 10,000 ft to 10.180 ft and5) Ton-Miles when drilling from 10,000 to 10,180 ft.

Derrick Capacity and Substructure


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The derrick sits on a substructure on which the drillingequipment is mounted.

The substructure must be rated to hold pipe setback plus the

load of the heaviest casing run.The height of the substructure above the ground varies

according to the size of the rig. It varies from 10 to 35

Derrick Capacity and Substructure

The derrick must support hookloads, deadline load, fastlineload, pipe setback and wind loads.

The derrick provides the necessary height and support to lift

loads in and out of the well

Derricks


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Standard Derrick:

Bolted structure that must be assembled part by part, usually used on offshoreplatforms.

Derrick installed on floating rigs are designed to withstand extra dynamic stressesdue to rolling, heaving and stresses from the wind

The space available between the rig floor and the crown block must be higher to

handle the wave-induced vertical movement of the floating support.

Derricks

Mast or Portable Derrick:

This type is pivoted at its base and is lowered to the horizontal by the use of

drawworks after completing the well and the rig is ready to move to anotherlocation

The mast is dismantled into a number of pin-jointed sections, each of which isusually a truck load.

Mast or Portable Derrick


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Mast or Portable Derrick



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1. Types of rigs

2. Hoisting system

Loads: hook, fastline and deadline

Drawworks sizing



3. Rotating System4. Circulating System

5. BOP System

6. Power System

7. Group exercise: Select a Rig for a 30000ft well


Rotating System


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Rotating System

Rotary HorsePower

The Rotary Horsepower requirement is usually

between 1.5 to 2 times the rotary speed, depending onthe hole depth.

Hence for rotary speed of 200 RPM, the powerrequirement is about 400 HP.

Circulating System


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Circulating System

Hydraulic Horsepower:The horsepower requirements of the

pumps depends on the flow-rateand the pressure.

1714

)psi(essurePrx)gpm(FlowRateHP =

The heart of the circulating system is

the mud pumps

Circulating System Mud Pumps


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A basic pump consists of a piston reciprocating inside a cylinder.

A pump is described as single acting if it pumps fluid on the forward strokes

(triplex pumps) and double-acting if it pumps fluid on both the forwardand backward strokes (duplex)

Pump Liners fit inside the pump cavity, these affect the pressure rating and

flowrate from the pump.

Circulating System Mud Pumps

For a given pump, different size liners have the same OD but different ID.

The smaller liner (small ID) is used in the deeper part of the well where lowflow-rate is required but much higher operating pressure

Circulating System Triplex Pumps


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Circulating System Triplex Pumps

Mud Pumps Stroke & Efficiency


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A full hydraulic program needs to be calculated to determine the

pressure requirement of the pump.

The size of the pump is determined by the length of its stroke and thesize of the liner.

Mud Pumps Stroke & Efficiency

Volumetric Efficiency:

Drilling mud usually contain little air and is slightly compressible. Hence thepiston moves through a shorter stroke than theoretically possible before

reaching discharge pressure,

As a result, the volumetric efficiency is always less than one; typically 95% fortriplex and 90% for duplex.

In addition, due to power losses in drives, the mechanical efficiency of mostpumps is about 85%.

Exercise RIG 05 Mud Pump Power


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Calculate the power requirement for the following pump:

Flowrate = 1200 gpm,

Pressure = 2000 psi,

Mechanical Efficiency = 0.85

p

Circulating System -Auxiliaries


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Centrifugal Pumps:

This type of pump uses an impeller for the movement of fluid, rather apiston reciprocating inside a cylinder. Centrifugal pumps are used

to surcharge mud pumps and to provide fluid to solids controlequipment and mud mixing equipment.

Mud Handling Equipment:

Shale Shakers: size, type.

Mud Pits: Number and size is determined by the size and the depth ofhole. Also by the size of the rig and space available, especially on

offshore rigs. Size of a pit usually 8-12 ft wide, 20-40 ft long and 6-12 ft high

Desanders, Desilters.

Centrifuges and mud cleaners

Degasser

g y

Pressure Control Equipment


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q p

Required as per IPM Standards HSE 001, WCI 003, WCI 005 :

Gas Detection Equipment

BOP Stack and Diverter Kick Detection Equipment (Trip Tank, Flowshow)

Required as per Good Oilfield Practice :

Choke manifold, Choke and Kill lines

Accumulator and BOP Control System

Rotating heads if air drilling or UBD

A fluids system with enough storage for all hole sections +100%

Power System


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The power on modern rigs is most commonly generatedby diesel-electric power units,

The power produced is AC current which is then isconverted to DC current by the use of SCR (SiliconControlled Rectifier),

The current is delivered by cables to electric motors

attached directly to the equipment involved such as mudpumps, rotary table, drawworks etc.

y

Power Requirements


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q

The total power requirements of a rig is the sum of the power requirement of:

Drawworks

Rotary table or top drive

Mud pumps Mud handling system.

Auxiliary power requirements for lighting etc,

Life support system.

The actual power required will depend on the operation being carried out:

- The maximum power used is during hoisting and circulation.

- The least power used is during wireline operations



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1. Types of rigs

2. Hoisting system

Loads: hook, fastline and deadline

Drawworks sizing



3. Rotating System4. Circulating System

5. BOP System

6. Power System

7. Group exercise: Select a Rig for a 30000ft well

g g g

dpt1 - 01 - rig sizing and selection

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