Driven by increased production rewards, multiple operators in the United States have been improving their unconventional wells by increasing the lateral length. Several "superlaterals" with lengths above 23,000 ft (7 km) have been drilled successfully in several U.S. basins. This paper describes the technical challenges to drill and run casing in superlaterals and the difficulties to make them possible in the Vaca Muerta unconventional play. Several mechanical and hydrodynamics models within the geomechanics constraints are combined with real-time data to illustrate the limitations observed in shorter wells and the steps needed to successfully deliver superlaterals. Drilling and running casing successful operational practices as well as "superlateral related" failures are also discussed.
As the lateral length increases, torsional and tensional loads increase. Buckling also becomes a much larger problem to overcome. Geomechanical constraints are a major challenge, especially at higher mud weights. The stability margin becomes narrower when transitioning from a shorter lateral to a superlateral because hydraulic friction increases with the lateral length and the risk of losses is increased.
Furthermore, wellbore stability is paramount to keep drag in acceptable values for a successful casing run. Conventional drill strings and casing configurations may not reach bottom and design changes are likely to be required. Better attention to the drilling and casing running practices is key to prevent catastrophic events.
In Vaca Muerta, the geomechanical constraints are particularly important. Changes in the wellbore geometry and/or drill pipe size can be required to maintain an acceptable mud weight window. When Quintuco and Vaca Muerta are drilled in the same section, the use of Managed Pressure Drilling (MPD) has reduced the effect of the uncertainties on the pore pressure and allowed successful drilling of shorter laterals, but as the lateral length increases, MPD alone is insufficient to mitigate this risk.
