Abstract
Production modeling is a process that requires analyzing several steps, from reservoir characterization, completion and hydraulic fracturing, up to the optimization in the production system. Traditionally these processes can be analyzed independently with separated specialized tools. However in unconventional reservoirs, as the Vaca Muerta shale, dependency between the stimulation treatment and the well productivity is critical. This work proposes a workflow to evaluate the joint impact of hydraulic fractures with the static and dynamic characterization of the reservoir.
The available static information (geophysics, petrophysics, geomechanics and natural fracture interpretation) is integrated to build a geological model. Then, hydraulic fracturing is simulated numerically using the Unconventional Fracture Model (UFM). The model takes into account the interaction between the existing natural fractures and the created hydraulic fractures during the stimulation treatment. The resulting geometry of the hydraulic fractures is gridded in an unstructured manner. The model reproduces explicitly the volume and permeability with the appropriate distribution along each branch of hydraulic fractures according to the executed completion. Dynamic simulation can be run to perform a history match of the available production data. Hydraulic fracture geometry, driven by geomechanics and natural fractures, is a key component of the process and might be reviewed if no production match can be achieved making the overall workflow iterative. Additionally, automation through assisted history matching is proposed to investigate different possible solution and reduce the timeframe of the study.
Once calibrated with production, the model allows several applications. The different possible solutions considered by the assisted history match process permit the evaluation of the uncertainty of final recovery when forecasting production. Sensitivity analysis over a given hydraulic fracture geometry shows the major role of the matrix saturation and conductivity degradation over the final recovery. Completion can be optimized by considering different scenarios and showing the direct correlation between generated propped surface and well productivity. Different fracture designs can be investigated to increase the propped surface highlighting the importance, not only of the proppant volume, but also of the proppant transport capability of the fracturing fluids to be used.
