Abstract

The factory-mode multitarget development of Vaca Muerta Formation requires both, precision targeting and geosteering within the optimum layers. An accurate geological, petrophysical, mineralogical and geomechanical model is thus mandatory to achieve these objectives. A stochastic geocellular model was built for Vaca Muerta in a limited area of Lindero Atravesado field combining geophysical and geological data. This model is currently being used to define landing points, well trajectories, and design hydraulic fractures.

Introduction

The exploration and development of conventional reservoirs started in the late 60’s in Lindero Atravesado field, located in the central part of Neuquén Basin, Argentina, with the first wells drilled to Quintuco and Sierras Blancas Formations (Figure 1). Lately, in 2000, the first exploratory well targeting Grupo Cuyo tight gas sands was drilled and fractured in the eastern sector of the field (Martínez et al., 2005) with encouraging results that led to the development of these unconventional reservoirs. Up to the present, more than 250 wells have been drilled in the field.

Most of the drilled wells in the field are deeper than Vaca Muerta Formation and have some log information that enabled a first evaluation of this formation as an unconventional reservoir. In 2012, two vertical exploratory wells were drilled to get information to characterize Vaca Muerta Formation as a shale oil reservoir. Both wells were logged with a complete set of tools and cored in some intervals of the formation. These wells were hydraulically fractured, and the fractures were monitored through wellbore microseismic. A detailed reservoir characterization of the formation was carried out using these data as input to an integrated workflow based on the simultaneous inversion of a 3D seismic dataset.

In 2018 the first two horizontal wells were drilled in the northern part of the field, an area where the total organic carbon content was very promising (Figure 1). Both wells targeted the lower section of Vaca Muerta Formation ("the kitchen"), at a depth where the relative content of organic matter, carbonates and silica favored both oil storage and successful hydraulic fracturing. These first two horizontal wells had initial peak productions over 1500 barrels/day; consequently, a "factory-mode" development program started in the block in 2019.

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