Unlocking the True Potential of the Vaca Muerta Shale via an Integrated Completion Optimization Approach
Authors: Hryb D. , Archimio A , Badessich M. , Ejofodomi E. , Diaz A. , Cavazzoli G. , Zalazar F. , Lagarrigue E. , Pichon S. 
Published: October 2014

This paper presents an operator's approach to optimize future well performance by fully integrating all the data captured in the Vaca Muerta shale. Based upon insight from the study, the operator needed to make more informed asset management decisions, understand the interaction between the shale and the hydraulic fracture network, and improve economics. Data were captured from several wells, both vertical and horizontal. The data incorporated into the study included fieldwide seismic data, as well as mineralogical, geomechanical, well plan, drilling, completion, microseismic monitoring, and production data from the wells.

The project comprised one case history involving the hydraulic fracture stimulation treatment of a cluster of horizontal wells. Microseismic hydraulic fracture monitoring (HFM) was utilized to "track" the development of the hydraulic fractures in real time as they propagated throughout the formation. The stimulation activity from the well was monitored from a horizontal array placed in a horizontal lateral drilled parallel to the target well but landed ~ 80 m shallower in the vertical section.

An integrated unconventional-reservoir-specific workflow was utilized to develop and evaluate the completion strategies for the subject well. First, a fieldwide 3D static geologic model was constructed using the aforementioned data to determine the best reservoir and completion qualities of the Vaca Muerta formation. Next, the model was used to develop the completion strategy, including staging, perforation scheme, stimulation design, etc., for the wells. The completion strategy and stimulation design were performed utilizing an automated, rigorous, and efficient multistaging algorithm (completion advisor). This enabled targeting the reservoir section having the best reservoir and completion qualities for the stimulation treatments. The stimulation designs were performed using a state-of-the-art unconventional hydraulic fracture simulator that properly simulates the complex fracture propagation in shale reservoirs, including the explicit interaction of the hydraulic fractures to the pre-existing natural fissures in the formation and performs automatic gridding of the created complex fractures to rigorously model the production response from the tridimensional fracture network.

A comparison between the microseismic fracture geometry to the planned fracture geometry is revealing; it shows that the application of this new technology can identify some of the complications and challenges involved in the process of fracturing a rock, improve the success of stimulation treatments, and identify opportunities to improve operational efficiency.

The calibrated complex hydraulic fracture simulation results were incorporated into a shale-oil, numerical simulator and further calibrated with current production history of the well. The results of the fracture and reservoir models were utilized to understand the fracture propagation mechanism in the Vaca Muerta shale formation.

As a result of the project, the team is now able to run different scenarios and assess the impact that each key parameter has over the well's estimated ultimate recovery. Based on these findings, the operator now has a powerful tool that can be used as the building block for future optimization of the hydraulic fracture design.