* Trading house Trafigura has record first half net profit
* Strong margins help to offset lower revenue
* Changes to market structure to temper second half
* (Adds context, quotes)
SINGAPORE/LONDON, June 8 (Reuters) - Switzerland's Trafigura reported record first half net profit on Monday on the back of stronger oil and metals trading, illustrating how trading houses have benefited from market volatility and price structure in recent months.
Trafigura's financial year ends in September so its first half results -- from September 2014 to March 2015 -- covered a period when oil prices collapsed and then partially recovered.
During most of the period the oil markets were in the "contango" structure -- when prompt prices, for immediate delivery, were cheaper than future prices. This encourages traders to store oil to resell it at a profit in the future.
The situation was similar to 2009, when oil traders enjoyed record profits following a fall in oil prices after the collapse of Lehman Brothers in 2008.
Trafigura said its first-half net profit jumped 39 percent to a record $654 million, while gross profit rose by 58 percent to $1.517 billion. That represented a gross trading margin of 3.1 percent, double the figure a year-ago.
Such a strong margin is in sharp contrast with margins that traders have been generating during recent years of low volatility when a margin of one percent was considered to be a good one.
"This is a very strong result, reflecting an excellent trading performance in the relatively favourable conditions prevailing in global oil and refined product markets, and profitable growth in both trading divisions," Trafigura Chief Executive Jeremy Weir said in a statement.
The results are unlikely to be repeated in the second half as the market structure has changed significantly in the past weeks, including the narrowing of contango.
Trafigura said gross profit at its oil and petroleum products division rose 77 percent from a year earlier to $1.01 billion, while gross profit at its metals and minerals division increased 31 percent to $509 million.
The jump in profits came despite revenue falling by 24 percent to $48.24 billion because of lower commodity prices.
Trafigura's head of oil, Jose Larocca, said in April the market structure wasn't encouraging crude storage at sea anymore although crude storage inland was still possible.
He also said the strength in oil products, observed throughout the first quarter of 2015, would ease sooner rather than later because of a persistent crude glut and refining overcapacity. (Reporting by Manolo Serapio Jr. and Dmitry Zhdannikov; Editing by Keith Weir)