1. Lesson 34 Horizontal Drilling
PETE 411 Well Drilling
Lesson 34 Horizontal Drilling

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

4. Why Drill Horizontal Wells?
Increase Reserves
Increase Production Rates
Control Water Production
Control Gas Production

5. 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.)

11. Production Rates Oryx - Austin Chalk
Vertical Horizontal Horizontal/Vertical
Well Well Production Ratio
B/D B/D

12. Production Rates Drilled 7 wells from 1986 to 1989.
Drilled ~ 85 wells in 1990
Vertical Well Drilling Cost: 235 $/ft
Horizontal Well Drilling Cost: $/ft
Cost Ratio:

13. 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. Rospo Mare - Italy

15. Prudhoe Bay Vertical Well: 3000 - 4000 B/D
Horizontal Well: 10, ,000 B/D
Production Ratio:
Vertical Well: $/ft
Horizontal Well: $/ft
Cost Ratio:

16. 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
~5,000 ft
~8,000 ft

17. 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

18. New Drilling Technology
Mud Motors
Drill without rotating pipe
Change hole direction while drilling
Steerable systems

20. Potential Problems in Horizontal Drilling
Running equipment in and out of hole
drillstring, casing, cables
Preventing/Remedying differential sticking
Excessive torque

21. 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

22. 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 times as much as vertical wells in the same area.
Horizontal wells are often very attractive in formations with extensive vertical fractures.

23. 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)

26. 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 ft (1995)

27. Method: Use conventional directional drilling technology
Use rigid bottom hole assemblies, motors & bent subs, stabilizers
or Use Navigation drilling systems with “steerable” drilling motors

28. Medium - Radius Wells Build Rate: ~ 8 - 20 degrees/100 ft
(up to 40 deg/100 ft in some cases)
Build Radius: ~ ft
Length of Horiz. Section: 1,000-6,000 ft

29. 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)

30. Short-Radius Wells Build Rate: ~ 1 - 3 degrees/ft
Build Radius: ~ ft
Length of Horiz. Section: ,000 ft

31. 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.

33. Horizontal Well Pair

34. Horizontal Well Pair

35. Vertical Injection Wells and Horizontal Production Well