Types of Directional Well Profiles

In general, there can be following types of well profiles-

1. L-Profile 
2. J-Profile
3. S-Profile
4. Horizontal Wells
5. ERD Wells (Extended Reach Drilling)

L-Profile-

L-Profile wells have Building section and Holding (or Tangent) section.

Features:

• Shallow KOP.
• May have one or more than one Build-up rates.

Applications:

• Deep wells with large vertical sections.

J-Profile-

Features:

• Deep KOP.
• Build-up section
• Short tangent section (optional)

Applications:

• Appraisal wells to access the extent of a newly discovered reservoirs.
• Re-positioning the bottom part of the well or re-drilling. 
• Salt dome drilling.

S-profile-

Features:

• Shallow KOP
• Building Section
• Tangent Section
• Dropping Section

There can be several variations such as,

-Build, Hold & Drop back to vertical

-Build, Hold & Drop & Hold (as shown)

-Build, Hold & Drop through reservoir.

Applications:

• Multiple pay zones
• Well spacing requirements
• Deep wells with small horizontal displacements
• Lease or target limitations
• Reduces final angle in reservoir

Disadvantages:

• Increased torque & drag
• Risk of key seating
• Logging problems due to inclination.

Horizontal Wells-

Features:

• Angle 90 deg or more is achieved.
• Can have one or more Building section.

Applications:

• Greater exposure to reservoir.
• Greater drainage capability.
• A single well can penetrate and produce from oil from multiple pockets.

Disadvantages:

• Increase in torque & drag.
• Increase in Equivalent Circulating Density.
• Hole cleaning problems.

Extended Reach Drilling Wells (ERD)-

Features:

• Generally, vertical sections of length > 5000 m.
• In many cases, they are referred as well having vertical section to TVD ratio of 2:1 or more.
• Similar sets of problems can be associated with ERD wells as with Horizontal wells.

When planning a directional well, a number of technical issues & constraints will have to be considered and accordingly well plan are prepared or approved. 

These includes:

• Target location
• Target shape & size
• Surface location (Rig)
• Sub surface obstacles (faults, salt dome, etc.)
• Adjacent Wells
• Casing Programs
• Mud Programs
• Geological Sections

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