By Marianna Parraga and Matt Spetalnick HOUSTON/WASHINGTON (Reuters) – Italian oil company Eni SpA and Spain’s Repsol SA could begin shipping Venezuelan oil to Europe as soon as next month to make up for Russian crude, five people familiar with the matter said, resuming oil-for-debt swaps halted two years ago when Washington stepped up sanctions on Venezuela. The volume of oil Eni and Repsol are expected to receive is not large, one of the people said, and any impact on global oil prices will be modest. But Washington’s greenlight to resume Venezuela’s long-frozen oil flows to Europe could pro…