Saudi has been trying out higher volume and lower prices for a while, and that means a 0.5 mn b/d ceiling cut next week in Vienna in the OPEC meet, according to BoFA Merrill Lynch.
This announcement will support prices at current levels before they bounce back towards $90/bbl over the next three months.

A $50/bbl oil price band may serve Saudi interests better than a tight $20/bbl band. After all, Saudi can ramp output up or down within 3 months, while it takes shale players 6-12 months to react to rising or falling prices. "We see Saudi trying out higher vol and lower prices for awhile."
OPEC was able to agree to a near-term reduction in output in exchange for long-run oil market share in 1998/99, 2001, and 2008/09 as global oil demand fell. Then the OPEC country quota system was replaced by a collective production ceiling in 2011.

Prorating former quotas to this ceiling would leave Saudi at 8.7 mn b/d, or 1 mn b/d below their current production levels. But at that output level their fiscal budget break-even would move to $110/bbl in 2015.
Saudi learned in 1985—following a 6 mn b/d retrenchment—that curbing supply to make room for others (now Libya and Iran) may not be a great strategy in the long-run.

How can OPEC slow US shale? The drop in prices has shut down financing for the smaller, more levered US shale players. Should prices average $76/bbl (current forward), shale oil growth would stand at just 500 k b/d next year, while $60 would leave production flat.
Source: BoFA Merrill Lynch