Microseismicity as a Surveillance Tool for Hydraulic Fracturing in Vaca Muerta Formation—Loma Jarillosa and Puesto Silva Blocks
Jose Gildardo Osorio Gallego
The geomechanics performance of hydraulic fractures in shales is the result of the interplay of several factors such as in-situ stresses, stress anisotropy, pore pressure distribution, rock mechanical properties, rock strength variations, rock brittleness, attributes of shale weakness planes, natural fracture systems, faults, wellbore orientation and initial failure type, among others.
For optimum hydraulic fracturing design, it is imperative to understand the effects of these factors, and their interaction, on the geomechanics performance of the hydraulic fracture (orientation, extension, complexity, temporal growth, etc.). To achieve this objective, the implementation of appropriate surveillance resources is a critical issue. Microseismic monitoring (also known as passive seismic) can be used as a surveillance tool for understanding the complex geomechanics performance of hydraulic fracturing in shales.
This presentation is focused on how microseismicity is being applied as a surveillance tool for hydraulic fracturing in Vaca Muerta formation of Loma Jarillosa Este and Puesto Silva Oeste blocks operated by PLUSPETROL. Basically, the discussion comprises two parts. First, design and fundamental applications of microseismic monitoring are addressed: criteria for set-up, down hole geophone deployment, events development, fracture mapping, estimated stimulated volumes, fracture complexity, maximum stress orientation and time dependent behavior.
Secondly, following a more proactive and innovative standpoint than in the first part, a discussion of potential “unconventional” microseismic applications for this type of “unconventional” reservoirs is brought up: Can microseismic events from hydraulic fracturing reveal shear wave polarization as to provide actively open fractured zones or trends of higher transmissibility in shales? To what extent can microseismicity disclose the contribution of reactivation of favorably oriented shale weakness planes to increasing fracture complexity? How can microseismicity contribute to optimize stress shadow effects on multi-stage frac growth and design? How can microseismicity add value to geomechanics modeling to determine dominant failure modes? At what point can synthetic microseismic modeling replace actual microseismicity surveillance?
AAPG Search and Discovery Article #90165©AAPG 2012 GEOSCIENCE TECHNOLOGY WORKSHOP, 2-4 December 2012, Buenos Aires, Argentina