Oil prices continue to be buffeted by the debt wrangling in Washington, and get mild support from supply issues. One such issue, the threatened strike at the Grangemouth refinery in Scotland, has cleared. The strike has been called off. The situation had diminished, anyway, on word that North Sea crude would flow. Support in the $101 per barrel remains enduring. The output outages from Iran to Angola remain supportive. Angola’s output is seen down in December from November, and Nigeria has, yet, another announced force majeur from Shell…