Multi-Disciplinary Approach for a Landing Point Criteria in Vaca Muerta Formation

Noguera, Ivan Lanusse (YPF) | Fantin, Manuel (Chevron) | Crespo, Pablo A. (Chevron) | Crousse, Luisa (Chevron) | Reijenstein, Hernan (Chevron) | Varela, Raul (YPF) | Bonelli, Andres (Chevron) | Morales, Fidel (Chevron)

OnePetro 

Abstract

Vaca Muerta Formation is very well known to be one of the most promising shale oil and gas emerging plays in the whole world. Petrophysical properties make this formation very attractive, however geomechanical characterization is critical due to the high pore pressure and stress relationship that tends to generate sub-optimal vertical fracture growth. The substantial thickness (50 to 450 meters) of Vaca Muerta play and lateral/vertical heterogeneity creates a big challenge for even the most specialized people when selecting the best place where to land a horizontal well.

Narambuena field is an exploratory block located in the Northern region of Neuquén Basin within the oil window (API 32° – 42°). A multi-disciplinary team carefully designed a data acquisition plan to optimize the value of information and achieve the best landing point decision. In order to delineate the play in this block, 3 vertical wells were drilled and completed. Decisions were made using full suites of logs for petrophysical and geomechanical evaluations, rock characterization (from cuttings, sidewall cores and core), fluid characterization, frac height analysis and production logging to identify the best performing zones. In order to evaluate horizontal well production performance for future development scenarios, a horizontal well was drilled and completed. An additional vertical well was executed in a lower maturity edge of the block to better characterize the size of the opportunity. This document describes the data acquisition plan and the decision process to successfully execute the delineation plan of this field.

Introduction

For unconventional plays the landing point definition of a horizontal well is critical to be taken by a subsurface team in order to improve the ultimate recovery factor of the well. Defining the right position depends on both the reservoir properties behind the wellbore and the frac efficiency of the stimulated zone.

The focus of this work has been the characterization of Vaca Muerta Formation as a shale reservoir in order to define the proper landing interval of the first horizontal well in Narambuena area. This early Tithonian to early Valanginian marine succession of siliciclastic to calcareous mudstones, first defined by Weaver (1931) as Vaca Muerta Formation, is the main source rock of the Neuquen Basin, which in the last 7 years has become a main target for the exploration and delineation of shale gas and oil.