ICE 2022


The case study refers to the Chachahuén Sur Field. The development dates to mid-2013, after the exploratory and extension drilling campaign targeted at Rayoso Formation, a succession of early Cretaceous fluvial cycles. These cycles are truncated by the Intersenonian unconformity, which lies between the reservoirs of the Rayoso Formation and the shaly base of the Neuquén Group and works as a regional seal. The main production cycles correspond to cycles 2a, 3a and 1c, being the best properties and the largest areal development, the sandstone of cycle 2. In the present, 395 wells have been drilled. 76 of them are injectors wells and 47 more are expected to be converted. Although injection into the block began at the end of 2014, due to different factors, it has not been possible to inject water according to the required flow rates and stability. As a result of this and because of the global adjustment was insufficient to define specific actions, the project focuses on achieving optimization at well level. Consequently, have a simulation model that responded with that degree of detail was necessary. Besides the large number of wells, this reservoir has different characteristics that make it complex when carrying out the analysis and modeling. The amount of data from the more than 300 wells together with the seismic interpretation allowed the identification of 24 regions with different water-oil-gas contacts. The presence of a gas cap at an intermediate level was also identified. Within the three reservoir cycles, three sedimentary facies were characterized through the analysis of nine core samples in conjunction with the geological environment understanding. Given the huge flow of information, the project was worked on in a probabilistic way. The facies model analysis, petrophysical variables sets, their relationships, and the different water-oil-gas contacts were used in the iteration process in the assisted adjustment of the history production. In a first sensitivity analysis, workflows allowed to iterate more than 300 variables between limited ranges, to achieve 67 impact variables in the optimization process by objective functions with wells and sandstone cycles vectors. Making use of this methodology, the historical adjustment reached was highly satisfactory and allowed to generate forecasts optimizing production according to the available injection.