Horizontal Drilling
14. Horizontal Drilling
PETE 661 - Drilling Engineering
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Lesson 14 - 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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14. Horizontal Drilling
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Why Drill Horizontal Wells? Increase Reserves Increase Production Rates Control Water Production Control Gas Production 14. Horizontal Drilling
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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.) 14. Horizontal Drilling
PETE 661 - Drilling Engineering
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14. Horizontal Drilling
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14. Horizontal Drilling
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Production Rates Oryx - Austin Chalk
Vertical Well B/D
Horizontal Well B/D
Horizontal/Vertical Production Ratio
12
507
42
15
215
14
5
107
21
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14. Horizontal Drilling
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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PETE 661 - Drilling Engineering
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Drilling Costs Austin 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} 14. Horizontal Drilling
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Rospo Mare - Italy
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Prudhoe Bay
Vertical Well: Horizontal Well: Production Ratio: Vertical Well: Horizontal Well: Cost Ratio:
14. Horizontal Drilling
3,000 – 4,000 B/D 10,000 - 12,000 B/D 3-4 235 $/ft 520 - 282 $/ft 2.2-1.2
PETE 661 - Drilling Engineering
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Long Radius (~1,000-3,000 ft) {~2-6 deg/100 ft}
Medium Radius (140~700 ft) {~8-40 deg/100 ft}
Short Radius (~20-40 ft) {~1.5-3 deg/ft}
<1,000 ft 14. Horizontal Drilling
~5,000 ft
~8,000 ft
PETE 661 - Drilling Engineering
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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 14. Horizontal Drilling
PETE 661 - Drilling Engineering
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New Drilling Technology Mud Motors Drill without rotating pipe Change hole direction while drilling Steerable systems
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14. Horizontal Drilling
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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 14. Horizontal Drilling
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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 14. Horizontal Drilling
PETE 661 - Drilling Engineering
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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. 14. Horizontal Drilling
PETE 661 - Drilling Engineering
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Summary • The use of horizontal wells is growing worldwide. • Horizontal wells has increased our recoverable reserves. • In the U.S. one rig in ten is drilling horizontal wells. (1994) (1998) ~ 7% in Oct. 2001 14. Horizontal Drilling
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14. Horizontal Drilling
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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 14. Horizontal Drilling
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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 14. Horizontal Drilling
PETE 661 - Drilling Engineering
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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 > 15 deg./100 ft. (CS drillpipe has integral wear knots every ~ 10 ft) 14. Horizontal Drilling
PETE 661 - Drilling Engineering
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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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PETE 661 - Drilling Engineering
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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. 14. Horizontal Drilling
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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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14. Horizontal Drilling
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