Alberta oil producers are in the eighth month of mandatory production curtailments. Have they worked?

On today's Capitol Crude, Rory Johnston, a commodity economist at Scotiabank, talks about the impact of the curtailments on prices, supply and investment in Western Canada's oil sector. The differentials between Western Canadian Select and WTI have narrowed from historic highs, but pipeline constraints remain and crude-by-rail economics don't quite work yet, Johnston says.

Johnston discusses why he thinks the curtailments could continue longer than expected and whether Alberta will consider such a move again.