Oil rose to $37 a barrel on Friday for the first time in eight weeks as supply disruptions affecting northern Iraq and Nigeria helped prices stabilise above recent lows.  A pipeline stoppage in Turkey has cut off about 600,000 barrels a day of crude from Iraqi Kurdistan for the past two weeks, with reports suggesting the line may not be back until the middle of March.  In Nigeria, Royal Dutch Shell has declared force majeure on about 250,000 b/d of its Forcados crude oil grade following a pipeline leak, with little clarity about when it will reopen.  The combined output loss of near 850,000 b/d, or just under 1 percent of world oil demand, has been enough to put Brent on course for its first monthly gain since October.  Saudi Arabia, Opec’s de facto leader, and Russia, the largest oil exporter outside the oil cartel, are also working towards an agreement to freeze output though it is yet to win the support of all Opec members.  During a major industry gathering in Houston this week Ali al-Naimi, Saudi Arabia’s oil minister, ruled out the possibility of cutting output, damping hopes of more aggressive action to curb a glut estimated by some traders to be as large as 2m b/d.