Falling crude oil prices will make it more difficult for Reliance Industries to get enough returns on its $7.4-billion investment in three US joint ventures, say analysts.As already reported, RIL plans to sell 45 per cent stake in its joint venture for shale gas in the US with Pioneer Natural Resources.As of now, RIL has had negligible return from this huge investment. If crude oil prices fall below $80 a barrel they’re dipping below $90, production of oil from shale gas formation in the US will become uneconomical, warn analysts. Such oil costs $50-100 a barrel to produce versus $10-25 a barrel for the normal supplies from the Gulf, says the Paris-based International Energy Agency.The return on capital employed on RIL’s shale gas investments were between three and four per cent in 2013-14 and were estimated to hit double digits by 2021. A fall in crude oil prices might change the game. RIL’s earnings per share from US shale gas assets was Rs 0.7 in 2013-14 and was expected to go up to Rs 11.2 by 2021, says Barclays. “Earnings from US shale, where Reliance has spent $7.4 billion so far, might rise as output increases but with the steady return on capital employed at 11-12 per cent, it might not be a key value driver,” says Barclays, in a report dated October 8. RIL is not alone. The entire shale gas sector in the US is redrawing its strategy as crude oil falls.Analysts say RIL was investing in the US as to learn the ropes and invest in India as and when the Indian government auctions shale gas blocks. With the company selling its stake in the Pioneer asset, it will be able to cut its losses in the future, they say.Pioneer admits falling prices are a concern. In a presentation to analysts, it said: “That’s a bit of a concern for Pioneer, which needs high oil prices to produce the cash flow to develop its assets in the Permian Basin.”For the first quarter of this financial year, RIL’s revenues and operating earnings from the shale gas business were $270 million and $201 million. Both grew lower than volumes on a sequential basis, owing to weakness in gas prices. Analysts have also lowered production estimates, largely driven by Marcellus Shale projects, though estimates for Pioneer are higher.