Gran Tierra reported in early November 2017, that the Siriri-1 NFW on the PUT-4 Block in the Caguan-Putumayo Basin, hit 65.8m of potential net oil pay across five prospective zones based on logging results. This includes zones primarily in the Villeta Formation - 21.3m of potential oil pay in the 'A' limestone, 19.5m of potential new oil play in the 'B' limestone, 12.2m in the 'M2' limestone, 2.4m of potential oil pay in the 'N' sands and 10.4m in the Upper Pepino Formation. Gran Tierra commenced production testing operations on the well in December 2017 which are still ongoing in early 2018. The well was spud on the western edge of the block on 20 August 2017, with the Pioneer '303' land rig tapped to drill the NFW to a PTD of 3,754m, targeting the 'N' sands and 'A' limestones of the Cretaceous Villeta Formation. By mid-September 2017, Siriri-1 was drilled to a TD of 3,864m. The preceding NFW which also hit oil pay in five zones, Vonu-1, drilled in the PUT-1 block approximately 40km away was brought onstream in the 'A' limestone in July 2017 and is averaging 1,803 boe/d. Costatyaco-19 was the first well tested in the 'A' limestone that was brought onstream in September 2016. Gran Tierra's primary fields in the Caguan-Putumayo Basin are the Costayaco and Mosqueta Fields which produce oil from multiple intervals in the Villeta Formation. Gran Tierra holds 100% WI in the block, after acquiring PetroLatina (which held 30% WI) in August 2016.
Colombia, PUT 4