The contract is between Rosneft and PDVSA, not between Venezuela and Russia. Rosneft is partially owned by the Russian Federation, but it's owned in part by BP, the old British Petroleum. The Venezuelans like to announce these deals as if they were country to country because they seem to be mentored by Cubans and they have a bit of jet lag, they don't realize the old communist style country to country agreements are not used. As a matter of fact, I seriously doubt Pdvsa's lawyers would ever allow a contract with a sovereign nation. This becomes a treaty and represents more of a commitment.
Regarding the news itself, I noticed they say Petrovictoria will sell 72% of the crude to Rosneft (it's not the Russian state). I bet Rosneft will then sell the oil to USA refineries. It's an interesting mechanism to provide political cover, because PDVSA is always saying they don't want to sell so much oil to the US market. Which brings up another point, this oil is similar to the Canadian tar sand crude. It will compete with the blend being shipped by pipeline from Alberta.