New information of formation pressure, groundwater physicochemical and environmental isotopes, allowed to carry out hypothesis on the origin and movement of formation water associated to hydrocarbons in Foothill and central part of the Llanos Orientales basin. In Piedemonte, overpressured individual hydraulic systems are suggested, associated to each structural style; founding a slightly subpressured system to the south of Cupiagua. The formation water origin in not clear, founding cognate waters with low salinities, waters with isotopic impoverishment and high salinities, and waters with deviations in the isotopic trajectories, that suggest action of mixture processes and/or interaction rock-fluid. It has been established a SW flow, with a W-SW anomaly (Cusiana), which is favoured by permeable channels originated by juxtaposition of permeable lythologies. In Llanos, slightly overpressured hydraulic systems are suggested (less than in Piedemonte), with subpressured zones for field parallel and adjacent to the deformation front. Isotopic analysis suggests the action of mixture processes and/or interaction fluid-rock. Pressure and physicochemical anomalies, suggest mixture of fluid in ascending form, with plumes parallel and adjacent to the deformation front. The flow is N-NW from SE, towards subpressured zones in the basin.