snubbing nugget

7/28/2019 Snubbing Nugget

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Hydraulic Workover Unit A Snubbing System is basically a well

servicing system capable of running and

retrieving jointed pipe under live well

conditions (but not necessarily high pressure). A snubbing unit or Hydraulic Workover (HWO)

unit can be used for:

drilling new wells (underbalanced if

required)

side-tracking existing wells (underbalancedif required)

completion (underbalanced if required)

fishing (underbalanced if required)

gravel packing (underbalanced)

perforating (underbalanced) clean-out (underbalanced)

Advantage is that the well does not require

killing.

Can carry out some work as a rig as long as

tubulars are less than 103/4 OD.

HWO Unit useful for pulling CT completions


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Live Well Workovers

less fluids lost to formation = less damage

shorter time with well off-line

less problems with kill fluids


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Hydraulic Workover Unit

Snubbing = process of tripping pipe in well

which as a surface pressure

great enough to eject the pipe

from the well if no restraining

force is applied.

Stripping = relates to the same operation,

but where the surface pressure

and workstring combinationwould result in the workstring

failing into the well under its

own weight if unrestrained.

Lubrication = process of inserting and

removing BHA and toolstrings

from the well.

Hydraulic Workover

(HWO) = Unit to run/pull tubulars in/out

of well (with or without

surface pressure), using

hydraulic power to transmitthe required forces to the pipe.

HWO Definitions


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Snubbing - An Introduction

Snubbing is a live well workover process

that uses standard jointed tubulars

Rig (cable) assisted snubbers date from the

1930s

Hydraulic snubbers a later addition.


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Components

A pipe movement system - cable assisted or

rig assisted

A sealing stack of pipe rams that allows

passage of tool joints and equipment into

and out of a well under pressure.


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A view of the pressure connection

tube between the upper isolation

chamber and the well.


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Schematics

from Cudd

Pressure

Control

Hydraulic snubber - top

of stroke.


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Pipe slip

elements in

hydraulic

snubber


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1. Close upper or

traveling slips.

2 Open lower orstationary slips.

3. Activate hydraulic

pressure to pull down

on pipe and force itinto the well.


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Weight Necessary to Pull Wire into a Wellhead

Under Pressure

0

50

100

150

200

250300

350

400

450

500

0 2000 4000 6000 8000 10000

Well Head Pressure, psi

We

ightNecessa

rytoPul

Wirelineintothe

Well,

lb

0.072" Wire

0.092" Wire

0.108" Wire

0.125" Wire

3/16" Wire

5/16" Wire


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Snubbing Pressure vs. WHP and Wire or

Tubing Size

0

500010000

15000

20000

2500030000

35000

40000

45000

50000

0 1000 2000 3000 4000 5000

Well Head Pressure, psi

Snu

bbingForce

orWeight

RequiredtoEnter

Wellhead,

lbs

0.108" Wire

3/16" Wire

1.5" CT

2-3/8" Tbg

2-7/8" Tbg

3-1/2" Tbg

4-1/2" Tbg


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Hydraulic snubber

nearing bottom of

stroke.


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1. Close lower or

stationary slips.

2. Open upper ortraveling slips.

3. Activate hydraulics

to extend cylinders.


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Tool joint nearing

slips.


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Stop tool joint

immediately above top

pipe ram on snubbingstack.


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Pipe seal

elements


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Tool joint above top

ram. System

pressurized below.


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Middle pipe seal closed


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Ready to bleed

off upper

straddled area.


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Upper straddled area

bled off.


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Open upper ram and

pass tool joint into

upper straddled area.


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Close upper ram and

prepare to pressurize

upper straddled area.


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Upper straddled area

pressurized, prepare to

open middle ram.

O iddl


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Open middle ram

and pass tool joint

into well.


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Rig assisted

snubbing using

rig draw worksand snubbing

stack below the

table.

Braided line

and pulleys

on the rigfloor.

Traveling

slips

Stationary

slips

Perforating Guns Run Under Pressure


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Description of job Length ofguns

Location Depthof well

SurfacePSI

TCP guns 33/8 using DHSV 1,200 Valhall/ N. Sea 13,123 2900

TCP guns 33/8 w/auger system using DHSV 250 Valhall/ N. Sea 12,467 2755

TCP guns 41/2 w/ aligning knobs using DHSV 500 Valhall/ N. Sea 14,108 3190

Halliburton Deployment system TCP guns 41/2 850 Statfjord B 13,123 1957Halliburton Deployment system TCP guns 41/2 1,100 Statfjord C 14,108 1812TCP guns 41/2 using DHSV 450 Gulfaks B 15,420 1595TCP guns 41/2 using DHSV 600 Gulfaks C 15,092 1740Halliburton Deployment System TCP guns 4 2,800 Statfjord B 16,076 3552TCP guns 4 using DHSV 1,800 Sleipner 13,780 3045TCP guns 4 using DHSV 3,200 Gulfaks B 17,717 2755TCP guns 4 Using FIV Valve 1,400 Veslifrik 12,795 2610Halliburton Deployment System TCP guns 4 950 Gulfaks C 13,780 3190Halliburton Deployment System TCP guns 4 1,100 Gulfaks A 13,451 2682

Perforating Guns Run Under Pressure

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