By Marta Nogueira
RIO DE JANEIRO, Aug 17 (Reuters) - Brazil's NationalPetroleum Agency (ANP) ruled that Royal Dutch Shell andits Qatari and Indian partners need to treat oil and gas fieldsin the Parque das Conchas area as a single deposit, Shell said,a move that could increase taxes on output.
Shell owns 50 percent of Parque das Conchas, its mainBrazilian asset. Qatar's state oil company Qatar Petroleum owns 23 percent and India's ONGC owns 27percent.
The ANP's decision to treat the fields as a single depositapplies to two of Shell's four fields in the block, also knownas BC-10, for which it holds exploration and production rights.
The decision comes as Shell prepares to expand production inthe block that now produces 50,000 barrels per day of oilequivalent and take over the Brazilian properties of Britain'sBG Group Plc, which it is buying.
Shell said the ANP has approved its development plan for theNautilus field but also stipulated that it must be joined withthe Argonauta field.
The ANP previously made a similar decision with the Lula andCernambi fields and seven other fields in the Parque das Baleiasarea, all operated by state oil company Petroleo Brasileiro.
Petrobras ended up challenging the ANP's previous decisions,which are still tied up in court and in internationalarbitration.
When oil companies discover fields with production potentialabove a certain level, they are subject to paying a windfall taxknow locally as a "special participation" tax on top of thebasic royalty they must pay the government. This can increasethe government tax on each barrel of oil produced to about 40percent from 10 percent.
Shell told Reuters in an email that it was not currentlypaying special participation for any of the fields in the Parquedas Conchas.
Shell's production expansion plans at Parque das Conchas isexpected to boost output by 30,000 barrels a day (bpd).
The company said it would not comment on the ANP's decisionuntil its management had discussed it.
The Brazilian Oil Institute, which represents the sector,said the companies operating in Brazil's oil explorationindustry are very concerned about the ANP's decision. (Writing by Reese Ewing; Editing by Jeb Blount and ChristianPlumb)
