Dasar Dasar Teknik Pemboran

DASAR-DASAR TEKNIK PEMBORAN

Types of Drilling Structures

Conventional Rotary Rig for drilling on Land

Alternate Drilling Structures

Structures for deep Water or Arctic Drilling

Hydrogen Sulfide and RULE 36

Standard Derrick - Engines close to derrick - Mechanical Transmission

700 hp ENGINE

COMPOUND 700 hp ENGINE

700 hp ENGINE

Drilling Structures:

Conventional Land RigJack-up RigDrillshipSemisubmersibleJacket PlatformGravel Island Ice IslandGuyed TowerTension Leg PlatformSpar Platform

Pile-founded steel jacket platform

Cost increases rapidly with depth

Bending moments

Natural Frequency

Mud Line

Buoyed tower concept of 1970

~100 sec nat.frequency(waves ~ 6-10 sec)

Pivot at bottom(problem)

Principal features of the Lena guyed tower

200 TON CLUMP WEIGHTS

FAIRLEAD

19831,000 ftof water

Arctic drilling structure - Ice Island

High ice forcesWeak soildShallow water

~1,000 ft dia.

Spar Platform in Transit

Spar Platform Installed

Lesson 2

Drilling Systems

Drilling Rigs

Drilling a Well

Definitions

l

l

Use?

Fig. 1.33 Schematic of Rotary System

Fig. 1.34 Cutaway View of Swivel

ROTATING* Seals* Bearings

Fig. 1.38 Cutaway View and

Dimensions for Example Tool Joint

PINBOX

TJShoulder

Fig. 1.39 Stabilizer

* Keeps pipe in center of hole

* Aids in drilling straight hole

* Prolongs bit life

Fig. 1.41 Kick Detection During Drilling

Operations

1

2

3

KICK

GAIN IN PITVOLUME EQUAL

TO KICK VOLUME

Fig. 1.46 Remote Control

Panel for operating Blowout

Preventers CHOKE

What to do if KICK occurs?

Fig. 1.44 Annular Blowout Preventer

DPTJDCOH

Press

Ram Blowout Preventer

Ram Blowout Preventer - cont’d

SHEAR / BLINDRAM ASSEMBLY

Fig. 1.48 Rotating Blowout Preventer

Fig. 1.51 High-

Pressure Circulating System for

Well Control

Operations

Keep BHP const.

Kick

Fig. 1.56 Subsurface

Well Monitoring

System

MWD

Fig. 1.57 Spread Mooring Systems

OFFSHORE DRILLING

Fig. 1.58 Schematic of Equipment for Marine

Drilling

Lesson 3

Hole Problems

Lesson 5 - Hole Problems

Lost Circulation Stuck Pipe

• Keyseat- Crooked Hole• Differential Sticking• Mechanical Sticking

Junk in Hole Kicks and Blowouts Crooked Hole

Hole Problems - Lost Circulation

Flow out < Flow in (e.g 400 < 500)

Drop in Mud Pit Volume

Blowout

Indication:

Hole Problems- Lost Circulation

Poor Drilling Fluid Characteristics

Induced Fracturing of Formation From Rapid Pipe Movement

Causes:

High Formation Permeability (e.g. fractures)

Low Formation Pore Pressure


Costly Mud Makeup

Loss of Production

Fire

Loss of Permit to Drill

Results:


Preventive Measures:

Crew Education

Good Mud Program

Study Wells in Area

…to be prepared


Use Lost Circulation Material as Mud Additive (fibrous or granular)

Drill Through Troublesome Interval and Case Off

Decrease Mud Weight

Decrease Circulation Rate

Remedial Measures:

Hole Problems - Stuck Pipe(drill pipe, drill collars, casing)

Indication:

Cannot Pick Up Pipe (Venezuela case)

Causes:

Cave - ins

Keyseat - Crooked Hole

Hole Problems - Stuck Pipe

Differential Pressure Sticking

Filter Cake

Deposited AFTER Circulation Stops

- While Still on Bottom

Causes, cont’d:


Results:

Fishing Operations

Back off, POH, RIG w/fishing string

Loss of Hole

or at least part of the hole


Use Minimum Mud Weight Required to Control Formation Pressures.

Use Special Drill Collars (spiral)

Use Centralizers on Casing

Periodically Establish Circulation while Running Casing or Drillpipe in Deep Hole



Erode Mud Filter Cake - at High Fluid Velocity (speed up pumps)

Spot Special Fluid; Oil, Acid Reduce Mud Weight as Far as Possible Rotate Pipe - Keep Moving Pipe

Remedial Measures:

If Circulation Can Be Established:


If Circulation Cannot Be Established:

Cut Pipe or Unscrew Joint - and Fish

Remedial Measures:

KEYSEAT

P1

P2

P1 >> P2

Thick Filter Cake

Thin Filter Cake

F = N

N = P A

F = P A

How is filter cake formed?

Pipe Stuck in Wall Cake

Hole Problems - Junk in Hole

Bit Parts Missing

Items from Surface Dropped into Hole

Erratic Torque

Indication:


Cause:

Negligence of Crew

Result:

Fishing Operation


Crew Education

Preventive Measure:

Remedial Measures:

Run Junk Basket

Run Basket with Collapsible Teeth (“Poor Boy” Basket)

Run Magnet

Hole Problems - Blowout(oil, gas or water)

Returns to Surface after Circulation is Stopped (KICK!)

Well Out of Control - Big Problem!

Lost Circulation . . .

Indication:

Hole Problems - Blowout (oil, gas or water) [surface or underground]

Causes:

Loss of Hydrostatic Head due to Lost Circulation

Poor drilling Fluid

Swabbing Effect while Pulling Drillpipe

Insufficient Mud Weight

Hole Problems - Blowout

Results:

Possible Loss of Life and Property

Legal and Financial Problems


Crew Education

Be Alert

Blowout Control Equipment on RIG including Pit Volume Indicators



Remedial Action:

If on Bottom:

Use proper Mud Weight

Add Lost Circulation Materials

In Extreme Case of Blowout:

May Have to Directionally Drill a Relief Well

Hole Problems - Crooked Hole

Periodic Directional Surveys

Stuck Drill String

Casing Problems

Indication:


Causes:

Too much Weight on Bit

Dipping Formation

Anisotropic Formation

Too Small Drill Collars

No Stabilizers


Results:

Uneven Spacing (on bottom)

Legal Problems

Production Problems

Cementing Problems


Avoid Buckling of Drill Pipe by using sufficient number of

drill collars Use “Oversize” Drill Collars Use Reamers and Stabilizers Start the Hole Vertically

Preventive Action:


Plug Back and Sidetrack

Use Whipstock

Use Reamers in 3 Locations

Remedial Action:

Documents

Dasar Dasar Teknik Pemboran