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Showing posts with label Horizontal drilling. Show all posts
Showing posts with label Horizontal drilling. Show all posts

Friday, March 16, 2012

Horizontal drilling methods(Reason and methods )


The choice of drilling method depends upon:
Cost,
Well spacing and
Mechanical conditions of a vertical well bore
In addition, reservoir consideration.





 BUILD RATES
Ultra-short Radius
Short Radius
Medium Radius
Long Radius
 ULTRA-SHORT RADIUS
45 to 90 degrees per foot
Special equipment
Horizontal lengths of 100’ to 200’
Used in unconsolidated, heavy oil sands and soft formation.
Impossible to log the open hole section.


 
An ultra-short radius drain hole is drilled using endless 1¼ inch tubing.
Uses a jet under high pressure to cut the formation and advance the endless tubing.
twenty-four laterals can be drilled at the same horizon.  
SHORT RADIUS
1.5 to 3 degrees per foot.
Needs special equipment
Mechanical and motor systems are available.
Typically used in sidetracking existing wells to bypass water producing or troublesome.
Bending stress and fatigue can be a problem
200’ to 1000’ horizontal section
The horizontal section can be cased with a slotted liner or left open hole. 
Open hole logging capabilities are limited for the horizontal section.
 
MEDIUM RADIUS
The first medium radius wells were drilled in 1985
6 to 35 degrees per 100’ build rates
Uses conventional equipment
Horizontal section lengths have been drilled over 7000’ but typically 2000’ to 4000’
LONG RADIUS
2 to 6 degrees per 100’ build rates
Uses conventional equipment
Horizontal section lengths have been drilled over 10,000’ but typically 3000’ to 5000’
No problem with bending stress, fatigue or completion equipment
Build section is steerable, which means the motor can be rotated in the build section
Offshore uses long radius almost exclusively since longer departures are required before the well gets to be horizontal
Wells are more easily logged.
    
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