Oil and gas group MX Oil has increased its stake in its Mexican venture with partner Geo Estratos.In a statement released on Friday, the London-listed company said its stake in the project will rise from 51% to 55% and it will no longer be obligated to finance Geo Estratos' share of costs once assets have been secured.The joint venture has applied for five licence blocks in Mexico, amid a boom in the industry that followed the end of decades of state monopoly."We are delighted with the progress we have made to date in Mexico," said group chief executive Stefan Olivier."In Geo we have a partner with an established relationship with Pemex, proven expertise in the provision of oil and gas services to local operators, and a comprehensive database on onshore Mexican concessions."Earlier this week, state-owned Pemex found an estimated 350m barrels of oil off the coast of the Tabasco and Campeche states, which could yield as much as 200,000 barrels per day by 2018.MX shares were up 2.34% to 3.04p at 11:38 on Friday.