Hello, Yejitheyeti, and welcome to the Grammar Exchange.
A. To survey the oil and marine markets , a marketing manager is needed.
b. A marketing manager is needed to look over the oil and marine markets.
also it would be great if you could change my wording!
According to our Guidelines, we are not a proofreading service. I can only tell you that the position of the infinitival clause depends on the context. Placed at the beginning, it seems to me that the markets were mentioned before. Placed at the end, the focus lies on the reason for requiring a marketing manager.