Production allocation by geochemistry is a non-disruptive and low-cost method to assess the mobility of fluids in a reservoir using natural tracers present in oils. The first step of the methodology is identification of representative fluids of geochemical flow units. Those samples, called "end members", are then analyzed by high-resolution gas chromatography (HRGC) to create chromatographic fingerprints diagnostic of those flow units. The fingerprints of the end members are used to calculate the proportion of fluid coming from each end member ("allocation") in the commingled samples. In this study, several production time-series oil samples from three producing horizontal wells in intervals C, Oi and Os from the Vaca Muerta Formation were allocated by using a set of oil end members extracted from cores from the section of interest (155 m) spanning the zones called Upper Organic (Os), Middle Organic (Om), Lower Organic (Oi), Regressive (Rg) and Cocina (C). From this study, we concluded that no interference (frac-induced lateral or vertical connectivity) exists among the target zones produced by these wells. Wells targeting the Os and C zones produce predominantly from the landing zone targeted by the well and the well landed in the Oi produced initially from three intervals (Oi, Om and Rg), with variable contributions from each zone. Then over the following a year, the drained rock volume shrank, such that production fluids were derived only from the Oi landing zone. Additionally, an effective drainage height was estimated for each well based on the geochemical production allocation.