How do horizontal wells help recover oil from previously inaccessible parts of a reservoir?

Horizontal wells allow for the recovery of oil from previously inaccessible parts of a reservoir by extending the reach of the well bore laterally through the target formation. Unlike traditional vertical wells, which only intersect a formation at a single point, horizontal drilling enables the well to turn at a "kickoff point" and travel horizontally for hundreds or thousands of meters within the reservoir.12

This technique provides several advantages for accessing bypassed or difficult-to-reach deposits:

• Increased Reservoir Contact: By drilling laterally, the well bore exposes a much larger surface area of the productive formation, significantly increasing the potential for oil flow compared to a vertical hole.12
• Accessing Bypassed Zones: In mature fields, engineers use directional drilling to "sidetrack" from existing well bores, allowing them to target smaller, previously bypassed deposits of oil.1
• Multi-well Efficiency: Multiple lateral sections can radiate from a single borehole or a single surface "pad," enabling operators to reach various parts of a reservoir or multiple deposits from one location.12
• Complex Formations: Modern rotary steerable systems allow for precise navigation through challenging geological formations, making once-noncommercial resources developable.1