Abstract

The Aguada Pichana Este block, located in the center part of the Neuquén Basin, is operated by Total since 1994, and the partners are YPF, Wintershall, and Pan American Energy. The block has hundreds of wells targeting conventional fields in the Mulichinco Formation. The production decline of the conventional fields encouraged to start this unconventional project aiming to prove the commerciality of the Vaca Muerta unconventional play.

Total started the activity in the Vaca Muerta play in 2011 by drilling the exploration well AP.xp-1001 with gas shale objective. An organic-rich stratigraphic unit 170 m (558 ft) thick was found and was stimulated by four frac stages.

A full data set acquisition for unconventional play characterization was adapted for each phase of the de-risking of the Vaca Muerta play: exploration, appraisal, and pilot. The acquisition program consisted of cores, image log, Litho Scanner, advanced cutting characterization, diagnostic fracture injection test (DFIT), microseismic, pressure volume temperature (PVT), production logging tool (PLT), tracers, and real-time production data.

The appraisal phase was necessary to prove the commerciality of the play in terms of productivity. During the appraisal, a short horizontal well, AP.e-1002(h), was drilled in 2013 showing encouraging productivity results that triggered the pilot phase.

The pilot (aka pre-development) phase consisted of 12 horizontal wells that targeted two different stratigraphic levels: an organic-rich unit and a naturally-fractured unit with low total organic carbon. Fracture design and lateral drain sensitivities were tested to identify optimum designs in terms of costs and productivity. The pilot wells enabled the realization of a realistic learning curve for drilling and stimulation costs that helped to build a roadmap for future optimizations. A multidisciplinary technical work was required to integrate all the available data.

Total has a big challenge to produce this world-class unconventional play with an industrial factory approach to deliver the project with competitive costs, time, and productivity.