Directional Drilling

Controlled Directional Drilling
The science of deviating a wellbore along a planned course to subsurface target whose location is at a given lateral distance and direction from the vertical, at a specified vertical depth.
Drilling a wellbore with planned deviation from vertical to pre-determined target(s)
Reasons for Drilling Directional Wells
Surface reasons
Subsurface reasons
Special needs
1. Surface Reasons
» Surface obstructions (rig/well positioning problems)
» Restrictions (health, safety or environmental)
» Economics of rig positioning
Rig/Well Positioning Problems
- Unsuitable terrain (sloped ground, marsh, forest, sand dunes, etc)
- Proximity to other wells, pipelines, oilfield facilities
- Populated area (city or rural area, farmhouse, industrial facility)
- Proximity to power lines
- Airports, radar or radio stations
- Access road and site preparation difficulties
2. Sub-surface Reasons
» Collision risk with existing wells
» Multiple targets to open for production
» Horizontal drain(s) needed
» Re-entering producing formations
» Drilling extended reach wells (ERD) to remote target(s)
» Geological problems exist
• Faults
• Floating Blocks,
• Salt Domes
» Known natural deviation tendencies caused by significant formation dip
» Sidetracking (lost) downhole objects
» Relief well required
Collision Risk
Economics - Return On Investment
- Multiple wells from a single surface location
- Extended reach - 5-6 miles
- Extended reach reentry and re-drilling options
Economics - Reservoir Drainage
- More borehole opens the productive formation
- More productive intervals in a given formation sequence

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