Shelf Drilling plans to raise at least $500 million in an initial public offering on the London Stock Exchange, joining other Gulf-based oil services firms seeking a listing on the bourse.

The Dubai-based offshore oil rig operator, which said revenues totalled $1.2 billion and net income reached $232 million in 2013, specialises in shallow water offshore drilling services to oil and gas customers.

It is targeting a minimum offer size of $500 million, split between the sale of $250 million of new shares as well as an unspecified amount of existing shares held by current investors, according to a regulatory filing in London.

Shelf Drilling aims to list a minimum of a quarter of the company's shares, a company spokesman said separately.

Private equity firms Castle Harlan, Champ and Lime Rock hold equal stakes in the firm, with management and independent non-executive directors holding the balance.

Once listed, the company and the three private equity firms will not be permitted to sell any more shares for 180 days, while the directors and some senior management will be curtailed for 360 days, the statement added.

Proceeds from the sale of new shares will be used to repay part of a $350 million loan facility.

The company plans a dividend payout ratio of between 40 to 60 percent of net income, chief executive David Mullen said in the statement.

Shelf Drilling will seek to grow by reactivating idle rigs, adding new rigs to the fleet which are supported by five-year contracts with Chevron in Thailand and by selectively acquire assets in the market, Mullen said.

Shelf Drilling was created in 2012 after buying 37 jackup rigs from Swiss-based Transocean. It operates mostly in the Middle East, Southeast Asia and West Africa. -Reuters