Lesson 5 Hole Problems

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PETE 411 Well Drilling

• Lesson 5 Hole Problems

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Lesson 5 - Hole Problems

• Lost Circulation
• Stuck Pipe
• Keyseat- Crooked Hole
• Differential Sticking
• Mechanical Sticking
• Junk in Hole
• Kicks and Blowouts
• Crooked Hole

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Read Applied Drilling Engineering, Ch. 1
DefinitionsHW 2 ADE 1.12, 1.13, 1.14 due
Friday, Sept. 13. 2002
Homework
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Hole Problems - Lost Circulation
Indication

• Flow out lt Flow in (e.g 400 lt 500)
• Drop in Mud Pit Volume
• Blowout

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Hole Problems- Lost Circulation
Causes

• High Formation Permeability (e.g. fractures)
• Low Formation Pore Pressure

• Poor Drilling Fluid Characteristics
• Induced Fracturing of Formation From
  Rapid Pipe Movement

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Hole Problems- Lost Circulation
Results

• Costly Mud Makeup
• Loss of Production
• Fire
• Loss of Permit to Drill

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Hole Problems- Lost Circulation
Preventive Measures

• Crew Education
• Good Mud Program
• Study Wells in Area
• to be prepared

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Hole Problems- Lost Circulation
Remedial Measures

• Use Lost Circulation Material as Mud
  Additive (fibrous or granular)
• Drill Through Troublesome Interval and Case
  Off
• Decrease Mud Weight
• Decrease Circulation Rate

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

• Cannot Pick Up Pipe (Venezuela case)

Causes

• Cave - ins
• Keyseat - Crooked Hole

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Hole Problems - Stuck Pipe
Causes, contd

• Differential Pressure Sticking
• Filter Cake
• Deposited AFTER Circulation Stops
• - While Still on Bottom

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Hole Problems - Stuck Pipe
Results

• Fishing Operations
• Back off, POH, RIG w/fishing string
• Loss of Hole
• or at least part of the hole

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Hole Problems - Stuck Pipe
Preventive Measures

• 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

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Hole Problems - Stuck Pipe
Remedial Measures If Circulation Can Be
Established

• 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

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Hole Problems - Stuck Pipe
Remedial Measures
If Circulation Cannot Be Established

• Cut Pipe or Unscrew Joint - and Fish

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KEY SEAT
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P1 gtgt P2
P1
P2
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F mN N DP A F m DP A
Thick Filter Cake
Thin Filter Cake
How is filter cake formed?
Pipe Stuck in Wall Cake
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Hole Problems - Junk in Hole
Indication

• Bit Parts Missing
• Items from Surface Dropped into Hole
• Erratic Torque

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Hole Problems - Junk in Hole
Cause

• Negligence of Crew

Result

• Fishing Operation

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Hole Problems - Junk in Hole
Preventive Measure

• Crew Education

Remedial Measures

• Run Junk Basket
• Run Basket with Collapsible Teeth (Poor Boy
  Basket)
• Run Magnet

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Hole Problems - Blowout(oil, gas or water)
Indication

• Returns to Surface after Circulation is Stopped
  (KICK!)
• Well Out of Control - Big Problem!
• Lost Circulation . . .

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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

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Hole Problems - Blowout
Results

• Possible Loss of Life and Property
• Legal and Financial Problems

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Hole Problems - Blowout
Preventive Measures

• Crew Education
• Be Alert
• Blowout Control Equipment on RIG including Pit
  Volume Indicators

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Hole Problems - Blowout

• 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

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Hole Problems - Crooked Hole
Indication

• Periodic Directional Surveys
• Stuck Drill String
• Casing Problems

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Hole Problems - Crooked Hole
Causes

• Too much Weight on Bit
• Dipping Formation
• Anisotropic Formation

• Too Small Drill Collars
• No Stabilizers

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Hole Problems - Crooked Hole
Results

• Uneven Spacing (on bottom)
• Legal Problems
• Production Problems
• Cementing Problems

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Hole Problems - Crooked Hole
Preventive Action

• Avoid Buckling of Drill Pipe by using
  sufficient number of drill collars
• Use Oversize Drill Collars
• Use Reamers and Stabilizers
• Start the Hole Vertically

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Hole Problems - Crooked Hole
Remedial Action

• Plug Back and Sidetrack
• Use Whipstock
• Use Reamers in 3 Locations

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Lost Circulation Example

• This Example shows how to determine the mud
  weight that can be supported by the formation and
  also the mud weight that will control the
  subsurface pressure.

• Well depth 16,000 ft
• Protective casing seat 12,500 ft
• Mud Weight 17.0 lb/gal
• Drillpipe size 4.5 in.
• Hole size, casing I.D. 8.5 in.
• Annulus volume 0.05 bbl/ft
• Water required to fill hole 20 bbl

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After Water
Before Water
Water - 20 bbls
400 ft
Mud - 17.0 lb/gal
12,500 ft
16,000 ft
BHP 13,963 psig
BHP ?
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Example - Solution

• Determine The effective hydrostatic head and
  mud weight in lb/gal.
• Solution

Water gradient 0.052 8.33 0.433 psi/ft Mud
gradient 0.052 17 0.884 psi/ft
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Example 3.1
Pressure imposed at total depth 400 ft of
water x 0.433 psi/ft 173 psi 15,600 ft
of mud x 0.884 psi/ft 13,790 psi Total
pressure at 16,000 ft 13,963 psi
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Example 3.1

• Pressure imposed at the casing seat
• 400 ft of water x 0.433 psi/ft 173
  psi
• 12,100 ft of mud x 0.884 psi/ft 10,696 psi
• Total pressure at 12,500 ft 10,869 psi

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After Water
Before Water
Water - 20 bbls
400 ft
Mud - 17.0 lb/gal
12,500 ft EMW 16.72 lb/gal
10,869 psig
16,000 ft EMW 16.78 lb/gal
BHP 13,963 psig
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• END
• of
• Lesson 5
• Hole Problems