One of the greatest challenges facing the development of unconventional shale resource systems by drilling horizontal wells in factory mode is the definition of the optimal spacing between wells and the appropriate stimulation design that allow maximizing the volume of hydrocarbon recovered while minimizing the cost of field development.
The Vaca Muerta formation in the Neuquén basin of Argentina is considered an unconventional shale play where the economic production of hydrocarbons has been proven through drilling and stimulation of horizontal wells.
To quantify the vertical and horizontal interferences between horizontal wells targeting different landing zones and estimating their effective drainage height, production allocation by geochemistry, chemical tracers, pressure interference analysis, and well performance techniques were integrated into several well pads in the oil and gas window.
Since the ‘80s, geochemical approaches have been used to solve reservoir and production problems in the oil and gas industry (Larter et al. 1994, Larter and Aplin 1995). These applications are known as reservoir and production geochemistry (allocation) and are based on the recognition of significant compositional differences between the fluids corresponding to each of the producing layers (vertical heterogeneities) or in different areas of the reservoir (lateral heterogeneities). Case studies with these applications have been documented in the main productive basins of the world and the geochemical allocation methodology has been successfully applied locally in Argentina in the Chihuido de la Sierra Negra – Lomitas, Señal Cerro Bayo and Auca Mahuida Volcano fields in the Neuquén basin (Labayén et al. 2004 and 2005) and Manantiales Behr, Cañadón La Escondida, Cañadón Perdido, Central Zone and Los Perales fields in San Jorge Gulf basin (Fasola et al. 2005 and 2008). However, for unconventional shale reservoir plays, there are precedents published only in the United States (McCaffrey et al. 2011 and 2016; Liu et al. 2017; Jweda et al. 2017; Kornacki et al. 2017, among others) and just one publication for the Vaca Muerta formation (Fasola et al. 2022).
