A fluid structure interaction model for hydraulic fracture simulation on Vaca Muerta Argentina shale formation
Alderete, Ignacio D.
Sosa Massaro, Agustín
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"Vaca Muerta Formation in Neuquén Basin, Argentina, is one of the great worldwide promises given its potential as a non-conventional reservoir. Because of the intrinsic heterogeneity and low permeability, hydraulic fracturing is a required operation to stimulate the reservoir for better production. Simulation becomes a desirable tool to make fractures more efficient and get predictable outcomes. For this purpose, a 3D finite element analysis is performed using ADINA software to model reservoir response during the hydraulic fracturing process. This iterative, fully coupled model uses fluid structure interaction (FSI), porous elastic media and stratified materials with transversely isotropic (TI) properties. The allowed fracture distribution is proposed beforehand. A cohesive model is added via non linear springs placed along the fracture proposed path. Material models are calibrated using data from well logs and microseismics taken from one well located in the field. All the information obtained from that well is then filtered for a particular region of interest in depth, determined by the mechanical properties observed. Regarding the calculation procedure, as initial condition for the stimulated reservoir volume (SRV) the stress strain state measured in the field is adopted. Then hydraulic fracture process is simulated pumping fluid through punched holes and then fracture opening is analyzed, based on nodes displacement along the proposed path, to characterize fracture's opening and extension. The resulting state of stress developed after the fracture is updated at every calculation step. Key information such as resulting pore pressure and effective stresses can be easily computed along the fracturing process. Once obtained results are compared to analytical solutions and experimental data obtained from fractures performed in similar soil conditions with good agreement. The developed model can tackle a variety of reservoir volumes, considering stratification, geomechanical properties, fracture fluid, fracture paths and the initial state of stress. Natural cracks can be added in a rather simple fashion by adding fractures to the proposed distribution with adequate fracture strengths."