CARACAS, Venezuela (Reuters) — Venezuela’s plan to boost oil output by 900,000 barrels a day in partnership with Russia and China faces major stumbling blocks in tight funding and a lack of technical expertise in drilling for heavier grades of oil and bringing it to market.

Delays in producing barrels from the oil-rich Orinoco belt may further reduce government revenues for the South American nation, where petroleum funds bankroll the social programs put in place by left-leaning President Hugo Chavez.

“These projects clearly will be beholden to foreign interests; if there are capital needs at home, foreign partners such as China and Russia, will prioritize these, likely slowing the pace of development in the Orinoco Belt,’’ said RoseAnne Franco, senior analyst at PFC Energy.

The energy deals with Russia and China are part of the “oil diplomacy’’ policy in which Chavez seeks allies by allowing countries access to the OPEC nation’s vast crude resources.

After signing energy deals with countries around the world, from Uruguay to Vietnam, Venezuela recently signed initial agreements with Russia and China to boost oil production by nearly a third in three years.

Venezuela’s joint venture with Russia will require an investment of $20 billion and is expected produce 450,000 barrels per day from the Junin 6 field by 2012.

The Russian consortium is also in preliminary stages of a development plan for three Orinoco belt fields expected to produce nearly 700,000 bpd barrels a day.

But experts said Russian companies do not have the funds to work in the Orinoco, whose tar-like oil that must be refined before export.

“Russian companies just don’t have the spare capex. They simply don’t have the money,’’ said Chris Weafer, Russia strategist at Uralsib Bank in Moscow.

Getting the project off the ground quickly would likely require financial backing from the Kremlin, Weafer said.

The Chinese-Venezuelan partnership to develop the Orinoco’s Junin 4 field with a $16-billion investment over the next three years was seen as much more likely to be fruitful due to vast Chinese financial resources.