Climb up the ledge move to the next area patrolled by 4 soldiers. Take out the 1^st from above. Dive in the water. Wait till the 2 soldiers split-up and then pull one in the water. Use empty bottle to distract the remaining 2 soldiers and take them out. Move forward and start climbing the hill. You’ll feel tremors after a while. Keep climbing; you will see a Trinity Chopper patrolling in the sky. After you climb up the hill a new base camp will be discovered. Rourke will call you in a while, after which you’ll enter Porvenir Oil Fields.

After entering Porvenir Oil Fields you’ll be in an area with 5 soldiers (2 of them wearing thermal vision goggles). Wait in the bushes until the soldier with thermal vision moves ahead (investigating a sound). Take out the 2 guards behind him and then quickly takeout the soldier with thermal vision. After taking him out take the path on the right and circle around to come behind the 2 remaining soldiers. Take them out separately or together, it’s your choice. 

Then enter through the crack in the hut’s wall to the next area, guarded by 8 guards. After taking them out, climb up the ledge on the left side of the area, from where the Oil refinery will be visible. At this point Jonah will call Lara. Move forwards and rappel down into the abandoned building. Jaguar’s Fear skill will unlock now. Move out the building and climb up the tree to enter the next area. You’ll be able to test the Jaguar’s Fear skill here. Push through the Trinity forces in this area to reach the gate on the left side. Once you exit this area you’ll get a call from Rourke. You are just outside the refinery now.