Chuong 10 horizontal drilling

Why Drill Horizontal Wells? Increase Reserves  Increase Production Rates  Control Water Production... New Drilling Technology Measurement While Drilling MWD Directional Surverying and

Well Drilling Engineering

Horizontal Drilling

Dr DO QUANG KHANH

Horizontal Drilling

 Why Drill Horizontal Wells?

 Relative Production Rates

 Relative Costs

 Types of Horizontal Wells

 Drilling Problems & Solutions

 How Popular is Horizontal Drilling?

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Why Drill Horizontal Wells?

 Increase Reserves

 Increase Production Rates

 Control Water Production

Why Drill Horizontal Wells?

 Produce From Thin Reservoirs

 Connect Vertical Fractures

 Produce Methane from Coal Seams

 Increase Injectivity

- (steam, water, polymers, etc.)

 Control Sand Production

Production Rates

Oryx - Austin Chalk

Vertical Horizontal Horizontal/Vertical Well Well Production Ratio B/D B/D

12 507 42

15 215 14

5 107 21

Drilling Costs

Austin Chalk (1993)

Recompletion as Horizontal Well ~ $375,000

Rospo Mare - Italy

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}

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

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

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

• 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.

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

Method:

• Use conventional directional drilling

technology

• Use rigid bottom hole assemblies,

motors & bent subs, stabilizers

• or Use Navigation drilling systems with

“steerable” drilling motors

Medium - Radius Wells

Build Rate: ~ 8 - 20 degrees/100 ft

(up to 40 deg/100 ft in some

cases)

Build Radius: ~ 300 - 700 ft

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)

Method:

 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.

Horizontal Well Pair

Horizontal Well Pair

Vertical Injection Wells and

Horizontal Production Well