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.
-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
-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.
- 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’
-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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