Transcript Petroleum Engineering 405 Drilling Engineering

PETE 411
Well Drilling
Lesson 5
Hole Problems
1
Lesson 5 - Hole Problems
 Lost Circulation
 Stuck Pipe
• Keyseat- Crooked Hole
• Differential Sticking
• Mechanical Sticking
 Junk in Hole
 Kicks and Blowouts
 Crooked Hole
2
Homework
Read:
* Applied Drilling Engineering, Ch. 1
* Definitions
HW #2 ADE 1.12, 1.13, 1.14
due Friday, Sept. 13. 2002
3
Hole Problems - Lost Circulation
Indication:
 Flow out < Flow in
(e.g 400 < 500)
 Drop in Mud Pit Volume
 Blowout
4
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
5
Hole Problems- Lost Circulation
Results:
 Costly Mud Makeup
 Loss of Production
 Fire
 Loss of Permit to Drill
6
Hole Problems- Lost Circulation
Preventive Measures:
 Crew Education
 Good Mud Program
 Study Wells in Area
…to be prepared
7
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
8
Hole Problems - Stuck Pipe
(drill pipe, drill collars, casing)
Indication:
 Cannot Pick Up Pipe
(Venezuela case)
Causes:
 Cave - ins
 Keyseat - Crooked Hole
9
Hole Problems - Stuck Pipe
Causes, cont’d:
 Differential Pressure Sticking
 Filter Cake
 Deposited AFTER Circulation Stops
- While Still on Bottom
10
Hole Problems - Stuck Pipe
Results:
 Fishing Operations
Back off, POH, RIG w/fishing string
 Loss of Hole
or at least part of the hole
11
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
12
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
13
Hole Problems - Stuck Pipe
Remedial Measures:
If Circulation Cannot Be
Established:
 Cut Pipe or Unscrew Joint
- and Fish
14
KEY
SEAT
15
P1 >> P2
P1
P2
16
F = mN
Thick Filter Cake
N = DP A
Thin Filter Cake
F = m DP A
How is filter cake formed?
Pipe Stuck in Wall Cake
17
Hole Problems - Junk in Hole
Indication:
 Bit Parts Missing
 Items from Surface Dropped
into Hole
 Erratic Torque
18
Hole Problems - Junk in Hole
Cause:
 Negligence of Crew
Result:
 Fishing Operation
19
Hole Problems - Junk in Hole
Preventive Measure:
Crew Education
Remedial Measures:
 Run Junk Basket
 Run Basket with Collapsible Teeth
(“Poor Boy” Basket)
 Run Magnet
20
Hole Problems - Blowout
(oil, gas or water)
Indication:
 Returns to Surface after Circulation is
Stopped (KICK!)
 Well Out of Control - Big Problem!
 Lost Circulation . . .
21
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
22
Hole Problems - Blowout
Results:
 Possible Loss of Life and Property
 Legal and Financial Problems
23
Hole Problems - Blowout
Preventive Measures:
 Crew Education
 Be Alert
 Blowout Control Equipment on RIG
including Pit Volume Indicators
24
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
25
Hole Problems - Crooked Hole
Indication:
 Periodic Directional Surveys
 Stuck Drill String
 Casing Problems
26
Hole Problems - Crooked Hole
Causes:
 Too much Weight on Bit
 Dipping Formation
 Anisotropic Formation
 Too Small Drill Collars
 No Stabilizers
27
Hole Problems - Crooked Hole
Results:
 Uneven Spacing (on bottom)
 Legal Problems
 Production Problems
 Cementing Problems
28
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
29
Hole Problems - Crooked Hole
Remedial Action:
 Plug Back and Sidetrack
 Use Whipstock
 Use Reamers in 3 Locations
30
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
31
Before Water
After Water
Water - 20 bbls
400 ft
Mud - 17.0 lb/gal
12,500 ft
16,000 ft
BHP = ?
BHP = 13,963 psig
32
Example - Solution
Determine: The effective hydrostatic head
and mud weight in lb/gal.
Solution:
20 bbl
 400 ft of water
0.05 bbl / ft
Water gradient = 0.052 * 8.33 = 0.433 psi/ft
Mud gradient = 0.052 * 17 = 0.884 psi/ft
33
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
13,963
Effective mud weight 
 16.78 lb/gal
(16,000)(0 .052)
34
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
10,869
Effective mud weight 
 16.72 lb/gal
(12,500)(0 .052)
35
After Water
Before Water
Water - 20 bbls
400 ft
Mud - 17.0 lb/gal
10,869 psig
BHP = 13,963 psig
12,500 ft
EMW = 16.72 lb/gal
16,000 ft
EMW = 16.78 lb/gal
36
END
of
Lesson 5
Hole Problems
37