Technology Focus: Multilateral/Extended Reach (May 2013)
Authors: Negrao Alvaro Felippe 
Published: February 2015

Technology Focus
The producing assets of unconventional shale-gas and shale-oil plays in North America are among the strategic alternatives for future growth of exploration-and-production companies. Although the economics of the unconventional plays was quite marginal at the beginning, further advancements in planning and operations have made feasible the exploitation of such assets with a reasonable return on investment. The use of horizontal drilling in conjunction with hydraulic fracturing has expanded the ability of operators to recover natural gas and oil from low-permeability geologic plays in a profitable way. However, there is still room for improvement in efficiency.
The exploitation of the unconventional areas with the current number of wells per acre and the amount of water used for the fracturing jobs is counterproductive. The current reality imposes fewer wells per acre, a reduction in drilling pads, and a minimum use of water in fracturing jobs. The implementation of multilateral, extended-reach, or fishbone wells is playing an essential role in the reduction of the wells, meanwhile maintaining or improving the production and recovery per acre. Thanks to the development of a new generation of fluids that improve hydraulics and wellbore stability, those wells can now reach targets farther from drilling centers, with a substantial increase in recovery and productivity per well.
The selected papers give a perspective on the challenges faced on these well profiles and the technologies used to overcome them. On the other hand, the fracturing treatment has reached a considerable number of stages because of the long extension of the wells, resulting in a required water volume that has jeopardized the economics of the project and created problems with the local communities. The environmental effect of the wastewater from the fracturing jobs has brought concerns, urging the development of techniques that reduce the amount of such water. The volume of water in fracturing jobs is directly proportional to the fluid-loss-coefficient property, so decreasing that will result in more-effective fracture propagation with less water.
Some research projects with the new generation of fracturing fluids—some including the use of nanotechnology—are aiming for this objective of improving fracturing jobs with a substantial reduction in water volume. The implementation of this new generation of fracturing fluids with multilateral/horizontal/extended-reach wells has the potential to enable the exploitation of unconventional reserves around the world with minimum visual and environmental effect, diminishing substantially the criticism about current unconventional shale operations.
Recommended additional reading at OnePetro: www.onepetro.org.
SPE 162099 Drilling World-Class ERD Wells in the North Caspian Sea by Sergey Bogdanov, Lukoil, et al.
SPE 161532 Drilling Multilateral Infill Wells for Incremental Oil Production: A Case Study From a Mature Field by E. Zuckmeyer, Total, et al.
SPE/IADC 163463 Extended-Reach Drilling—New Solution With a Unique Potential by O. Vestavik, Reelwell, et al.