Horizontal well completion

the completion that can be run through a given radius of curvature will depend on

1.the radial clearance between the completion item and hole(liner size),

2. the length and flexibility of the completion,

3.the rating of the connection

 

Horizontal well Completion Options

 

1.Open hole 25%

2.Slotted Liner 55%

3.Liner with Partial Isolations  15%

4.Cemented and Perforated Liners 5%

 

 Open hole 25%

1.This type of completion is the simplest and cheapest typed used in consolidated & competent reservoir Rock with almost no sand production.

2.It is represented 25% from total or all completions worldwide

 

  Slotted Liner 55%

1.It is used with or without a screen

2.It is used when the reservoir is unconsolidated or loosely consolidated sands.

3.It is formed 55% from all completions worldwide and it is considered as a prevailing well completion type.

4.its main purpose

—to guard against hole collapse

—to provides a convenient path to insert various tools such as coiled tubing in a horizontal well

●

  Liner with Partial Isolations  15%

—Slotted liner in open hole with blank sections and External Casing Packer (ECP).

—This is 15% of total completions worldwide.

—

  Cemented and Perforated Liners 5%

—It is expensive and used in long-radius horizontal sections or for medium-radius horizontal sections. It is formed only 5% of all completions worldwide.

—Problems like difficulty of cement job or leakage of cement sheath may arise in this type

 

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Horizontal Wells (why and advantages)

 

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Horizontal drilling methods(Reason and methods )

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.

    

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Directional Drilling Applications

—Sidetracking a Stuck Bottom hole Assembly 

 

 

—Multiple Sidetracks

 

—Straighten The Hole Drilling 

 

—Multiple Wells from an Artificial Structure 

—Multilateral Wells Drilled From a Platform. 

 

—Drilling Multiple Sands from a Single Wellbore

 

—Inaccessible Location

 

—Fault Drilling

 

—Salt Dome Drilling 

 

—Relief Well Drilling 

 

—Horizontal Drilling

 

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Directional Concepts

Dogleg

an abrupt change in direction in the wellbore, frequently resulting in the formation of a key-seat.

a sharp bend permanently put in an object such as a pipe, wire rope, or a wire rope sling.

Deflection angel > 3o/100 ft

Angle of Deflection

—in directional drilling, the angle at which a well diverts from vertical

—usually expressed in degrees

—In vertical, being zero.

Azimuth

—in directional drilling, the direction of the wellbore or of the face of a deflection tool in degrees (0 -359 ) clockwise from true north.

—an arc of the horizon measured between a fixed point (such as true north) and the vertical circle passing through the center of an object.

 Steering Tool

—A directional survey instrument used in combination with a deflected downhole motor. It shows, on a rig floor monitor, the inclination and direction of a downhole sensing unit.

—MWD+LWD

 

Systems and Coordinates

Depth Reference

—Measured Depth (MD)

—True Vertical Depth (TVD)

 

Inclination (Drift)

—The angle (in degrees) between the local vertical (local gravity vector as indicated by a plumb bob) and the tangent to the well bore axis at a particular point.

—By oilfield convention, 0° is vertical and 90° is horizontal.

 

Toolface

—Rigsite use of the term “toolface” is often used as a shortening of the phrase “toolface orientation”. This can be expressed as a direction from North or topside of the wellbore.

—Toolface Orientation is the angular measurement of the toolface of a deflection tool with respect to either North or up (highside).

Highside/Magnetic Toolface

   —Highside Toolface 

—indicates whether a component is facing up, down, to the left or right 

—Magnetic Toolface 

—an angular measurement from North

Mag TFO = Azimuth + Highside

Azimuth (Hole Direction)

—the direction of the borehole on the horizontal plane, measured as a clockwise angle (0°- 360°) from the North reference.

—All magnetic tools give readings referenced to Magnetic North; however, the final calculated coordinates are referenced to True North

Quadrant Bearings

—the directions are expressed in degrees from 0°to 90° measured from North in the two Northern quadrants and from the South in the Southern quadrants, e.g., N87°E, S12°W, S90°W.

Direction Measurement

—Azimuth Reference

—Quadrant Bearings

         

  

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