As Opera San Antonio’s first production of its third season approaches — Georges Bizet’s “Carmen,” which opens Thursday — its new general and artistic director begins his duties convinced his life and training has prepared him for his administrative role at the organization. Enrique Carreón-Robledo assumed his new position in early August, when much of the planning for the opera company’s upcoming season already had been made. “The structure of the company is so strong,” Carreón-Robledo said. “Its vision is similar to mine. I know of the cast members who have been selected (for the season’s main productions, ‘Carmen’ and ‘Barber of Seville’). It’s the kind of casting I would do myself. I have no hesitation working on the projects already planned.” The title role will be sung by soprano Kirstin Chávez. Tenor Adam Diegel returns to San Antonio for the role of Don José. Diegel performed the same role at the Glimmerglass Festival in 2011 and sang the role last year of Lt. B.F. Pinkerton in Opera San Antonio’s “Madama Butterfly,” which also used Glimmerglass Festival sets and costumes.The San Antonio Symphony will perform in the Tobin Center for the Performing Arts pit for “Carmen,” guest conducted by Garrett Keast, who has Houston roots but now lives in Berlin, Germany, and is active primarily in Europe, Weingart said.