PETE 411 Well Drilling

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PETE 411Well Drilling
Lesson 34Horizontal Drilling
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Horizontal Drilling

• Why Drill Horizontal Wells?
• Relative Production Rates
• Relative Costs
• Types of Horizontal Wells
• Drilling Problems Solutions
• How Popular is Horizontal Drilling?
• Examples

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Why Drill Horizontal Wells?

• Increase Reserves
• Increase Production Rates
• Control Water Production
• Control Gas Production

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Why Drill Horizontal Wells?

• Control Sand Production

• Produce From Thin Reservoirs
• Connect Vertical Fractures
• Produce Methane from Coal Seams
• Increase Injectivity
• - (steam, water, polymers, etc.)

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Production RatesOryx - Austin Chalk

• Vertical Horizontal Horizontal/Vertical
• Well Well Production Ratio
• B/D B/D
• 12 507
  42
• 15 215
  14
• 5 107
  21

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Production Rates

• Drilled 7 wells from 1986 to 1989.
• Drilled 85 wells in 1990
• Vertical Well Drilling Cost 235 /ft
• Horizontal Well Drilling Cost 520-282 /ft
• Cost Ratio 2.2-1.2

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Drilling CostsAustin Chalk (1993)

• Vertical well 500,000
• Recompletion as Horizontal Well 375,000
• New Horizontal Well
  1,000,000-2,000,000
• 100/ft to 150/ft
• these numbers are rough estimates only

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Rospo Mare - Italy
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Prudhoe Bay

• Vertical Well 3000 - 4000 B/D
• Horizontal Well 10,000 - 12,000 B/D
• Production Ratio 3 - 4
• Vertical Well 235 /ft
• Horizontal Well 520 - 282 /ft
• Cost Ratio 2.2-1.2

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Long Radius (1,000-3,000 ft) 2-6 deg/100 ft
Medium Radius (140700 ft) 8-40 deg/100 ft
Short Radius (20-40 ft) 1.5-3 deg/ft
lt1,000 ft
5,000 ft
8,000 ft
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New Drilling Technology

• Measurement While Drilling (MWD)
• Directional Surverying and Control
• Indentification of Markers (identify zones)
• Top Drive
• Drill with 90-ft stands instead of 30-ft joints
• Circulate while pulling drillpipe out of hole
• Rotate drillpipe while pulling out of hole

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New Drilling Technology

• Mud Motors
• Drill without rotating pipe
• Change hole direction while drilling
• Steerable systems

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Potential Problems in Horizontal Drilling

• Running equipment in and out of hole
• drillstring, casing, cables
• Preventing/Remedying differential sticking
• Excessive torque

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Potential Problems in Horizontal Drilling

• Cleaning the hole and preventing cuttings from
  settling along the hole bottom
• Controlling weight on bit to achieve and
  maintain directional control
• Cementing casing or liner

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Summary

• Horizontal wells may produce at 3-5 times the
  rate of vertical wells in the same area
• ( as much as 20 times higher in special
  cases).
• Horizontal wells typically cost 1.5-3 times as
  much as vertical wells in the same area.
• Horizontal wells are often very attractive in
  formations with extensive vertical fractures.

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Summary

• The use of horizontal wells has been growing -
  worldwide.
• Horizontal wells has increased our
  recoverable reserves.
• In the U.S. one rig in ten is drilling
  horizontal wells. (1994) (1998)
• Today one rig in fifteen is drilling
  horizontal wells. (2002)

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Long - Radius Wells

• Used for achieving large horizontal
• displacements from platforms or drilling pads
• Used for achieving very long horizontal
  sections (to 6,000 ft )
• Build Rate 2-6 degrees/100 ft
• Build Radius 1,000-3,000 ft
• Length of Horiz. Section 1,000 - 8,000 ft (1995)

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Method

• Use conventional directional drilling
  technology
• Use rigid bottom hole assemblies, motors
  bent subs, stabilizers
• or Use Navigation drilling systems with
  steerable drilling motors

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Medium - Radius Wells

• Build Rate 8 - 20 degrees/100 ft
• (up to 40 deg/100 ft in some
  cases)
• Build Radius 300 - 700 ft
• Length of Horiz. Section 1,000-6,000 ft

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Method

• Use modified long-radius drilling technology
• Use different motors for Angle Build and
  Angle Hold sections.
• Use a Tangent Section between the two build
  sections
• Use compressive service drillpipe through the
  curve if Build Rate gt 15 deg./100 ft.
• (CS drillpipe has integral wear knots every
  10 ft)

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Short-Radius Wells

• Build Rate 1 - 3 degrees/ft
• Build Radius 20 - 40 ft
• Length of Horiz. Section 200 - 1,000 ft

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Method

• Two downhole motor designs are available
• Drill vertical rathole to identify horizon
• Build angle with special curve-drilling
  assembly with a non-rotating shell that gives
  curvature to the tool
• After building angle to horizontal, use a
  special angle-hold assembly this consists of
  two undergauge stabilizers behind the bit, and
  flexible drillpipe.

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Horizontal Well Pair
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Horizontal Well Pair
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Vertical Injection Wells and Horizontal
Production Well
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