Three Rivers Operating Company, an oil and gas E&P operating in Texas and New Mexico, registered with the SEC on Friday for a $300 million initial public offering. The Austin, TX-based company, which was founded in 2010, booked $124 million in sales for the twelve months ended September 30, 2011. The company also reported preliminary financials, with estimated 2011 sales (at the midpoint) increasing 19% to $118 million and net income increasing 23% to $26 million. The primary financial backer is Riverstone/Carlyle Energy Group. Three Rivers plans to list on the New York Stock Exchange under the symbol TROC. Goldman Sachs, J.P. Morgan and Credit Suisse have been chosen to manage the offering.