Two horizontal wells were completed in Vaca Muerta Formation, Neuquén Basin, Argentina in June 2019. The hydraulic fracture treatments were monitored with a large surface microseismic array. The data acquired present several interesting observations about the results of the frac’ing and the interaction of the treatment with a nearby, previously completed producing well. This paper discusses the monitoring and the results achieved.
Lindero Atravesado field is located in the central part of Neuquén Basin, Argentina, in a geological region known as the "engulfment" (see Figure 1). To date more than 250 conventional and unconventional wells have been drilled in the field. Exploration and development activity in this particular field began in the late 60’s, with the first wells targeting Sierras Blancas and Quintuco formations.
The development of conventional oil and gas reservoirs in these formations began in the eastern sector of the field, moving lately towards the western sector. In 2000, the first deep well to Lajas and Punta Rosada tight gas sands was drilled and fractured in the eastern sector (Martínez et al., 2005). The encouraging results from this well led to the development of these unconventional reservoirs over the period of 2012 to 2018.
In 2012 the first two vertical exploratory wells were drilled to test the Vaca Muerta Formation as an unconventional shale oil reservoir. Logging, coring and microseismic monitoring of the hydraulic fracturing were done in both wells. A detailed reservoir characterization of the formation was carried out with these data as input to an integrated workflow centered on the simultaneous inversion of a 3D seismic dataset.
The results of the initial vertical wells and the detailed reservoir study led to the drilling of two horizontal wells in 2018. The wells were placed in the northern part of the field where the total organic carbon content and porosity seemed to be the most promising. Both wells were targeted to the lower part of Vaca Muerta Formation, at a depth where the proportion of organic matter, carbonates and silica favored both oil storage and successful hydraulic fracturing, informally known as "the kitchen".