* Exports set to fall slightly to 1.56 mln bpd
* Indonesian demand falters, prefers spot
* For a related table: (Adds bullet with table link, detail)
By Emma Farge
GENEVA, March 23 (Reuters) - Asian imports of West African crude oil are set to slip to 1.56 million barrels per day (bpd) in April while holding above the average level for 2011, a Reuters survey of oil flows showed.
Asia is expected to import 51 cargoes from West Africa in April, compared with an average of 50 during last year.
Asian imports from the region hit a record high in the first quarter as purchases of Iranian oil decline and Chinese and Indian refiners build stocks from alternative sources.
Daily imported volumes were down from an estimate of 1.81 million bpd in March.
Traders pointed to a change in Indonesia's buying patterns as the main factor behind the fall in volumes.
Petral, the trading unit of Indonesian state-run energy firm Pertamina, failed to award a tender to buy sweet grades for May-July arrival and is expected to focus instead on spot purchases.
"They are staying high, although we have Indonesia taking less," said a trader.
Demand from China was little changed, with an estimated 30 cargoes scheduled to load versus a planned 31 cargoes. Traders said Unipec was the main buyer for the Chinese market, taking at least 20 cargoes.
India was expected to import 13 cargoes versus 15 in March, the survey showed.
North American, Asian and European refiners vie to purchase West Africa's mostly high quality, low sulphur crude oil from countries such as Nigeria, Angola and Chad.
Increasingly, Indian, Chinese and other Asian buyers have been buying crude from the region to meet booming demand.
"There's not any fundamental reason for it. They have just built the units to consume this type of crude so they are buying it. Demand is structural," said a West African oil trader, asked to explain the consistently high demand from Asia. (Reporting by Emma Farge; Editing by Anthony Barker and David Hulmes)