Wellheads (2)

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Development Phase

September October 2005abalt solutions limited - 2005

INTRODUCTION TO HYDROCARBON EXPLOITATION

Introduction to Hydrocarbon Exploitation

2005 Abalt Solutions Limited. All rights reserved

Development Phase

Well Heads

DrillingEngineering-Wellhead

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Introduction

All Surface equipment topping off the architecture

of a well. It consists of Hangers, Christmas treeand all other hardware suspended with respect

to safety and reliability of a well.

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Introduction


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Changes in Wellhead

Changes in wellhead during a drilling operation

are described based on the following

Drilling 17 Hole

Casing 13 3/8

Drilling 12 Hole

Casing 9 5/8

Drilling 8 Hole

Casing 7

Drilling 6 Hole

Completions

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Drilling 17 Hole

The initial architecture of well consists of bellnipple or conductor.

Only if there is shallow gas-Diverter is used

Surface casing is run in and cemented right tothe surface.

Wait on Cement and then mount the Casing-

head housing.

Diverter Its an annular type BOP .

Working pressure is low

Functions to divert any blow out to a flare.


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Drilling 17 Hole

Casing Head Housing

First Component screwed,welded or forged to surfacecasing.

In the event casing stringgets stuck on the waydown, connection can bemade only after pipe is cutoff and welded.

Bore in upper part ofhousing can be cylindricalor tapered to supportcasing hangers and sealsfor next casing string.

The surface casing andhousing support all thecasings and BOPsanticipated.

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Drilling 17 Hole

Assembling BOP The Wellhead is

complete for thisdrilling phase withmud cross andOperatorsrecommendedBOP.

Wear bushinglocked with

locking flange andradial threadedrods inside casinghead housing toprotect bore fromerosion.


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Drilling 17 Hole

Pressure Tests

Wellhead must be pressure tested Whenever anything is assembled

Whenever anything is dismantled

Periodically according to Operator

All valves and pair of pipe rams aretested by pumping into annulus viakill line

Tested using

Tester cup Tool screwed on to end of DP and to

10 to 30m into casing.

All valves and pipe rams are tested

Tester plug Plug with O rings are rested in casing

head

Pipe rams, annular and accessoriescan be tested.

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Drilling 12 Hole

Drilling with 12 bit.

9 5/8 casing is run and then cemented up to

desired height from shoe.

Wear bushing is removed from casing-headhousing.

Casing tensioned and anchored placing weight

of 9 5/8 on casing spider and disconnectingflanges between mud cross and CHH.

Lift BOP Structure. Place Casing Hangers in between 9 5/8 casing

and bore of the casing head housing.


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Drilling 12 Hole

Casing Hangers

Devices to anchor and hangcasing strings in the CHH.

Each has slips to hang thecasing into tapered sectionof CHH.

Contains rubber ring sealingassembly.

Types

Separate Packers andHangers

Hangers and incorporatedpackers

Automatic hangers.

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Drilling 12 Hole

Casing Head Spools

Also supports casingstrings.

2 Flanges of differentsizes and workingpressures

Lower flange-samedimension andworking pressure as

casing-head housing.It has a cylindrical

bore and seal system. Upper part-cylindrical

or tapered toaccommodate casing

hangers of next string


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Drilling 8 Hole

Principle is same aspreceding phase

Casing stringanchored after wearbushing has beenremoved.

Casing cut-offaccording to thecomponents that willbe assembled on topof 7 string.

Testing/Pack-offflange is connected

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Drilling 8 Hole

Tubing Head Spools Identical to double flanged casing-head spools and suspend tubing.

Tubing Hangers Consist of threaded hanger with seal on tapered outside part which

corresponds to tubing head.

Held by screws on upper flange of tubing head.

Length of tubing is screwed on to upper female part of hanger. For dual completions, special tubing head must be used.


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Drilling 8 Hole

Dual tubing hangerconnection

Well head for 6 Drilling

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Drilling 8 Hole

Courtesy:ABB


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Drilling 6 Hole

The 7casing is run in holeand cemented at top of payzone.

Producing layer is drilledand completed by running5 liner anchored in the 7

casing. Casing is perforated and

production packer set.

Tubing & hanger are run in.

After BOPs are dismantled,an adapter flange fitting onthe tubing head &supporting lower part ofmaster valves completeswellhead.

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Blowout Preventers

Pressure control devices that hold and maintain pressureduring drilling operations.

Designed to:

Seal off the well when formations are encountered thatcontain pressure>hydrostatic pressure of drilling mud.

Allow mud circulation & density adjustment according toformation fluids under pressure.

Characterized by:

Make

Type

Nominal size

Working pressure


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Characteristics for each Preventer:

Maximum opening diameter allowing drilling bits to pass through. Opening & closing ratios; ratio between pressure prevailing in well

when the Preventer is closed or opened) and hydrostatic pressurerequired to close or open) the preventers.

Working pressure 1000;2000;3000;5000;10,000;15,000 & 20,000

Nominal diameters 30,29,21 ,20 ,18 ,16 ,13 5/8,11 & 7 1/6

Make Cameron

Shaffer

Hydril Vetco Gray

Blowout Preventers

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Types of BOPs

Ram type preventers

Pipe rams

Blind rams

Shear rams

Annular type preventers

Rotating preventers

Inside preventers


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Ram preventers

Pipe Rams Semi circular openings which match

diameter of pipe sizes for whichdesigned.

If more than one size of drill pipe is

used, additional preventers must beused on stack.

Blind rams Designed to close when no pipe is

used.

Will flatten drill pipe if inadvertently

closed with drill string in hole, but willnot stop flow from well.

Shear rams Designed to shear drill string.

Will cause drill string to drop in hole &

stop flow from well.

Used mainly when all pipe rams andannular preventers have failed.

Types of BOPs

Courtesy :Cameron

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Types of BOPs

Shear rams

Blind rams

Pipe rams


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Annular Preventer Sometimes called bag-type Preventer

Stops flow from well using a ring of synthetic rubber that contractsin the fluid passage.

Rubber packing conforms to shape pf pipe

Working pressures:

2000 psi

5000 psi

10,000 psi

Types of BOPs

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Rotating Preventer This type of Preventer

allows the drill string to

be rotated & run in orout.

Placed above normal

preventers and used fordrilling under pressure

when low density mud isrequired.

Used for drilling with air

or gas as fluid

Types of BOPs


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Different BOP Stack combinations

According to IADC:

3-Ram and 1 Bag type-10,000 psi15,000Very High Pressure

3-Ram and 1 Bag type-5000 psi10,000High Pressure

2-Ram and 1 Bag type5000Medium Pressure

2-Ram and 1 Bag type3000Low Pressure

2-Ram or 1 Bag type2000Light

StackWorking Pressure (psi)Duty

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Different BOP Stack combinations

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BOP Hydraulic Control Systems

Principles

All Bops and wellhead valves are hydraulically

actuated & operated.

There is always one line on opening side & one

on closing side.

Volume of fluid required to carry out a givennumber of emergency open/close functionsshould be specified by operator.

Pressure must be exerted to get a good seal.

Time required to close all BOPs must be

calculated.

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Several Air/Oil accumulators

Set of hydraulic pumps

Direct control manifold

Remote controlled manifold



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Operation Hydraulic fluid

discharged by pumpsto accumulatorscompress a bladderfilled with Nitrogen.

Pressure equilibriumbetween gas & fluid inaccumulator.

Gas acts as a springthat expels the oil whencircuit is opened bymeans of one of fourway valves that selectsthe functions.

Hydraulic pumps start& stop automaticallyand main circuit isregulated at 1500 psi.


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Wellheads (2)