SINGAPORE, July 29 (Reuters) – Choo Chiau Beng, head of the world's biggest rig maker, doesn't believe in quick returns.

Choo, who holds the top post at Singapore's $10-billion Keppel Corp. had to work his way up after starting his career as a ship repair management in 1971.

As Keppel fights a slump in orders after a five-year boom that ended in 2008, the naval architect needs to steer the firm through difficult times.

Oilfield service firms face an uncertain outlook following BP's massive oil spill that led to a halt in US deepwater drilling.

Choo, also Singapore's non-resident ambassador to Brazil, has to rely on his persuasion skills to help Keppel win big orders from the Latin American nation, where state firm Petrobras wants to buy 28 rigs in the five years to 2018. The total order value is estimated at around $20 billion.

Analysts said the 62-year old, who began his career with Keppel Group and is an avid art lover, must diversify the business, which is highly dependent on the offshore oil sector.

''Everyone will watch the Petrobras situation closely. That is an important agenda for the CEO,'' said Kwok Chern Yeh, fund manager at Aberdeen Asset Management, which owns Keppel shares.

''Obviously there are other challenges such as the Gulf of Mexico spill, but from the company's orderbook stand point Petrobras is a bigger issue at this point.''

Keppel, 21 percent owned by Singapore's state investor Temasek Holdings, received S$1.7 billion in new offshore and marine contracts last year. At the end of the first quarter, Keppel had new orders worth S$1.6 billion and on Wednesday, it won an order valued at S$170 million.

Last year, around half of the total orders came from Brazil related projects and the rest from Europe, Asia and other places.

The UK-educated Choo, took home as much as S$11.75 million ($8.5 million) last year, earning more than Singapore's top bank CEOs and making him one of the top paid CEOs in the city-state.

Choo pleased investors when he oversaw the sale of Keppel's 45.5 percent stake in Singapore Petroleum Company to PetroChina for S$1.47 billion in 2009, a move that helped streamline Keppel's portfolio.