The big global corporations who bid on leases, tend to block out smaller companies who may be able to work a marginal field. The scraps are left to the small ones who generally go into old fields and could afford to work the remainder.

There have been a few successful smaller Alaska oil companies; independents. Check out the recent (last 20 years) local history. 

Drilling was OK when large capacities of reserves were untapped; they were taken away in short order. Nobody small back in those days would have been able to swing finances to build the infrastructure to bring the quantity to market.

Low oil prices in the past were no problem for the North Slope fields when they held reserves and the pipeline was running full. That won't happen again... and natural gas is the final blow generally. 

Relieving the pressure necessary to help oil to the surface, won't be replaced by water injection; there's no giant fields left in Alaska. Only smaller ones, we should conserve for our future.